diff options
| author | Tom Sepez <tsepez@chromium.org> | 2015-02-23 15:59:57 -0800 |
|---|---|---|
| committer | Tom Sepez <tsepez@chromium.org> | 2015-02-23 15:59:57 -0800 |
| commit | ef1e85caf492e1b9bf9803647d3c5db1abea77c7 (patch) | |
| tree | 862726a78c398a617968e4dfde2ef105b52acf77 /samples/fx_lpng/lpng_v163/fx_pngrtran.c | |
| parent | 28ddd48bfd84c55cc51d0b16fa533c51affdeb5b (diff) | |
| download | pdfium-ef1e85caf492e1b9bf9803647d3c5db1abea77c7.tar.xz | |
Backport PNG output format to origin/master branch.
The pdfium library itself does not support the format, but the test utility
can convert to this output format.
GN build can't be tested standalone, so push this out to the next CL.
R=jam@chromium.org
Review URL: https://codereview.chromium.org/950113002
Diffstat (limited to 'samples/fx_lpng/lpng_v163/fx_pngrtran.c')
| -rw-r--r-- | samples/fx_lpng/lpng_v163/fx_pngrtran.c | 5102 |
1 files changed, 5102 insertions, 0 deletions
diff --git a/samples/fx_lpng/lpng_v163/fx_pngrtran.c b/samples/fx_lpng/lpng_v163/fx_pngrtran.c new file mode 100644 index 0000000000..a81034cdf1 --- /dev/null +++ b/samples/fx_lpng/lpng_v163/fx_pngrtran.c @@ -0,0 +1,5102 @@ +/* pngrtran.c - transforms the data in a row for PNG readers
+ *
+ * Last changed in libpng 1.6.2 [April 25, 2013]
+ * Copyright (c) 1998-2013 Glenn Randers-Pehrson
+ * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
+ * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ *
+ * This code is released under the libpng license.
+ * For conditions of distribution and use, see the disclaimer
+ * and license in png.h
+ *
+ * This file contains functions optionally called by an application
+ * in order to tell libpng how to handle data when reading a PNG.
+ * Transformations that are used in both reading and writing are
+ * in pngtrans.c.
+ */
+
+#include "pngpriv.h"
+
+#ifdef PNG_READ_SUPPORTED
+
+/* Set the action on getting a CRC error for an ancillary or critical chunk. */
+void PNGAPI
+png_set_crc_action(png_structrp png_ptr, int crit_action, int ancil_action)
+{
+ png_debug(1, "in png_set_crc_action");
+
+ if (png_ptr == NULL)
+ return;
+
+ /* Tell libpng how we react to CRC errors in critical chunks */
+ switch (crit_action)
+ {
+ case PNG_CRC_NO_CHANGE: /* Leave setting as is */
+ break;
+
+ case PNG_CRC_WARN_USE: /* Warn/use data */
+ png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK;
+ png_ptr->flags |= PNG_FLAG_CRC_CRITICAL_USE;
+ break;
+
+ case PNG_CRC_QUIET_USE: /* Quiet/use data */
+ png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK;
+ png_ptr->flags |= PNG_FLAG_CRC_CRITICAL_USE |
+ PNG_FLAG_CRC_CRITICAL_IGNORE;
+ break;
+
+ case PNG_CRC_WARN_DISCARD: /* Not a valid action for critical data */
+ png_warning(png_ptr,
+ "Can't discard critical data on CRC error");
+ case PNG_CRC_ERROR_QUIT: /* Error/quit */
+
+ case PNG_CRC_DEFAULT:
+ default:
+ png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK;
+ break;
+ }
+
+ /* Tell libpng how we react to CRC errors in ancillary chunks */
+ switch (ancil_action)
+ {
+ case PNG_CRC_NO_CHANGE: /* Leave setting as is */
+ break;
+
+ case PNG_CRC_WARN_USE: /* Warn/use data */
+ png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
+ png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_USE;
+ break;
+
+ case PNG_CRC_QUIET_USE: /* Quiet/use data */
+ png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
+ png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_USE |
+ PNG_FLAG_CRC_ANCILLARY_NOWARN;
+ break;
+
+ case PNG_CRC_ERROR_QUIT: /* Error/quit */
+ png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
+ png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_NOWARN;
+ break;
+
+ case PNG_CRC_WARN_DISCARD: /* Warn/discard data */
+
+ case PNG_CRC_DEFAULT:
+ default:
+ png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
+ break;
+ }
+}
+
+#ifdef PNG_READ_TRANSFORMS_SUPPORTED
+/* Is it OK to set a transformation now? Only if png_start_read_image or
+ * png_read_update_info have not been called. It is not necessary for the IHDR
+ * to have been read in all cases, the parameter allows for this check too.
+ */
+static int
+png_rtran_ok(png_structrp png_ptr, int need_IHDR)
+{
+ if (png_ptr != NULL)
+ {
+ if (png_ptr->flags & PNG_FLAG_ROW_INIT)
+ png_app_error(png_ptr,
+ "invalid after png_start_read_image or png_read_update_info");
+
+ else if (need_IHDR && (png_ptr->mode & PNG_HAVE_IHDR) == 0)
+ png_app_error(png_ptr, "invalid before the PNG header has been read");
+
+ else
+ {
+ /* Turn on failure to initialize correctly for all transforms. */
+ png_ptr->flags |= PNG_FLAG_DETECT_UNINITIALIZED;
+
+ return 1; /* Ok */
+ }
+ }
+
+ return 0; /* no png_error possible! */
+}
+#endif
+
+#ifdef PNG_READ_BACKGROUND_SUPPORTED
+/* Handle alpha and tRNS via a background color */
+void PNGFAPI
+png_set_background_fixed(png_structrp png_ptr,
+ png_const_color_16p background_color, int background_gamma_code,
+ int need_expand, png_fixed_point background_gamma)
+{
+ png_debug(1, "in png_set_background_fixed");
+
+ if (!png_rtran_ok(png_ptr, 0) || background_color == NULL)
+ return;
+
+ if (background_gamma_code == PNG_BACKGROUND_GAMMA_UNKNOWN)
+ {
+ png_warning(png_ptr, "Application must supply a known background gamma");
+ return;
+ }
+
+ png_ptr->transformations |= PNG_COMPOSE | PNG_STRIP_ALPHA;
+ png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
+ png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
+
+ png_ptr->background = *background_color;
+ png_ptr->background_gamma = background_gamma;
+ png_ptr->background_gamma_type = (png_byte)(background_gamma_code);
+ if (need_expand)
+ png_ptr->transformations |= PNG_BACKGROUND_EXPAND;
+ else
+ png_ptr->transformations &= ~PNG_BACKGROUND_EXPAND;
+}
+
+# ifdef PNG_FLOATING_POINT_SUPPORTED
+void PNGAPI
+png_set_background(png_structrp png_ptr,
+ png_const_color_16p background_color, int background_gamma_code,
+ int need_expand, double background_gamma)
+{
+ png_set_background_fixed(png_ptr, background_color, background_gamma_code,
+ need_expand, png_fixed(png_ptr, background_gamma, "png_set_background"));
+}
+# endif /* FLOATING_POINT */
+#endif /* READ_BACKGROUND */
+
+/* Scale 16-bit depth files to 8-bit depth. If both of these are set then the
+ * one that pngrtran does first (scale) happens. This is necessary to allow the
+ * TRANSFORM and API behavior to be somewhat consistent, and it's simpler.
+ */
+#ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
+void PNGAPI
+png_set_scale_16(png_structrp png_ptr)
+{
+ png_debug(1, "in png_set_scale_16");
+
+ if (!png_rtran_ok(png_ptr, 0))
+ return;
+
+ png_ptr->transformations |= PNG_SCALE_16_TO_8;
+}
+#endif
+
+#ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
+/* Chop 16-bit depth files to 8-bit depth */
+void PNGAPI
+png_set_strip_16(png_structrp png_ptr)
+{
+ png_debug(1, "in png_set_strip_16");
+
+ if (!png_rtran_ok(png_ptr, 0))
+ return;
+
+ png_ptr->transformations |= PNG_16_TO_8;
+}
+#endif
+
+#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
+void PNGAPI
+png_set_strip_alpha(png_structrp png_ptr)
+{
+ png_debug(1, "in png_set_strip_alpha");
+
+ if (!png_rtran_ok(png_ptr, 0))
+ return;
+
+ png_ptr->transformations |= PNG_STRIP_ALPHA;
+}
+#endif
+
+#if defined(PNG_READ_ALPHA_MODE_SUPPORTED) || defined(PNG_READ_GAMMA_SUPPORTED)
+static png_fixed_point
+translate_gamma_flags(png_structrp png_ptr, png_fixed_point output_gamma,
+ int is_screen)
+{
+ /* Check for flag values. The main reason for having the old Mac value as a
+ * flag is that it is pretty near impossible to work out what the correct
+ * value is from Apple documentation - a working Mac system is needed to
+ * discover the value!
+ */
+ if (output_gamma == PNG_DEFAULT_sRGB ||
+ output_gamma == PNG_FP_1 / PNG_DEFAULT_sRGB)
+ {
+ /* If there is no sRGB support this just sets the gamma to the standard
+ * sRGB value. (This is a side effect of using this function!)
+ */
+# ifdef PNG_READ_sRGB_SUPPORTED
+ png_ptr->flags |= PNG_FLAG_ASSUME_sRGB;
+# else
+ PNG_UNUSED(png_ptr)
+# endif
+ if (is_screen)
+ output_gamma = PNG_GAMMA_sRGB;
+ else
+ output_gamma = PNG_GAMMA_sRGB_INVERSE;
+ }
+
+ else if (output_gamma == PNG_GAMMA_MAC_18 ||
+ output_gamma == PNG_FP_1 / PNG_GAMMA_MAC_18)
+ {
+ if (is_screen)
+ output_gamma = PNG_GAMMA_MAC_OLD;
+ else
+ output_gamma = PNG_GAMMA_MAC_INVERSE;
+ }
+
+ return output_gamma;
+}
+
+# ifdef PNG_FLOATING_POINT_SUPPORTED
+static png_fixed_point
+convert_gamma_value(png_structrp png_ptr, double output_gamma)
+{
+ /* The following silently ignores cases where fixed point (times 100,000)
+ * gamma values are passed to the floating point API. This is safe and it
+ * means the fixed point constants work just fine with the floating point
+ * API. The alternative would just lead to undetected errors and spurious
+ * bug reports. Negative values fail inside the _fixed API unless they
+ * correspond to the flag values.
+ */
+ if (output_gamma > 0 && output_gamma < 128)
+ output_gamma *= PNG_FP_1;
+
+ /* This preserves -1 and -2 exactly: */
+ output_gamma = floor(output_gamma + .5);
+
+ if (output_gamma > PNG_FP_MAX || output_gamma < PNG_FP_MIN)
+ png_fixed_error(png_ptr, "gamma value");
+
+ return (png_fixed_point)output_gamma;
+}
+# endif
+#endif /* READ_ALPHA_MODE || READ_GAMMA */
+
+#ifdef PNG_READ_ALPHA_MODE_SUPPORTED
+void PNGFAPI
+png_set_alpha_mode_fixed(png_structrp png_ptr, int mode,
+ png_fixed_point output_gamma)
+{
+ int compose = 0;
+ png_fixed_point file_gamma;
+
+ png_debug(1, "in png_set_alpha_mode");
+
+ if (!png_rtran_ok(png_ptr, 0))
+ return;
+
+ output_gamma = translate_gamma_flags(png_ptr, output_gamma, 1/*screen*/);
+
+ /* Validate the value to ensure it is in a reasonable range. The value
+ * is expected to be 1 or greater, but this range test allows for some
+ * viewing correction values. The intent is to weed out users of this API
+ * who use the inverse of the gamma value accidentally! Since some of these
+ * values are reasonable this may have to be changed.
+ */
+ if (output_gamma < 70000 || output_gamma > 300000)
+ png_error(png_ptr, "output gamma out of expected range");
+
+ /* The default file gamma is the inverse of the output gamma; the output
+ * gamma may be changed below so get the file value first:
+ */
+ file_gamma = png_reciprocal(output_gamma);
+
+ /* There are really 8 possibilities here, composed of any combination
+ * of:
+ *
+ * premultiply the color channels
+ * do not encode non-opaque pixels
+ * encode the alpha as well as the color channels
+ *
+ * The differences disappear if the input/output ('screen') gamma is 1.0,
+ * because then the encoding is a no-op and there is only the choice of
+ * premultiplying the color channels or not.
+ *
+ * png_set_alpha_mode and png_set_background interact because both use
+ * png_compose to do the work. Calling both is only useful when
+ * png_set_alpha_mode is used to set the default mode - PNG_ALPHA_PNG - along
+ * with a default gamma value. Otherwise PNG_COMPOSE must not be set.
+ */
+ switch (mode)
+ {
+ case PNG_ALPHA_PNG: /* default: png standard */
+ /* No compose, but it may be set by png_set_background! */
+ png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
+ png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
+ break;
+
+ case PNG_ALPHA_ASSOCIATED: /* color channels premultiplied */
+ compose = 1;
+ png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
+ png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
+ /* The output is linear: */
+ output_gamma = PNG_FP_1;
+ break;
+
+ case PNG_ALPHA_OPTIMIZED: /* associated, non-opaque pixels linear */
+ compose = 1;
+ png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
+ png_ptr->flags |= PNG_FLAG_OPTIMIZE_ALPHA;
+ /* output_gamma records the encoding of opaque pixels! */
+ break;
+
+ case PNG_ALPHA_BROKEN: /* associated, non-linear, alpha encoded */
+ compose = 1;
+ png_ptr->transformations |= PNG_ENCODE_ALPHA;
+ png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
+ break;
+
+ default:
+ png_error(png_ptr, "invalid alpha mode");
+ }
+
+ /* Only set the default gamma if the file gamma has not been set (this has
+ * the side effect that the gamma in a second call to png_set_alpha_mode will
+ * be ignored.)
+ */
+ if (png_ptr->colorspace.gamma == 0)
+ {
+ png_ptr->colorspace.gamma = file_gamma;
+ png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
+ }
+
+ /* But always set the output gamma: */
+ png_ptr->screen_gamma = output_gamma;
+
+ /* Finally, if pre-multiplying, set the background fields to achieve the
+ * desired result.
+ */
+ if (compose)
+ {
+ /* And obtain alpha pre-multiplication by composing on black: */
+ memset(&png_ptr->background, 0, (sizeof png_ptr->background));
+ png_ptr->background_gamma = png_ptr->colorspace.gamma; /* just in case */
+ png_ptr->background_gamma_type = PNG_BACKGROUND_GAMMA_FILE;
+ png_ptr->transformations &= ~PNG_BACKGROUND_EXPAND;
+
+ if (png_ptr->transformations & PNG_COMPOSE)
+ png_error(png_ptr,
+ "conflicting calls to set alpha mode and background");
+
+ png_ptr->transformations |= PNG_COMPOSE;
+ }
+}
+
+# ifdef PNG_FLOATING_POINT_SUPPORTED
+void PNGAPI
+png_set_alpha_mode(png_structrp png_ptr, int mode, double output_gamma)
+{
+ png_set_alpha_mode_fixed(png_ptr, mode, convert_gamma_value(png_ptr,
+ output_gamma));
+}
+# endif
+#endif
+
+#ifdef PNG_READ_QUANTIZE_SUPPORTED
+/* Dither file to 8-bit. Supply a palette, the current number
+ * of elements in the palette, the maximum number of elements
+ * allowed, and a histogram if possible. If the current number
+ * of colors is greater then the maximum number, the palette will be
+ * modified to fit in the maximum number. "full_quantize" indicates
+ * whether we need a quantizing cube set up for RGB images, or if we
+ * simply are reducing the number of colors in a paletted image.
+ */
+
+typedef struct png_dsort_struct
+{
+ struct png_dsort_struct * next;
+ png_byte left;
+ png_byte right;
+} png_dsort;
+typedef png_dsort * png_dsortp;
+typedef png_dsort * * png_dsortpp;
+
+void PNGAPI
+png_set_quantize(png_structrp png_ptr, png_colorp palette,
+ int num_palette, int maximum_colors, png_const_uint_16p histogram,
+ int full_quantize)
+{
+ png_debug(1, "in png_set_quantize");
+
+ if (!png_rtran_ok(png_ptr, 0))
+ return;
+
+ png_ptr->transformations |= PNG_QUANTIZE;
+
+ if (!full_quantize)
+ {
+ int i;
+
+ png_ptr->quantize_index = (png_bytep)png_malloc(png_ptr,
+ (png_uint_32)(num_palette * (sizeof (png_byte))));
+ for (i = 0; i < num_palette; i++)
+ png_ptr->quantize_index[i] = (png_byte)i;
+ }
+
+ if (num_palette > maximum_colors)
+ {
+ if (histogram != NULL)
+ {
+ /* This is easy enough, just throw out the least used colors.
+ * Perhaps not the best solution, but good enough.
+ */
+
+ int i;
+
+ /* Initialize an array to sort colors */
+ png_ptr->quantize_sort = (png_bytep)png_malloc(png_ptr,
+ (png_uint_32)(num_palette * (sizeof (png_byte))));
+
+ /* Initialize the quantize_sort array */
+ for (i = 0; i < num_palette; i++)
+ png_ptr->quantize_sort[i] = (png_byte)i;
+
+ /* Find the least used palette entries by starting a
+ * bubble sort, and running it until we have sorted
+ * out enough colors. Note that we don't care about
+ * sorting all the colors, just finding which are
+ * least used.
+ */
+
+ for (i = num_palette - 1; i >= maximum_colors; i--)
+ {
+ int done; /* To stop early if the list is pre-sorted */
+ int j;
+
+ done = 1;
+ for (j = 0; j < i; j++)
+ {
+ if (histogram[png_ptr->quantize_sort[j]]
+ < histogram[png_ptr->quantize_sort[j + 1]])
+ {
+ png_byte t;
+
+ t = png_ptr->quantize_sort[j];
+ png_ptr->quantize_sort[j] = png_ptr->quantize_sort[j + 1];
+ png_ptr->quantize_sort[j + 1] = t;
+ done = 0;
+ }
+ }
+
+ if (done)
+ break;
+ }
+
+ /* Swap the palette around, and set up a table, if necessary */
+ if (full_quantize)
+ {
+ int j = num_palette;
+
+ /* Put all the useful colors within the max, but don't
+ * move the others.
+ */
+ for (i = 0; i < maximum_colors; i++)
+ {
+ if ((int)png_ptr->quantize_sort[i] >= maximum_colors)
+ {
+ do
+ j--;
+ while ((int)png_ptr->quantize_sort[j] >= maximum_colors);
+
+ palette[i] = palette[j];
+ }
+ }
+ }
+ else
+ {
+ int j = num_palette;
+
+ /* Move all the used colors inside the max limit, and
+ * develop a translation table.
+ */
+ for (i = 0; i < maximum_colors; i++)
+ {
+ /* Only move the colors we need to */
+ if ((int)png_ptr->quantize_sort[i] >= maximum_colors)
+ {
+ png_color tmp_color;
+
+ do
+ j--;
+ while ((int)png_ptr->quantize_sort[j] >= maximum_colors);
+
+ tmp_color = palette[j];
+ palette[j] = palette[i];
+ palette[i] = tmp_color;
+ /* Indicate where the color went */
+ png_ptr->quantize_index[j] = (png_byte)i;
+ png_ptr->quantize_index[i] = (png_byte)j;
+ }
+ }
+
+ /* Find closest color for those colors we are not using */
+ for (i = 0; i < num_palette; i++)
+ {
+ if ((int)png_ptr->quantize_index[i] >= maximum_colors)
+ {
+ int min_d, k, min_k, d_index;
+
+ /* Find the closest color to one we threw out */
+ d_index = png_ptr->quantize_index[i];
+ min_d = PNG_COLOR_DIST(palette[d_index], palette[0]);
+ for (k = 1, min_k = 0; k < maximum_colors; k++)
+ {
+ int d;
+
+ d = PNG_COLOR_DIST(palette[d_index], palette[k]);
+
+ if (d < min_d)
+ {
+ min_d = d;
+ min_k = k;
+ }
+ }
+ /* Point to closest color */
+ png_ptr->quantize_index[i] = (png_byte)min_k;
+ }
+ }
+ }
+ png_free(png_ptr, png_ptr->quantize_sort);
+ png_ptr->quantize_sort = NULL;
+ }
+ else
+ {
+ /* This is much harder to do simply (and quickly). Perhaps
+ * we need to go through a median cut routine, but those
+ * don't always behave themselves with only a few colors
+ * as input. So we will just find the closest two colors,
+ * and throw out one of them (chosen somewhat randomly).
+ * [We don't understand this at all, so if someone wants to
+ * work on improving it, be our guest - AED, GRP]
+ */
+ int i;
+ int max_d;
+ int num_new_palette;
+ png_dsortp t;
+ png_dsortpp hash;
+
+ t = NULL;
+
+ /* Initialize palette index arrays */
+ png_ptr->index_to_palette = (png_bytep)png_malloc(png_ptr,
+ (png_uint_32)(num_palette * (sizeof (png_byte))));
+ png_ptr->palette_to_index = (png_bytep)png_malloc(png_ptr,
+ (png_uint_32)(num_palette * (sizeof (png_byte))));
+
+ /* Initialize the sort array */
+ for (i = 0; i < num_palette; i++)
+ {
+ png_ptr->index_to_palette[i] = (png_byte)i;
+ png_ptr->palette_to_index[i] = (png_byte)i;
+ }
+
+ hash = (png_dsortpp)png_calloc(png_ptr, (png_uint_32)(769 *
+ (sizeof (png_dsortp))));
+
+ num_new_palette = num_palette;
+
+ /* Initial wild guess at how far apart the farthest pixel
+ * pair we will be eliminating will be. Larger
+ * numbers mean more areas will be allocated, Smaller
+ * numbers run the risk of not saving enough data, and
+ * having to do this all over again.
+ *
+ * I have not done extensive checking on this number.
+ */
+ max_d = 96;
+
+ while (num_new_palette > maximum_colors)
+ {
+ for (i = 0; i < num_new_palette - 1; i++)
+ {
+ int j;
+
+ for (j = i + 1; j < num_new_palette; j++)
+ {
+ int d;
+
+ d = PNG_COLOR_DIST(palette[i], palette[j]);
+
+ if (d <= max_d)
+ {
+
+ t = (png_dsortp)png_malloc_warn(png_ptr,
+ (png_uint_32)(sizeof (png_dsort)));
+
+ if (t == NULL)
+ break;
+
+ t->next = hash[d];
+ t->left = (png_byte)i;
+ t->right = (png_byte)j;
+ hash[d] = t;
+ }
+ }
+ if (t == NULL)
+ break;
+ }
+
+ if (t != NULL)
+ for (i = 0; i <= max_d; i++)
+ {
+ if (hash[i] != NULL)
+ {
+ png_dsortp p;
+
+ for (p = hash[i]; p; p = p->next)
+ {
+ if ((int)png_ptr->index_to_palette[p->left]
+ < num_new_palette &&
+ (int)png_ptr->index_to_palette[p->right]
+ < num_new_palette)
+ {
+ int j, next_j;
+
+ if (num_new_palette & 0x01)
+ {
+ j = p->left;
+ next_j = p->right;
+ }
+ else
+ {
+ j = p->right;
+ next_j = p->left;
+ }
+
+ num_new_palette--;
+ palette[png_ptr->index_to_palette[j]]
+ = palette[num_new_palette];
+ if (!full_quantize)
+ {
+ int k;
+
+ for (k = 0; k < num_palette; k++)
+ {
+ if (png_ptr->quantize_index[k] ==
+ png_ptr->index_to_palette[j])
+ png_ptr->quantize_index[k] =
+ png_ptr->index_to_palette[next_j];
+
+ if ((int)png_ptr->quantize_index[k] ==
+ num_new_palette)
+ png_ptr->quantize_index[k] =
+ png_ptr->index_to_palette[j];
+ }
+ }
+
+ png_ptr->index_to_palette[png_ptr->palette_to_index
+ [num_new_palette]] = png_ptr->index_to_palette[j];
+
+ png_ptr->palette_to_index[png_ptr->index_to_palette[j]]
+ = png_ptr->palette_to_index[num_new_palette];
+
+ png_ptr->index_to_palette[j] =
+ (png_byte)num_new_palette;
+
+ png_ptr->palette_to_index[num_new_palette] =
+ (png_byte)j;
+ }
+ if (num_new_palette <= maximum_colors)
+ break;
+ }
+ if (num_new_palette <= maximum_colors)
+ break;
+ }
+ }
+
+ for (i = 0; i < 769; i++)
+ {
+ if (hash[i] != NULL)
+ {
+ png_dsortp p = hash[i];
+ while (p)
+ {
+ t = p->next;
+ png_free(png_ptr, p);
+ p = t;
+ }
+ }
+ hash[i] = 0;
+ }
+ max_d += 96;
+ }
+ png_free(png_ptr, hash);
+ png_free(png_ptr, png_ptr->palette_to_index);
+ png_free(png_ptr, png_ptr->index_to_palette);
+ png_ptr->palette_to_index = NULL;
+ png_ptr->index_to_palette = NULL;
+ }
+ num_palette = maximum_colors;
+ }
+ if (png_ptr->palette == NULL)
+ {
+ png_ptr->palette = palette;
+ }
+ png_ptr->num_palette = (png_uint_16)num_palette;
+
+ if (full_quantize)
+ {
+ int i;
+ png_bytep distance;
+ int total_bits = PNG_QUANTIZE_RED_BITS + PNG_QUANTIZE_GREEN_BITS +
+ PNG_QUANTIZE_BLUE_BITS;
+ int num_red = (1 << PNG_QUANTIZE_RED_BITS);
+ int num_green = (1 << PNG_QUANTIZE_GREEN_BITS);
+ int num_blue = (1 << PNG_QUANTIZE_BLUE_BITS);
+ png_size_t num_entries = ((png_size_t)1 << total_bits);
+
+ png_ptr->palette_lookup = (png_bytep)png_calloc(png_ptr,
+ (png_uint_32)(num_entries * (sizeof (png_byte))));
+
+ distance = (png_bytep)png_malloc(png_ptr, (png_uint_32)(num_entries *
+ (sizeof (png_byte))));
+
+ memset(distance, 0xff, num_entries * (sizeof (png_byte)));
+
+ for (i = 0; i < num_palette; i++)
+ {
+ int ir, ig, ib;
+ int r = (palette[i].red >> (8 - PNG_QUANTIZE_RED_BITS));
+ int g = (palette[i].green >> (8 - PNG_QUANTIZE_GREEN_BITS));
+ int b = (palette[i].blue >> (8 - PNG_QUANTIZE_BLUE_BITS));
+
+ for (ir = 0; ir < num_red; ir++)
+ {
+ /* int dr = abs(ir - r); */
+ int dr = ((ir > r) ? ir - r : r - ir);
+ int index_r = (ir << (PNG_QUANTIZE_BLUE_BITS +
+ PNG_QUANTIZE_GREEN_BITS));
+
+ for (ig = 0; ig < num_green; ig++)
+ {
+ /* int dg = abs(ig - g); */
+ int dg = ((ig > g) ? ig - g : g - ig);
+ int dt = dr + dg;
+ int dm = ((dr > dg) ? dr : dg);
+ int index_g = index_r | (ig << PNG_QUANTIZE_BLUE_BITS);
+
+ for (ib = 0; ib < num_blue; ib++)
+ {
+ int d_index = index_g | ib;
+ /* int db = abs(ib - b); */
+ int db = ((ib > b) ? ib - b : b - ib);
+ int dmax = ((dm > db) ? dm : db);
+ int d = dmax + dt + db;
+
+ if (d < (int)distance[d_index])
+ {
+ distance[d_index] = (png_byte)d;
+ png_ptr->palette_lookup[d_index] = (png_byte)i;
+ }
+ }
+ }
+ }
+ }
+
+ png_free(png_ptr, distance);
+ }
+}
+#endif /* PNG_READ_QUANTIZE_SUPPORTED */
+
+#ifdef PNG_READ_GAMMA_SUPPORTED
+void PNGFAPI
+png_set_gamma_fixed(png_structrp png_ptr, png_fixed_point scrn_gamma,
+ png_fixed_point file_gamma)
+{
+ png_debug(1, "in png_set_gamma_fixed");
+
+ if (!png_rtran_ok(png_ptr, 0))
+ return;
+
+ /* New in libpng-1.5.4 - reserve particular negative values as flags. */
+ scrn_gamma = translate_gamma_flags(png_ptr, scrn_gamma, 1/*screen*/);
+ file_gamma = translate_gamma_flags(png_ptr, file_gamma, 0/*file*/);
+
+ /* Checking the gamma values for being >0 was added in 1.5.4 along with the
+ * premultiplied alpha support; this actually hides an undocumented feature
+ * of the previous implementation which allowed gamma processing to be
+ * disabled in background handling. There is no evidence (so far) that this
+ * was being used; however, png_set_background itself accepted and must still
+ * accept '0' for the gamma value it takes, because it isn't always used.
+ *
+ * Since this is an API change (albeit a very minor one that removes an
+ * undocumented API feature) the following checks were only enabled in
+ * libpng-1.6.0.
+ */
+ if (file_gamma <= 0)
+ png_error(png_ptr, "invalid file gamma in png_set_gamma");
+
+ if (scrn_gamma <= 0)
+ png_error(png_ptr, "invalid screen gamma in png_set_gamma");
+
+ /* Set the gamma values unconditionally - this overrides the value in the PNG
+ * file if a gAMA chunk was present. png_set_alpha_mode provides a
+ * different, easier, way to default the file gamma.
+ */
+ png_ptr->colorspace.gamma = file_gamma;
+ png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
+ png_ptr->screen_gamma = scrn_gamma;
+}
+
+# ifdef PNG_FLOATING_POINT_SUPPORTED
+void PNGAPI
+png_set_gamma(png_structrp png_ptr, double scrn_gamma, double file_gamma)
+{
+ png_set_gamma_fixed(png_ptr, convert_gamma_value(png_ptr, scrn_gamma),
+ convert_gamma_value(png_ptr, file_gamma));
+}
+# endif /* FLOATING_POINT_SUPPORTED */
+#endif /* READ_GAMMA */
+
+#ifdef PNG_READ_EXPAND_SUPPORTED
+/* Expand paletted images to RGB, expand grayscale images of
+ * less than 8-bit depth to 8-bit depth, and expand tRNS chunks
+ * to alpha channels.
+ */
+void PNGAPI
+png_set_expand(png_structrp png_ptr)
+{
+ png_debug(1, "in png_set_expand");
+
+ if (!png_rtran_ok(png_ptr, 0))
+ return;
+
+ png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
+}
+
+/* GRR 19990627: the following three functions currently are identical
+ * to png_set_expand(). However, it is entirely reasonable that someone
+ * might wish to expand an indexed image to RGB but *not* expand a single,
+ * fully transparent palette entry to a full alpha channel--perhaps instead
+ * convert tRNS to the grayscale/RGB format (16-bit RGB value), or replace
+ * the transparent color with a particular RGB value, or drop tRNS entirely.
+ * IOW, a future version of the library may make the transformations flag
+ * a bit more fine-grained, with separate bits for each of these three
+ * functions.
+ *
+ * More to the point, these functions make it obvious what libpng will be
+ * doing, whereas "expand" can (and does) mean any number of things.
+ *
+ * GRP 20060307: In libpng-1.2.9, png_set_gray_1_2_4_to_8() was modified
+ * to expand only the sample depth but not to expand the tRNS to alpha
+ * and its name was changed to png_set_expand_gray_1_2_4_to_8().
+ */
+
+/* Expand paletted images to RGB. */
+void PNGAPI
+png_set_palette_to_rgb(png_structrp png_ptr)
+{
+ png_debug(1, "in png_set_palette_to_rgb");
+
+ if (!png_rtran_ok(png_ptr, 0))
+ return;
+
+ png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
+}
+
+/* Expand grayscale images of less than 8-bit depth to 8 bits. */
+void PNGAPI
+png_set_expand_gray_1_2_4_to_8(png_structrp png_ptr)
+{
+ png_debug(1, "in png_set_expand_gray_1_2_4_to_8");
+
+ if (!png_rtran_ok(png_ptr, 0))
+ return;
+
+ png_ptr->transformations |= PNG_EXPAND;
+}
+
+/* Expand tRNS chunks to alpha channels. */
+void PNGAPI
+png_set_tRNS_to_alpha(png_structrp png_ptr)
+{
+ png_debug(1, "in png_set_tRNS_to_alpha");
+
+ if (!png_rtran_ok(png_ptr, 0))
+ return;
+
+ png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
+}
+#endif /* defined(PNG_READ_EXPAND_SUPPORTED) */
+
+#ifdef PNG_READ_EXPAND_16_SUPPORTED
+/* Expand to 16-bit channels, expand the tRNS chunk too (because otherwise
+ * it may not work correctly.)
+ */
+void PNGAPI
+png_set_expand_16(png_structrp png_ptr)
+{
+ png_debug(1, "in png_set_expand_16");
+
+ if (!png_rtran_ok(png_ptr, 0))
+ return;
+
+ png_ptr->transformations |= (PNG_EXPAND_16 | PNG_EXPAND | PNG_EXPAND_tRNS);
+}
+#endif
+
+#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
+void PNGAPI
+png_set_gray_to_rgb(png_structrp png_ptr)
+{
+ png_debug(1, "in png_set_gray_to_rgb");
+
+ if (!png_rtran_ok(png_ptr, 0))
+ return;
+
+ /* Because rgb must be 8 bits or more: */
+ png_set_expand_gray_1_2_4_to_8(png_ptr);
+ png_ptr->transformations |= PNG_GRAY_TO_RGB;
+}
+#endif
+
+#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
+void PNGFAPI
+png_set_rgb_to_gray_fixed(png_structrp png_ptr, int error_action,
+ png_fixed_point red, png_fixed_point green)
+{
+ png_debug(1, "in png_set_rgb_to_gray");
+
+ /* Need the IHDR here because of the check on color_type below. */
+ /* TODO: fix this */
+ if (!png_rtran_ok(png_ptr, 1))
+ return;
+
+ switch(error_action)
+ {
+ case PNG_ERROR_ACTION_NONE:
+ png_ptr->transformations |= PNG_RGB_TO_GRAY;
+ break;
+
+ case PNG_ERROR_ACTION_WARN:
+ png_ptr->transformations |= PNG_RGB_TO_GRAY_WARN;
+ break;
+
+ case PNG_ERROR_ACTION_ERROR:
+ png_ptr->transformations |= PNG_RGB_TO_GRAY_ERR;
+ break;
+
+ default:
+ png_error(png_ptr, "invalid error action to rgb_to_gray");
+ break;
+ }
+
+ if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
+#ifdef PNG_READ_EXPAND_SUPPORTED
+ png_ptr->transformations |= PNG_EXPAND;
+#else
+ {
+ /* Make this an error in 1.6 because otherwise the application may assume
+ * that it just worked and get a memory overwrite.
+ */
+ png_error(png_ptr,
+ "Cannot do RGB_TO_GRAY without EXPAND_SUPPORTED");
+
+ /* png_ptr->transformations &= ~PNG_RGB_TO_GRAY; */
+ }
+#endif
+ {
+ if (red >= 0 && green >= 0 && red + green <= PNG_FP_1)
+ {
+ png_uint_16 red_int, green_int;
+
+ /* NOTE: this calculation does not round, but this behavior is retained
+ * for consistency, the inaccuracy is very small. The code here always
+ * overwrites the coefficients, regardless of whether they have been
+ * defaulted or set already.
+ */
+ red_int = (png_uint_16)(((png_uint_32)red*32768)/100000);
+ green_int = (png_uint_16)(((png_uint_32)green*32768)/100000);
+
+ png_ptr->rgb_to_gray_red_coeff = red_int;
+ png_ptr->rgb_to_gray_green_coeff = green_int;
+ png_ptr->rgb_to_gray_coefficients_set = 1;
+ }
+
+ else
+ {
+ if (red >= 0 && green >= 0)
+ png_app_warning(png_ptr,
+ "ignoring out of range rgb_to_gray coefficients");
+
+ /* Use the defaults, from the cHRM chunk if set, else the historical
+ * values which are close to the sRGB/HDTV/ITU-Rec 709 values. See
+ * png_do_rgb_to_gray for more discussion of the values. In this case
+ * the coefficients are not marked as 'set' and are not overwritten if
+ * something has already provided a default.
+ */
+ if (png_ptr->rgb_to_gray_red_coeff == 0 &&
+ png_ptr->rgb_to_gray_green_coeff == 0)
+ {
+ png_ptr->rgb_to_gray_red_coeff = 6968;
+ png_ptr->rgb_to_gray_green_coeff = 23434;
+ /* png_ptr->rgb_to_gray_blue_coeff = 2366; */
+ }
+ }
+ }
+}
+
+#ifdef PNG_FLOATING_POINT_SUPPORTED
+/* Convert a RGB image to a grayscale of the same width. This allows us,
+ * for example, to convert a 24 bpp RGB image into an 8 bpp grayscale image.
+ */
+
+void PNGAPI
+png_set_rgb_to_gray(png_structrp png_ptr, int error_action, double red,
+ double green)
+{
+ png_set_rgb_to_gray_fixed(png_ptr, error_action,
+ png_fixed(png_ptr, red, "rgb to gray red coefficient"),
+ png_fixed(png_ptr, green, "rgb to gray green coefficient"));
+}
+#endif /* FLOATING POINT */
+
+#endif /* RGB_TO_GRAY */
+
+#if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
+ defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
+void PNGAPI
+png_set_read_user_transform_fn(png_structrp png_ptr, png_user_transform_ptr
+ read_user_transform_fn)
+{
+ png_debug(1, "in png_set_read_user_transform_fn");
+
+#ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
+ png_ptr->transformations |= PNG_USER_TRANSFORM;
+ png_ptr->read_user_transform_fn = read_user_transform_fn;
+#endif
+}
+#endif
+
+#ifdef PNG_READ_TRANSFORMS_SUPPORTED
+#ifdef PNG_READ_GAMMA_SUPPORTED
+/* In the case of gamma transformations only do transformations on images where
+ * the [file] gamma and screen_gamma are not close reciprocals, otherwise it
+ * slows things down slightly, and also needlessly introduces small errors.
+ */
+static int /* PRIVATE */
+png_gamma_threshold(png_fixed_point screen_gamma, png_fixed_point file_gamma)
+{
+ /* PNG_GAMMA_THRESHOLD is the threshold for performing gamma
+ * correction as a difference of the overall transform from 1.0
+ *
+ * We want to compare the threshold with s*f - 1, if we get
+ * overflow here it is because of wacky gamma values so we
+ * turn on processing anyway.
+ */
+ png_fixed_point gtest;
+ return !png_muldiv(>est, screen_gamma, file_gamma, PNG_FP_1) ||
+ png_gamma_significant(gtest);
+}
+#endif
+
+/* Initialize everything needed for the read. This includes modifying
+ * the palette.
+ */
+
+/*For the moment 'png_init_palette_transformations' and
+ * 'png_init_rgb_transformations' only do some flag canceling optimizations.
+ * The intent is that these two routines should have palette or rgb operations
+ * extracted from 'png_init_read_transformations'.
+ */
+static void /* PRIVATE */
+png_init_palette_transformations(png_structrp png_ptr)
+{
+ /* Called to handle the (input) palette case. In png_do_read_transformations
+ * the first step is to expand the palette if requested, so this code must
+ * take care to only make changes that are invariant with respect to the
+ * palette expansion, or only do them if there is no expansion.
+ *
+ * STRIP_ALPHA has already been handled in the caller (by setting num_trans
+ * to 0.)
+ */
+ int input_has_alpha = 0;
+ int input_has_transparency = 0;
+
+ if (png_ptr->num_trans > 0)
+ {
+ int i;
+
+ /* Ignore if all the entries are opaque (unlikely!) */
+ for (i=0; i<png_ptr->num_trans; ++i)
+ if (png_ptr->trans_alpha[i] == 255)
+ continue;
+ else if (png_ptr->trans_alpha[i] == 0)
+ input_has_transparency = 1;
+ else
+ input_has_alpha = 1;
+ }
+
+ /* If no alpha we can optimize. */
+ if (!input_has_alpha)
+ {
+ /* Any alpha means background and associative alpha processing is
+ * required, however if the alpha is 0 or 1 throughout OPTIIMIZE_ALPHA
+ * and ENCODE_ALPHA are irrelevant.
+ */
+ png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
+ png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
+
+ if (!input_has_transparency)
+ png_ptr->transformations &= ~(PNG_COMPOSE | PNG_BACKGROUND_EXPAND);
+ }
+
+#if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
+ /* png_set_background handling - deals with the complexity of whether the
+ * background color is in the file format or the screen format in the case
+ * where an 'expand' will happen.
+ */
+
+ /* The following code cannot be entered in the alpha pre-multiplication case
+ * because PNG_BACKGROUND_EXPAND is cancelled below.
+ */
+ if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) &&
+ (png_ptr->transformations & PNG_EXPAND))
+ {
+ {
+ png_ptr->background.red =
+ png_ptr->palette[png_ptr->background.index].red;
+ png_ptr->background.green =
+ png_ptr->palette[png_ptr->background.index].green;
+ png_ptr->background.blue =
+ png_ptr->palette[png_ptr->background.index].blue;
+
+#ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
+ if (png_ptr->transformations & PNG_INVERT_ALPHA)
+ {
+ if (!(png_ptr->transformations & PNG_EXPAND_tRNS))
+ {
+ /* Invert the alpha channel (in tRNS) unless the pixels are
+ * going to be expanded, in which case leave it for later
+ */
+ int i, istop = png_ptr->num_trans;
+
+ for (i=0; i<istop; i++)
+ png_ptr->trans_alpha[i] = (png_byte)(255 -
+ png_ptr->trans_alpha[i]);
+ }
+ }
+#endif /* PNG_READ_INVERT_ALPHA_SUPPORTED */
+ }
+ } /* background expand and (therefore) no alpha association. */
+#endif /* PNG_READ_EXPAND_SUPPORTED && PNG_READ_BACKGROUND_SUPPORTED */
+}
+
+static void /* PRIVATE */
+png_init_rgb_transformations(png_structrp png_ptr)
+{
+ /* Added to libpng-1.5.4: check the color type to determine whether there
+ * is any alpha or transparency in the image and simply cancel the
+ * background and alpha mode stuff if there isn't.
+ */
+ int input_has_alpha = (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0;
+ int input_has_transparency = png_ptr->num_trans > 0;
+
+ /* If no alpha we can optimize. */
+ if (!input_has_alpha)
+ {
+ /* Any alpha means background and associative alpha processing is
+ * required, however if the alpha is 0 or 1 throughout OPTIIMIZE_ALPHA
+ * and ENCODE_ALPHA are irrelevant.
+ */
+# ifdef PNG_READ_ALPHA_MODE_SUPPORTED
+ png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
+ png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
+# endif
+
+ if (!input_has_transparency)
+ png_ptr->transformations &= ~(PNG_COMPOSE | PNG_BACKGROUND_EXPAND);
+ }
+
+#if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
+ /* png_set_background handling - deals with the complexity of whether the
+ * background color is in the file format or the screen format in the case
+ * where an 'expand' will happen.
+ */
+
+ /* The following code cannot be entered in the alpha pre-multiplication case
+ * because PNG_BACKGROUND_EXPAND is cancelled below.
+ */
+ if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) &&
+ (png_ptr->transformations & PNG_EXPAND) &&
+ !(png_ptr->color_type & PNG_COLOR_MASK_COLOR))
+ /* i.e., GRAY or GRAY_ALPHA */
+ {
+ {
+ /* Expand background and tRNS chunks */
+ int gray = png_ptr->background.gray;
+ int trans_gray = png_ptr->trans_color.gray;
+
+ switch (png_ptr->bit_depth)
+ {
+ case 1:
+ gray *= 0xff;
+ trans_gray *= 0xff;
+ break;
+
+ case 2:
+ gray *= 0x55;
+ trans_gray *= 0x55;
+ break;
+
+ case 4:
+ gray *= 0x11;
+ trans_gray *= 0x11;
+ break;
+
+ default:
+
+ case 8:
+ /* FALL THROUGH (Already 8 bits) */
+
+ case 16:
+ /* Already a full 16 bits */
+ break;
+ }
+
+ png_ptr->background.red = png_ptr->background.green =
+ png_ptr->background.blue = (png_uint_16)gray;
+
+ if (!(png_ptr->transformations & PNG_EXPAND_tRNS))
+ {
+ png_ptr->trans_color.red = png_ptr->trans_color.green =
+ png_ptr->trans_color.blue = (png_uint_16)trans_gray;
+ }
+ }
+ } /* background expand and (therefore) no alpha association. */
+#endif /* PNG_READ_EXPAND_SUPPORTED && PNG_READ_BACKGROUND_SUPPORTED */
+}
+
+void /* PRIVATE */
+png_init_read_transformations(png_structrp png_ptr)
+{
+ png_debug(1, "in png_init_read_transformations");
+
+ /* This internal function is called from png_read_start_row in pngrutil.c
+ * and it is called before the 'rowbytes' calculation is done, so the code
+ * in here can change or update the transformations flags.
+ *
+ * First do updates that do not depend on the details of the PNG image data
+ * being processed.
+ */
+
+#ifdef PNG_READ_GAMMA_SUPPORTED
+ /* Prior to 1.5.4 these tests were performed from png_set_gamma, 1.5.4 adds
+ * png_set_alpha_mode and this is another source for a default file gamma so
+ * the test needs to be performed later - here. In addition prior to 1.5.4
+ * the tests were repeated for the PALETTE color type here - this is no
+ * longer necessary (and doesn't seem to have been necessary before.)
+ */
+ {
+ /* The following temporary indicates if overall gamma correction is
+ * required.
+ */
+ int gamma_correction = 0;
+
+ if (png_ptr->colorspace.gamma != 0) /* has been set */
+ {
+ if (png_ptr->screen_gamma != 0) /* screen set too */
+ gamma_correction = png_gamma_threshold(png_ptr->colorspace.gamma,
+ png_ptr->screen_gamma);
+
+ else
+ /* Assume the output matches the input; a long time default behavior
+ * of libpng, although the standard has nothing to say about this.
+ */
+ png_ptr->screen_gamma = png_reciprocal(png_ptr->colorspace.gamma);
+ }
+
+ else if (png_ptr->screen_gamma != 0)
+ /* The converse - assume the file matches the screen, note that this
+ * perhaps undesireable default can (from 1.5.4) be changed by calling
+ * png_set_alpha_mode (even if the alpha handling mode isn't required
+ * or isn't changed from the default.)
+ */
+ png_ptr->colorspace.gamma = png_reciprocal(png_ptr->screen_gamma);
+
+ else /* neither are set */
+ /* Just in case the following prevents any processing - file and screen
+ * are both assumed to be linear and there is no way to introduce a
+ * third gamma value other than png_set_background with 'UNIQUE', and,
+ * prior to 1.5.4
+ */
+ png_ptr->screen_gamma = png_ptr->colorspace.gamma = PNG_FP_1;
+
+ /* We have a gamma value now. */
+ png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
+
+ /* Now turn the gamma transformation on or off as appropriate. Notice
+ * that PNG_GAMMA just refers to the file->screen correction. Alpha
+ * composition may independently cause gamma correction because it needs
+ * linear data (e.g. if the file has a gAMA chunk but the screen gamma
+ * hasn't been specified.) In any case this flag may get turned off in
+ * the code immediately below if the transform can be handled outside the
+ * row loop.
+ */
+ if (gamma_correction)
+ png_ptr->transformations |= PNG_GAMMA;
+
+ else
+ png_ptr->transformations &= ~PNG_GAMMA;
+ }
+#endif
+
+ /* Certain transformations have the effect of preventing other
+ * transformations that happen afterward in png_do_read_transformations,
+ * resolve the interdependencies here. From the code of
+ * png_do_read_transformations the order is:
+ *
+ * 1) PNG_EXPAND (including PNG_EXPAND_tRNS)
+ * 2) PNG_STRIP_ALPHA (if no compose)
+ * 3) PNG_RGB_TO_GRAY
+ * 4) PNG_GRAY_TO_RGB iff !PNG_BACKGROUND_IS_GRAY
+ * 5) PNG_COMPOSE
+ * 6) PNG_GAMMA
+ * 7) PNG_STRIP_ALPHA (if compose)
+ * 8) PNG_ENCODE_ALPHA
+ * 9) PNG_SCALE_16_TO_8
+ * 10) PNG_16_TO_8
+ * 11) PNG_QUANTIZE (converts to palette)
+ * 12) PNG_EXPAND_16
+ * 13) PNG_GRAY_TO_RGB iff PNG_BACKGROUND_IS_GRAY
+ * 14) PNG_INVERT_MONO
+ * 15) PNG_SHIFT
+ * 16) PNG_PACK
+ * 17) PNG_BGR
+ * 18) PNG_PACKSWAP
+ * 19) PNG_FILLER (includes PNG_ADD_ALPHA)
+ * 20) PNG_INVERT_ALPHA
+ * 21) PNG_SWAP_ALPHA
+ * 22) PNG_SWAP_BYTES
+ * 23) PNG_USER_TRANSFORM [must be last]
+ */
+#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
+ if ((png_ptr->transformations & PNG_STRIP_ALPHA) &&
+ !(png_ptr->transformations & PNG_COMPOSE))
+ {
+ /* Stripping the alpha channel happens immediately after the 'expand'
+ * transformations, before all other transformation, so it cancels out
+ * the alpha handling. It has the side effect negating the effect of
+ * PNG_EXPAND_tRNS too:
+ */
+ png_ptr->transformations &= ~(PNG_BACKGROUND_EXPAND | PNG_ENCODE_ALPHA |
+ PNG_EXPAND_tRNS);
+ png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
+
+ /* Kill the tRNS chunk itself too. Prior to 1.5.4 this did not happen
+ * so transparency information would remain just so long as it wasn't
+ * expanded. This produces unexpected API changes if the set of things
+ * that do PNG_EXPAND_tRNS changes (perfectly possible given the
+ * documentation - which says ask for what you want, accept what you
+ * get.) This makes the behavior consistent from 1.5.4:
+ */
+ png_ptr->num_trans = 0;
+ }
+#endif /* STRIP_ALPHA supported, no COMPOSE */
+
+#ifdef PNG_READ_ALPHA_MODE_SUPPORTED
+ /* If the screen gamma is about 1.0 then the OPTIMIZE_ALPHA and ENCODE_ALPHA
+ * settings will have no effect.
+ */
+ if (!png_gamma_significant(png_ptr->screen_gamma))
+ {
+ png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
+ png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
+ }
+#endif
+
+#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
+ /* Make sure the coefficients for the rgb to gray conversion are set
+ * appropriately.
+ */
+ if (png_ptr->transformations & PNG_RGB_TO_GRAY)
+ png_colorspace_set_rgb_coefficients(png_ptr);
+#endif
+
+#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
+#if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
+ /* Detect gray background and attempt to enable optimization for
+ * gray --> RGB case.
+ *
+ * Note: if PNG_BACKGROUND_EXPAND is set and color_type is either RGB or
+ * RGB_ALPHA (in which case need_expand is superfluous anyway), the
+ * background color might actually be gray yet not be flagged as such.
+ * This is not a problem for the current code, which uses
+ * PNG_BACKGROUND_IS_GRAY only to decide when to do the
+ * png_do_gray_to_rgb() transformation.
+ *
+ * TODO: this code needs to be revised to avoid the complexity and
+ * interdependencies. The color type of the background should be recorded in
+ * png_set_background, along with the bit depth, then the code has a record
+ * of exactly what color space the background is currently in.
+ */
+ if (png_ptr->transformations & PNG_BACKGROUND_EXPAND)
+ {
+ /* PNG_BACKGROUND_EXPAND: the background is in the file color space, so if
+ * the file was grayscale the background value is gray.
+ */
+ if (!(png_ptr->color_type & PNG_COLOR_MASK_COLOR))
+ png_ptr->mode |= PNG_BACKGROUND_IS_GRAY;
+ }
+
+ else if (png_ptr->transformations & PNG_COMPOSE)
+ {
+ /* PNG_COMPOSE: png_set_background was called with need_expand false,
+ * so the color is in the color space of the output or png_set_alpha_mode
+ * was called and the color is black. Ignore RGB_TO_GRAY because that
+ * happens before GRAY_TO_RGB.
+ */
+ if (png_ptr->transformations & PNG_GRAY_TO_RGB)
+ {
+ if (png_ptr->background.red == png_ptr->background.green &&
+ png_ptr->background.red == png_ptr->background.blue)
+ {
+ png_ptr->mode |= PNG_BACKGROUND_IS_GRAY;
+ png_ptr->background.gray = png_ptr->background.red;
+ }
+ }
+ }
+#endif /* PNG_READ_EXPAND_SUPPORTED && PNG_READ_BACKGROUND_SUPPORTED */
+#endif /* PNG_READ_GRAY_TO_RGB_SUPPORTED */
+
+ /* For indexed PNG data (PNG_COLOR_TYPE_PALETTE) many of the transformations
+ * can be performed directly on the palette, and some (such as rgb to gray)
+ * can be optimized inside the palette. This is particularly true of the
+ * composite (background and alpha) stuff, which can be pretty much all done
+ * in the palette even if the result is expanded to RGB or gray afterward.
+ *
+ * NOTE: this is Not Yet Implemented, the code behaves as in 1.5.1 and
+ * earlier and the palette stuff is actually handled on the first row. This
+ * leads to the reported bug that the palette returned by png_get_PLTE is not
+ * updated.
+ */
+ if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
+ png_init_palette_transformations(png_ptr);
+
+ else
+ png_init_rgb_transformations(png_ptr);
+
+#if defined(PNG_READ_BACKGROUND_SUPPORTED) && \
+ defined(PNG_READ_EXPAND_16_SUPPORTED)
+ if ((png_ptr->transformations & PNG_EXPAND_16) &&
+ (png_ptr->transformations & PNG_COMPOSE) &&
+ !(png_ptr->transformations & PNG_BACKGROUND_EXPAND) &&
+ png_ptr->bit_depth != 16)
+ {
+ /* TODO: fix this. Because the expand_16 operation is after the compose
+ * handling the background color must be 8, not 16, bits deep, but the
+ * application will supply a 16-bit value so reduce it here.
+ *
+ * The PNG_BACKGROUND_EXPAND code above does not expand to 16 bits at
+ * present, so that case is ok (until do_expand_16 is moved.)
+ *
+ * NOTE: this discards the low 16 bits of the user supplied background
+ * color, but until expand_16 works properly there is no choice!
+ */
+# define CHOP(x) (x)=((png_uint_16)PNG_DIV257(x))
+ CHOP(png_ptr->background.red);
+ CHOP(png_ptr->background.green);
+ CHOP(png_ptr->background.blue);
+ CHOP(png_ptr->background.gray);
+# undef CHOP
+ }
+#endif /* PNG_READ_BACKGROUND_SUPPORTED && PNG_READ_EXPAND_16_SUPPORTED */
+
+#if defined(PNG_READ_BACKGROUND_SUPPORTED) && \
+ (defined(PNG_READ_SCALE_16_TO_8_SUPPORTED) || \
+ defined(PNG_READ_STRIP_16_TO_8_SUPPORTED))
+ if ((png_ptr->transformations & (PNG_16_TO_8|PNG_SCALE_16_TO_8)) &&
+ (png_ptr->transformations & PNG_COMPOSE) &&
+ !(png_ptr->transformations & PNG_BACKGROUND_EXPAND) &&
+ png_ptr->bit_depth == 16)
+ {
+ /* On the other hand, if a 16-bit file is to be reduced to 8-bits per
+ * component this will also happen after PNG_COMPOSE and so the background
+ * color must be pre-expanded here.
+ *
+ * TODO: fix this too.
+ */
+ png_ptr->background.red = (png_uint_16)(png_ptr->background.red * 257);
+ png_ptr->background.green =
+ (png_uint_16)(png_ptr->background.green * 257);
+ png_ptr->background.blue = (png_uint_16)(png_ptr->background.blue * 257);
+ png_ptr->background.gray = (png_uint_16)(png_ptr->background.gray * 257);
+ }
+#endif
+
+ /* NOTE: below 'PNG_READ_ALPHA_MODE_SUPPORTED' is presumed to also enable the
+ * background support (see the comments in scripts/pnglibconf.dfa), this
+ * allows pre-multiplication of the alpha channel to be implemented as
+ * compositing on black. This is probably sub-optimal and has been done in
+ * 1.5.4 betas simply to enable external critique and testing (i.e. to
+ * implement the new API quickly, without lots of internal changes.)
+ */
+
+#ifdef PNG_READ_GAMMA_SUPPORTED
+# ifdef PNG_READ_BACKGROUND_SUPPORTED
+ /* Includes ALPHA_MODE */
+ png_ptr->background_1 = png_ptr->background;
+# endif
+
+ /* This needs to change - in the palette image case a whole set of tables are
+ * built when it would be quicker to just calculate the correct value for
+ * each palette entry directly. Also, the test is too tricky - why check
+ * PNG_RGB_TO_GRAY if PNG_GAMMA is not set? The answer seems to be that
+ * PNG_GAMMA is cancelled even if the gamma is known? The test excludes the
+ * PNG_COMPOSE case, so apparently if there is no *overall* gamma correction
+ * the gamma tables will not be built even if composition is required on a
+ * gamma encoded value.
+ *
+ * In 1.5.4 this is addressed below by an additional check on the individual
+ * file gamma - if it is not 1.0 both RGB_TO_GRAY and COMPOSE need the
+ * tables.
+ */
+ if ((png_ptr->transformations & PNG_GAMMA)
+ || ((png_ptr->transformations & PNG_RGB_TO_GRAY)
+ && (png_gamma_significant(png_ptr->colorspace.gamma) ||
+ png_gamma_significant(png_ptr->screen_gamma)))
+ || ((png_ptr->transformations & PNG_COMPOSE)
+ && (png_gamma_significant(png_ptr->colorspace.gamma)
+ || png_gamma_significant(png_ptr->screen_gamma)
+# ifdef PNG_READ_BACKGROUND_SUPPORTED
+ || (png_ptr->background_gamma_type == PNG_BACKGROUND_GAMMA_UNIQUE
+ && png_gamma_significant(png_ptr->background_gamma))
+# endif
+ )) || ((png_ptr->transformations & PNG_ENCODE_ALPHA)
+ && png_gamma_significant(png_ptr->screen_gamma))
+ )
+ {
+ png_build_gamma_table(png_ptr, png_ptr->bit_depth);
+
+#ifdef PNG_READ_BACKGROUND_SUPPORTED
+ if (png_ptr->transformations & PNG_COMPOSE)
+ {
+ /* Issue a warning about this combination: because RGB_TO_GRAY is
+ * optimized to do the gamma transform if present yet do_background has
+ * to do the same thing if both options are set a
+ * double-gamma-correction happens. This is true in all versions of
+ * libpng to date.
+ */
+ if (png_ptr->transformations & PNG_RGB_TO_GRAY)
+ png_warning(png_ptr,
+ "libpng does not support gamma+background+rgb_to_gray");
+
+ if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
+ {
+ /* We don't get to here unless there is a tRNS chunk with non-opaque
+ * entries - see the checking code at the start of this function.
+ */
+ png_color back, back_1;
+ png_colorp palette = png_ptr->palette;
+ int num_palette = png_ptr->num_palette;
+ int i;
+ if (png_ptr->background_gamma_type == PNG_BACKGROUND_GAMMA_FILE)
+ {
+
+ back.red = png_ptr->gamma_table[png_ptr->background.red];
+ back.green = png_ptr->gamma_table[png_ptr->background.green];
+ back.blue = png_ptr->gamma_table[png_ptr->background.blue];
+
+ back_1.red = png_ptr->gamma_to_1[png_ptr->background.red];
+ back_1.green = png_ptr->gamma_to_1[png_ptr->background.green];
+ back_1.blue = png_ptr->gamma_to_1[png_ptr->background.blue];
+ }
+ else
+ {
+ png_fixed_point g, gs;
+
+ switch (png_ptr->background_gamma_type)
+ {
+ case PNG_BACKGROUND_GAMMA_SCREEN:
+ g = (png_ptr->screen_gamma);
+ gs = PNG_FP_1;
+ break;
+
+ case PNG_BACKGROUND_GAMMA_FILE:
+ g = png_reciprocal(png_ptr->colorspace.gamma);
+ gs = png_reciprocal2(png_ptr->colorspace.gamma,
+ png_ptr->screen_gamma);
+ break;
+
+ case PNG_BACKGROUND_GAMMA_UNIQUE:
+ g = png_reciprocal(png_ptr->background_gamma);
+ gs = png_reciprocal2(png_ptr->background_gamma,
+ png_ptr->screen_gamma);
+ break;
+ default:
+ g = PNG_FP_1; /* back_1 */
+ gs = PNG_FP_1; /* back */
+ break;
+ }
+
+ if (png_gamma_significant(gs))
+ {
+ back.red = png_gamma_8bit_correct(png_ptr->background.red,
+ gs);
+ back.green = png_gamma_8bit_correct(png_ptr->background.green,
+ gs);
+ back.blue = png_gamma_8bit_correct(png_ptr->background.blue,
+ gs);
+ }
+
+ else
+ {
+ back.red = (png_byte)png_ptr->background.red;
+ back.green = (png_byte)png_ptr->background.green;
+ back.blue = (png_byte)png_ptr->background.blue;
+ }
+
+ if (png_gamma_significant(g))
+ {
+ back_1.red = png_gamma_8bit_correct(png_ptr->background.red,
+ g);
+ back_1.green = png_gamma_8bit_correct(
+ png_ptr->background.green, g);
+ back_1.blue = png_gamma_8bit_correct(png_ptr->background.blue,
+ g);
+ }
+
+ else
+ {
+ back_1.red = (png_byte)png_ptr->background.red;
+ back_1.green = (png_byte)png_ptr->background.green;
+ back_1.blue = (png_byte)png_ptr->background.blue;
+ }
+ }
+
+ for (i = 0; i < num_palette; i++)
+ {
+ if (i < (int)png_ptr->num_trans &&
+ png_ptr->trans_alpha[i] != 0xff)
+ {
+ if (png_ptr->trans_alpha[i] == 0)
+ {
+ palette[i] = back;
+ }
+ else /* if (png_ptr->trans_alpha[i] != 0xff) */
+ {
+ png_byte v, w;
+
+ v = png_ptr->gamma_to_1[palette[i].red];
+ png_composite(w, v, png_ptr->trans_alpha[i], back_1.red);
+ palette[i].red = png_ptr->gamma_from_1[w];
+
+ v = png_ptr->gamma_to_1[palette[i].green];
+ png_composite(w, v, png_ptr->trans_alpha[i], back_1.green);
+ palette[i].green = png_ptr->gamma_from_1[w];
+
+ v = png_ptr->gamma_to_1[palette[i].blue];
+ png_composite(w, v, png_ptr->trans_alpha[i], back_1.blue);
+ palette[i].blue = png_ptr->gamma_from_1[w];
+ }
+ }
+ else
+ {
+ palette[i].red = png_ptr->gamma_table[palette[i].red];
+ palette[i].green = png_ptr->gamma_table[palette[i].green];
+ palette[i].blue = png_ptr->gamma_table[palette[i].blue];
+ }
+ }
+
+ /* Prevent the transformations being done again.
+ *
+ * NOTE: this is highly dubious; it removes the transformations in
+ * place. This seems inconsistent with the general treatment of the
+ * transformations elsewhere.
+ */
+ png_ptr->transformations &= ~(PNG_COMPOSE | PNG_GAMMA);
+ } /* color_type == PNG_COLOR_TYPE_PALETTE */
+
+ /* if (png_ptr->background_gamma_type!=PNG_BACKGROUND_GAMMA_UNKNOWN) */
+ else /* color_type != PNG_COLOR_TYPE_PALETTE */
+ {
+ int gs_sig, g_sig;
+ png_fixed_point g = PNG_FP_1; /* Correction to linear */
+ png_fixed_point gs = PNG_FP_1; /* Correction to screen */
+
+ switch (png_ptr->background_gamma_type)
+ {
+ case PNG_BACKGROUND_GAMMA_SCREEN:
+ g = png_ptr->screen_gamma;
+ /* gs = PNG_FP_1; */
+ break;
+
+ case PNG_BACKGROUND_GAMMA_FILE:
+ g = png_reciprocal(png_ptr->colorspace.gamma);
+ gs = png_reciprocal2(png_ptr->colorspace.gamma,
+ png_ptr->screen_gamma);
+ break;
+
+ case PNG_BACKGROUND_GAMMA_UNIQUE:
+ g = png_reciprocal(png_ptr->background_gamma);
+ gs = png_reciprocal2(png_ptr->background_gamma,
+ png_ptr->screen_gamma);
+ break;
+
+ default:
+ png_error(png_ptr, "invalid background gamma type");
+ }
+
+ g_sig = png_gamma_significant(g);
+ gs_sig = png_gamma_significant(gs);
+
+ if (g_sig)
+ png_ptr->background_1.gray = png_gamma_correct(png_ptr,
+ png_ptr->background.gray, g);
+
+ if (gs_sig)
+ png_ptr->background.gray = png_gamma_correct(png_ptr,
+ png_ptr->background.gray, gs);
+
+ if ((png_ptr->background.red != png_ptr->background.green) ||
+ (png_ptr->background.red != png_ptr->background.blue) ||
+ (png_ptr->background.red != png_ptr->background.gray))
+ {
+ /* RGB or RGBA with color background */
+ if (g_sig)
+ {
+ png_ptr->background_1.red = png_gamma_correct(png_ptr,
+ png_ptr->background.red, g);
+
+ png_ptr->background_1.green = png_gamma_correct(png_ptr,
+ png_ptr->background.green, g);
+
+ png_ptr->background_1.blue = png_gamma_correct(png_ptr,
+ png_ptr->background.blue, g);
+ }
+
+ if (gs_sig)
+ {
+ png_ptr->background.red = png_gamma_correct(png_ptr,
+ png_ptr->background.red, gs);
+
+ png_ptr->background.green = png_gamma_correct(png_ptr,
+ png_ptr->background.green, gs);
+
+ png_ptr->background.blue = png_gamma_correct(png_ptr,
+ png_ptr->background.blue, gs);
+ }
+ }
+
+ else
+ {
+ /* GRAY, GRAY ALPHA, RGB, or RGBA with gray background */
+ png_ptr->background_1.red = png_ptr->background_1.green
+ = png_ptr->background_1.blue = png_ptr->background_1.gray;
+
+ png_ptr->background.red = png_ptr->background.green
+ = png_ptr->background.blue = png_ptr->background.gray;
+ }
+
+ /* The background is now in screen gamma: */
+ png_ptr->background_gamma_type = PNG_BACKGROUND_GAMMA_SCREEN;
+ } /* color_type != PNG_COLOR_TYPE_PALETTE */
+ }/* png_ptr->transformations & PNG_BACKGROUND */
+
+ else
+ /* Transformation does not include PNG_BACKGROUND */
+#endif /* PNG_READ_BACKGROUND_SUPPORTED */
+ if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE
+#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
+ /* RGB_TO_GRAY needs to have non-gamma-corrected values! */
+ && ((png_ptr->transformations & PNG_EXPAND) == 0 ||
+ (png_ptr->transformations & PNG_RGB_TO_GRAY) == 0)
+#endif
+ )
+ {
+ png_colorp palette = png_ptr->palette;
+ int num_palette = png_ptr->num_palette;
+ int i;
+
+ /* NOTE: there are other transformations that should probably be in
+ * here too.
+ */
+ for (i = 0; i < num_palette; i++)
+ {
+ palette[i].red = png_ptr->gamma_table[palette[i].red];
+ palette[i].green = png_ptr->gamma_table[palette[i].green];
+ palette[i].blue = png_ptr->gamma_table[palette[i].blue];
+ }
+
+ /* Done the gamma correction. */
+ png_ptr->transformations &= ~PNG_GAMMA;
+ } /* color_type == PALETTE && !PNG_BACKGROUND transformation */
+ }
+#ifdef PNG_READ_BACKGROUND_SUPPORTED
+ else
+#endif
+#endif /* PNG_READ_GAMMA_SUPPORTED */
+
+#ifdef PNG_READ_BACKGROUND_SUPPORTED
+ /* No GAMMA transformation (see the hanging else 4 lines above) */
+ if ((png_ptr->transformations & PNG_COMPOSE) &&
+ (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE))
+ {
+ int i;
+ int istop = (int)png_ptr->num_trans;
+ png_color back;
+ png_colorp palette = png_ptr->palette;
+
+ back.red = (png_byte)png_ptr->background.red;
+ back.green = (png_byte)png_ptr->background.green;
+ back.blue = (png_byte)png_ptr->background.blue;
+
+ for (i = 0; i < istop; i++)
+ {
+ if (png_ptr->trans_alpha[i] == 0)
+ {
+ palette[i] = back;
+ }
+
+ else if (png_ptr->trans_alpha[i] != 0xff)
+ {
+ /* The png_composite() macro is defined in png.h */
+ png_composite(palette[i].red, palette[i].red,
+ png_ptr->trans_alpha[i], back.red);
+
+ png_composite(palette[i].green, palette[i].green,
+ png_ptr->trans_alpha[i], back.green);
+
+ png_composite(palette[i].blue, palette[i].blue,
+ png_ptr->trans_alpha[i], back.blue);
+ }
+ }
+
+ png_ptr->transformations &= ~PNG_COMPOSE;
+
+ //png_ptr->flags |= PNG_FLAG_STRIP_ALPHA; /* Add by Sunliang.Liu */
+ }
+#endif /* PNG_READ_BACKGROUND_SUPPORTED */
+
+#ifdef PNG_READ_SHIFT_SUPPORTED
+ if ((png_ptr->transformations & PNG_SHIFT) &&
+ !(png_ptr->transformations & PNG_EXPAND) &&
+ (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE))
+ {
+ int i;
+ int istop = png_ptr->num_palette;
+ int shift = 8 - png_ptr->sig_bit.red;
+
+ png_ptr->transformations &= ~PNG_SHIFT;
+
+ /* significant bits can be in the range 1 to 7 for a meaninful result, if
+ * the number of significant bits is 0 then no shift is done (this is an
+ * error condition which is silently ignored.)
+ */
+ if (shift > 0 && shift < 8) for (i=0; i<istop; ++i)
+ {
+ int component = png_ptr->palette[i].red;
+
+ component >>= shift;
+ png_ptr->palette[i].red = (png_byte)component;
+ }
+
+ shift = 8 - png_ptr->sig_bit.green;
+ if (shift > 0 && shift < 8) for (i=0; i<istop; ++i)
+ {
+ int component = png_ptr->palette[i].green;
+
+ component >>= shift;
+ png_ptr->palette[i].green = (png_byte)component;
+ }
+
+ shift = 8 - png_ptr->sig_bit.blue;
+ if (shift > 0 && shift < 8) for (i=0; i<istop; ++i)
+ {
+ int component = png_ptr->palette[i].blue;
+
+ component >>= shift;
+ png_ptr->palette[i].blue = (png_byte)component;
+ }
+ }
+#endif /* PNG_READ_SHIFT_SUPPORTED */
+}
+
+/* Modify the info structure to reflect the transformations. The
+ * info should be updated so a PNG file could be written with it,
+ * assuming the transformations result in valid PNG data.
+ */
+void /* PRIVATE */
+png_read_transform_info(png_structrp png_ptr, png_inforp info_ptr)
+{
+ png_debug(1, "in png_read_transform_info");
+
+#ifdef PNG_READ_EXPAND_SUPPORTED
+ if (png_ptr->transformations & PNG_EXPAND)
+ {
+ if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
+ {
+ /* This check must match what actually happens in
+ * png_do_expand_palette; if it ever checks the tRNS chunk to see if
+ * it is all opaque we must do the same (at present it does not.)
+ */
+ if (png_ptr->num_trans > 0)
+ info_ptr->color_type = PNG_COLOR_TYPE_RGB_ALPHA;
+
+ else
+ info_ptr->color_type = PNG_COLOR_TYPE_RGB;
+
+ info_ptr->bit_depth = 8;
+ info_ptr->num_trans = 0;
+ }
+ else
+ {
+ if (png_ptr->num_trans)
+ {
+ if (png_ptr->transformations & PNG_EXPAND_tRNS)
+ info_ptr->color_type |= PNG_COLOR_MASK_ALPHA;
+ }
+ if (info_ptr->bit_depth < 8)
+ info_ptr->bit_depth = 8;
+
+ info_ptr->num_trans = 0;
+ }
+ }
+#endif
+
+#if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
+ defined(PNG_READ_ALPHA_MODE_SUPPORTED)
+ /* The following is almost certainly wrong unless the background value is in
+ * the screen space!
+ */
+ if (png_ptr->transformations & PNG_COMPOSE)
+ info_ptr->background = png_ptr->background;
+#endif
+
+#ifdef PNG_READ_GAMMA_SUPPORTED
+ /* The following used to be conditional on PNG_GAMMA (prior to 1.5.4),
+ * however it seems that the code in png_init_read_transformations, which has
+ * been called before this from png_read_update_info->png_read_start_row
+ * sometimes does the gamma transform and cancels the flag.
+ *
+ * TODO: this looks wrong; the info_ptr should end up with a gamma equal to
+ * the screen_gamma value. The following probably results in weirdness if
+ * the info_ptr is used by the app after the rows have been read.
+ */
+ info_ptr->colorspace.gamma = png_ptr->colorspace.gamma;
+#endif
+
+ if (info_ptr->bit_depth == 16)
+ {
+# ifdef PNG_READ_16BIT_SUPPORTED
+# ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
+ if (png_ptr->transformations & PNG_SCALE_16_TO_8)
+ info_ptr->bit_depth = 8;
+# endif
+
+# ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
+ if (png_ptr->transformations & PNG_16_TO_8)
+ info_ptr->bit_depth = 8;
+# endif
+
+# else
+ /* No 16 bit support: force chopping 16-bit input down to 8, in this case
+ * the app program can chose if both APIs are available by setting the
+ * correct scaling to use.
+ */
+# ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
+ /* For compatibility with previous versions use the strip method by
+ * default. This code works because if PNG_SCALE_16_TO_8 is already
+ * set the code below will do that in preference to the chop.
+ */
+ png_ptr->transformations |= PNG_16_TO_8;
+ info_ptr->bit_depth = 8;
+# else
+
+# ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
+ png_ptr->transformations |= PNG_SCALE_16_TO_8;
+ info_ptr->bit_depth = 8;
+# else
+
+ CONFIGURATION ERROR: you must enable at least one 16 to 8 method
+# endif
+# endif
+#endif /* !READ_16BIT_SUPPORTED */
+ }
+
+#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
+ if (png_ptr->transformations & PNG_GRAY_TO_RGB)
+ info_ptr->color_type = (png_byte)(info_ptr->color_type |
+ PNG_COLOR_MASK_COLOR);
+#endif
+
+#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
+ if (png_ptr->transformations & PNG_RGB_TO_GRAY)
+ info_ptr->color_type = (png_byte)(info_ptr->color_type &
+ ~PNG_COLOR_MASK_COLOR);
+#endif
+
+#ifdef PNG_READ_QUANTIZE_SUPPORTED
+ if (png_ptr->transformations & PNG_QUANTIZE)
+ {
+ if (((info_ptr->color_type == PNG_COLOR_TYPE_RGB) ||
+ (info_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)) &&
+ png_ptr->palette_lookup && info_ptr->bit_depth == 8)
+ {
+ info_ptr->color_type = PNG_COLOR_TYPE_PALETTE;
+ }
+ }
+#endif
+
+#ifdef PNG_READ_EXPAND_16_SUPPORTED
+ if (png_ptr->transformations & PNG_EXPAND_16 && info_ptr->bit_depth == 8 &&
+ info_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
+ {
+ info_ptr->bit_depth = 16;
+ }
+#endif
+
+#ifdef PNG_READ_PACK_SUPPORTED
+ if ((png_ptr->transformations & PNG_PACK) && (info_ptr->bit_depth < 8))
+ info_ptr->bit_depth = 8;
+#endif
+
+ if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
+ info_ptr->channels = 1;
+
+ else if (info_ptr->color_type & PNG_COLOR_MASK_COLOR)
+ info_ptr->channels = 3;
+
+ else
+ info_ptr->channels = 1;
+
+#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
+ if (png_ptr->transformations & PNG_STRIP_ALPHA)
+ {
+ info_ptr->color_type = (png_byte)(info_ptr->color_type &
+ ~PNG_COLOR_MASK_ALPHA);
+ info_ptr->num_trans = 0;
+ }
+#endif
+
+ if (info_ptr->color_type & PNG_COLOR_MASK_ALPHA)
+ info_ptr->channels++;
+
+#ifdef PNG_READ_FILLER_SUPPORTED
+ /* STRIP_ALPHA and FILLER allowed: MASK_ALPHA bit stripped above */
+ if ((png_ptr->transformations & PNG_FILLER) &&
+ ((info_ptr->color_type == PNG_COLOR_TYPE_RGB) ||
+ (info_ptr->color_type == PNG_COLOR_TYPE_GRAY)))
+ {
+ info_ptr->channels++;
+ /* If adding a true alpha channel not just filler */
+ if (png_ptr->transformations & PNG_ADD_ALPHA)
+ info_ptr->color_type |= PNG_COLOR_MASK_ALPHA;
+ }
+#endif
+
+#if defined(PNG_USER_TRANSFORM_PTR_SUPPORTED) && \
+defined(PNG_READ_USER_TRANSFORM_SUPPORTED)
+ if (png_ptr->transformations & PNG_USER_TRANSFORM)
+ {
+ if (info_ptr->bit_depth < png_ptr->user_transform_depth)
+ info_ptr->bit_depth = png_ptr->user_transform_depth;
+
+ if (info_ptr->channels < png_ptr->user_transform_channels)
+ info_ptr->channels = png_ptr->user_transform_channels;
+ }
+#endif
+
+ info_ptr->pixel_depth = (png_byte)(info_ptr->channels *
+ info_ptr->bit_depth);
+
+ info_ptr->rowbytes = PNG_ROWBYTES(info_ptr->pixel_depth, info_ptr->width);
+
+ /* Adding in 1.5.4: cache the above value in png_struct so that we can later
+ * check in png_rowbytes that the user buffer won't get overwritten. Note
+ * that the field is not always set - if png_read_update_info isn't called
+ * the application has to either not do any transforms or get the calculation
+ * right itself.
+ */
+ png_ptr->info_rowbytes = info_ptr->rowbytes;
+
+#ifndef PNG_READ_EXPAND_SUPPORTED
+ if (png_ptr)
+ return;
+#endif
+}
+
+/* Transform the row. The order of transformations is significant,
+ * and is very touchy. If you add a transformation, take care to
+ * decide how it fits in with the other transformations here.
+ */
+void /* PRIVATE */
+png_do_read_transformations(png_structrp png_ptr, png_row_infop row_info)
+{
+ png_debug(1, "in png_do_read_transformations");
+
+ if (png_ptr->row_buf == NULL)
+ {
+ /* Prior to 1.5.4 this output row/pass where the NULL pointer is, but this
+ * error is incredibly rare and incredibly easy to debug without this
+ * information.
+ */
+ png_error(png_ptr, "NULL row buffer");
+ }
+
+ /* The following is debugging; prior to 1.5.4 the code was never compiled in;
+ * in 1.5.4 PNG_FLAG_DETECT_UNINITIALIZED was added and the macro
+ * PNG_WARN_UNINITIALIZED_ROW removed. In 1.6 the new flag is set only for
+ * all transformations, however in practice the ROW_INIT always gets done on
+ * demand, if necessary.
+ */
+ if ((png_ptr->flags & PNG_FLAG_DETECT_UNINITIALIZED) != 0 &&
+ !(png_ptr->flags & PNG_FLAG_ROW_INIT))
+ {
+ /* Application has failed to call either png_read_start_image() or
+ * png_read_update_info() after setting transforms that expand pixels.
+ * This check added to libpng-1.2.19 (but not enabled until 1.5.4).
+ */
+ png_error(png_ptr, "Uninitialized row");
+ }
+
+#ifdef PNG_READ_EXPAND_SUPPORTED
+ if (png_ptr->transformations & PNG_EXPAND)
+ {
+ if (row_info->color_type == PNG_COLOR_TYPE_PALETTE)
+ {
+ png_do_expand_palette(row_info, png_ptr->row_buf + 1,
+ png_ptr->palette, png_ptr->trans_alpha, png_ptr->num_trans);
+ }
+
+ else
+ {
+ if (png_ptr->num_trans &&
+ (png_ptr->transformations & PNG_EXPAND_tRNS))
+ png_do_expand(row_info, png_ptr->row_buf + 1,
+ &(png_ptr->trans_color));
+
+ else
+ png_do_expand(row_info, png_ptr->row_buf + 1,
+ NULL);
+ }
+ }
+#endif
+
+#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
+ if ((png_ptr->transformations & PNG_STRIP_ALPHA) &&
+ !(png_ptr->transformations & PNG_COMPOSE) &&
+ (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
+ row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA))
+ png_do_strip_channel(row_info, png_ptr->row_buf + 1,
+ 0 /* at_start == false, because SWAP_ALPHA happens later */);
+#endif
+
+#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
+ if (png_ptr->transformations & PNG_RGB_TO_GRAY)
+ {
+ int rgb_error =
+ png_do_rgb_to_gray(png_ptr, row_info,
+ png_ptr->row_buf + 1);
+
+ if (rgb_error)
+ {
+ png_ptr->rgb_to_gray_status=1;
+ if ((png_ptr->transformations & PNG_RGB_TO_GRAY) ==
+ PNG_RGB_TO_GRAY_WARN)
+ png_warning(png_ptr, "png_do_rgb_to_gray found nongray pixel");
+
+ if ((png_ptr->transformations & PNG_RGB_TO_GRAY) ==
+ PNG_RGB_TO_GRAY_ERR)
+ png_error(png_ptr, "png_do_rgb_to_gray found nongray pixel");
+ }
+ }
+#endif
+
+/* From Andreas Dilger e-mail to png-implement, 26 March 1998:
+ *
+ * In most cases, the "simple transparency" should be done prior to doing
+ * gray-to-RGB, or you will have to test 3x as many bytes to check if a
+ * pixel is transparent. You would also need to make sure that the
+ * transparency information is upgraded to RGB.
+ *
+ * To summarize, the current flow is:
+ * - Gray + simple transparency -> compare 1 or 2 gray bytes and composite
+ * with background "in place" if transparent,
+ * convert to RGB if necessary
+ * - Gray + alpha -> composite with gray background and remove alpha bytes,
+ * convert to RGB if necessary
+ *
+ * To support RGB backgrounds for gray images we need:
+ * - Gray + simple transparency -> convert to RGB + simple transparency,
+ * compare 3 or 6 bytes and composite with
+ * background "in place" if transparent
+ * (3x compare/pixel compared to doing
+ * composite with gray bkgrnd)
+ * - Gray + alpha -> convert to RGB + alpha, composite with background and
+ * remove alpha bytes (3x float
+ * operations/pixel compared with composite
+ * on gray background)
+ *
+ * Greg's change will do this. The reason it wasn't done before is for
+ * performance, as this increases the per-pixel operations. If we would check
+ * in advance if the background was gray or RGB, and position the gray-to-RGB
+ * transform appropriately, then it would save a lot of work/time.
+ */
+
+#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
+ /* If gray -> RGB, do so now only if background is non-gray; else do later
+ * for performance reasons
+ */
+ if ((png_ptr->transformations & PNG_GRAY_TO_RGB) &&
+ !(png_ptr->mode & PNG_BACKGROUND_IS_GRAY))
+ png_do_gray_to_rgb(row_info, png_ptr->row_buf + 1);
+#endif
+
+#if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
+ defined(PNG_READ_ALPHA_MODE_SUPPORTED)
+ if (png_ptr->transformations & PNG_COMPOSE)
+ png_do_compose(row_info, png_ptr->row_buf + 1, png_ptr);
+#endif
+
+#ifdef PNG_READ_GAMMA_SUPPORTED
+ if ((png_ptr->transformations & PNG_GAMMA) &&
+#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
+ /* Because RGB_TO_GRAY does the gamma transform. */
+ !(png_ptr->transformations & PNG_RGB_TO_GRAY) &&
+#endif
+#if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
+ defined(PNG_READ_ALPHA_MODE_SUPPORTED)
+ /* Because PNG_COMPOSE does the gamma transform if there is something to
+ * do (if there is an alpha channel or transparency.)
+ */
+ !((png_ptr->transformations & PNG_COMPOSE) &&
+ ((png_ptr->num_trans != 0) ||
+ (png_ptr->color_type & PNG_COLOR_MASK_ALPHA))) &&
+#endif
+ /* Because png_init_read_transformations transforms the palette, unless
+ * RGB_TO_GRAY will do the transform.
+ */
+ (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE))
+ png_do_gamma(row_info, png_ptr->row_buf + 1, png_ptr);
+#endif
+
+#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
+ if ((png_ptr->transformations & PNG_STRIP_ALPHA) &&
+ (png_ptr->transformations & PNG_COMPOSE) &&
+ (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
+ row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA))
+ png_do_strip_channel(row_info, png_ptr->row_buf + 1,
+ 0 /* at_start == false, because SWAP_ALPHA happens later */);
+#endif
+
+#ifdef PNG_READ_ALPHA_MODE_SUPPORTED
+ if ((png_ptr->transformations & PNG_ENCODE_ALPHA) &&
+ (row_info->color_type & PNG_COLOR_MASK_ALPHA))
+ png_do_encode_alpha(row_info, png_ptr->row_buf + 1, png_ptr);
+#endif
+
+#ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
+ if (png_ptr->transformations & PNG_SCALE_16_TO_8)
+ png_do_scale_16_to_8(row_info, png_ptr->row_buf + 1);
+#endif
+
+#ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
+ /* There is no harm in doing both of these because only one has any effect,
+ * by putting the 'scale' option first if the app asks for scale (either by
+ * calling the API or in a TRANSFORM flag) this is what happens.
+ */
+ if (png_ptr->transformations & PNG_16_TO_8)
+ png_do_chop(row_info, png_ptr->row_buf + 1);
+#endif
+
+#ifdef PNG_READ_QUANTIZE_SUPPORTED
+ if (png_ptr->transformations & PNG_QUANTIZE)
+ {
+ png_do_quantize(row_info, png_ptr->row_buf + 1,
+ png_ptr->palette_lookup, png_ptr->quantize_index);
+
+ if (row_info->rowbytes == 0)
+ png_error(png_ptr, "png_do_quantize returned rowbytes=0");
+ }
+#endif /* PNG_READ_QUANTIZE_SUPPORTED */
+
+#ifdef PNG_READ_EXPAND_16_SUPPORTED
+ /* Do the expansion now, after all the arithmetic has been done. Notice
+ * that previous transformations can handle the PNG_EXPAND_16 flag if this
+ * is efficient (particularly true in the case of gamma correction, where
+ * better accuracy results faster!)
+ */
+ if (png_ptr->transformations & PNG_EXPAND_16)
+ png_do_expand_16(row_info, png_ptr->row_buf + 1);
+#endif
+
+#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
+ /* NOTE: moved here in 1.5.4 (from much later in this list.) */
+ if ((png_ptr->transformations & PNG_GRAY_TO_RGB) &&
+ (png_ptr->mode & PNG_BACKGROUND_IS_GRAY))
+ png_do_gray_to_rgb(row_info, png_ptr->row_buf + 1);
+#endif
+
+#ifdef PNG_READ_INVERT_SUPPORTED
+ if (png_ptr->transformations & PNG_INVERT_MONO)
+ png_do_invert(row_info, png_ptr->row_buf + 1);
+#endif
+
+#ifdef PNG_READ_SHIFT_SUPPORTED
+ if (png_ptr->transformations & PNG_SHIFT)
+ png_do_unshift(row_info, png_ptr->row_buf + 1,
+ &(png_ptr->shift));
+#endif
+
+#ifdef PNG_READ_PACK_SUPPORTED
+ if (png_ptr->transformations & PNG_PACK)
+ png_do_unpack(row_info, png_ptr->row_buf + 1);
+#endif
+
+#ifdef PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED
+ /* Added at libpng-1.5.10 */
+ if (row_info->color_type == PNG_COLOR_TYPE_PALETTE &&
+ png_ptr->num_palette_max >= 0)
+ png_do_check_palette_indexes(png_ptr, row_info);
+#endif
+
+#ifdef PNG_READ_BGR_SUPPORTED
+ if (png_ptr->transformations & PNG_BGR)
+ png_do_bgr(row_info, png_ptr->row_buf + 1);
+#endif
+
+#ifdef PNG_READ_PACKSWAP_SUPPORTED
+ if (png_ptr->transformations & PNG_PACKSWAP)
+ png_do_packswap(row_info, png_ptr->row_buf + 1);
+#endif
+
+#ifdef PNG_READ_FILLER_SUPPORTED
+ if (png_ptr->transformations & PNG_FILLER)
+ png_do_read_filler(row_info, png_ptr->row_buf + 1,
+ (png_uint_32)png_ptr->filler, png_ptr->flags);
+#endif
+
+#ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
+ if (png_ptr->transformations & PNG_INVERT_ALPHA)
+ png_do_read_invert_alpha(row_info, png_ptr->row_buf + 1);
+#endif
+
+#ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
+ if (png_ptr->transformations & PNG_SWAP_ALPHA)
+ png_do_read_swap_alpha(row_info, png_ptr->row_buf + 1);
+#endif
+
+#ifdef PNG_READ_16BIT_SUPPORTED
+#ifdef PNG_READ_SWAP_SUPPORTED
+ if (png_ptr->transformations & PNG_SWAP_BYTES)
+ png_do_swap(row_info, png_ptr->row_buf + 1);
+#endif
+#endif
+
+#ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
+ if (png_ptr->transformations & PNG_USER_TRANSFORM)
+ {
+ if (png_ptr->read_user_transform_fn != NULL)
+ (*(png_ptr->read_user_transform_fn)) /* User read transform function */
+ (png_ptr, /* png_ptr */
+ row_info, /* row_info: */
+ /* png_uint_32 width; width of row */
+ /* png_size_t rowbytes; number of bytes in row */
+ /* png_byte color_type; color type of pixels */
+ /* png_byte bit_depth; bit depth of samples */
+ /* png_byte channels; number of channels (1-4) */
+ /* png_byte pixel_depth; bits per pixel (depth*channels) */
+ png_ptr->row_buf + 1); /* start of pixel data for row */
+#ifdef PNG_USER_TRANSFORM_PTR_SUPPORTED
+ if (png_ptr->user_transform_depth)
+ row_info->bit_depth = png_ptr->user_transform_depth;
+
+ if (png_ptr->user_transform_channels)
+ row_info->channels = png_ptr->user_transform_channels;
+#endif
+ row_info->pixel_depth = (png_byte)(row_info->bit_depth *
+ row_info->channels);
+
+ row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_info->width);
+ }
+#endif
+}
+
+#ifdef PNG_READ_PACK_SUPPORTED
+/* Unpack pixels of 1, 2, or 4 bits per pixel into 1 byte per pixel,
+ * without changing the actual values. Thus, if you had a row with
+ * a bit depth of 1, you would end up with bytes that only contained
+ * the numbers 0 or 1. If you would rather they contain 0 and 255, use
+ * png_do_shift() after this.
+ */
+void /* PRIVATE */
+png_do_unpack(png_row_infop row_info, png_bytep row)
+{
+ png_debug(1, "in png_do_unpack");
+
+ if (row_info->bit_depth < 8)
+ {
+ png_uint_32 i;
+ png_uint_32 row_width=row_info->width;
+
+ switch (row_info->bit_depth)
+ {
+ case 1:
+ {
+ png_bytep sp = row + (png_size_t)((row_width - 1) >> 3);
+ png_bytep dp = row + (png_size_t)row_width - 1;
+ png_uint_32 shift = 7 - (int)((row_width + 7) & 0x07);
+ for (i = 0; i < row_width; i++)
+ {
+ *dp = (png_byte)((*sp >> shift) & 0x01);
+
+ if (shift == 7)
+ {
+ shift = 0;
+ sp--;
+ }
+
+ else
+ shift++;
+
+ dp--;
+ }
+ break;
+ }
+
+ case 2:
+ {
+
+ png_bytep sp = row + (png_size_t)((row_width - 1) >> 2);
+ png_bytep dp = row + (png_size_t)row_width - 1;
+ png_uint_32 shift = (int)((3 - ((row_width + 3) & 0x03)) << 1);
+ for (i = 0; i < row_width; i++)
+ {
+ *dp = (png_byte)((*sp >> shift) & 0x03);
+
+ if (shift == 6)
+ {
+ shift = 0;
+ sp--;
+ }
+
+ else
+ shift += 2;
+
+ dp--;
+ }
+ break;
+ }
+
+ case 4:
+ {
+ png_bytep sp = row + (png_size_t)((row_width - 1) >> 1);
+ png_bytep dp = row + (png_size_t)row_width - 1;
+ png_uint_32 shift = (int)((1 - ((row_width + 1) & 0x01)) << 2);
+ for (i = 0; i < row_width; i++)
+ {
+ *dp = (png_byte)((*sp >> shift) & 0x0f);
+
+ if (shift == 4)
+ {
+ shift = 0;
+ sp--;
+ }
+
+ else
+ shift = 4;
+
+ dp--;
+ }
+ break;
+ }
+
+ default:
+ break;
+ }
+ row_info->bit_depth = 8;
+ row_info->pixel_depth = (png_byte)(8 * row_info->channels);
+ row_info->rowbytes = row_width * row_info->channels;
+ }
+}
+#endif
+
+#ifdef PNG_READ_SHIFT_SUPPORTED
+/* Reverse the effects of png_do_shift. This routine merely shifts the
+ * pixels back to their significant bits values. Thus, if you have
+ * a row of bit depth 8, but only 5 are significant, this will shift
+ * the values back to 0 through 31.
+ */
+void /* PRIVATE */
+png_do_unshift(png_row_infop row_info, png_bytep row,
+ png_const_color_8p sig_bits)
+{
+ int color_type;
+
+ png_debug(1, "in png_do_unshift");
+
+ /* The palette case has already been handled in the _init routine. */
+ color_type = row_info->color_type;
+
+ if (color_type != PNG_COLOR_TYPE_PALETTE)
+ {
+ int shift[4];
+ int channels = 0;
+ int bit_depth = row_info->bit_depth;
+
+ if (color_type & PNG_COLOR_MASK_COLOR)
+ {
+ shift[channels++] = bit_depth - sig_bits->red;
+ shift[channels++] = bit_depth - sig_bits->green;
+ shift[channels++] = bit_depth - sig_bits->blue;
+ }
+
+ else
+ {
+ shift[channels++] = bit_depth - sig_bits->gray;
+ }
+
+ if (color_type & PNG_COLOR_MASK_ALPHA)
+ {
+ shift[channels++] = bit_depth - sig_bits->alpha;
+ }
+
+ {
+ int c, have_shift;
+
+ for (c = have_shift = 0; c < channels; ++c)
+ {
+ /* A shift of more than the bit depth is an error condition but it
+ * gets ignored here.
+ */
+ if (shift[c] <= 0 || shift[c] >= bit_depth)
+ shift[c] = 0;
+
+ else
+ have_shift = 1;
+ }
+
+ if (!have_shift)
+ return;
+ }
+
+ switch (bit_depth)
+ {
+ default:
+ /* Must be 1bpp gray: should not be here! */
+ /* NOTREACHED */
+ break;
+
+ case 2:
+ /* Must be 2bpp gray */
+ /* assert(channels == 1 && shift[0] == 1) */
+ {
+ png_bytep bp = row;
+ png_bytep bp_end = bp + row_info->rowbytes;
+
+ while (bp < bp_end)
+ {
+ int b = (*bp >> 1) & 0x55;
+ *bp++ = (png_byte)b;
+ }
+ break;
+ }
+
+ case 4:
+ /* Must be 4bpp gray */
+ /* assert(channels == 1) */
+ {
+ png_bytep bp = row;
+ png_bytep bp_end = bp + row_info->rowbytes;
+ int gray_shift = shift[0];
+ int mask = 0xf >> gray_shift;
+
+ mask |= mask << 4;
+
+ while (bp < bp_end)
+ {
+ int b = (*bp >> gray_shift) & mask;
+ *bp++ = (png_byte)b;
+ }
+ break;
+ }
+
+ case 8:
+ /* Single byte components, G, GA, RGB, RGBA */
+ {
+ png_bytep bp = row;
+ png_bytep bp_end = bp + row_info->rowbytes;
+ int channel = 0;
+
+ while (bp < bp_end)
+ {
+ int b = *bp >> shift[channel];
+ if (++channel >= channels)
+ channel = 0;
+ *bp++ = (png_byte)b;
+ }
+ break;
+ }
+
+#ifdef PNG_READ_16BIT_SUPPORTED
+ case 16:
+ /* Double byte components, G, GA, RGB, RGBA */
+ {
+ png_bytep bp = row;
+ png_bytep bp_end = bp + row_info->rowbytes;
+ int channel = 0;
+
+ while (bp < bp_end)
+ {
+ int value = (bp[0] << 8) + bp[1];
+
+ value >>= shift[channel];
+ if (++channel >= channels)
+ channel = 0;
+ *bp++ = (png_byte)(value >> 8);
+ *bp++ = (png_byte)(value & 0xff);
+ }
+ break;
+ }
+#endif
+ }
+ }
+}
+#endif
+
+#ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
+/* Scale rows of bit depth 16 down to 8 accurately */
+void /* PRIVATE */
+png_do_scale_16_to_8(png_row_infop row_info, png_bytep row)
+{
+ png_debug(1, "in png_do_scale_16_to_8");
+
+ if (row_info->bit_depth == 16)
+ {
+ png_bytep sp = row; /* source */
+ png_bytep dp = row; /* destination */
+ png_bytep ep = sp + row_info->rowbytes; /* end+1 */
+
+ while (sp < ep)
+ {
+ /* The input is an array of 16 bit components, these must be scaled to
+ * 8 bits each. For a 16 bit value V the required value (from the PNG
+ * specification) is:
+ *
+ * (V * 255) / 65535
+ *
+ * This reduces to round(V / 257), or floor((V + 128.5)/257)
+ *
+ * Represent V as the two byte value vhi.vlo. Make a guess that the
+ * result is the top byte of V, vhi, then the correction to this value
+ * is:
+ *
+ * error = floor(((V-vhi.vhi) + 128.5) / 257)
+ * = floor(((vlo-vhi) + 128.5) / 257)
+ *
+ * This can be approximated using integer arithmetic (and a signed
+ * shift):
+ *
+ * error = (vlo-vhi+128) >> 8;
+ *
+ * The approximate differs from the exact answer only when (vlo-vhi) is
+ * 128; it then gives a correction of +1 when the exact correction is
+ * 0. This gives 128 errors. The exact answer (correct for all 16 bit
+ * input values) is:
+ *
+ * error = (vlo-vhi+128)*65535 >> 24;
+ *
+ * An alternative arithmetic calculation which also gives no errors is:
+ *
+ * (V * 255 + 32895) >> 16
+ */
+
+ png_int_32 tmp = *sp++; /* must be signed! */
+ tmp += (((int)*sp++ - tmp + 128) * 65535) >> 24;
+ *dp++ = (png_byte)tmp;
+ }
+
+ row_info->bit_depth = 8;
+ row_info->pixel_depth = (png_byte)(8 * row_info->channels);
+ row_info->rowbytes = row_info->width * row_info->channels;
+ }
+}
+#endif
+
+#ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
+void /* PRIVATE */
+/* Simply discard the low byte. This was the default behavior prior
+ * to libpng-1.5.4.
+ */
+png_do_chop(png_row_infop row_info, png_bytep row)
+{
+ png_debug(1, "in png_do_chop");
+
+ if (row_info->bit_depth == 16)
+ {
+ png_bytep sp = row; /* source */
+ png_bytep dp = row; /* destination */
+ png_bytep ep = sp + row_info->rowbytes; /* end+1 */
+
+ while (sp < ep)
+ {
+ *dp++ = *sp;
+ sp += 2; /* skip low byte */
+ }
+
+ row_info->bit_depth = 8;
+ row_info->pixel_depth = (png_byte)(8 * row_info->channels);
+ row_info->rowbytes = row_info->width * row_info->channels;
+ }
+}
+#endif
+
+#ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
+void /* PRIVATE */
+png_do_read_swap_alpha(png_row_infop row_info, png_bytep row)
+{
+ png_debug(1, "in png_do_read_swap_alpha");
+
+ {
+ png_uint_32 row_width = row_info->width;
+ if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
+ {
+ /* This converts from RGBA to ARGB */
+ if (row_info->bit_depth == 8)
+ {
+ png_bytep sp = row + row_info->rowbytes;
+ png_bytep dp = sp;
+ png_byte save;
+ png_uint_32 i;
+
+ for (i = 0; i < row_width; i++)
+ {
+ save = *(--sp);
+ *(--dp) = *(--sp);
+ *(--dp) = *(--sp);
+ *(--dp) = *(--sp);
+ *(--dp) = save;
+ }
+ }
+
+#ifdef PNG_READ_16BIT_SUPPORTED
+ /* This converts from RRGGBBAA to AARRGGBB */
+ else
+ {
+ png_bytep sp = row + row_info->rowbytes;
+ png_bytep dp = sp;
+ png_byte save[2];
+ png_uint_32 i;
+
+ for (i = 0; i < row_width; i++)
+ {
+ save[0] = *(--sp);
+ save[1] = *(--sp);
+ *(--dp) = *(--sp);
+ *(--dp) = *(--sp);
+ *(--dp) = *(--sp);
+ *(--dp) = *(--sp);
+ *(--dp) = *(--sp);
+ *(--dp) = *(--sp);
+ *(--dp) = save[0];
+ *(--dp) = save[1];
+ }
+ }
+#endif
+ }
+
+ else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
+ {
+ /* This converts from GA to AG */
+ if (row_info->bit_depth == 8)
+ {
+ png_bytep sp = row + row_info->rowbytes;
+ png_bytep dp = sp;
+ png_byte save;
+ png_uint_32 i;
+
+ for (i = 0; i < row_width; i++)
+ {
+ save = *(--sp);
+ *(--dp) = *(--sp);
+ *(--dp) = save;
+ }
+ }
+
+#ifdef PNG_READ_16BIT_SUPPORTED
+ /* This converts from GGAA to AAGG */
+ else
+ {
+ png_bytep sp = row + row_info->rowbytes;
+ png_bytep dp = sp;
+ png_byte save[2];
+ png_uint_32 i;
+
+ for (i = 0; i < row_width; i++)
+ {
+ save[0] = *(--sp);
+ save[1] = *(--sp);
+ *(--dp) = *(--sp);
+ *(--dp) = *(--sp);
+ *(--dp) = save[0];
+ *(--dp) = save[1];
+ }
+ }
+#endif
+ }
+ }
+}
+#endif
+
+#ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
+void /* PRIVATE */
+png_do_read_invert_alpha(png_row_infop row_info, png_bytep row)
+{
+ png_uint_32 row_width;
+ png_debug(1, "in png_do_read_invert_alpha");
+
+ row_width = row_info->width;
+ if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
+ {
+ if (row_info->bit_depth == 8)
+ {
+ /* This inverts the alpha channel in RGBA */
+ png_bytep sp = row + row_info->rowbytes;
+ png_bytep dp = sp;
+ png_uint_32 i;
+
+ for (i = 0; i < row_width; i++)
+ {
+ *(--dp) = (png_byte)(255 - *(--sp));
+
+/* This does nothing:
+ *(--dp) = *(--sp);
+ *(--dp) = *(--sp);
+ *(--dp) = *(--sp);
+ We can replace it with:
+*/
+ sp-=3;
+ dp=sp;
+ }
+ }
+
+#ifdef PNG_READ_16BIT_SUPPORTED
+ /* This inverts the alpha channel in RRGGBBAA */
+ else
+ {
+ png_bytep sp = row + row_info->rowbytes;
+ png_bytep dp = sp;
+ png_uint_32 i;
+
+ for (i = 0; i < row_width; i++)
+ {
+ *(--dp) = (png_byte)(255 - *(--sp));
+ *(--dp) = (png_byte)(255 - *(--sp));
+
+/* This does nothing:
+ *(--dp) = *(--sp);
+ *(--dp) = *(--sp);
+ *(--dp) = *(--sp);
+ *(--dp) = *(--sp);
+ *(--dp) = *(--sp);
+ *(--dp) = *(--sp);
+ We can replace it with:
+*/
+ sp-=6;
+ dp=sp;
+ }
+ }
+#endif
+ }
+ else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
+ {
+ if (row_info->bit_depth == 8)
+ {
+ /* This inverts the alpha channel in GA */
+ png_bytep sp = row + row_info->rowbytes;
+ png_bytep dp = sp;
+ png_uint_32 i;
+
+ for (i = 0; i < row_width; i++)
+ {
+ *(--dp) = (png_byte)(255 - *(--sp));
+ *(--dp) = *(--sp);
+ }
+ }
+
+#ifdef PNG_READ_16BIT_SUPPORTED
+ else
+ {
+ /* This inverts the alpha channel in GGAA */
+ png_bytep sp = row + row_info->rowbytes;
+ png_bytep dp = sp;
+ png_uint_32 i;
+
+ for (i = 0; i < row_width; i++)
+ {
+ *(--dp) = (png_byte)(255 - *(--sp));
+ *(--dp) = (png_byte)(255 - *(--sp));
+/*
+ *(--dp) = *(--sp);
+ *(--dp) = *(--sp);
+*/
+ sp-=2;
+ dp=sp;
+ }
+ }
+#endif
+ }
+}
+#endif
+
+#ifdef PNG_READ_FILLER_SUPPORTED
+/* Add filler channel if we have RGB color */
+void /* PRIVATE */
+png_do_read_filler(png_row_infop row_info, png_bytep row,
+ png_uint_32 filler, png_uint_32 flags)
+{
+ png_uint_32 i;
+ png_uint_32 row_width = row_info->width;
+
+#ifdef PNG_READ_16BIT_SUPPORTED
+ png_byte hi_filler = (png_byte)((filler>>8) & 0xff);
+#endif
+ png_byte lo_filler = (png_byte)(filler & 0xff);
+
+ png_debug(1, "in png_do_read_filler");
+
+ if (
+ row_info->color_type == PNG_COLOR_TYPE_GRAY)
+ {
+ if (row_info->bit_depth == 8)
+ {
+ if (flags & PNG_FLAG_FILLER_AFTER)
+ {
+ /* This changes the data from G to GX */
+ png_bytep sp = row + (png_size_t)row_width;
+ png_bytep dp = sp + (png_size_t)row_width;
+ for (i = 1; i < row_width; i++)
+ {
+ *(--dp) = lo_filler;
+ *(--dp) = *(--sp);
+ }
+ *(--dp) = lo_filler;
+ row_info->channels = 2;
+ row_info->pixel_depth = 16;
+ row_info->rowbytes = row_width * 2;
+ }
+
+ else
+ {
+ /* This changes the data from G to XG */
+ png_bytep sp = row + (png_size_t)row_width;
+ png_bytep dp = sp + (png_size_t)row_width;
+ for (i = 0; i < row_width; i++)
+ {
+ *(--dp) = *(--sp);
+ *(--dp) = lo_filler;
+ }
+ row_info->channels = 2;
+ row_info->pixel_depth = 16;
+ row_info->rowbytes = row_width * 2;
+ }
+ }
+
+#ifdef PNG_READ_16BIT_SUPPORTED
+ else if (row_info->bit_depth == 16)
+ {
+ if (flags & PNG_FLAG_FILLER_AFTER)
+ {
+ /* This changes the data from GG to GGXX */
+ png_bytep sp = row + (png_size_t)row_width * 2;
+ png_bytep dp = sp + (png_size_t)row_width * 2;
+ for (i = 1; i < row_width; i++)
+ {
+ *(--dp) = hi_filler;
+ *(--dp) = lo_filler;
+ *(--dp) = *(--sp);
+ *(--dp) = *(--sp);
+ }
+ *(--dp) = hi_filler;
+ *(--dp) = lo_filler;
+ row_info->channels = 2;
+ row_info->pixel_depth = 32;
+ row_info->rowbytes = row_width * 4;
+ }
+
+ else
+ {
+ /* This changes the data from GG to XXGG */
+ png_bytep sp = row + (png_size_t)row_width * 2;
+ png_bytep dp = sp + (png_size_t)row_width * 2;
+ for (i = 0; i < row_width; i++)
+ {
+ *(--dp) = *(--sp);
+ *(--dp) = *(--sp);
+ *(--dp) = hi_filler;
+ *(--dp) = lo_filler;
+ }
+ row_info->channels = 2;
+ row_info->pixel_depth = 32;
+ row_info->rowbytes = row_width * 4;
+ }
+ }
+#endif
+ } /* COLOR_TYPE == GRAY */
+ else if (row_info->color_type == PNG_COLOR_TYPE_RGB)
+ {
+ if (row_info->bit_depth == 8)
+ {
+ if (flags & PNG_FLAG_FILLER_AFTER)
+ {
+ /* This changes the data from RGB to RGBX */
+ png_bytep sp = row + (png_size_t)row_width * 3;
+ png_bytep dp = sp + (png_size_t)row_width;
+ for (i = 1; i < row_width; i++)
+ {
+ *(--dp) = lo_filler;
+ *(--dp) = *(--sp);
+ *(--dp) = *(--sp);
+ *(--dp) = *(--sp);
+ }
+ *(--dp) = lo_filler;
+ row_info->channels = 4;
+ row_info->pixel_depth = 32;
+ row_info->rowbytes = row_width * 4;
+ }
+
+ else
+ {
+ /* This changes the data from RGB to XRGB */
+ png_bytep sp = row + (png_size_t)row_width * 3;
+ png_bytep dp = sp + (png_size_t)row_width;
+ for (i = 0; i < row_width; i++)
+ {
+ *(--dp) = *(--sp);
+ *(--dp) = *(--sp);
+ *(--dp) = *(--sp);
+ *(--dp) = lo_filler;
+ }
+ row_info->channels = 4;
+ row_info->pixel_depth = 32;
+ row_info->rowbytes = row_width * 4;
+ }
+ }
+
+#ifdef PNG_READ_16BIT_SUPPORTED
+ else if (row_info->bit_depth == 16)
+ {
+ if (flags & PNG_FLAG_FILLER_AFTER)
+ {
+ /* This changes the data from RRGGBB to RRGGBBXX */
+ png_bytep sp = row + (png_size_t)row_width * 6;
+ png_bytep dp = sp + (png_size_t)row_width * 2;
+ for (i = 1; i < row_width; i++)
+ {
+ *(--dp) = hi_filler;
+ *(--dp) = lo_filler;
+ *(--dp) = *(--sp);
+ *(--dp) = *(--sp);
+ *(--dp) = *(--sp);
+ *(--dp) = *(--sp);
+ *(--dp) = *(--sp);
+ *(--dp) = *(--sp);
+ }
+ *(--dp) = hi_filler;
+ *(--dp) = lo_filler;
+ row_info->channels = 4;
+ row_info->pixel_depth = 64;
+ row_info->rowbytes = row_width * 8;
+ }
+
+ else
+ {
+ /* This changes the data from RRGGBB to XXRRGGBB */
+ png_bytep sp = row + (png_size_t)row_width * 6;
+ png_bytep dp = sp + (png_size_t)row_width * 2;
+ for (i = 0; i < row_width; i++)
+ {
+ *(--dp) = *(--sp);
+ *(--dp) = *(--sp);
+ *(--dp) = *(--sp);
+ *(--dp) = *(--sp);
+ *(--dp) = *(--sp);
+ *(--dp) = *(--sp);
+ *(--dp) = hi_filler;
+ *(--dp) = lo_filler;
+ }
+
+ row_info->channels = 4;
+ row_info->pixel_depth = 64;
+ row_info->rowbytes = row_width * 8;
+ }
+ }
+#endif
+ } /* COLOR_TYPE == RGB */
+}
+#endif
+
+#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
+/* Expand grayscale files to RGB, with or without alpha */
+void /* PRIVATE */
+png_do_gray_to_rgb(png_row_infop row_info, png_bytep row)
+{
+ png_uint_32 i;
+ png_uint_32 row_width = row_info->width;
+
+ png_debug(1, "in png_do_gray_to_rgb");
+
+ if (row_info->bit_depth >= 8 &&
+ !(row_info->color_type & PNG_COLOR_MASK_COLOR))
+ {
+ if (row_info->color_type == PNG_COLOR_TYPE_GRAY)
+ {
+ if (row_info->bit_depth == 8)
+ {
+ /* This changes G to RGB */
+ png_bytep sp = row + (png_size_t)row_width - 1;
+ png_bytep dp = sp + (png_size_t)row_width * 2;
+ for (i = 0; i < row_width; i++)
+ {
+ *(dp--) = *sp;
+ *(dp--) = *sp;
+ *(dp--) = *(sp--);
+ }
+ }
+
+ else
+ {
+ /* This changes GG to RRGGBB */
+ png_bytep sp = row + (png_size_t)row_width * 2 - 1;
+ png_bytep dp = sp + (png_size_t)row_width * 4;
+ for (i = 0; i < row_width; i++)
+ {
+ *(dp--) = *sp;
+ *(dp--) = *(sp - 1);
+ *(dp--) = *sp;
+ *(dp--) = *(sp - 1);
+ *(dp--) = *(sp--);
+ *(dp--) = *(sp--);
+ }
+ }
+ }
+
+ else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
+ {
+ if (row_info->bit_depth == 8)
+ {
+ /* This changes GA to RGBA */
+ png_bytep sp = row + (png_size_t)row_width * 2 - 1;
+ png_bytep dp = sp + (png_size_t)row_width * 2;
+ for (i = 0; i < row_width; i++)
+ {
+ *(dp--) = *(sp--);
+ *(dp--) = *sp;
+ *(dp--) = *sp;
+ *(dp--) = *(sp--);
+ }
+ }
+
+ else
+ {
+ /* This changes GGAA to RRGGBBAA */
+ png_bytep sp = row + (png_size_t)row_width * 4 - 1;
+ png_bytep dp = sp + (png_size_t)row_width * 4;
+ for (i = 0; i < row_width; i++)
+ {
+ *(dp--) = *(sp--);
+ *(dp--) = *(sp--);
+ *(dp--) = *sp;
+ *(dp--) = *(sp - 1);
+ *(dp--) = *sp;
+ *(dp--) = *(sp - 1);
+ *(dp--) = *(sp--);
+ *(dp--) = *(sp--);
+ }
+ }
+ }
+ row_info->channels = (png_byte)(row_info->channels + 2);
+ row_info->color_type |= PNG_COLOR_MASK_COLOR;
+ row_info->pixel_depth = (png_byte)(row_info->channels *
+ row_info->bit_depth);
+ row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
+ }
+}
+#endif
+
+#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
+/* Reduce RGB files to grayscale, with or without alpha
+ * using the equation given in Poynton's ColorFAQ of 1998-01-04 at
+ * <http://www.inforamp.net/~poynton/> (THIS LINK IS DEAD June 2008 but
+ * versions dated 1998 through November 2002 have been archived at
+ * http://web.archive.org/web/20000816232553/http://www.inforamp.net/
+ * ~poynton/notes/colour_and_gamma/ColorFAQ.txt )
+ * Charles Poynton poynton at poynton.com
+ *
+ * Y = 0.212671 * R + 0.715160 * G + 0.072169 * B
+ *
+ * which can be expressed with integers as
+ *
+ * Y = (6969 * R + 23434 * G + 2365 * B)/32768
+ *
+ * Poynton's current link (as of January 2003 through July 2011):
+ * <http://www.poynton.com/notes/colour_and_gamma/>
+ * has changed the numbers slightly:
+ *
+ * Y = 0.2126*R + 0.7152*G + 0.0722*B
+ *
+ * which can be expressed with integers as
+ *
+ * Y = (6966 * R + 23436 * G + 2366 * B)/32768
+ *
+ * Historically, however, libpng uses numbers derived from the ITU-R Rec 709
+ * end point chromaticities and the D65 white point. Depending on the
+ * precision used for the D65 white point this produces a variety of different
+ * numbers, however if the four decimal place value used in ITU-R Rec 709 is
+ * used (0.3127,0.3290) the Y calculation would be:
+ *
+ * Y = (6968 * R + 23435 * G + 2366 * B)/32768
+ *
+ * While this is correct the rounding results in an overflow for white, because
+ * the sum of the rounded coefficients is 32769, not 32768. Consequently
+ * libpng uses, instead, the closest non-overflowing approximation:
+ *
+ * Y = (6968 * R + 23434 * G + 2366 * B)/32768
+ *
+ * Starting with libpng-1.5.5, if the image being converted has a cHRM chunk
+ * (including an sRGB chunk) then the chromaticities are used to calculate the
+ * coefficients. See the chunk handling in pngrutil.c for more information.
+ *
+ * In all cases the calculation is to be done in a linear colorspace. If no
+ * gamma information is available to correct the encoding of the original RGB
+ * values this results in an implicit assumption that the original PNG RGB
+ * values were linear.
+ *
+ * Other integer coefficents can be used via png_set_rgb_to_gray(). Because
+ * the API takes just red and green coefficients the blue coefficient is
+ * calculated to make the sum 32768. This will result in different rounding
+ * to that used above.
+ */
+int /* PRIVATE */
+png_do_rgb_to_gray(png_structrp png_ptr, png_row_infop row_info, png_bytep row)
+
+{
+ int rgb_error = 0;
+
+ png_debug(1, "in png_do_rgb_to_gray");
+
+ if (!(row_info->color_type & PNG_COLOR_MASK_PALETTE) &&
+ (row_info->color_type & PNG_COLOR_MASK_COLOR))
+ {
+ PNG_CONST png_uint_32 rc = png_ptr->rgb_to_gray_red_coeff;
+ PNG_CONST png_uint_32 gc = png_ptr->rgb_to_gray_green_coeff;
+ PNG_CONST png_uint_32 bc = 32768 - rc - gc;
+ PNG_CONST png_uint_32 row_width = row_info->width;
+ PNG_CONST int have_alpha =
+ (row_info->color_type & PNG_COLOR_MASK_ALPHA) != 0;
+
+ if (row_info->bit_depth == 8)
+ {
+#ifdef PNG_READ_GAMMA_SUPPORTED
+ /* Notice that gamma to/from 1 are not necessarily inverses (if
+ * there is an overall gamma correction). Prior to 1.5.5 this code
+ * checked the linearized values for equality; this doesn't match
+ * the documentation, the original values must be checked.
+ */
+ if (png_ptr->gamma_from_1 != NULL && png_ptr->gamma_to_1 != NULL)
+ {
+ png_bytep sp = row;
+ png_bytep dp = row;
+ png_uint_32 i;
+
+ for (i = 0; i < row_width; i++)
+ {
+ png_byte red = *(sp++);
+ png_byte green = *(sp++);
+ png_byte blue = *(sp++);
+
+ if (red != green || red != blue)
+ {
+ red = png_ptr->gamma_to_1[red];
+ green = png_ptr->gamma_to_1[green];
+ blue = png_ptr->gamma_to_1[blue];
+
+ rgb_error |= 1;
+ *(dp++) = png_ptr->gamma_from_1[
+ (rc*red + gc*green + bc*blue + 16384)>>15];
+ }
+
+ else
+ {
+ /* If there is no overall correction the table will not be
+ * set.
+ */
+ if (png_ptr->gamma_table != NULL)
+ red = png_ptr->gamma_table[red];
+
+ *(dp++) = red;
+ }
+
+ if (have_alpha)
+ *(dp++) = *(sp++);
+ }
+ }
+ else
+#endif
+ {
+ png_bytep sp = row;
+ png_bytep dp = row;
+ png_uint_32 i;
+
+ for (i = 0; i < row_width; i++)
+ {
+ png_byte red = *(sp++);
+ png_byte green = *(sp++);
+ png_byte blue = *(sp++);
+
+ if (red != green || red != blue)
+ {
+ rgb_error |= 1;
+ /* NOTE: this is the historical approach which simply
+ * truncates the results.
+ */
+ *(dp++) = (png_byte)((rc*red + gc*green + bc*blue)>>15);
+ }
+
+ else
+ *(dp++) = red;
+
+ if (have_alpha)
+ *(dp++) = *(sp++);
+ }
+ }
+ }
+
+ else /* RGB bit_depth == 16 */
+ {
+#ifdef PNG_READ_GAMMA_SUPPORTED
+ if (png_ptr->gamma_16_to_1 != NULL && png_ptr->gamma_16_from_1 != NULL)
+ {
+ png_bytep sp = row;
+ png_bytep dp = row;
+ png_uint_32 i;
+
+ for (i = 0; i < row_width; i++)
+ {
+ png_uint_16 red, green, blue, w;
+
+ red = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
+ green = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
+ blue = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
+
+ if (red == green && red == blue)
+ {
+ if (png_ptr->gamma_16_table != NULL)
+ w = png_ptr->gamma_16_table[(red&0xff)
+ >> png_ptr->gamma_shift][red>>8];
+
+ else
+ w = red;
+ }
+
+ else
+ {
+ png_uint_16 red_1 = png_ptr->gamma_16_to_1[(red&0xff)
+ >> png_ptr->gamma_shift][red>>8];
+ png_uint_16 green_1 =
+ png_ptr->gamma_16_to_1[(green&0xff) >>
+ png_ptr->gamma_shift][green>>8];
+ png_uint_16 blue_1 = png_ptr->gamma_16_to_1[(blue&0xff)
+ >> png_ptr->gamma_shift][blue>>8];
+ png_uint_16 gray16 = (png_uint_16)((rc*red_1 + gc*green_1
+ + bc*blue_1 + 16384)>>15);
+ w = png_ptr->gamma_16_from_1[(gray16&0xff) >>
+ png_ptr->gamma_shift][gray16 >> 8];
+ rgb_error |= 1;
+ }
+
+ *(dp++) = (png_byte)((w>>8) & 0xff);
+ *(dp++) = (png_byte)(w & 0xff);
+
+ if (have_alpha)
+ {
+ *(dp++) = *(sp++);
+ *(dp++) = *(sp++);
+ }
+ }
+ }
+ else
+#endif
+ {
+ png_bytep sp = row;
+ png_bytep dp = row;
+ png_uint_32 i;
+
+ for (i = 0; i < row_width; i++)
+ {
+ png_uint_16 red, green, blue, gray16;
+
+ red = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
+ green = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
+ blue = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
+
+ if (red != green || red != blue)
+ rgb_error |= 1;
+
+ /* From 1.5.5 in the 16 bit case do the accurate conversion even
+ * in the 'fast' case - this is because this is where the code
+ * ends up when handling linear 16 bit data.
+ */
+ gray16 = (png_uint_16)((rc*red + gc*green + bc*blue + 16384) >>
+ 15);
+ *(dp++) = (png_byte)((gray16>>8) & 0xff);
+ *(dp++) = (png_byte)(gray16 & 0xff);
+
+ if (have_alpha)
+ {
+ *(dp++) = *(sp++);
+ *(dp++) = *(sp++);
+ }
+ }
+ }
+ }
+
+ row_info->channels = (png_byte)(row_info->channels - 2);
+ row_info->color_type = (png_byte)(row_info->color_type &
+ ~PNG_COLOR_MASK_COLOR);
+ row_info->pixel_depth = (png_byte)(row_info->channels *
+ row_info->bit_depth);
+ row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
+ }
+ return rgb_error;
+}
+#endif
+#endif /* PNG_READ_TRANSFORMS_SUPPORTED */
+
+#ifdef PNG_BUILD_GRAYSCALE_PALETTE_SUPPORTED
+/* Build a grayscale palette. Palette is assumed to be 1 << bit_depth
+ * large of png_color. This lets grayscale images be treated as
+ * paletted. Most useful for gamma correction and simplification
+ * of code. This API is not used internally.
+ */
+void PNGAPI
+png_build_grayscale_palette(int bit_depth, png_colorp palette)
+{
+ int num_palette;
+ int color_inc;
+ int i;
+ int v;
+
+ png_debug(1, "in png_do_build_grayscale_palette");
+
+ if (palette == NULL)
+ return;
+
+ switch (bit_depth)
+ {
+ case 1:
+ num_palette = 2;
+ color_inc = 0xff;
+ break;
+
+ case 2:
+ num_palette = 4;
+ color_inc = 0x55;
+ break;
+
+ case 4:
+ num_palette = 16;
+ color_inc = 0x11;
+ break;
+
+ case 8:
+ num_palette = 256;
+ color_inc = 1;
+ break;
+
+ default:
+ num_palette = 0;
+ color_inc = 0;
+ break;
+ }
+
+ for (i = 0, v = 0; i < num_palette; i++, v += color_inc)
+ {
+ palette[i].red = (png_byte)v;
+ palette[i].green = (png_byte)v;
+ palette[i].blue = (png_byte)v;
+ }
+}
+#endif
+
+
+#ifdef PNG_READ_TRANSFORMS_SUPPORTED
+#if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
+ defined(PNG_READ_ALPHA_MODE_SUPPORTED)
+/* Replace any alpha or transparency with the supplied background color.
+ * "background" is already in the screen gamma, while "background_1" is
+ * at a gamma of 1.0. Paletted files have already been taken care of.
+ */
+void /* PRIVATE */
+png_do_compose(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
+{
+#ifdef PNG_READ_GAMMA_SUPPORTED
+ png_const_bytep gamma_table = png_ptr->gamma_table;
+ png_const_bytep gamma_from_1 = png_ptr->gamma_from_1;
+ png_const_bytep gamma_to_1 = png_ptr->gamma_to_1;
+ png_const_uint_16pp gamma_16 = png_ptr->gamma_16_table;
+ png_const_uint_16pp gamma_16_from_1 = png_ptr->gamma_16_from_1;
+ png_const_uint_16pp gamma_16_to_1 = png_ptr->gamma_16_to_1;
+ int gamma_shift = png_ptr->gamma_shift;
+ int optimize = (png_ptr->flags & PNG_FLAG_OPTIMIZE_ALPHA) != 0;
+#endif
+
+ png_bytep sp;
+ png_uint_32 i;
+ png_uint_32 row_width = row_info->width;
+ int shift;
+
+ png_debug(1, "in png_do_compose");
+
+ {
+ switch (row_info->color_type)
+ {
+ case PNG_COLOR_TYPE_GRAY:
+ {
+ switch (row_info->bit_depth)
+ {
+ case 1:
+ {
+ sp = row;
+ shift = 7;
+ for (i = 0; i < row_width; i++)
+ {
+ if ((png_uint_16)((*sp >> shift) & 0x01)
+ == png_ptr->trans_color.gray)
+ {
+ unsigned int tmp = *sp & (0x7f7f >> (7 - shift));
+ tmp |= png_ptr->background.gray << shift;
+ *sp = (png_byte)(tmp & 0xff);
+ }
+
+ if (!shift)
+ {
+ shift = 7;
+ sp++;
+ }
+
+ else
+ shift--;
+ }
+ break;
+ }
+
+ case 2:
+ {
+#ifdef PNG_READ_GAMMA_SUPPORTED
+ if (gamma_table != NULL)
+ {
+ sp = row;
+ shift = 6;
+ for (i = 0; i < row_width; i++)
+ {
+ if ((png_uint_16)((*sp >> shift) & 0x03)
+ == png_ptr->trans_color.gray)
+ {
+ unsigned int tmp = *sp & (0x3f3f >> (6 - shift));
+ tmp |= png_ptr->background.gray << shift;
+ *sp = (png_byte)(tmp & 0xff);
+ }
+
+ else
+ {
+ unsigned int p = (*sp >> shift) & 0x03;
+ unsigned int g = (gamma_table [p | (p << 2) |
+ (p << 4) | (p << 6)] >> 6) & 0x03;
+ unsigned int tmp = *sp & (0x3f3f >> (6 - shift));
+ tmp |= g << shift;
+ *sp = (png_byte)(tmp & 0xff);
+ }
+
+ if (!shift)
+ {
+ shift = 6;
+ sp++;
+ }
+
+ else
+ shift -= 2;
+ }
+ }
+
+ else
+#endif
+ {
+ sp = row;
+ shift = 6;
+ for (i = 0; i < row_width; i++)
+ {
+ if ((png_uint_16)((*sp >> shift) & 0x03)
+ == png_ptr->trans_color.gray)
+ {
+ unsigned int tmp = *sp & (0x3f3f >> (6 - shift));
+ tmp |= png_ptr->background.gray << shift;
+ *sp = (png_byte)(tmp & 0xff);
+ }
+
+ if (!shift)
+ {
+ shift = 6;
+ sp++;
+ }
+
+ else
+ shift -= 2;
+ }
+ }
+ break;
+ }
+
+ case 4:
+ {
+#ifdef PNG_READ_GAMMA_SUPPORTED
+ if (gamma_table != NULL)
+ {
+ sp = row;
+ shift = 4;
+ for (i = 0; i < row_width; i++)
+ {
+ if ((png_uint_16)((*sp >> shift) & 0x0f)
+ == png_ptr->trans_color.gray)
+ {
+ unsigned int tmp = *sp & (0xf0f >> (4 - shift));
+ tmp |= png_ptr->background.gray << shift;
+ *sp = (png_byte)(tmp & 0xff);
+ }
+
+ else
+ {
+ unsigned int p = (*sp >> shift) & 0x0f;
+ unsigned int g = (gamma_table[p | (p << 4)] >> 4) &
+ 0x0f;
+ unsigned int tmp = *sp & (0xf0f >> (4 - shift));
+ tmp |= g << shift;
+ *sp = (png_byte)(tmp & 0xff);
+ }
+
+ if (!shift)
+ {
+ shift = 4;
+ sp++;
+ }
+
+ else
+ shift -= 4;
+ }
+ }
+
+ else
+#endif
+ {
+ sp = row;
+ shift = 4;
+ for (i = 0; i < row_width; i++)
+ {
+ if ((png_uint_16)((*sp >> shift) & 0x0f)
+ == png_ptr->trans_color.gray)
+ {
+ unsigned int tmp = *sp & (0xf0f >> (4 - shift));
+ tmp |= png_ptr->background.gray << shift;
+ *sp = (png_byte)(tmp & 0xff);
+ }
+
+ if (!shift)
+ {
+ shift = 4;
+ sp++;
+ }
+
+ else
+ shift -= 4;
+ }
+ }
+ break;
+ }
+
+ case 8:
+ {
+#ifdef PNG_READ_GAMMA_SUPPORTED
+ if (gamma_table != NULL)
+ {
+ sp = row;
+ for (i = 0; i < row_width; i++, sp++)
+ {
+ if (*sp == png_ptr->trans_color.gray)
+ *sp = (png_byte)png_ptr->background.gray;
+
+ else
+ *sp = gamma_table[*sp];
+ }
+ }
+ else
+#endif
+ {
+ sp = row;
+ for (i = 0; i < row_width; i++, sp++)
+ {
+ if (*sp == png_ptr->trans_color.gray)
+ *sp = (png_byte)png_ptr->background.gray;
+ }
+ }
+ break;
+ }
+
+ case 16:
+ {
+#ifdef PNG_READ_GAMMA_SUPPORTED
+ if (gamma_16 != NULL)
+ {
+ sp = row;
+ for (i = 0; i < row_width; i++, sp += 2)
+ {
+ png_uint_16 v;
+
+ v = (png_uint_16)(((*sp) << 8) + *(sp + 1));
+
+ if (v == png_ptr->trans_color.gray)
+ {
+ /* Background is already in screen gamma */
+ *sp = (png_byte)((png_ptr->background.gray >> 8)
+ & 0xff);
+ *(sp + 1) = (png_byte)(png_ptr->background.gray
+ & 0xff);
+ }
+
+ else
+ {
+ v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
+ *sp = (png_byte)((v >> 8) & 0xff);
+ *(sp + 1) = (png_byte)(v & 0xff);
+ }
+ }
+ }
+ else
+#endif
+ {
+ sp = row;
+ for (i = 0; i < row_width; i++, sp += 2)
+ {
+ png_uint_16 v;
+
+ v = (png_uint_16)(((*sp) << 8) + *(sp + 1));
+
+ if (v == png_ptr->trans_color.gray)
+ {
+ *sp = (png_byte)((png_ptr->background.gray >> 8)
+ & 0xff);
+ *(sp + 1) = (png_byte)(png_ptr->background.gray
+ & 0xff);
+ }
+ }
+ }
+ break;
+ }
+
+ default:
+ break;
+ }
+ break;
+ }
+
+ case PNG_COLOR_TYPE_RGB:
+ {
+ if (row_info->bit_depth == 8)
+ {
+#ifdef PNG_READ_GAMMA_SUPPORTED
+ if (gamma_table != NULL)
+ {
+ sp = row;
+ for (i = 0; i < row_width; i++, sp += 3)
+ {
+ if (*sp == png_ptr->trans_color.red &&
+ *(sp + 1) == png_ptr->trans_color.green &&
+ *(sp + 2) == png_ptr->trans_color.blue)
+ {
+ *sp = (png_byte)png_ptr->background.red;
+ *(sp + 1) = (png_byte)png_ptr->background.green;
+ *(sp + 2) = (png_byte)png_ptr->background.blue;
+ }
+
+ else
+ {
+ *sp = gamma_table[*sp];
+ *(sp + 1) = gamma_table[*(sp + 1)];
+ *(sp + 2) = gamma_table[*(sp + 2)];
+ }
+ }
+ }
+ else
+#endif
+ {
+ sp = row;
+ for (i = 0; i < row_width; i++, sp += 3)
+ {
+ if (*sp == png_ptr->trans_color.red &&
+ *(sp + 1) == png_ptr->trans_color.green &&
+ *(sp + 2) == png_ptr->trans_color.blue)
+ {
+ *sp = (png_byte)png_ptr->background.red;
+ *(sp + 1) = (png_byte)png_ptr->background.green;
+ *(sp + 2) = (png_byte)png_ptr->background.blue;
+ }
+ }
+ }
+ }
+ else /* if (row_info->bit_depth == 16) */
+ {
+#ifdef PNG_READ_GAMMA_SUPPORTED
+ if (gamma_16 != NULL)
+ {
+ sp = row;
+ for (i = 0; i < row_width; i++, sp += 6)
+ {
+ png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1));
+
+ png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8)
+ + *(sp + 3));
+
+ png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8)
+ + *(sp + 5));
+
+ if (r == png_ptr->trans_color.red &&
+ g == png_ptr->trans_color.green &&
+ b == png_ptr->trans_color.blue)
+ {
+ /* Background is already in screen gamma */
+ *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
+ *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
+ *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
+ & 0xff);
+ *(sp + 3) = (png_byte)(png_ptr->background.green
+ & 0xff);
+ *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
+ & 0xff);
+ *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
+ }
+
+ else
+ {
+ png_uint_16 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
+ *sp = (png_byte)((v >> 8) & 0xff);
+ *(sp + 1) = (png_byte)(v & 0xff);
+
+ v = gamma_16[*(sp + 3) >> gamma_shift][*(sp + 2)];
+ *(sp + 2) = (png_byte)((v >> 8) & 0xff);
+ *(sp + 3) = (png_byte)(v & 0xff);
+
+ v = gamma_16[*(sp + 5) >> gamma_shift][*(sp + 4)];
+ *(sp + 4) = (png_byte)((v >> 8) & 0xff);
+ *(sp + 5) = (png_byte)(v & 0xff);
+ }
+ }
+ }
+
+ else
+#endif
+ {
+ sp = row;
+ for (i = 0; i < row_width; i++, sp += 6)
+ {
+ png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1));
+
+ png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8)
+ + *(sp + 3));
+
+ png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8)
+ + *(sp + 5));
+
+ if (r == png_ptr->trans_color.red &&
+ g == png_ptr->trans_color.green &&
+ b == png_ptr->trans_color.blue)
+ {
+ *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
+ *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
+ *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
+ & 0xff);
+ *(sp + 3) = (png_byte)(png_ptr->background.green
+ & 0xff);
+ *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
+ & 0xff);
+ *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
+ }
+ }
+ }
+ }
+ break;
+ }
+
+ case PNG_COLOR_TYPE_GRAY_ALPHA:
+ {
+ if (row_info->bit_depth == 8)
+ {
+#ifdef PNG_READ_GAMMA_SUPPORTED
+ if (gamma_to_1 != NULL && gamma_from_1 != NULL &&
+ gamma_table != NULL)
+ {
+ sp = row;
+ for (i = 0; i < row_width; i++, sp += 2)
+ {
+ png_uint_16 a = *(sp + 1);
+
+ if (a == 0xff)
+ *sp = gamma_table[*sp];
+
+ else if (a == 0)
+ {
+ /* Background is already in screen gamma */
+ *sp = (png_byte)png_ptr->background.gray;
+ }
+
+ else
+ {
+ png_byte v, w;
+
+ v = gamma_to_1[*sp];
+ png_composite(w, v, a, png_ptr->background_1.gray);
+ if (!optimize)
+ w = gamma_from_1[w];
+ *sp = w;
+ }
+ }
+ }
+ else
+#endif
+ {
+ sp = row;
+ for (i = 0; i < row_width; i++, sp += 2)
+ {
+ png_byte a = *(sp + 1);
+
+ if (a == 0)
+ *sp = (png_byte)png_ptr->background.gray;
+
+ else if (a < 0xff)
+ png_composite(*sp, *sp, a, png_ptr->background.gray);
+ }
+ }
+ }
+ else /* if (png_ptr->bit_depth == 16) */
+ {
+#ifdef PNG_READ_GAMMA_SUPPORTED
+ if (gamma_16 != NULL && gamma_16_from_1 != NULL &&
+ gamma_16_to_1 != NULL)
+ {
+ sp = row;
+ for (i = 0; i < row_width; i++, sp += 4)
+ {
+ png_uint_16 a = (png_uint_16)(((*(sp + 2)) << 8)
+ + *(sp + 3));
+
+ if (a == (png_uint_16)0xffff)
+ {
+ png_uint_16 v;
+
+ v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
+ *sp = (png_byte)((v >> 8) & 0xff);
+ *(sp + 1) = (png_byte)(v & 0xff);
+ }
+
+ else if (a == 0)
+ {
+ /* Background is already in screen gamma */
+ *sp = (png_byte)((png_ptr->background.gray >> 8)
+ & 0xff);
+ *(sp + 1) = (png_byte)(png_ptr->background.gray & 0xff);
+ }
+
+ else
+ {
+ png_uint_16 g, v, w;
+
+ g = gamma_16_to_1[*(sp + 1) >> gamma_shift][*sp];
+ png_composite_16(v, g, a, png_ptr->background_1.gray);
+ if (optimize)
+ w = v;
+ else
+ w = gamma_16_from_1[(v&0xff) >> gamma_shift][v >> 8];
+ *sp = (png_byte)((w >> 8) & 0xff);
+ *(sp + 1) = (png_byte)(w & 0xff);
+ }
+ }
+ }
+ else
+#endif
+ {
+ sp = row;
+ for (i = 0; i < row_width; i++, sp += 4)
+ {
+ png_uint_16 a = (png_uint_16)(((*(sp + 2)) << 8)
+ + *(sp + 3));
+
+ if (a == 0)
+ {
+ *sp = (png_byte)((png_ptr->background.gray >> 8)
+ & 0xff);
+ *(sp + 1) = (png_byte)(png_ptr->background.gray & 0xff);
+ }
+
+ else if (a < 0xffff)
+ {
+ png_uint_16 g, v;
+
+ g = (png_uint_16)(((*sp) << 8) + *(sp + 1));
+ png_composite_16(v, g, a, png_ptr->background.gray);
+ *sp = (png_byte)((v >> 8) & 0xff);
+ *(sp + 1) = (png_byte)(v & 0xff);
+ }
+ }
+ }
+ }
+ break;
+ }
+
+ case PNG_COLOR_TYPE_RGB_ALPHA:
+ {
+ if (row_info->bit_depth == 8)
+ {
+#ifdef PNG_READ_GAMMA_SUPPORTED
+ if (gamma_to_1 != NULL && gamma_from_1 != NULL &&
+ gamma_table != NULL)
+ {
+ sp = row;
+ for (i = 0; i < row_width; i++, sp += 4)
+ {
+ png_byte a = *(sp + 3);
+
+ if (a == 0xff)
+ {
+ *sp = gamma_table[*sp];
+ *(sp + 1) = gamma_table[*(sp + 1)];
+ *(sp + 2) = gamma_table[*(sp + 2)];
+ }
+
+ else if (a == 0)
+ {
+ /* Background is already in screen gamma */
+ *sp = (png_byte)png_ptr->background.red;
+ *(sp + 1) = (png_byte)png_ptr->background.green;
+ *(sp + 2) = (png_byte)png_ptr->background.blue;
+ }
+
+ else
+ {
+ png_byte v, w;
+
+ v = gamma_to_1[*sp];
+ png_composite(w, v, a, png_ptr->background_1.red);
+ if (!optimize) w = gamma_from_1[w];
+ *sp = w;
+
+ v = gamma_to_1[*(sp + 1)];
+ png_composite(w, v, a, png_ptr->background_1.green);
+ if (!optimize) w = gamma_from_1[w];
+ *(sp + 1) = w;
+
+ v = gamma_to_1[*(sp + 2)];
+ png_composite(w, v, a, png_ptr->background_1.blue);
+ if (!optimize) w = gamma_from_1[w];
+ *(sp + 2) = w;
+ }
+ }
+ }
+ else
+#endif
+ {
+ sp = row;
+ for (i = 0; i < row_width; i++, sp += 4)
+ {
+ png_byte a = *(sp + 3);
+
+ if (a == 0)
+ {
+ *sp = (png_byte)png_ptr->background.red;
+ *(sp + 1) = (png_byte)png_ptr->background.green;
+ *(sp + 2) = (png_byte)png_ptr->background.blue;
+ }
+
+ else if (a < 0xff)
+ {
+ png_composite(*sp, *sp, a, png_ptr->background.red);
+
+ png_composite(*(sp + 1), *(sp + 1), a,
+ png_ptr->background.green);
+
+ png_composite(*(sp + 2), *(sp + 2), a,
+ png_ptr->background.blue);
+ }
+ }
+ }
+ }
+ else /* if (row_info->bit_depth == 16) */
+ {
+#ifdef PNG_READ_GAMMA_SUPPORTED
+ if (gamma_16 != NULL && gamma_16_from_1 != NULL &&
+ gamma_16_to_1 != NULL)
+ {
+ sp = row;
+ for (i = 0; i < row_width; i++, sp += 8)
+ {
+ png_uint_16 a = (png_uint_16)(((png_uint_16)(*(sp + 6))
+ << 8) + (png_uint_16)(*(sp + 7)));
+
+ if (a == (png_uint_16)0xffff)
+ {
+ png_uint_16 v;
+
+ v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
+ *sp = (png_byte)((v >> 8) & 0xff);
+ *(sp + 1) = (png_byte)(v & 0xff);
+
+ v = gamma_16[*(sp + 3) >> gamma_shift][*(sp + 2)];
+ *(sp + 2) = (png_byte)((v >> 8) & 0xff);
+ *(sp + 3) = (png_byte)(v & 0xff);
+
+ v = gamma_16[*(sp + 5) >> gamma_shift][*(sp + 4)];
+ *(sp + 4) = (png_byte)((v >> 8) & 0xff);
+ *(sp + 5) = (png_byte)(v & 0xff);
+ }
+
+ else if (a == 0)
+ {
+ /* Background is already in screen gamma */
+ *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
+ *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
+ *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
+ & 0xff);
+ *(sp + 3) = (png_byte)(png_ptr->background.green
+ & 0xff);
+ *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
+ & 0xff);
+ *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
+ }
+
+ else
+ {
+ png_uint_16 v, w;
+
+ v = gamma_16_to_1[*(sp + 1) >> gamma_shift][*sp];
+ png_composite_16(w, v, a, png_ptr->background_1.red);
+ if (!optimize)
+ w = gamma_16_from_1[((w&0xff) >> gamma_shift)][w >>
+ 8];
+ *sp = (png_byte)((w >> 8) & 0xff);
+ *(sp + 1) = (png_byte)(w & 0xff);
+
+ v = gamma_16_to_1[*(sp + 3) >> gamma_shift][*(sp + 2)];
+ png_composite_16(w, v, a, png_ptr->background_1.green);
+ if (!optimize)
+ w = gamma_16_from_1[((w&0xff) >> gamma_shift)][w >>
+ 8];
+
+ *(sp + 2) = (png_byte)((w >> 8) & 0xff);
+ *(sp + 3) = (png_byte)(w & 0xff);
+
+ v = gamma_16_to_1[*(sp + 5) >> gamma_shift][*(sp + 4)];
+ png_composite_16(w, v, a, png_ptr->background_1.blue);
+ if (!optimize)
+ w = gamma_16_from_1[((w&0xff) >> gamma_shift)][w >>
+ 8];
+
+ *(sp + 4) = (png_byte)((w >> 8) & 0xff);
+ *(sp + 5) = (png_byte)(w & 0xff);
+ }
+ }
+ }
+
+ else
+#endif
+ {
+ sp = row;
+ for (i = 0; i < row_width; i++, sp += 8)
+ {
+ png_uint_16 a = (png_uint_16)(((png_uint_16)(*(sp + 6))
+ << 8) + (png_uint_16)(*(sp + 7)));
+
+ if (a == 0)
+ {
+ *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
+ *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
+ *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
+ & 0xff);
+ *(sp + 3) = (png_byte)(png_ptr->background.green
+ & 0xff);
+ *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
+ & 0xff);
+ *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
+ }
+
+ else if (a < 0xffff)
+ {
+ png_uint_16 v;
+
+ png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1));
+ png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8)
+ + *(sp + 3));
+ png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8)
+ + *(sp + 5));
+
+ png_composite_16(v, r, a, png_ptr->background.red);
+ *sp = (png_byte)((v >> 8) & 0xff);
+ *(sp + 1) = (png_byte)(v & 0xff);
+
+ png_composite_16(v, g, a, png_ptr->background.green);
+ *(sp + 2) = (png_byte)((v >> 8) & 0xff);
+ *(sp + 3) = (png_byte)(v & 0xff);
+
+ png_composite_16(v, b, a, png_ptr->background.blue);
+ *(sp + 4) = (png_byte)((v >> 8) & 0xff);
+ *(sp + 5) = (png_byte)(v & 0xff);
+ }
+ }
+ }
+ }
+ break;
+ }
+
+ default:
+ break;
+ }
+ }
+}
+#endif /* PNG_READ_BACKGROUND_SUPPORTED || PNG_READ_ALPHA_MODE_SUPPORTED */
+
+#ifdef PNG_READ_GAMMA_SUPPORTED
+/* Gamma correct the image, avoiding the alpha channel. Make sure
+ * you do this after you deal with the transparency issue on grayscale
+ * or RGB images. If your bit depth is 8, use gamma_table, if it
+ * is 16, use gamma_16_table and gamma_shift. Build these with
+ * build_gamma_table().
+ */
+void /* PRIVATE */
+png_do_gamma(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
+{
+ png_const_bytep gamma_table = png_ptr->gamma_table;
+ png_const_uint_16pp gamma_16_table = png_ptr->gamma_16_table;
+ int gamma_shift = png_ptr->gamma_shift;
+
+ png_bytep sp;
+ png_uint_32 i;
+ png_uint_32 row_width=row_info->width;
+
+ png_debug(1, "in png_do_gamma");
+
+ if (((row_info->bit_depth <= 8 && gamma_table != NULL) ||
+ (row_info->bit_depth == 16 && gamma_16_table != NULL)))
+ {
+ switch (row_info->color_type)
+ {
+ case PNG_COLOR_TYPE_RGB:
+ {
+ if (row_info->bit_depth == 8)
+ {
+ sp = row;
+ for (i = 0; i < row_width; i++)
+ {
+ *sp = gamma_table[*sp];
+ sp++;
+ *sp = gamma_table[*sp];
+ sp++;
+ *sp = gamma_table[*sp];
+ sp++;
+ }
+ }
+
+ else /* if (row_info->bit_depth == 16) */
+ {
+ sp = row;
+ for (i = 0; i < row_width; i++)
+ {
+ png_uint_16 v;
+
+ v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
+ *sp = (png_byte)((v >> 8) & 0xff);
+ *(sp + 1) = (png_byte)(v & 0xff);
+ sp += 2;
+
+ v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
+ *sp = (png_byte)((v >> 8) & 0xff);
+ *(sp + 1) = (png_byte)(v & 0xff);
+ sp += 2;
+
+ v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
+ *sp = (png_byte)((v >> 8) & 0xff);
+ *(sp + 1) = (png_byte)(v & 0xff);
+ sp += 2;
+ }
+ }
+ break;
+ }
+
+ case PNG_COLOR_TYPE_RGB_ALPHA:
+ {
+ if (row_info->bit_depth == 8)
+ {
+ sp = row;
+ for (i = 0; i < row_width; i++)
+ {
+ *sp = gamma_table[*sp];
+ sp++;
+
+ *sp = gamma_table[*sp];
+ sp++;
+
+ *sp = gamma_table[*sp];
+ sp++;
+
+ sp++;
+ }
+ }
+
+ else /* if (row_info->bit_depth == 16) */
+ {
+ sp = row;
+ for (i = 0; i < row_width; i++)
+ {
+ png_uint_16 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
+ *sp = (png_byte)((v >> 8) & 0xff);
+ *(sp + 1) = (png_byte)(v & 0xff);
+ sp += 2;
+
+ v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
+ *sp = (png_byte)((v >> 8) & 0xff);
+ *(sp + 1) = (png_byte)(v & 0xff);
+ sp += 2;
+
+ v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
+ *sp = (png_byte)((v >> 8) & 0xff);
+ *(sp + 1) = (png_byte)(v & 0xff);
+ sp += 4;
+ }
+ }
+ break;
+ }
+
+ case PNG_COLOR_TYPE_GRAY_ALPHA:
+ {
+ if (row_info->bit_depth == 8)
+ {
+ sp = row;
+ for (i = 0; i < row_width; i++)
+ {
+ *sp = gamma_table[*sp];
+ sp += 2;
+ }
+ }
+
+ else /* if (row_info->bit_depth == 16) */
+ {
+ sp = row;
+ for (i = 0; i < row_width; i++)
+ {
+ png_uint_16 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
+ *sp = (png_byte)((v >> 8) & 0xff);
+ *(sp + 1) = (png_byte)(v & 0xff);
+ sp += 4;
+ }
+ }
+ break;
+ }
+
+ case PNG_COLOR_TYPE_GRAY:
+ {
+ if (row_info->bit_depth == 2)
+ {
+ sp = row;
+ for (i = 0; i < row_width; i += 4)
+ {
+ int a = *sp & 0xc0;
+ int b = *sp & 0x30;
+ int c = *sp & 0x0c;
+ int d = *sp & 0x03;
+
+ *sp = (png_byte)(
+ ((((int)gamma_table[a|(a>>2)|(a>>4)|(a>>6)]) ) & 0xc0)|
+ ((((int)gamma_table[(b<<2)|b|(b>>2)|(b>>4)])>>2) & 0x30)|
+ ((((int)gamma_table[(c<<4)|(c<<2)|c|(c>>2)])>>4) & 0x0c)|
+ ((((int)gamma_table[(d<<6)|(d<<4)|(d<<2)|d])>>6) ));
+ sp++;
+ }
+ }
+
+ if (row_info->bit_depth == 4)
+ {
+ sp = row;
+ for (i = 0; i < row_width; i += 2)
+ {
+ int msb = *sp & 0xf0;
+ int lsb = *sp & 0x0f;
+
+ *sp = (png_byte)((((int)gamma_table[msb | (msb >> 4)]) & 0xf0)
+ | (((int)gamma_table[(lsb << 4) | lsb]) >> 4));
+ sp++;
+ }
+ }
+
+ else if (row_info->bit_depth == 8)
+ {
+ sp = row;
+ for (i = 0; i < row_width; i++)
+ {
+ *sp = gamma_table[*sp];
+ sp++;
+ }
+ }
+
+ else if (row_info->bit_depth == 16)
+ {
+ sp = row;
+ for (i = 0; i < row_width; i++)
+ {
+ png_uint_16 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
+ *sp = (png_byte)((v >> 8) & 0xff);
+ *(sp + 1) = (png_byte)(v & 0xff);
+ sp += 2;
+ }
+ }
+ break;
+ }
+
+ default:
+ break;
+ }
+ }
+}
+#endif
+
+#ifdef PNG_READ_ALPHA_MODE_SUPPORTED
+/* Encode the alpha channel to the output gamma (the input channel is always
+ * linear.) Called only with color types that have an alpha channel. Needs the
+ * from_1 tables.
+ */
+void /* PRIVATE */
+png_do_encode_alpha(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
+{
+ png_uint_32 row_width = row_info->width;
+
+ png_debug(1, "in png_do_encode_alpha");
+
+ if (row_info->color_type & PNG_COLOR_MASK_ALPHA)
+ {
+ if (row_info->bit_depth == 8)
+ {
+ PNG_CONST png_bytep table = png_ptr->gamma_from_1;
+
+ if (table != NULL)
+ {
+ PNG_CONST int step =
+ (row_info->color_type & PNG_COLOR_MASK_COLOR) ? 4 : 2;
+
+ /* The alpha channel is the last component: */
+ row += step - 1;
+
+ for (; row_width > 0; --row_width, row += step)
+ *row = table[*row];
+
+ return;
+ }
+ }
+
+ else if (row_info->bit_depth == 16)
+ {
+ PNG_CONST png_uint_16pp table = png_ptr->gamma_16_from_1;
+ PNG_CONST int gamma_shift = png_ptr->gamma_shift;
+
+ if (table != NULL)
+ {
+ PNG_CONST int step =
+ (row_info->color_type & PNG_COLOR_MASK_COLOR) ? 8 : 4;
+
+ /* The alpha channel is the last component: */
+ row += step - 2;
+
+ for (; row_width > 0; --row_width, row += step)
+ {
+ png_uint_16 v;
+
+ v = table[*(row + 1) >> gamma_shift][*row];
+ *row = (png_byte)((v >> 8) & 0xff);
+ *(row + 1) = (png_byte)(v & 0xff);
+ }
+
+ return;
+ }
+ }
+ }
+
+ /* Only get to here if called with a weird row_info; no harm has been done,
+ * so just issue a warning.
+ */
+ png_warning(png_ptr, "png_do_encode_alpha: unexpected call");
+}
+#endif
+
+#ifdef PNG_READ_EXPAND_SUPPORTED
+/* Expands a palette row to an RGB or RGBA row depending
+ * upon whether you supply trans and num_trans.
+ */
+void /* PRIVATE */
+png_do_expand_palette(png_row_infop row_info, png_bytep row,
+ png_const_colorp palette, png_const_bytep trans_alpha, int num_trans)
+{
+ int shift, value;
+ png_bytep sp, dp;
+ png_uint_32 i;
+ png_uint_32 row_width=row_info->width;
+
+ png_debug(1, "in png_do_expand_palette");
+
+ if (row_info->color_type == PNG_COLOR_TYPE_PALETTE)
+ {
+ if (row_info->bit_depth < 8)
+ {
+ switch (row_info->bit_depth)
+ {
+ case 1:
+ {
+ sp = row + (png_size_t)((row_width - 1) >> 3);
+ dp = row + (png_size_t)row_width - 1;
+ shift = 7 - (int)((row_width + 7) & 0x07);
+ for (i = 0; i < row_width; i++)
+ {
+ if ((*sp >> shift) & 0x01)
+ *dp = 1;
+
+ else
+ *dp = 0;
+
+ if (shift == 7)
+ {
+ shift = 0;
+ sp--;
+ }
+
+ else
+ shift++;
+
+ dp--;
+ }
+ break;
+ }
+
+ case 2:
+ {
+ sp = row + (png_size_t)((row_width - 1) >> 2);
+ dp = row + (png_size_t)row_width - 1;
+ shift = (int)((3 - ((row_width + 3) & 0x03)) << 1);
+ for (i = 0; i < row_width; i++)
+ {
+ value = (*sp >> shift) & 0x03;
+ *dp = (png_byte)value;
+ if (shift == 6)
+ {
+ shift = 0;
+ sp--;
+ }
+
+ else
+ shift += 2;
+
+ dp--;
+ }
+ break;
+ }
+
+ case 4:
+ {
+ sp = row + (png_size_t)((row_width - 1) >> 1);
+ dp = row + (png_size_t)row_width - 1;
+ shift = (int)((row_width & 0x01) << 2);
+ for (i = 0; i < row_width; i++)
+ {
+ value = (*sp >> shift) & 0x0f;
+ *dp = (png_byte)value;
+ if (shift == 4)
+ {
+ shift = 0;
+ sp--;
+ }
+
+ else
+ shift += 4;
+
+ dp--;
+ }
+ break;
+ }
+
+ default:
+ break;
+ }
+ row_info->bit_depth = 8;
+ row_info->pixel_depth = 8;
+ row_info->rowbytes = row_width;
+ }
+
+ if (row_info->bit_depth == 8)
+ {
+ {
+ if (num_trans > 0)
+ {
+ sp = row + (png_size_t)row_width - 1;
+ dp = row + (png_size_t)(row_width << 2) - 1;
+
+ for (i = 0; i < row_width; i++)
+ {
+ if ((int)(*sp) >= num_trans)
+ *dp-- = 0xff;
+
+ else
+ *dp-- = trans_alpha[*sp];
+
+ *dp-- = palette[*sp].blue;
+ *dp-- = palette[*sp].green;
+ *dp-- = palette[*sp].red;
+ sp--;
+ }
+ row_info->bit_depth = 8;
+ row_info->pixel_depth = 32;
+ row_info->rowbytes = row_width * 4;
+ row_info->color_type = 6;
+ row_info->channels = 4;
+ }
+
+ else
+ {
+ sp = row + (png_size_t)row_width - 1;
+ dp = row + (png_size_t)(row_width * 3) - 1;
+
+ for (i = 0; i < row_width; i++)
+ {
+ *dp-- = palette[*sp].blue;
+ *dp-- = palette[*sp].green;
+ *dp-- = palette[*sp].red;
+ sp--;
+ }
+
+ row_info->bit_depth = 8;
+ row_info->pixel_depth = 24;
+ row_info->rowbytes = row_width * 3;
+ row_info->color_type = 2;
+ row_info->channels = 3;
+ }
+ }
+ }
+ }
+}
+
+/* If the bit depth < 8, it is expanded to 8. Also, if the already
+ * expanded transparency value is supplied, an alpha channel is built.
+ */
+void /* PRIVATE */
+png_do_expand(png_row_infop row_info, png_bytep row,
+ png_const_color_16p trans_color)
+{
+ int shift, value;
+ png_bytep sp, dp;
+ png_uint_32 i;
+ png_uint_32 row_width=row_info->width;
+
+ png_debug(1, "in png_do_expand");
+
+ {
+ if (row_info->color_type == PNG_COLOR_TYPE_GRAY)
+ {
+ unsigned int gray = trans_color ? trans_color->gray : 0;
+
+ if (row_info->bit_depth < 8)
+ {
+ switch (row_info->bit_depth)
+ {
+ case 1:
+ {
+ gray = (gray & 0x01) * 0xff;
+ sp = row + (png_size_t)((row_width - 1) >> 3);
+ dp = row + (png_size_t)row_width - 1;
+ shift = 7 - (int)((row_width + 7) & 0x07);
+ for (i = 0; i < row_width; i++)
+ {
+ if ((*sp >> shift) & 0x01)
+ *dp = 0xff;
+
+ else
+ *dp = 0;
+
+ if (shift == 7)
+ {
+ shift = 0;
+ sp--;
+ }
+
+ else
+ shift++;
+
+ dp--;
+ }
+ break;
+ }
+
+ case 2:
+ {
+ gray = (gray & 0x03) * 0x55;
+ sp = row + (png_size_t)((row_width - 1) >> 2);
+ dp = row + (png_size_t)row_width - 1;
+ shift = (int)((3 - ((row_width + 3) & 0x03)) << 1);
+ for (i = 0; i < row_width; i++)
+ {
+ value = (*sp >> shift) & 0x03;
+ *dp = (png_byte)(value | (value << 2) | (value << 4) |
+ (value << 6));
+ if (shift == 6)
+ {
+ shift = 0;
+ sp--;
+ }
+
+ else
+ shift += 2;
+
+ dp--;
+ }
+ break;
+ }
+
+ case 4:
+ {
+ gray = (gray & 0x0f) * 0x11;
+ sp = row + (png_size_t)((row_width - 1) >> 1);
+ dp = row + (png_size_t)row_width - 1;
+ shift = (int)((1 - ((row_width + 1) & 0x01)) << 2);
+ for (i = 0; i < row_width; i++)
+ {
+ value = (*sp >> shift) & 0x0f;
+ *dp = (png_byte)(value | (value << 4));
+ if (shift == 4)
+ {
+ shift = 0;
+ sp--;
+ }
+
+ else
+ shift = 4;
+
+ dp--;
+ }
+ break;
+ }
+
+ default:
+ break;
+ }
+
+ row_info->bit_depth = 8;
+ row_info->pixel_depth = 8;
+ row_info->rowbytes = row_width;
+ }
+
+ if (trans_color != NULL)
+ {
+ if (row_info->bit_depth == 8)
+ {
+ gray = gray & 0xff;
+ sp = row + (png_size_t)row_width - 1;
+ dp = row + (png_size_t)(row_width << 1) - 1;
+
+ for (i = 0; i < row_width; i++)
+ {
+ if (*sp == gray)
+ *dp-- = 0;
+
+ else
+ *dp-- = 0xff;
+
+ *dp-- = *sp--;
+ }
+ }
+
+ else if (row_info->bit_depth == 16)
+ {
+ unsigned int gray_high = (gray >> 8) & 0xff;
+ unsigned int gray_low = gray & 0xff;
+ sp = row + row_info->rowbytes - 1;
+ dp = row + (row_info->rowbytes << 1) - 1;
+ for (i = 0; i < row_width; i++)
+ {
+ if (*(sp - 1) == gray_high && *(sp) == gray_low)
+ {
+ *dp-- = 0;
+ *dp-- = 0;
+ }
+
+ else
+ {
+ *dp-- = 0xff;
+ *dp-- = 0xff;
+ }
+
+ *dp-- = *sp--;
+ *dp-- = *sp--;
+ }
+ }
+
+ row_info->color_type = PNG_COLOR_TYPE_GRAY_ALPHA;
+ row_info->channels = 2;
+ row_info->pixel_depth = (png_byte)(row_info->bit_depth << 1);
+ row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth,
+ row_width);
+ }
+ }
+ else if (row_info->color_type == PNG_COLOR_TYPE_RGB && trans_color)
+ {
+ if (row_info->bit_depth == 8)
+ {
+ png_byte red = (png_byte)(trans_color->red & 0xff);
+ png_byte green = (png_byte)(trans_color->green & 0xff);
+ png_byte blue = (png_byte)(trans_color->blue & 0xff);
+ sp = row + (png_size_t)row_info->rowbytes - 1;
+ dp = row + (png_size_t)(row_width << 2) - 1;
+ for (i = 0; i < row_width; i++)
+ {
+ if (*(sp - 2) == red && *(sp - 1) == green && *(sp) == blue)
+ *dp-- = 0;
+
+ else
+ *dp-- = 0xff;
+
+ *dp-- = *sp--;
+ *dp-- = *sp--;
+ *dp-- = *sp--;
+ }
+ }
+ else if (row_info->bit_depth == 16)
+ {
+ png_byte red_high = (png_byte)((trans_color->red >> 8) & 0xff);
+ png_byte green_high = (png_byte)((trans_color->green >> 8) & 0xff);
+ png_byte blue_high = (png_byte)((trans_color->blue >> 8) & 0xff);
+ png_byte red_low = (png_byte)(trans_color->red & 0xff);
+ png_byte green_low = (png_byte)(trans_color->green & 0xff);
+ png_byte blue_low = (png_byte)(trans_color->blue & 0xff);
+ sp = row + row_info->rowbytes - 1;
+ dp = row + (png_size_t)(row_width << 3) - 1;
+ for (i = 0; i < row_width; i++)
+ {
+ if (*(sp - 5) == red_high &&
+ *(sp - 4) == red_low &&
+ *(sp - 3) == green_high &&
+ *(sp - 2) == green_low &&
+ *(sp - 1) == blue_high &&
+ *(sp ) == blue_low)
+ {
+ *dp-- = 0;
+ *dp-- = 0;
+ }
+
+ else
+ {
+ *dp-- = 0xff;
+ *dp-- = 0xff;
+ }
+
+ *dp-- = *sp--;
+ *dp-- = *sp--;
+ *dp-- = *sp--;
+ *dp-- = *sp--;
+ *dp-- = *sp--;
+ *dp-- = *sp--;
+ }
+ }
+ row_info->color_type = PNG_COLOR_TYPE_RGB_ALPHA;
+ row_info->channels = 4;
+ row_info->pixel_depth = (png_byte)(row_info->bit_depth << 2);
+ row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
+ }
+ }
+}
+#endif
+
+#ifdef PNG_READ_EXPAND_16_SUPPORTED
+/* If the bit depth is 8 and the color type is not a palette type expand the
+ * whole row to 16 bits. Has no effect otherwise.
+ */
+void /* PRIVATE */
+png_do_expand_16(png_row_infop row_info, png_bytep row)
+{
+ if (row_info->bit_depth == 8 &&
+ row_info->color_type != PNG_COLOR_TYPE_PALETTE)
+ {
+ /* The row have a sequence of bytes containing [0..255] and we need
+ * to turn it into another row containing [0..65535], to do this we
+ * calculate:
+ *
+ * (input / 255) * 65535
+ *
+ * Which happens to be exactly input * 257 and this can be achieved
+ * simply by byte replication in place (copying backwards).
+ */
+ png_byte *sp = row + row_info->rowbytes; /* source, last byte + 1 */
+ png_byte *dp = sp + row_info->rowbytes; /* destination, end + 1 */
+ while (dp > sp)
+ dp[-2] = dp[-1] = *--sp, dp -= 2;
+
+ row_info->rowbytes *= 2;
+ row_info->bit_depth = 16;
+ row_info->pixel_depth = (png_byte)(row_info->channels * 16);
+ }
+}
+#endif
+
+#ifdef PNG_READ_QUANTIZE_SUPPORTED
+void /* PRIVATE */
+png_do_quantize(png_row_infop row_info, png_bytep row,
+ png_const_bytep palette_lookup, png_const_bytep quantize_lookup)
+{
+ png_bytep sp, dp;
+ png_uint_32 i;
+ png_uint_32 row_width=row_info->width;
+
+ png_debug(1, "in png_do_quantize");
+
+ if (row_info->bit_depth == 8)
+ {
+ if (row_info->color_type == PNG_COLOR_TYPE_RGB && palette_lookup)
+ {
+ int r, g, b, p;
+ sp = row;
+ dp = row;
+ for (i = 0; i < row_width; i++)
+ {
+ r = *sp++;
+ g = *sp++;
+ b = *sp++;
+
+ /* This looks real messy, but the compiler will reduce
+ * it down to a reasonable formula. For example, with
+ * 5 bits per color, we get:
+ * p = (((r >> 3) & 0x1f) << 10) |
+ * (((g >> 3) & 0x1f) << 5) |
+ * ((b >> 3) & 0x1f);
+ */
+ p = (((r >> (8 - PNG_QUANTIZE_RED_BITS)) &
+ ((1 << PNG_QUANTIZE_RED_BITS) - 1)) <<
+ (PNG_QUANTIZE_GREEN_BITS + PNG_QUANTIZE_BLUE_BITS)) |
+ (((g >> (8 - PNG_QUANTIZE_GREEN_BITS)) &
+ ((1 << PNG_QUANTIZE_GREEN_BITS) - 1)) <<
+ (PNG_QUANTIZE_BLUE_BITS)) |
+ ((b >> (8 - PNG_QUANTIZE_BLUE_BITS)) &
+ ((1 << PNG_QUANTIZE_BLUE_BITS) - 1));
+
+ *dp++ = palette_lookup[p];
+ }
+
+ row_info->color_type = PNG_COLOR_TYPE_PALETTE;
+ row_info->channels = 1;
+ row_info->pixel_depth = row_info->bit_depth;
+ row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
+ }
+
+ else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA &&
+ palette_lookup != NULL)
+ {
+ int r, g, b, p;
+ sp = row;
+ dp = row;
+ for (i = 0; i < row_width; i++)
+ {
+ r = *sp++;
+ g = *sp++;
+ b = *sp++;
+ sp++;
+
+ p = (((r >> (8 - PNG_QUANTIZE_RED_BITS)) &
+ ((1 << PNG_QUANTIZE_RED_BITS) - 1)) <<
+ (PNG_QUANTIZE_GREEN_BITS + PNG_QUANTIZE_BLUE_BITS)) |
+ (((g >> (8 - PNG_QUANTIZE_GREEN_BITS)) &
+ ((1 << PNG_QUANTIZE_GREEN_BITS) - 1)) <<
+ (PNG_QUANTIZE_BLUE_BITS)) |
+ ((b >> (8 - PNG_QUANTIZE_BLUE_BITS)) &
+ ((1 << PNG_QUANTIZE_BLUE_BITS) - 1));
+
+ *dp++ = palette_lookup[p];
+ }
+
+ row_info->color_type = PNG_COLOR_TYPE_PALETTE;
+ row_info->channels = 1;
+ row_info->pixel_depth = row_info->bit_depth;
+ row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
+ }
+
+ else if (row_info->color_type == PNG_COLOR_TYPE_PALETTE &&
+ quantize_lookup)
+ {
+ sp = row;
+
+ for (i = 0; i < row_width; i++, sp++)
+ {
+ *sp = quantize_lookup[*sp];
+ }
+ }
+ }
+}
+#endif /* PNG_READ_QUANTIZE_SUPPORTED */
+#endif /* PNG_READ_TRANSFORMS_SUPPORTED */
+
+#ifdef PNG_MNG_FEATURES_SUPPORTED
+/* Undoes intrapixel differencing */
+void /* PRIVATE */
+png_do_read_intrapixel(png_row_infop row_info, png_bytep row)
+{
+ png_debug(1, "in png_do_read_intrapixel");
+
+ if (
+ (row_info->color_type & PNG_COLOR_MASK_COLOR))
+ {
+ int bytes_per_pixel;
+ png_uint_32 row_width = row_info->width;
+
+ if (row_info->bit_depth == 8)
+ {
+ png_bytep rp;
+ png_uint_32 i;
+
+ if (row_info->color_type == PNG_COLOR_TYPE_RGB)
+ bytes_per_pixel = 3;
+
+ else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
+ bytes_per_pixel = 4;
+
+ else
+ return;
+
+ for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
+ {
+ *(rp) = (png_byte)((256 + *rp + *(rp + 1)) & 0xff);
+ *(rp+2) = (png_byte)((256 + *(rp + 2) + *(rp + 1)) & 0xff);
+ }
+ }
+ else if (row_info->bit_depth == 16)
+ {
+ png_bytep rp;
+ png_uint_32 i;
+
+ if (row_info->color_type == PNG_COLOR_TYPE_RGB)
+ bytes_per_pixel = 6;
+
+ else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
+ bytes_per_pixel = 8;
+
+ else
+ return;
+
+ for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
+ {
+ png_uint_32 s0 = (*(rp ) << 8) | *(rp + 1);
+ png_uint_32 s1 = (*(rp + 2) << 8) | *(rp + 3);
+ png_uint_32 s2 = (*(rp + 4) << 8) | *(rp + 5);
+ png_uint_32 red = (s0 + s1 + 65536) & 0xffff;
+ png_uint_32 blue = (s2 + s1 + 65536) & 0xffff;
+ *(rp ) = (png_byte)((red >> 8) & 0xff);
+ *(rp + 1) = (png_byte)(red & 0xff);
+ *(rp + 4) = (png_byte)((blue >> 8) & 0xff);
+ *(rp + 5) = (png_byte)(blue & 0xff);
+ }
+ }
+ }
+}
+#endif /* PNG_MNG_FEATURES_SUPPORTED */
+#endif /* PNG_READ_SUPPORTED */
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