diff options
Diffstat (limited to 'third_party/libjpeg/fpdfapi_jcprepct.c')
| -rw-r--r-- | third_party/libjpeg/fpdfapi_jcprepct.c | 357 |
1 files changed, 357 insertions, 0 deletions
diff --git a/third_party/libjpeg/fpdfapi_jcprepct.c b/third_party/libjpeg/fpdfapi_jcprepct.c new file mode 100644 index 0000000000..57f3fc1108 --- /dev/null +++ b/third_party/libjpeg/fpdfapi_jcprepct.c @@ -0,0 +1,357 @@ +#if !defined(_FX_JPEG_TURBO_) +/* + * jcprepct.c + * + * Copyright (C) 1994-1996, Thomas G. Lane. + * This file is part of the Independent JPEG Group's software. + * For conditions of distribution and use, see the accompanying README file. + * + * This file contains the compression preprocessing controller. + * This controller manages the color conversion, downsampling, + * and edge expansion steps. + * + * Most of the complexity here is associated with buffering input rows + * as required by the downsampler. See the comments at the head of + * jcsample.c for the downsampler's needs. + */ + +#define JPEG_INTERNALS +#include "jinclude.h" +#include "jpeglib.h" + + +/* At present, jcsample.c can request context rows only for smoothing. + * In the future, we might also need context rows for CCIR601 sampling + * or other more-complex downsampling procedures. The code to support + * context rows should be compiled only if needed. + */ +#ifdef INPUT_SMOOTHING_SUPPORTED +#define CONTEXT_ROWS_SUPPORTED +#endif + + +/* + * For the simple (no-context-row) case, we just need to buffer one + * row group's worth of pixels for the downsampling step. At the bottom of + * the image, we pad to a full row group by replicating the last pixel row. + * The downsampler's last output row is then replicated if needed to pad + * out to a full iMCU row. + * + * When providing context rows, we must buffer three row groups' worth of + * pixels. Three row groups are physically allocated, but the row pointer + * arrays are made five row groups high, with the extra pointers above and + * below "wrapping around" to point to the last and first real row groups. + * This allows the downsampler to access the proper context rows. + * At the top and bottom of the image, we create dummy context rows by + * copying the first or last real pixel row. This copying could be avoided + * by pointer hacking as is done in jdmainct.c, but it doesn't seem worth the + * trouble on the compression side. + */ + + +/* Private buffer controller object */ + +typedef struct { + struct jpeg_c_prep_controller pub; /* public fields */ + + /* Downsampling input buffer. This buffer holds color-converted data + * until we have enough to do a downsample step. + */ + JSAMPARRAY color_buf[MAX_COMPONENTS]; + + JDIMENSION rows_to_go; /* counts rows remaining in source image */ + int next_buf_row; /* index of next row to store in color_buf */ + +#ifdef CONTEXT_ROWS_SUPPORTED /* only needed for context case */ + int this_row_group; /* starting row index of group to process */ + int next_buf_stop; /* downsample when we reach this index */ +#endif +} my_prep_controller; + +typedef my_prep_controller * my_prep_ptr; + + +/* + * Initialize for a processing pass. + */ + +METHODDEF(void) +start_pass_prep (j_compress_ptr cinfo, J_BUF_MODE pass_mode) +{ + my_prep_ptr prep = (my_prep_ptr) cinfo->prep; + + if (pass_mode != JBUF_PASS_THRU) + ERREXIT(cinfo, JERR_BAD_BUFFER_MODE); + + /* Initialize total-height counter for detecting bottom of image */ + prep->rows_to_go = cinfo->image_height; + /* Mark the conversion buffer empty */ + prep->next_buf_row = 0; +#ifdef CONTEXT_ROWS_SUPPORTED + /* Preset additional state variables for context mode. + * These aren't used in non-context mode, so we needn't test which mode. + */ + prep->this_row_group = 0; + /* Set next_buf_stop to stop after two row groups have been read in. */ + prep->next_buf_stop = 2 * cinfo->max_v_samp_factor; +#endif +} + + +/* + * Expand an image vertically from height input_rows to height output_rows, + * by duplicating the bottom row. + */ + +LOCAL(void) +expand_bottom_edge (JSAMPARRAY image_data, JDIMENSION num_cols, + int input_rows, int output_rows) +{ + register int row; + + for (row = input_rows; row < output_rows; row++) { + jcopy_sample_rows(image_data, input_rows-1, image_data, row, + 1, num_cols); + } +} + + +/* + * Process some data in the simple no-context case. + * + * Preprocessor output data is counted in "row groups". A row group + * is defined to be v_samp_factor sample rows of each component. + * Downsampling will produce this much data from each max_v_samp_factor + * input rows. + */ + +METHODDEF(void) +pre_process_data (j_compress_ptr cinfo, + JSAMPARRAY input_buf, JDIMENSION *in_row_ctr, + JDIMENSION in_rows_avail, + JSAMPIMAGE output_buf, JDIMENSION *out_row_group_ctr, + JDIMENSION out_row_groups_avail) +{ + my_prep_ptr prep = (my_prep_ptr) cinfo->prep; + int numrows, ci; + JDIMENSION inrows; + jpeg_component_info * compptr; + + while (*in_row_ctr < in_rows_avail && + *out_row_group_ctr < out_row_groups_avail) { + /* Do color conversion to fill the conversion buffer. */ + inrows = in_rows_avail - *in_row_ctr; + numrows = cinfo->max_v_samp_factor - prep->next_buf_row; + numrows = (int) MIN((JDIMENSION) numrows, inrows); + (*cinfo->cconvert->color_convert) (cinfo, input_buf + *in_row_ctr, + prep->color_buf, + (JDIMENSION) prep->next_buf_row, + numrows); + *in_row_ctr += numrows; + prep->next_buf_row += numrows; + prep->rows_to_go -= numrows; + /* If at bottom of image, pad to fill the conversion buffer. */ + if (prep->rows_to_go == 0 && + prep->next_buf_row < cinfo->max_v_samp_factor) { + for (ci = 0; ci < cinfo->num_components; ci++) { + expand_bottom_edge(prep->color_buf[ci], cinfo->image_width, + prep->next_buf_row, cinfo->max_v_samp_factor); + } + prep->next_buf_row = cinfo->max_v_samp_factor; + } + /* If we've filled the conversion buffer, empty it. */ + if (prep->next_buf_row == cinfo->max_v_samp_factor) { + (*cinfo->downsample->downsample) (cinfo, + prep->color_buf, (JDIMENSION) 0, + output_buf, *out_row_group_ctr); + prep->next_buf_row = 0; + (*out_row_group_ctr)++; + } + /* If at bottom of image, pad the output to a full iMCU height. + * Note we assume the caller is providing a one-iMCU-height output buffer! + */ + if (prep->rows_to_go == 0 && + *out_row_group_ctr < out_row_groups_avail) { + for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; + ci++, compptr++) { + expand_bottom_edge(output_buf[ci], + compptr->width_in_blocks * DCTSIZE, + (int) (*out_row_group_ctr * compptr->v_samp_factor), + (int) (out_row_groups_avail * compptr->v_samp_factor)); + } + *out_row_group_ctr = out_row_groups_avail; + break; /* can exit outer loop without test */ + } + } +} + + +#ifdef CONTEXT_ROWS_SUPPORTED + +/* + * Process some data in the context case. + */ + +METHODDEF(void) +pre_process_context (j_compress_ptr cinfo, + JSAMPARRAY input_buf, JDIMENSION *in_row_ctr, + JDIMENSION in_rows_avail, + JSAMPIMAGE output_buf, JDIMENSION *out_row_group_ctr, + JDIMENSION out_row_groups_avail) +{ + my_prep_ptr prep = (my_prep_ptr) cinfo->prep; + int numrows, ci; + int buf_height = cinfo->max_v_samp_factor * 3; + JDIMENSION inrows; + + while (*out_row_group_ctr < out_row_groups_avail) { + if (*in_row_ctr < in_rows_avail) { + /* Do color conversion to fill the conversion buffer. */ + inrows = in_rows_avail - *in_row_ctr; + numrows = prep->next_buf_stop - prep->next_buf_row; + numrows = (int) MIN((JDIMENSION) numrows, inrows); + (*cinfo->cconvert->color_convert) (cinfo, input_buf + *in_row_ctr, + prep->color_buf, + (JDIMENSION) prep->next_buf_row, + numrows); + /* Pad at top of image, if first time through */ + if (prep->rows_to_go == cinfo->image_height) { + for (ci = 0; ci < cinfo->num_components; ci++) { + int row; + for (row = 1; row <= cinfo->max_v_samp_factor; row++) { + jcopy_sample_rows(prep->color_buf[ci], 0, + prep->color_buf[ci], -row, + 1, cinfo->image_width); + } + } + } + *in_row_ctr += numrows; + prep->next_buf_row += numrows; + prep->rows_to_go -= numrows; + } else { + /* Return for more data, unless we are at the bottom of the image. */ + if (prep->rows_to_go != 0) + break; + /* When at bottom of image, pad to fill the conversion buffer. */ + if (prep->next_buf_row < prep->next_buf_stop) { + for (ci = 0; ci < cinfo->num_components; ci++) { + expand_bottom_edge(prep->color_buf[ci], cinfo->image_width, + prep->next_buf_row, prep->next_buf_stop); + } + prep->next_buf_row = prep->next_buf_stop; + } + } + /* If we've gotten enough data, downsample a row group. */ + if (prep->next_buf_row == prep->next_buf_stop) { + (*cinfo->downsample->downsample) (cinfo, + prep->color_buf, + (JDIMENSION) prep->this_row_group, + output_buf, *out_row_group_ctr); + (*out_row_group_ctr)++; + /* Advance pointers with wraparound as necessary. */ + prep->this_row_group += cinfo->max_v_samp_factor; + if (prep->this_row_group >= buf_height) + prep->this_row_group = 0; + if (prep->next_buf_row >= buf_height) + prep->next_buf_row = 0; + prep->next_buf_stop = prep->next_buf_row + cinfo->max_v_samp_factor; + } + } +} + + +/* + * Create the wrapped-around downsampling input buffer needed for context mode. + */ + +LOCAL(void) +create_context_buffer (j_compress_ptr cinfo) +{ + my_prep_ptr prep = (my_prep_ptr) cinfo->prep; + int rgroup_height = cinfo->max_v_samp_factor; + int ci, i; + jpeg_component_info * compptr; + JSAMPARRAY true_buffer, fake_buffer; + + /* Grab enough space for fake row pointers for all the components; + * we need five row groups' worth of pointers for each component. + */ + fake_buffer = (JSAMPARRAY) + (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, + (cinfo->num_components * 5 * rgroup_height) * + SIZEOF(JSAMPROW)); + + for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; + ci++, compptr++) { + /* Allocate the actual buffer space (3 row groups) for this component. + * We make the buffer wide enough to allow the downsampler to edge-expand + * horizontally within the buffer, if it so chooses. + */ + true_buffer = (*cinfo->mem->alloc_sarray) + ((j_common_ptr) cinfo, JPOOL_IMAGE, + (JDIMENSION) (((long) compptr->width_in_blocks * DCTSIZE * + cinfo->max_h_samp_factor) / compptr->h_samp_factor), + (JDIMENSION) (3 * rgroup_height)); + /* Copy true buffer row pointers into the middle of the fake row array */ + MEMCOPY(fake_buffer + rgroup_height, true_buffer, + 3 * rgroup_height * SIZEOF(JSAMPROW)); + /* Fill in the above and below wraparound pointers */ + for (i = 0; i < rgroup_height; i++) { + fake_buffer[i] = true_buffer[2 * rgroup_height + i]; + fake_buffer[4 * rgroup_height + i] = true_buffer[i]; + } + prep->color_buf[ci] = fake_buffer + rgroup_height; + fake_buffer += 5 * rgroup_height; /* point to space for next component */ + } +} + +#endif /* CONTEXT_ROWS_SUPPORTED */ + + +/* + * Initialize preprocessing controller. + */ + +GLOBAL(void) +jinit_c_prep_controller (j_compress_ptr cinfo, boolean need_full_buffer) +{ + my_prep_ptr prep; + int ci; + jpeg_component_info * compptr; + + if (need_full_buffer) /* safety check */ + ERREXIT(cinfo, JERR_BAD_BUFFER_MODE); + + prep = (my_prep_ptr) + (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, + SIZEOF(my_prep_controller)); + cinfo->prep = (struct jpeg_c_prep_controller *) prep; + prep->pub.start_pass = start_pass_prep; + + /* Allocate the color conversion buffer. + * We make the buffer wide enough to allow the downsampler to edge-expand + * horizontally within the buffer, if it so chooses. + */ + if (cinfo->downsample->need_context_rows) { + /* Set up to provide context rows */ +#ifdef CONTEXT_ROWS_SUPPORTED + prep->pub.pre_process_data = pre_process_context; + create_context_buffer(cinfo); +#else + ERREXIT(cinfo, JERR_NOT_COMPILED); +#endif + } else { + /* No context, just make it tall enough for one row group */ + prep->pub.pre_process_data = pre_process_data; + for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; + ci++, compptr++) { + prep->color_buf[ci] = (*cinfo->mem->alloc_sarray) + ((j_common_ptr) cinfo, JPOOL_IMAGE, + (JDIMENSION) (((long) compptr->width_in_blocks * DCTSIZE * + cinfo->max_h_samp_factor) / compptr->h_samp_factor), + (JDIMENSION) cinfo->max_v_samp_factor); + } + } +} + +#endif //_FX_JPEG_TURBO_ |