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Diffstat (limited to 'third_party/libpng16/pngwutil.c')
| -rw-r--r-- | third_party/libpng16/pngwutil.c | 2709 |
1 files changed, 2709 insertions, 0 deletions
diff --git a/third_party/libpng16/pngwutil.c b/third_party/libpng16/pngwutil.c new file mode 100644 index 0000000000..0ee102b5fb --- /dev/null +++ b/third_party/libpng16/pngwutil.c @@ -0,0 +1,2709 @@ + +/* pngwutil.c - utilities to write a PNG file + * + * Last changed in libpng 1.6.19 [November 12, 2015] + * Copyright (c) 1998-2015 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 + */ + +#include "pngpriv.h" + +#ifdef PNG_WRITE_SUPPORTED + +#ifdef PNG_WRITE_INT_FUNCTIONS_SUPPORTED +/* Place a 32-bit number into a buffer in PNG byte order. We work + * with unsigned numbers for convenience, although one supported + * ancillary chunk uses signed (two's complement) numbers. + */ +void PNGAPI +png_save_uint_32(png_bytep buf, png_uint_32 i) +{ + buf[0] = (png_byte)(i >> 24); + buf[1] = (png_byte)(i >> 16); + buf[2] = (png_byte)(i >> 8); + buf[3] = (png_byte)(i ); +} + +/* Place a 16-bit number into a buffer in PNG byte order. + * The parameter is declared unsigned int, not png_uint_16, + * just to avoid potential problems on pre-ANSI C compilers. + */ +void PNGAPI +png_save_uint_16(png_bytep buf, unsigned int i) +{ + buf[0] = (png_byte)(i >> 8); + buf[1] = (png_byte)(i ); +} +#endif + +/* Simple function to write the signature. If we have already written + * the magic bytes of the signature, or more likely, the PNG stream is + * being embedded into another stream and doesn't need its own signature, + * we should call png_set_sig_bytes() to tell libpng how many of the + * bytes have already been written. + */ +void PNGAPI +png_write_sig(png_structrp png_ptr) +{ + png_byte png_signature[8] = {137, 80, 78, 71, 13, 10, 26, 10}; + +#ifdef PNG_IO_STATE_SUPPORTED + /* Inform the I/O callback that the signature is being written */ + png_ptr->io_state = PNG_IO_WRITING | PNG_IO_SIGNATURE; +#endif + + /* Write the rest of the 8 byte signature */ + png_write_data(png_ptr, &png_signature[png_ptr->sig_bytes], + (png_size_t)(8 - png_ptr->sig_bytes)); + + if (png_ptr->sig_bytes < 3) + png_ptr->mode |= PNG_HAVE_PNG_SIGNATURE; +} + +/* Write the start of a PNG chunk. The type is the chunk type. + * The total_length is the sum of the lengths of all the data you will be + * passing in png_write_chunk_data(). + */ +static void +png_write_chunk_header(png_structrp png_ptr, png_uint_32 chunk_name, + png_uint_32 length) +{ + png_byte buf[8]; + +#if defined(PNG_DEBUG) && (PNG_DEBUG > 0) + PNG_CSTRING_FROM_CHUNK(buf, chunk_name); + png_debug2(0, "Writing %s chunk, length = %lu", buf, (unsigned long)length); +#endif + + if (png_ptr == NULL) + return; + +#ifdef PNG_IO_STATE_SUPPORTED + /* Inform the I/O callback that the chunk header is being written. + * PNG_IO_CHUNK_HDR requires a single I/O call. + */ + png_ptr->io_state = PNG_IO_WRITING | PNG_IO_CHUNK_HDR; +#endif + + /* Write the length and the chunk name */ + png_save_uint_32(buf, length); + png_save_uint_32(buf + 4, chunk_name); + png_write_data(png_ptr, buf, 8); + + /* Put the chunk name into png_ptr->chunk_name */ + png_ptr->chunk_name = chunk_name; + + /* Reset the crc and run it over the chunk name */ + png_reset_crc(png_ptr); + + png_calculate_crc(png_ptr, buf + 4, 4); + +#ifdef PNG_IO_STATE_SUPPORTED + /* Inform the I/O callback that chunk data will (possibly) be written. + * PNG_IO_CHUNK_DATA does NOT require a specific number of I/O calls. + */ + png_ptr->io_state = PNG_IO_WRITING | PNG_IO_CHUNK_DATA; +#endif +} + +void PNGAPI +png_write_chunk_start(png_structrp png_ptr, png_const_bytep chunk_string, + png_uint_32 length) +{ + png_write_chunk_header(png_ptr, PNG_CHUNK_FROM_STRING(chunk_string), length); +} + +/* Write the data of a PNG chunk started with png_write_chunk_header(). + * Note that multiple calls to this function are allowed, and that the + * sum of the lengths from these calls *must* add up to the total_length + * given to png_write_chunk_header(). + */ +void PNGAPI +png_write_chunk_data(png_structrp png_ptr, png_const_bytep data, + png_size_t length) +{ + /* Write the data, and run the CRC over it */ + if (png_ptr == NULL) + return; + + if (data != NULL && length > 0) + { + png_write_data(png_ptr, data, length); + + /* Update the CRC after writing the data, + * in case the user I/O routine alters it. + */ + png_calculate_crc(png_ptr, data, length); + } +} + +/* Finish a chunk started with png_write_chunk_header(). */ +void PNGAPI +png_write_chunk_end(png_structrp png_ptr) +{ + png_byte buf[4]; + + if (png_ptr == NULL) return; + +#ifdef PNG_IO_STATE_SUPPORTED + /* Inform the I/O callback that the chunk CRC is being written. + * PNG_IO_CHUNK_CRC requires a single I/O function call. + */ + png_ptr->io_state = PNG_IO_WRITING | PNG_IO_CHUNK_CRC; +#endif + + /* Write the crc in a single operation */ + png_save_uint_32(buf, png_ptr->crc); + + png_write_data(png_ptr, buf, (png_size_t)4); +} + +/* Write a PNG chunk all at once. The type is an array of ASCII characters + * representing the chunk name. The array must be at least 4 bytes in + * length, and does not need to be null terminated. To be safe, pass the + * pre-defined chunk names here, and if you need a new one, define it + * where the others are defined. The length is the length of the data. + * All the data must be present. If that is not possible, use the + * png_write_chunk_start(), png_write_chunk_data(), and png_write_chunk_end() + * functions instead. + */ +static void +png_write_complete_chunk(png_structrp png_ptr, png_uint_32 chunk_name, + png_const_bytep data, png_size_t length) +{ + if (png_ptr == NULL) + return; + + /* On 64-bit architectures 'length' may not fit in a png_uint_32. */ + if (length > PNG_UINT_31_MAX) + png_error(png_ptr, "length exceeds PNG maximum"); + + png_write_chunk_header(png_ptr, chunk_name, (png_uint_32)length); + png_write_chunk_data(png_ptr, data, length); + png_write_chunk_end(png_ptr); +} + +/* This is the API that calls the internal function above. */ +void PNGAPI +png_write_chunk(png_structrp png_ptr, png_const_bytep chunk_string, + png_const_bytep data, png_size_t length) +{ + png_write_complete_chunk(png_ptr, PNG_CHUNK_FROM_STRING(chunk_string), data, + length); +} + +/* This is used below to find the size of an image to pass to png_deflate_claim, + * so it only needs to be accurate if the size is less than 16384 bytes (the + * point at which a lower LZ window size can be used.) + */ +static png_alloc_size_t +png_image_size(png_structrp png_ptr) +{ + /* Only return sizes up to the maximum of a png_uint_32; do this by limiting + * the width and height used to 15 bits. + */ + png_uint_32 h = png_ptr->height; + + if (png_ptr->rowbytes < 32768 && h < 32768) + { + if (png_ptr->interlaced != 0) + { + /* Interlacing makes the image larger because of the replication of + * both the filter byte and the padding to a byte boundary. + */ + png_uint_32 w = png_ptr->width; + unsigned int pd = png_ptr->pixel_depth; + png_alloc_size_t cb_base; + int pass; + + for (cb_base=0, pass=0; pass<=6; ++pass) + { + png_uint_32 pw = PNG_PASS_COLS(w, pass); + + if (pw > 0) + cb_base += (PNG_ROWBYTES(pd, pw)+1) * PNG_PASS_ROWS(h, pass); + } + + return cb_base; + } + + else + return (png_ptr->rowbytes+1) * h; + } + + else + return 0xffffffffU; +} + +#ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED + /* This is the code to hack the first two bytes of the deflate stream (the + * deflate header) to correct the windowBits value to match the actual data + * size. Note that the second argument is the *uncompressed* size but the + * first argument is the *compressed* data (and it must be deflate + * compressed.) + */ +static void +optimize_cmf(png_bytep data, png_alloc_size_t data_size) +{ + /* Optimize the CMF field in the zlib stream. The resultant zlib stream is + * still compliant to the stream specification. + */ + if (data_size <= 16384) /* else windowBits must be 15 */ + { + unsigned int z_cmf = data[0]; /* zlib compression method and flags */ + + if ((z_cmf & 0x0f) == 8 && (z_cmf & 0xf0) <= 0x70) + { + unsigned int z_cinfo; + unsigned int half_z_window_size; + + z_cinfo = z_cmf >> 4; + half_z_window_size = 1U << (z_cinfo + 7); + + if (data_size <= half_z_window_size) /* else no change */ + { + unsigned int tmp; + + do + { + half_z_window_size >>= 1; + --z_cinfo; + } + while (z_cinfo > 0 && data_size <= half_z_window_size); + + z_cmf = (z_cmf & 0x0f) | (z_cinfo << 4); + + data[0] = (png_byte)z_cmf; + tmp = data[1] & 0xe0; + tmp += 0x1f - ((z_cmf << 8) + tmp) % 0x1f; + data[1] = (png_byte)tmp; + } + } + } +} +#endif /* WRITE_OPTIMIZE_CMF */ + +/* Initialize the compressor for the appropriate type of compression. */ +static int +png_deflate_claim(png_structrp png_ptr, png_uint_32 owner, + png_alloc_size_t data_size) +{ + if (png_ptr->zowner != 0) + { +#if defined(PNG_WARNINGS_SUPPORTED) || defined(PNG_ERROR_TEXT_SUPPORTED) + char msg[64]; + + PNG_STRING_FROM_CHUNK(msg, owner); + msg[4] = ':'; + msg[5] = ' '; + PNG_STRING_FROM_CHUNK(msg+6, png_ptr->zowner); + /* So the message that results is "<chunk> using zstream"; this is an + * internal error, but is very useful for debugging. i18n requirements + * are minimal. + */ + (void)png_safecat(msg, (sizeof msg), 10, " using zstream"); +#endif +#if PNG_RELEASE_BUILD + png_warning(png_ptr, msg); + + /* Attempt sane error recovery */ + if (png_ptr->zowner == png_IDAT) /* don't steal from IDAT */ + { + png_ptr->zstream.msg = PNGZ_MSG_CAST("in use by IDAT"); + return Z_STREAM_ERROR; + } + + png_ptr->zowner = 0; +#else + png_error(png_ptr, msg); +#endif + } + + { + int level = png_ptr->zlib_level; + int method = png_ptr->zlib_method; + int windowBits = png_ptr->zlib_window_bits; + int memLevel = png_ptr->zlib_mem_level; + int strategy; /* set below */ + int ret; /* zlib return code */ + + if (owner == png_IDAT) + { + if ((png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_STRATEGY) != 0) + strategy = png_ptr->zlib_strategy; + + else if (png_ptr->do_filter != PNG_FILTER_NONE) + strategy = PNG_Z_DEFAULT_STRATEGY; + + else + strategy = PNG_Z_DEFAULT_NOFILTER_STRATEGY; + } + + else + { +#ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED + level = png_ptr->zlib_text_level; + method = png_ptr->zlib_text_method; + windowBits = png_ptr->zlib_text_window_bits; + memLevel = png_ptr->zlib_text_mem_level; + strategy = png_ptr->zlib_text_strategy; +#else + /* If customization is not supported the values all come from the + * IDAT values except for the strategy, which is fixed to the + * default. (This is the pre-1.6.0 behavior too, although it was + * implemented in a very different way.) + */ + strategy = Z_DEFAULT_STRATEGY; +#endif + } + + /* Adjust 'windowBits' down if larger than 'data_size'; to stop this + * happening just pass 32768 as the data_size parameter. Notice that zlib + * requires an extra 262 bytes in the window in addition to the data to be + * able to see the whole of the data, so if data_size+262 takes us to the + * next windowBits size we need to fix up the value later. (Because even + * though deflate needs the extra window, inflate does not!) + */ + if (data_size <= 16384) + { + /* IMPLEMENTATION NOTE: this 'half_window_size' stuff is only here to + * work round a Microsoft Visual C misbehavior which, contrary to C-90, + * widens the result of the following shift to 64-bits if (and, + * apparently, only if) it is used in a test. + */ + unsigned int half_window_size = 1U << (windowBits-1); + + while (data_size + 262 <= half_window_size) + { + half_window_size >>= 1; + --windowBits; + } + } + + /* Check against the previous initialized values, if any. */ + if ((png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED) != 0 && + (png_ptr->zlib_set_level != level || + png_ptr->zlib_set_method != method || + png_ptr->zlib_set_window_bits != windowBits || + png_ptr->zlib_set_mem_level != memLevel || + png_ptr->zlib_set_strategy != strategy)) + { + if (deflateEnd(&png_ptr->zstream) != Z_OK) + png_warning(png_ptr, "deflateEnd failed (ignored)"); + + png_ptr->flags &= ~PNG_FLAG_ZSTREAM_INITIALIZED; + } + + /* For safety clear out the input and output pointers (currently zlib + * doesn't use them on Init, but it might in the future). + */ + png_ptr->zstream.next_in = NULL; + png_ptr->zstream.avail_in = 0; + png_ptr->zstream.next_out = NULL; + png_ptr->zstream.avail_out = 0; + + /* Now initialize if required, setting the new parameters, otherwise just + * to a simple reset to the previous parameters. + */ + if ((png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED) != 0) + ret = deflateReset(&png_ptr->zstream); + + else + { + ret = deflateInit2(&png_ptr->zstream, level, method, windowBits, + memLevel, strategy); + + if (ret == Z_OK) + png_ptr->flags |= PNG_FLAG_ZSTREAM_INITIALIZED; + } + + /* The return code is from either deflateReset or deflateInit2; they have + * pretty much the same set of error codes. + */ + if (ret == Z_OK) + png_ptr->zowner = owner; + + else + png_zstream_error(png_ptr, ret); + + return ret; + } +} + +/* Clean up (or trim) a linked list of compression buffers. */ +void /* PRIVATE */ +png_free_buffer_list(png_structrp png_ptr, png_compression_bufferp *listp) +{ + png_compression_bufferp list = *listp; + + if (list != NULL) + { + *listp = NULL; + + do + { + png_compression_bufferp next = list->next; + + png_free(png_ptr, list); + list = next; + } + while (list != NULL); + } +} + +#ifdef PNG_WRITE_COMPRESSED_TEXT_SUPPORTED +/* This pair of functions encapsulates the operation of (a) compressing a + * text string, and (b) issuing it later as a series of chunk data writes. + * The compression_state structure is shared context for these functions + * set up by the caller to allow access to the relevant local variables. + * + * compression_buffer (new in 1.6.0) is just a linked list of zbuffer_size + * temporary buffers. From 1.6.0 it is retained in png_struct so that it will + * be correctly freed in the event of a write error (previous implementations + * just leaked memory.) + */ +typedef struct +{ + png_const_bytep input; /* The uncompressed input data */ + png_alloc_size_t input_len; /* Its length */ + png_uint_32 output_len; /* Final compressed length */ + png_byte output[1024]; /* First block of output */ +} compression_state; + +static void +png_text_compress_init(compression_state *comp, png_const_bytep input, + png_alloc_size_t input_len) +{ + comp->input = input; + comp->input_len = input_len; + comp->output_len = 0; +} + +/* Compress the data in the compression state input */ +static int +png_text_compress(png_structrp png_ptr, png_uint_32 chunk_name, + compression_state *comp, png_uint_32 prefix_len) +{ + int ret; + + /* To find the length of the output it is necessary to first compress the + * input. The result is buffered rather than using the two-pass algorithm + * that is used on the inflate side; deflate is assumed to be slower and a + * PNG writer is assumed to have more memory available than a PNG reader. + * + * IMPLEMENTATION NOTE: the zlib API deflateBound() can be used to find an + * upper limit on the output size, but it is always bigger than the input + * size so it is likely to be more efficient to use this linked-list + * approach. + */ + ret = png_deflate_claim(png_ptr, chunk_name, comp->input_len); + + if (ret != Z_OK) + return ret; + + /* Set up the compression buffers, we need a loop here to avoid overflowing a + * uInt. Use ZLIB_IO_MAX to limit the input. The output is always limited + * by the output buffer size, so there is no need to check that. Since this + * is ANSI-C we know that an 'int', hence a uInt, is always at least 16 bits + * in size. + */ + { + png_compression_bufferp *end = &png_ptr->zbuffer_list; + png_alloc_size_t input_len = comp->input_len; /* may be zero! */ + png_uint_32 output_len; + + /* zlib updates these for us: */ + png_ptr->zstream.next_in = PNGZ_INPUT_CAST(comp->input); + png_ptr->zstream.avail_in = 0; /* Set below */ + png_ptr->zstream.next_out = comp->output; + png_ptr->zstream.avail_out = (sizeof comp->output); + + output_len = png_ptr->zstream.avail_out; + + do + { + uInt avail_in = ZLIB_IO_MAX; + + if (avail_in > input_len) + avail_in = (uInt)input_len; + + input_len -= avail_in; + + png_ptr->zstream.avail_in = avail_in; + + if (png_ptr->zstream.avail_out == 0) + { + png_compression_buffer *next; + + /* Chunk data is limited to 2^31 bytes in length, so the prefix + * length must be counted here. + */ + if (output_len + prefix_len > PNG_UINT_31_MAX) + { + ret = Z_MEM_ERROR; + break; + } + + /* Need a new (malloc'ed) buffer, but there may be one present + * already. + */ + next = *end; + if (next == NULL) + { + next = png_voidcast(png_compression_bufferp, png_malloc_base + (png_ptr, PNG_COMPRESSION_BUFFER_SIZE(png_ptr))); + + if (next == NULL) + { + ret = Z_MEM_ERROR; + break; + } + + /* Link in this buffer (so that it will be freed later) */ + next->next = NULL; + *end = next; + } + + png_ptr->zstream.next_out = next->output; + png_ptr->zstream.avail_out = png_ptr->zbuffer_size; + output_len += png_ptr->zstream.avail_out; + + /* Move 'end' to the next buffer pointer. */ + end = &next->next; + } + + /* Compress the data */ + ret = deflate(&png_ptr->zstream, + input_len > 0 ? Z_NO_FLUSH : Z_FINISH); + + /* Claw back input data that was not consumed (because avail_in is + * reset above every time round the loop). + */ + input_len += png_ptr->zstream.avail_in; + png_ptr->zstream.avail_in = 0; /* safety */ + } + while (ret == Z_OK); + + /* There may be some space left in the last output buffer. This needs to + * be subtracted from output_len. + */ + output_len -= png_ptr->zstream.avail_out; + png_ptr->zstream.avail_out = 0; /* safety */ + comp->output_len = output_len; + + /* Now double check the output length, put in a custom message if it is + * too long. Otherwise ensure the z_stream::msg pointer is set to + * something. + */ + if (output_len + prefix_len >= PNG_UINT_31_MAX) + { + png_ptr->zstream.msg = PNGZ_MSG_CAST("compressed data too long"); + ret = Z_MEM_ERROR; + } + + else + png_zstream_error(png_ptr, ret); + + /* Reset zlib for another zTXt/iTXt or image data */ + png_ptr->zowner = 0; + + /* The only success case is Z_STREAM_END, input_len must be 0; if not this + * is an internal error. + */ + if (ret == Z_STREAM_END && input_len == 0) + { +#ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED + /* Fix up the deflate header, if required */ + optimize_cmf(comp->output, comp->input_len); +#endif + /* But Z_OK is returned, not Z_STREAM_END; this allows the claim + * function above to return Z_STREAM_END on an error (though it never + * does in the current versions of zlib.) + */ + return Z_OK; + } + + else + return ret; + } +} + +/* Ship the compressed text out via chunk writes */ +static void +png_write_compressed_data_out(png_structrp png_ptr, compression_state *comp) +{ + png_uint_32 output_len = comp->output_len; + png_const_bytep output = comp->output; + png_uint_32 avail = (sizeof comp->output); + png_compression_buffer *next = png_ptr->zbuffer_list; + + for (;;) + { + if (avail > output_len) + avail = output_len; + + png_write_chunk_data(png_ptr, output, avail); + + output_len -= avail; + + if (output_len == 0 || next == NULL) + break; + + avail = png_ptr->zbuffer_size; + output = next->output; + next = next->next; + } + + /* This is an internal error; 'next' must have been NULL! */ + if (output_len > 0) + png_error(png_ptr, "error writing ancillary chunked compressed data"); +} +#endif /* WRITE_COMPRESSED_TEXT */ + +#if defined(PNG_WRITE_TEXT_SUPPORTED) || defined(PNG_WRITE_pCAL_SUPPORTED) || \ + defined(PNG_WRITE_iCCP_SUPPORTED) || defined(PNG_WRITE_sPLT_SUPPORTED) +/* Check that the tEXt or zTXt keyword is valid per PNG 1.0 specification, + * and if invalid, correct the keyword rather than discarding the entire + * chunk. The PNG 1.0 specification requires keywords 1-79 characters in + * length, forbids leading or trailing whitespace, multiple internal spaces, + * and the non-break space (0x80) from ISO 8859-1. Returns keyword length. + * + * The 'new_key' buffer must be 80 characters in size (for the keyword plus a + * trailing '\0'). If this routine returns 0 then there was no keyword, or a + * valid one could not be generated, and the caller must png_error. + */ +static png_uint_32 +png_check_keyword(png_structrp png_ptr, png_const_charp key, png_bytep new_key) +{ + png_const_charp orig_key = key; + png_uint_32 key_len = 0; + int bad_character = 0; + int space = 1; + + png_debug(1, "in png_check_keyword"); + + if (key == NULL) + { + *new_key = 0; + return 0; + } + + while (*key && key_len < 79) + { + png_byte ch = (png_byte)*key++; + + if ((ch > 32 && ch <= 126) || (ch >= 161 /*&& ch <= 255*/)) + *new_key++ = ch, ++key_len, space = 0; + + else if (space == 0) + { + /* A space or an invalid character when one wasn't seen immediately + * before; output just a space. + */ + *new_key++ = 32, ++key_len, space = 1; + + /* If the character was not a space then it is invalid. */ + if (ch != 32) + bad_character = ch; + } + + else if (bad_character == 0) + bad_character = ch; /* just skip it, record the first error */ + } + + if (key_len > 0 && space != 0) /* trailing space */ + { + --key_len, --new_key; + if (bad_character == 0) + bad_character = 32; + } + + /* Terminate the keyword */ + *new_key = 0; + + if (key_len == 0) + return 0; + +#ifdef PNG_WARNINGS_SUPPORTED + /* Try to only output one warning per keyword: */ + if (*key != 0) /* keyword too long */ + png_warning(png_ptr, "keyword truncated"); + + else if (bad_character != 0) + { + PNG_WARNING_PARAMETERS(p) + + png_warning_parameter(p, 1, orig_key); + png_warning_parameter_signed(p, 2, PNG_NUMBER_FORMAT_02x, bad_character); + + png_formatted_warning(png_ptr, p, "keyword \"@1\": bad character '0x@2'"); + } +#endif /* WARNINGS */ + + return key_len; +} +#endif /* WRITE_TEXT || WRITE_pCAL || WRITE_iCCP || WRITE_sPLT */ + +/* Write the IHDR chunk, and update the png_struct with the necessary + * information. Note that the rest of this code depends upon this + * information being correct. + */ +void /* PRIVATE */ +png_write_IHDR(png_structrp png_ptr, png_uint_32 width, png_uint_32 height, + int bit_depth, int color_type, int compression_type, int filter_type, + int interlace_type) +{ + png_byte buf[13]; /* Buffer to store the IHDR info */ + + png_debug(1, "in png_write_IHDR"); + + /* Check that we have valid input data from the application info */ + switch (color_type) + { + case PNG_COLOR_TYPE_GRAY: + switch (bit_depth) + { + case 1: + case 2: + case 4: + case 8: +#ifdef PNG_WRITE_16BIT_SUPPORTED + case 16: +#endif + png_ptr->channels = 1; break; + + default: + png_error(png_ptr, + "Invalid bit depth for grayscale image"); + } + break; + + case PNG_COLOR_TYPE_RGB: +#ifdef PNG_WRITE_16BIT_SUPPORTED + if (bit_depth != 8 && bit_depth != 16) +#else + if (bit_depth != 8) +#endif + png_error(png_ptr, "Invalid bit depth for RGB image"); + + png_ptr->channels = 3; + break; + + case PNG_COLOR_TYPE_PALETTE: + switch (bit_depth) + { + case 1: + case 2: + case 4: + case 8: + png_ptr->channels = 1; + break; + + default: + png_error(png_ptr, "Invalid bit depth for paletted image"); + } + break; + + case PNG_COLOR_TYPE_GRAY_ALPHA: + if (bit_depth != 8 && bit_depth != 16) + png_error(png_ptr, "Invalid bit depth for grayscale+alpha image"); + + png_ptr->channels = 2; + break; + + case PNG_COLOR_TYPE_RGB_ALPHA: +#ifdef PNG_WRITE_16BIT_SUPPORTED + if (bit_depth != 8 && bit_depth != 16) +#else + if (bit_depth != 8) +#endif + png_error(png_ptr, "Invalid bit depth for RGBA image"); + + png_ptr->channels = 4; + break; + + default: + png_error(png_ptr, "Invalid image color type specified"); + } + + if (compression_type != PNG_COMPRESSION_TYPE_BASE) + { + png_warning(png_ptr, "Invalid compression type specified"); + compression_type = PNG_COMPRESSION_TYPE_BASE; + } + + /* Write filter_method 64 (intrapixel differencing) only if + * 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and + * 2. Libpng did not write a PNG signature (this filter_method is only + * used in PNG datastreams that are embedded in MNG datastreams) and + * 3. The application called png_permit_mng_features with a mask that + * included PNG_FLAG_MNG_FILTER_64 and + * 4. The filter_method is 64 and + * 5. The color_type is RGB or RGBA + */ + if ( +#ifdef PNG_MNG_FEATURES_SUPPORTED + !((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 && + ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) == 0) && + (color_type == PNG_COLOR_TYPE_RGB || + color_type == PNG_COLOR_TYPE_RGB_ALPHA) && + (filter_type == PNG_INTRAPIXEL_DIFFERENCING)) && +#endif + filter_type != PNG_FILTER_TYPE_BASE) + { + png_warning(png_ptr, "Invalid filter type specified"); + filter_type = PNG_FILTER_TYPE_BASE; + } + +#ifdef PNG_WRITE_INTERLACING_SUPPORTED + if (interlace_type != PNG_INTERLACE_NONE && + interlace_type != PNG_INTERLACE_ADAM7) + { + png_warning(png_ptr, "Invalid interlace type specified"); + interlace_type = PNG_INTERLACE_ADAM7; + } +#else + interlace_type=PNG_INTERLACE_NONE; +#endif + + /* Save the relevant information */ + png_ptr->bit_depth = (png_byte)bit_depth; + png_ptr->color_type = (png_byte)color_type; + png_ptr->interlaced = (png_byte)interlace_type; +#ifdef PNG_MNG_FEATURES_SUPPORTED + png_ptr->filter_type = (png_byte)filter_type; +#endif + png_ptr->compression_type = (png_byte)compression_type; + png_ptr->width = width; + png_ptr->height = height; + + png_ptr->pixel_depth = (png_byte)(bit_depth * png_ptr->channels); + png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth, width); + /* Set the usr info, so any transformations can modify it */ + png_ptr->usr_width = png_ptr->width; + png_ptr->usr_bit_depth = png_ptr->bit_depth; + png_ptr->usr_channels = png_ptr->channels; + + /* Pack the header information into the buffer */ + png_save_uint_32(buf, width); + png_save_uint_32(buf + 4, height); + buf[8] = (png_byte)bit_depth; + buf[9] = (png_byte)color_type; + buf[10] = (png_byte)compression_type; + buf[11] = (png_byte)filter_type; + buf[12] = (png_byte)interlace_type; + + /* Write the chunk */ + png_write_complete_chunk(png_ptr, png_IHDR, buf, (png_size_t)13); + + if ((png_ptr->do_filter) == PNG_NO_FILTERS) + { + if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE || + png_ptr->bit_depth < 8) + png_ptr->do_filter = PNG_FILTER_NONE; + + else + png_ptr->do_filter = PNG_ALL_FILTERS; + } + + png_ptr->mode = PNG_HAVE_IHDR; /* not READY_FOR_ZTXT */ +} + +/* Write the palette. We are careful not to trust png_color to be in the + * correct order for PNG, so people can redefine it to any convenient + * structure. + */ +void /* PRIVATE */ +png_write_PLTE(png_structrp png_ptr, png_const_colorp palette, + png_uint_32 num_pal) +{ + png_uint_32 max_palette_length, i; + png_const_colorp pal_ptr; + png_byte buf[3]; + + png_debug(1, "in png_write_PLTE"); + + max_palette_length = (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) ? + (1 << png_ptr->bit_depth) : PNG_MAX_PALETTE_LENGTH; + + if (( +#ifdef PNG_MNG_FEATURES_SUPPORTED + (png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE) == 0 && +#endif + num_pal == 0) || num_pal > max_palette_length) + { + if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) + { + png_error(png_ptr, "Invalid number of colors in palette"); + } + + else + { + png_warning(png_ptr, "Invalid number of colors in palette"); + return; + } + } + + if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0) + { + png_warning(png_ptr, + "Ignoring request to write a PLTE chunk in grayscale PNG"); + + return; + } + + png_ptr->num_palette = (png_uint_16)num_pal; + png_debug1(3, "num_palette = %d", png_ptr->num_palette); + + png_write_chunk_header(png_ptr, png_PLTE, (png_uint_32)(num_pal * 3)); +#ifdef PNG_POINTER_INDEXING_SUPPORTED + + for (i = 0, pal_ptr = palette; i < num_pal; i++, pal_ptr++) + { + buf[0] = pal_ptr->red; + buf[1] = pal_ptr->green; + buf[2] = pal_ptr->blue; + png_write_chunk_data(png_ptr, buf, (png_size_t)3); + } + +#else + /* This is a little slower but some buggy compilers need to do this + * instead + */ + pal_ptr=palette; + + for (i = 0; i < num_pal; i++) + { + buf[0] = pal_ptr[i].red; + buf[1] = pal_ptr[i].green; + buf[2] = pal_ptr[i].blue; + png_write_chunk_data(png_ptr, buf, (png_size_t)3); + } + +#endif + png_write_chunk_end(png_ptr); + png_ptr->mode |= PNG_HAVE_PLTE; +} + +/* This is similar to png_text_compress, above, except that it does not require + * all of the data at once and, instead of buffering the compressed result, + * writes it as IDAT chunks. Unlike png_text_compress it *can* png_error out + * because it calls the write interface. As a result it does its own error + * reporting and does not return an error code. In the event of error it will + * just call png_error. The input data length may exceed 32-bits. The 'flush' + * parameter is exactly the same as that to deflate, with the following + * meanings: + * + * Z_NO_FLUSH: normal incremental output of compressed data + * Z_SYNC_FLUSH: do a SYNC_FLUSH, used by png_write_flush + * Z_FINISH: this is the end of the input, do a Z_FINISH and clean up + * + * The routine manages the acquire and release of the png_ptr->zstream by + * checking and (at the end) clearing png_ptr->zowner; it does some sanity + * checks on the 'mode' flags while doing this. + */ +void /* PRIVATE */ +png_compress_IDAT(png_structrp png_ptr, png_const_bytep input, + png_alloc_size_t input_len, int flush) +{ + if (png_ptr->zowner != png_IDAT) + { + /* First time. Ensure we have a temporary buffer for compression and + * trim the buffer list if it has more than one entry to free memory. + * If 'WRITE_COMPRESSED_TEXT' is not set the list will never have been + * created at this point, but the check here is quick and safe. + */ + if (png_ptr->zbuffer_list == NULL) + { + png_ptr->zbuffer_list = png_voidcast(png_compression_bufferp, + png_malloc(png_ptr, PNG_COMPRESSION_BUFFER_SIZE(png_ptr))); + png_ptr->zbuffer_list->next = NULL; + } + + else + png_free_buffer_list(png_ptr, &png_ptr->zbuffer_list->next); + + /* It is a terminal error if we can't claim the zstream. */ + if (png_deflate_claim(png_ptr, png_IDAT, png_image_size(png_ptr)) != Z_OK) + png_error(png_ptr, png_ptr->zstream.msg); + + /* The output state is maintained in png_ptr->zstream, so it must be + * initialized here after the claim. + */ + png_ptr->zstream.next_out = png_ptr->zbuffer_list->output; + png_ptr->zstream.avail_out = png_ptr->zbuffer_size; + } + + /* Now loop reading and writing until all the input is consumed or an error + * terminates the operation. The _out values are maintained across calls to + * this function, but the input must be reset each time. + */ + png_ptr->zstream.next_in = PNGZ_INPUT_CAST(input); + png_ptr->zstream.avail_in = 0; /* set below */ + for (;;) + { + int ret; + + /* INPUT: from the row data */ + uInt avail = ZLIB_IO_MAX; + + if (avail > input_len) + avail = (uInt)input_len; /* safe because of the check */ + + png_ptr->zstream.avail_in = avail; + input_len -= avail; + + ret = deflate(&png_ptr->zstream, input_len > 0 ? Z_NO_FLUSH : flush); + + /* Include as-yet unconsumed input */ + input_len += png_ptr->zstream.avail_in; + png_ptr->zstream.avail_in = 0; + + /* OUTPUT: write complete IDAT chunks when avail_out drops to zero. Note + * that these two zstream fields are preserved across the calls, therefore + * there is no need to set these up on entry to the loop. + */ + if (png_ptr->zstream.avail_out == 0) + { + png_bytep data = png_ptr->zbuffer_list->output; + uInt size = png_ptr->zbuffer_size; + + /* Write an IDAT containing the data then reset the buffer. The + * first IDAT may need deflate header optimization. + */ +#ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED + if ((png_ptr->mode & PNG_HAVE_IDAT) == 0 && + png_ptr->compression_type == PNG_COMPRESSION_TYPE_BASE) + optimize_cmf(data, png_image_size(png_ptr)); +#endif + + png_write_complete_chunk(png_ptr, png_IDAT, data, size); + png_ptr->mode |= PNG_HAVE_IDAT; + + png_ptr->zstream.next_out = data; + png_ptr->zstream.avail_out = size; + + /* For SYNC_FLUSH or FINISH it is essential to keep calling zlib with + * the same flush parameter until it has finished output, for NO_FLUSH + * it doesn't matter. + */ + if (ret == Z_OK && flush != Z_NO_FLUSH) + continue; + } + + /* The order of these checks doesn't matter much; it just affects which + * possible error might be detected if multiple things go wrong at once. + */ + if (ret == Z_OK) /* most likely return code! */ + { + /* If all the input has been consumed then just return. If Z_FINISH + * was used as the flush parameter something has gone wrong if we get + * here. + */ + if (input_len == 0) + { + if (flush == Z_FINISH) + png_error(png_ptr, "Z_OK on Z_FINISH with output space"); + + return; + } + } + + else if (ret == Z_STREAM_END && flush == Z_FINISH) + { + /* This is the end of the IDAT data; any pending output must be + * flushed. For small PNG files we may still be at the beginning. + */ + png_bytep data = png_ptr->zbuffer_list->output; + uInt size = png_ptr->zbuffer_size - png_ptr->zstream.avail_out; + +#ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED + if ((png_ptr->mode & PNG_HAVE_IDAT) == 0 && + png_ptr->compression_type == PNG_COMPRESSION_TYPE_BASE) + optimize_cmf(data, png_image_size(png_ptr)); +#endif + + png_write_complete_chunk(png_ptr, png_IDAT, data, size); + png_ptr->zstream.avail_out = 0; + png_ptr->zstream.next_out = NULL; + png_ptr->mode |= PNG_HAVE_IDAT | PNG_AFTER_IDAT; + + png_ptr->zowner = 0; /* Release the stream */ + return; + } + + else + { + /* This is an error condition. */ + png_zstream_error(png_ptr, ret); + png_error(png_ptr, png_ptr->zstream.msg); + } + } +} + +/* Write an IEND chunk */ +void /* PRIVATE */ +png_write_IEND(png_structrp png_ptr) +{ + png_debug(1, "in png_write_IEND"); + + png_write_complete_chunk(png_ptr, png_IEND, NULL, (png_size_t)0); + png_ptr->mode |= PNG_HAVE_IEND; +} + +#ifdef PNG_WRITE_gAMA_SUPPORTED +/* Write a gAMA chunk */ +void /* PRIVATE */ +png_write_gAMA_fixed(png_structrp png_ptr, png_fixed_point file_gamma) +{ + png_byte buf[4]; + + png_debug(1, "in png_write_gAMA"); + + /* file_gamma is saved in 1/100,000ths */ + png_save_uint_32(buf, (png_uint_32)file_gamma); + png_write_complete_chunk(png_ptr, png_gAMA, buf, (png_size_t)4); +} +#endif + +#ifdef PNG_WRITE_sRGB_SUPPORTED +/* Write a sRGB chunk */ +void /* PRIVATE */ +png_write_sRGB(png_structrp png_ptr, int srgb_intent) +{ + png_byte buf[1]; + + png_debug(1, "in png_write_sRGB"); + + if (srgb_intent >= PNG_sRGB_INTENT_LAST) + png_warning(png_ptr, + "Invalid sRGB rendering intent specified"); + + buf[0]=(png_byte)srgb_intent; + png_write_complete_chunk(png_ptr, png_sRGB, buf, (png_size_t)1); +} +#endif + +#ifdef PNG_WRITE_iCCP_SUPPORTED +/* Write an iCCP chunk */ +void /* PRIVATE */ +png_write_iCCP(png_structrp png_ptr, png_const_charp name, + png_const_bytep profile) +{ + png_uint_32 name_len; + png_uint_32 profile_len; + png_byte new_name[81]; /* 1 byte for the compression byte */ + compression_state comp; + png_uint_32 temp; + + png_debug(1, "in png_write_iCCP"); + + /* These are all internal problems: the profile should have been checked + * before when it was stored. + */ + if (profile == NULL) + png_error(png_ptr, "No profile for iCCP chunk"); /* internal error */ + + profile_len = png_get_uint_32(profile); + + if (profile_len < 132) + png_error(png_ptr, "ICC profile too short"); + + temp = (png_uint_32) (*(profile+8)); + if (temp > 3 && (profile_len & 0x03)) + png_error(png_ptr, "ICC profile length invalid (not a multiple of 4)"); + + { + png_uint_32 embedded_profile_len = png_get_uint_32(profile); + + if (profile_len != embedded_profile_len) + png_error(png_ptr, "Profile length does not match profile"); + } + + name_len = png_check_keyword(png_ptr, name, new_name); + + if (name_len == 0) + png_error(png_ptr, "iCCP: invalid keyword"); + + new_name[++name_len] = PNG_COMPRESSION_TYPE_BASE; + + /* Make sure we include the NULL after the name and the compression type */ + ++name_len; + + png_text_compress_init(&comp, profile, profile_len); + + /* Allow for keyword terminator and compression byte */ + if (png_text_compress(png_ptr, png_iCCP, &comp, name_len) != Z_OK) + png_error(png_ptr, png_ptr->zstream.msg); + + png_write_chunk_header(png_ptr, png_iCCP, name_len + comp.output_len); + + png_write_chunk_data(png_ptr, new_name, name_len); + + png_write_compressed_data_out(png_ptr, &comp); + + png_write_chunk_end(png_ptr); +} +#endif + +#ifdef PNG_WRITE_sPLT_SUPPORTED +/* Write a sPLT chunk */ +void /* PRIVATE */ +png_write_sPLT(png_structrp png_ptr, png_const_sPLT_tp spalette) +{ + png_uint_32 name_len; + png_byte new_name[80]; + png_byte entrybuf[10]; + png_size_t entry_size = (spalette->depth == 8 ? 6 : 10); + png_size_t palette_size = entry_size * spalette->nentries; + png_sPLT_entryp ep; +#ifndef PNG_POINTER_INDEXING_SUPPORTED + int i; +#endif + + png_debug(1, "in png_write_sPLT"); + + name_len = png_check_keyword(png_ptr, spalette->name, new_name); + + if (name_len == 0) + png_error(png_ptr, "sPLT: invalid keyword"); + + /* Make sure we include the NULL after the name */ + png_write_chunk_header(png_ptr, png_sPLT, + (png_uint_32)(name_len + 2 + palette_size)); + + png_write_chunk_data(png_ptr, (png_bytep)new_name, + (png_size_t)(name_len + 1)); + + png_write_chunk_data(png_ptr, &spalette->depth, (png_size_t)1); + + /* Loop through each palette entry, writing appropriately */ +#ifdef PNG_POINTER_INDEXING_SUPPORTED + for (ep = spalette->entries; ep<spalette->entries + spalette->nentries; ep++) + { + if (spalette->depth == 8) + { + entrybuf[0] = (png_byte)ep->red; + entrybuf[1] = (png_byte)ep->green; + entrybuf[2] = (png_byte)ep->blue; + entrybuf[3] = (png_byte)ep->alpha; + png_save_uint_16(entrybuf + 4, ep->frequency); + } + + else + { + png_save_uint_16(entrybuf + 0, ep->red); + png_save_uint_16(entrybuf + 2, ep->green); + png_save_uint_16(entrybuf + 4, ep->blue); + png_save_uint_16(entrybuf + 6, ep->alpha); + png_save_uint_16(entrybuf + 8, ep->frequency); + } + + png_write_chunk_data(png_ptr, entrybuf, entry_size); + } +#else + ep=spalette->entries; + for (i = 0; i>spalette->nentries; i++) + { + if (spalette->depth == 8) + { + entrybuf[0] = (png_byte)ep[i].red; + entrybuf[1] = (png_byte)ep[i].green; + entrybuf[2] = (png_byte)ep[i].blue; + entrybuf[3] = (png_byte)ep[i].alpha; + png_save_uint_16(entrybuf + 4, ep[i].frequency); + } + + else + { + png_save_uint_16(entrybuf + 0, ep[i].red); + png_save_uint_16(entrybuf + 2, ep[i].green); + png_save_uint_16(entrybuf + 4, ep[i].blue); + png_save_uint_16(entrybuf + 6, ep[i].alpha); + png_save_uint_16(entrybuf + 8, ep[i].frequency); + } + + png_write_chunk_data(png_ptr, entrybuf, entry_size); + } +#endif + + png_write_chunk_end(png_ptr); +} +#endif + +#ifdef PNG_WRITE_sBIT_SUPPORTED +/* Write the sBIT chunk */ +void /* PRIVATE */ +png_write_sBIT(png_structrp png_ptr, png_const_color_8p sbit, int color_type) +{ + png_byte buf[4]; + png_size_t size; + + png_debug(1, "in png_write_sBIT"); + + /* Make sure we don't depend upon the order of PNG_COLOR_8 */ + if ((color_type & PNG_COLOR_MASK_COLOR) != 0) + { + png_byte maxbits; + + maxbits = (png_byte)(color_type==PNG_COLOR_TYPE_PALETTE ? 8 : + png_ptr->usr_bit_depth); + + if (sbit->red == 0 || sbit->red > maxbits || + sbit->green == 0 || sbit->green > maxbits || + sbit->blue == 0 || sbit->blue > maxbits) + { + png_warning(png_ptr, "Invalid sBIT depth specified"); + return; + } + + buf[0] = sbit->red; + buf[1] = sbit->green; + buf[2] = sbit->blue; + size = 3; + } + + else + { + if (sbit->gray == 0 || sbit->gray > png_ptr->usr_bit_depth) + { + png_warning(png_ptr, "Invalid sBIT depth specified"); + return; + } + + buf[0] = sbit->gray; + size = 1; + } + + if ((color_type & PNG_COLOR_MASK_ALPHA) != 0) + { + if (sbit->alpha == 0 || sbit->alpha > png_ptr->usr_bit_depth) + { + png_warning(png_ptr, "Invalid sBIT depth specified"); + return; + } + + buf[size++] = sbit->alpha; + } + + png_write_complete_chunk(png_ptr, png_sBIT, buf, size); +} +#endif + +#ifdef PNG_WRITE_cHRM_SUPPORTED +/* Write the cHRM chunk */ +void /* PRIVATE */ +png_write_cHRM_fixed(png_structrp png_ptr, const png_xy *xy) +{ + png_byte buf[32]; + + png_debug(1, "in png_write_cHRM"); + + /* Each value is saved in 1/100,000ths */ + png_save_int_32(buf, xy->whitex); + png_save_int_32(buf + 4, xy->whitey); + + png_save_int_32(buf + 8, xy->redx); + png_save_int_32(buf + 12, xy->redy); + + png_save_int_32(buf + 16, xy->greenx); + png_save_int_32(buf + 20, xy->greeny); + + png_save_int_32(buf + 24, xy->bluex); + png_save_int_32(buf + 28, xy->bluey); + + png_write_complete_chunk(png_ptr, png_cHRM, buf, 32); +} +#endif + +#ifdef PNG_WRITE_tRNS_SUPPORTED +/* Write the tRNS chunk */ +void /* PRIVATE */ +png_write_tRNS(png_structrp png_ptr, png_const_bytep trans_alpha, + png_const_color_16p tran, int num_trans, int color_type) +{ + png_byte buf[6]; + + png_debug(1, "in png_write_tRNS"); + + if (color_type == PNG_COLOR_TYPE_PALETTE) + { + if (num_trans <= 0 || num_trans > (int)png_ptr->num_palette) + { + png_app_warning(png_ptr, + "Invalid number of transparent colors specified"); + return; + } + + /* Write the chunk out as it is */ + png_write_complete_chunk(png_ptr, png_tRNS, trans_alpha, + (png_size_t)num_trans); + } + + else if (color_type == PNG_COLOR_TYPE_GRAY) + { + /* One 16-bit value */ + if (tran->gray >= (1 << png_ptr->bit_depth)) + { + png_app_warning(png_ptr, + "Ignoring attempt to write tRNS chunk out-of-range for bit_depth"); + + return; + } + + png_save_uint_16(buf, tran->gray); + png_write_complete_chunk(png_ptr, png_tRNS, buf, (png_size_t)2); + } + + else if (color_type == PNG_COLOR_TYPE_RGB) + { + /* Three 16-bit values */ + png_save_uint_16(buf, tran->red); + png_save_uint_16(buf + 2, tran->green); + png_save_uint_16(buf + 4, tran->blue); +#ifdef PNG_WRITE_16BIT_SUPPORTED + if (png_ptr->bit_depth == 8 && (buf[0] | buf[2] | buf[4]) != 0) +#else + if ((buf[0] | buf[2] | buf[4]) != 0) +#endif + { + png_app_warning(png_ptr, + "Ignoring attempt to write 16-bit tRNS chunk when bit_depth is 8"); + return; + } + + png_write_complete_chunk(png_ptr, png_tRNS, buf, (png_size_t)6); + } + + else + { + png_app_warning(png_ptr, "Can't write tRNS with an alpha channel"); + } +} +#endif + +#ifdef PNG_WRITE_bKGD_SUPPORTED +/* Write the background chunk */ +void /* PRIVATE */ +png_write_bKGD(png_structrp png_ptr, png_const_color_16p back, int color_type) +{ + png_byte buf[6]; + + png_debug(1, "in png_write_bKGD"); + + if (color_type == PNG_COLOR_TYPE_PALETTE) + { + if ( +#ifdef PNG_MNG_FEATURES_SUPPORTED + (png_ptr->num_palette != 0 || + (png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE) == 0) && +#endif + back->index >= png_ptr->num_palette) + { + png_warning(png_ptr, "Invalid background palette index"); + return; + } + + buf[0] = back->index; + png_write_complete_chunk(png_ptr, png_bKGD, buf, (png_size_t)1); + } + + else if ((color_type & PNG_COLOR_MASK_COLOR) != 0) + { + png_save_uint_16(buf, back->red); + png_save_uint_16(buf + 2, back->green); + png_save_uint_16(buf + 4, back->blue); +#ifdef PNG_WRITE_16BIT_SUPPORTED + if (png_ptr->bit_depth == 8 && (buf[0] | buf[2] | buf[4]) != 0) +#else + if ((buf[0] | buf[2] | buf[4]) != 0) +#endif + { + png_warning(png_ptr, + "Ignoring attempt to write 16-bit bKGD chunk when bit_depth is 8"); + + return; + } + + png_write_complete_chunk(png_ptr, png_bKGD, buf, (png_size_t)6); + } + + else + { + if (back->gray >= (1 << png_ptr->bit_depth)) + { + png_warning(png_ptr, + "Ignoring attempt to write bKGD chunk out-of-range for bit_depth"); + + return; + } + + png_save_uint_16(buf, back->gray); + png_write_complete_chunk(png_ptr, png_bKGD, buf, (png_size_t)2); + } +} +#endif + +#ifdef PNG_WRITE_hIST_SUPPORTED +/* Write the histogram */ +void /* PRIVATE */ +png_write_hIST(png_structrp png_ptr, png_const_uint_16p hist, int num_hist) +{ + int i; + png_byte buf[3]; + + png_debug(1, "in png_write_hIST"); + + if (num_hist > (int)png_ptr->num_palette) + { + png_debug2(3, "num_hist = %d, num_palette = %d", num_hist, + png_ptr->num_palette); + + png_warning(png_ptr, "Invalid number of histogram entries specified"); + return; + } + + png_write_chunk_header(png_ptr, png_hIST, (png_uint_32)(num_hist * 2)); + + for (i = 0; i < num_hist; i++) + { + png_save_uint_16(buf, hist[i]); + png_write_chunk_data(png_ptr, buf, (png_size_t)2); + } + + png_write_chunk_end(png_ptr); +} +#endif + +#ifdef PNG_WRITE_tEXt_SUPPORTED +/* Write a tEXt chunk */ +void /* PRIVATE */ +png_write_tEXt(png_structrp png_ptr, png_const_charp key, png_const_charp text, + png_size_t text_len) +{ + png_uint_32 key_len; + png_byte new_key[80]; + + png_debug(1, "in png_write_tEXt"); + + key_len = png_check_keyword(png_ptr, key, new_key); + + if (key_len == 0) + png_error(png_ptr, "tEXt: invalid keyword"); + + if (text == NULL || *text == '\0') + text_len = 0; + + else + text_len = strlen(text); + + if (text_len > PNG_UINT_31_MAX - (key_len+1)) + png_error(png_ptr, "tEXt: text too long"); + + /* Make sure we include the 0 after the key */ + png_write_chunk_header(png_ptr, png_tEXt, + (png_uint_32)/*checked above*/(key_len + text_len + 1)); + /* + * We leave it to the application to meet PNG-1.0 requirements on the + * contents of the text. PNG-1.0 through PNG-1.2 discourage the use of + * any non-Latin-1 characters except for NEWLINE. ISO PNG will forbid them. + * The NUL character is forbidden by PNG-1.0 through PNG-1.2 and ISO PNG. + */ + png_write_chunk_data(png_ptr, new_key, key_len + 1); + + if (text_len != 0) + png_write_chunk_data(png_ptr, (png_const_bytep)text, text_len); + + png_write_chunk_end(png_ptr); +} +#endif + +#ifdef PNG_WRITE_zTXt_SUPPORTED +/* Write a compressed text chunk */ +void /* PRIVATE */ +png_write_zTXt(png_structrp png_ptr, png_const_charp key, png_const_charp text, + int compression) +{ + png_uint_32 key_len; + png_byte new_key[81]; + compression_state comp; + + png_debug(1, "in png_write_zTXt"); + + if (compression == PNG_TEXT_COMPRESSION_NONE) + { + png_write_tEXt(png_ptr, key, text, 0); + return; + } + + if (compression != PNG_TEXT_COMPRESSION_zTXt) + png_error(png_ptr, "zTXt: invalid compression type"); + + key_len = png_check_keyword(png_ptr, key, new_key); + + if (key_len == 0) + png_error(png_ptr, "zTXt: invalid keyword"); + + /* Add the compression method and 1 for the keyword separator. */ + new_key[++key_len] = PNG_COMPRESSION_TYPE_BASE; + ++key_len; + + /* Compute the compressed data; do it now for the length */ + png_text_compress_init(&comp, (png_const_bytep)text, + text == NULL ? 0 : strlen(text)); + + if (png_text_compress(png_ptr, png_zTXt, &comp, key_len) != Z_OK) + png_error(png_ptr, png_ptr->zstream.msg); + + /* Write start of chunk */ + png_write_chunk_header(png_ptr, png_zTXt, key_len + comp.output_len); + + /* Write key */ + png_write_chunk_data(png_ptr, new_key, key_len); + + /* Write the compressed data */ + png_write_compressed_data_out(png_ptr, &comp); + + /* Close the chunk */ + png_write_chunk_end(png_ptr); +} +#endif + +#ifdef PNG_WRITE_iTXt_SUPPORTED +/* Write an iTXt chunk */ +void /* PRIVATE */ +png_write_iTXt(png_structrp png_ptr, int compression, png_const_charp key, + png_const_charp lang, png_const_charp lang_key, png_const_charp text) +{ + png_uint_32 key_len, prefix_len; + png_size_t lang_len, lang_key_len; + png_byte new_key[82]; + compression_state comp; + + png_debug(1, "in png_write_iTXt"); + + key_len = png_check_keyword(png_ptr, key, new_key); + + if (key_len == 0) + png_error(png_ptr, "iTXt: invalid keyword"); + + /* Set the compression flag */ + switch (compression) + { + case PNG_ITXT_COMPRESSION_NONE: + case PNG_TEXT_COMPRESSION_NONE: + compression = new_key[++key_len] = 0; /* no compression */ + break; + + case PNG_TEXT_COMPRESSION_zTXt: + case PNG_ITXT_COMPRESSION_zTXt: + compression = new_key[++key_len] = 1; /* compressed */ + break; + + default: + png_error(png_ptr, "iTXt: invalid compression"); + } + + new_key[++key_len] = PNG_COMPRESSION_TYPE_BASE; + ++key_len; /* for the keywod separator */ + + /* We leave it to the application to meet PNG-1.0 requirements on the + * contents of the text. PNG-1.0 through PNG-1.2 discourage the use of + * any non-Latin-1 characters except for NEWLINE. ISO PNG, however, + * specifies that the text is UTF-8 and this really doesn't require any + * checking. + * + * The NUL character is forbidden by PNG-1.0 through PNG-1.2 and ISO PNG. + * + * TODO: validate the language tag correctly (see the spec.) + */ + if (lang == NULL) lang = ""; /* empty language is valid */ + lang_len = strlen(lang)+1; + if (lang_key == NULL) lang_key = ""; /* may be empty */ + lang_key_len = strlen(lang_key)+1; + if (text == NULL) text = ""; /* may be empty */ + + prefix_len = key_len; + if (lang_len > PNG_UINT_31_MAX-prefix_len) + prefix_len = PNG_UINT_31_MAX; + else + prefix_len = (png_uint_32)(prefix_len + lang_len); + + if (lang_key_len > PNG_UINT_31_MAX-prefix_len) + prefix_len = PNG_UINT_31_MAX; + else + prefix_len = (png_uint_32)(prefix_len + lang_key_len); + + png_text_compress_init(&comp, (png_const_bytep)text, strlen(text)); + + if (compression != 0) + { + if (png_text_compress(png_ptr, png_iTXt, &comp, prefix_len) != Z_OK) + png_error(png_ptr, png_ptr->zstream.msg); + } + + else + { + if (comp.input_len > PNG_UINT_31_MAX-prefix_len) + png_error(png_ptr, "iTXt: uncompressed text too long"); + + /* So the string will fit in a chunk: */ + comp.output_len = (png_uint_32)/*SAFE*/comp.input_len; + } + + png_write_chunk_header(png_ptr, png_iTXt, comp.output_len + prefix_len); + + png_write_chunk_data(png_ptr, new_key, key_len); + + png_write_chunk_data(png_ptr, (png_const_bytep)lang, lang_len); + + png_write_chunk_data(png_ptr, (png_const_bytep)lang_key, lang_key_len); + + if (compression != 0) + png_write_compressed_data_out(png_ptr, &comp); + + else + png_write_chunk_data(png_ptr, (png_const_bytep)text, comp.output_len); + + png_write_chunk_end(png_ptr); +} +#endif + +#ifdef PNG_WRITE_oFFs_SUPPORTED +/* Write the oFFs chunk */ +void /* PRIVATE */ +png_write_oFFs(png_structrp png_ptr, png_int_32 x_offset, png_int_32 y_offset, + int unit_type) +{ + png_byte buf[9]; + + png_debug(1, "in png_write_oFFs"); + + if (unit_type >= PNG_OFFSET_LAST) + png_warning(png_ptr, "Unrecognized unit type for oFFs chunk"); + + png_save_int_32(buf, x_offset); + png_save_int_32(buf + 4, y_offset); + buf[8] = (png_byte)unit_type; + + png_write_complete_chunk(png_ptr, png_oFFs, buf, (png_size_t)9); +} +#endif +#ifdef PNG_WRITE_pCAL_SUPPORTED +/* Write the pCAL chunk (described in the PNG extensions document) */ +void /* PRIVATE */ +png_write_pCAL(png_structrp png_ptr, png_charp purpose, png_int_32 X0, + png_int_32 X1, int type, int nparams, png_const_charp units, + png_charpp params) +{ + png_uint_32 purpose_len; + png_size_t units_len, total_len; + png_size_tp params_len; + png_byte buf[10]; + png_byte new_purpose[80]; + int i; + + png_debug1(1, "in png_write_pCAL (%d parameters)", nparams); + + if (type >= PNG_EQUATION_LAST) + png_error(png_ptr, "Unrecognized equation type for pCAL chunk"); + + purpose_len = png_check_keyword(png_ptr, purpose, new_purpose); + + if (purpose_len == 0) + png_error(png_ptr, "pCAL: invalid keyword"); + + ++purpose_len; /* terminator */ + + png_debug1(3, "pCAL purpose length = %d", (int)purpose_len); + units_len = strlen(units) + (nparams == 0 ? 0 : 1); + png_debug1(3, "pCAL units length = %d", (int)units_len); + total_len = purpose_len + units_len + 10; + + params_len = (png_size_tp)png_malloc(png_ptr, + (png_alloc_size_t)(nparams * (sizeof (png_size_t)))); + + /* Find the length of each parameter, making sure we don't count the + * null terminator for the last parameter. + */ + for (i = 0; i < nparams; i++) + { + params_len[i] = strlen(params[i]) + (i == nparams - 1 ? 0 : 1); + png_debug2(3, "pCAL parameter %d length = %lu", i, + (unsigned long)params_len[i]); + total_len += params_len[i]; + } + + png_debug1(3, "pCAL total length = %d", (int)total_len); + png_write_chunk_header(png_ptr, png_pCAL, (png_uint_32)total_len); + png_write_chunk_data(png_ptr, new_purpose, purpose_len); + png_save_int_32(buf, X0); + png_save_int_32(buf + 4, X1); + buf[8] = (png_byte)type; + buf[9] = (png_byte)nparams; + png_write_chunk_data(png_ptr, buf, (png_size_t)10); + png_write_chunk_data(png_ptr, (png_const_bytep)units, (png_size_t)units_len); + + for (i = 0; i < nparams; i++) + { + png_write_chunk_data(png_ptr, (png_const_bytep)params[i], params_len[i]); + } + + png_free(png_ptr, params_len); + png_write_chunk_end(png_ptr); +} +#endif + +#ifdef PNG_WRITE_sCAL_SUPPORTED +/* Write the sCAL chunk */ +void /* PRIVATE */ +png_write_sCAL_s(png_structrp png_ptr, int unit, png_const_charp width, + png_const_charp height) +{ + png_byte buf[64]; + png_size_t wlen, hlen, total_len; + + png_debug(1, "in png_write_sCAL_s"); + + wlen = strlen(width); + hlen = strlen(height); + total_len = wlen + hlen + 2; + + if (total_len > 64) + { + png_warning(png_ptr, "Can't write sCAL (buffer too small)"); + return; + } + + buf[0] = (png_byte)unit; + memcpy(buf + 1, width, wlen + 1); /* Append the '\0' here */ + memcpy(buf + wlen + 2, height, hlen); /* Do NOT append the '\0' here */ + + png_debug1(3, "sCAL total length = %u", (unsigned int)total_len); + png_write_complete_chunk(png_ptr, png_sCAL, buf, total_len); +} +#endif + +#ifdef PNG_WRITE_pHYs_SUPPORTED +/* Write the pHYs chunk */ +void /* PRIVATE */ +png_write_pHYs(png_structrp png_ptr, png_uint_32 x_pixels_per_unit, + png_uint_32 y_pixels_per_unit, + int unit_type) +{ + png_byte buf[9]; + + png_debug(1, "in png_write_pHYs"); + + if (unit_type >= PNG_RESOLUTION_LAST) + png_warning(png_ptr, "Unrecognized unit type for pHYs chunk"); + + png_save_uint_32(buf, x_pixels_per_unit); + png_save_uint_32(buf + 4, y_pixels_per_unit); + buf[8] = (png_byte)unit_type; + + png_write_complete_chunk(png_ptr, png_pHYs, buf, (png_size_t)9); +} +#endif + +#ifdef PNG_WRITE_tIME_SUPPORTED +/* Write the tIME chunk. Use either png_convert_from_struct_tm() + * or png_convert_from_time_t(), or fill in the structure yourself. + */ +void /* PRIVATE */ +png_write_tIME(png_structrp png_ptr, png_const_timep mod_time) +{ + png_byte buf[7]; + + png_debug(1, "in png_write_tIME"); + + if (mod_time->month > 12 || mod_time->month < 1 || + mod_time->day > 31 || mod_time->day < 1 || + mod_time->hour > 23 || mod_time->second > 60) + { + png_warning(png_ptr, "Invalid time specified for tIME chunk"); + return; + } + + png_save_uint_16(buf, mod_time->year); + buf[2] = mod_time->month; + buf[3] = mod_time->day; + buf[4] = mod_time->hour; + buf[5] = mod_time->minute; + buf[6] = mod_time->second; + + png_write_complete_chunk(png_ptr, png_tIME, buf, (png_size_t)7); +} +#endif + +/* Initializes the row writing capability of libpng */ +void /* PRIVATE */ +png_write_start_row(png_structrp png_ptr) +{ +#ifdef PNG_WRITE_INTERLACING_SUPPORTED + /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */ + + /* Start of interlace block */ + static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0}; + + /* Offset to next interlace block */ + static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1}; + + /* Start of interlace block in the y direction */ + static PNG_CONST png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1}; + + /* Offset to next interlace block in the y direction */ + static PNG_CONST png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2}; +#endif + + png_alloc_size_t buf_size; + int usr_pixel_depth; + +#ifdef PNG_WRITE_FILTER_SUPPORTED + png_byte filters; +#endif + + png_debug(1, "in png_write_start_row"); + + usr_pixel_depth = png_ptr->usr_channels * png_ptr->usr_bit_depth; + buf_size = PNG_ROWBYTES(usr_pixel_depth, png_ptr->width) + 1; + + /* 1.5.6: added to allow checking in the row write code. */ + png_ptr->transformed_pixel_depth = png_ptr->pixel_depth; + png_ptr->maximum_pixel_depth = (png_byte)usr_pixel_depth; + + /* Set up row buffer */ + png_ptr->row_buf = png_voidcast(png_bytep, png_malloc(png_ptr, buf_size)); + + png_ptr->row_buf[0] = PNG_FILTER_VALUE_NONE; + +#ifdef PNG_WRITE_FILTER_SUPPORTED + filters = png_ptr->do_filter; + + if (png_ptr->height == 1) + filters &= 0xff & ~(PNG_FILTER_UP|PNG_FILTER_AVG|PNG_FILTER_PAETH); + + if (png_ptr->width == 1) + filters &= 0xff & ~(PNG_FILTER_SUB|PNG_FILTER_AVG|PNG_FILTER_PAETH); + + if (filters == 0) + filters = PNG_FILTER_NONE; + + png_ptr->do_filter = filters; + + if (((filters & (PNG_FILTER_SUB | PNG_FILTER_UP | PNG_FILTER_AVG | + PNG_FILTER_PAETH)) != 0) && png_ptr->try_row == NULL) + { + int num_filters = 0; + + png_ptr->try_row = png_voidcast(png_bytep, png_malloc(png_ptr, buf_size)); + + if (filters & PNG_FILTER_SUB) + num_filters++; + + if (filters & PNG_FILTER_UP) + num_filters++; + + if (filters & PNG_FILTER_AVG) + num_filters++; + + if (filters & PNG_FILTER_PAETH) + num_filters++; + + if (num_filters > 1) + png_ptr->tst_row = png_voidcast(png_bytep, png_malloc(png_ptr, + buf_size)); + } + + /* We only need to keep the previous row if we are using one of the following + * filters. + */ + if ((filters & (PNG_FILTER_AVG | PNG_FILTER_UP | PNG_FILTER_PAETH)) != 0) + png_ptr->prev_row = png_voidcast(png_bytep, + png_calloc(png_ptr, buf_size)); +#endif /* WRITE_FILTER */ + +#ifdef PNG_WRITE_INTERLACING_SUPPORTED + /* If interlaced, we need to set up width and height of pass */ + if (png_ptr->interlaced != 0) + { + if ((png_ptr->transformations & PNG_INTERLACE) == 0) + { + png_ptr->num_rows = (png_ptr->height + png_pass_yinc[0] - 1 - + png_pass_ystart[0]) / png_pass_yinc[0]; + + png_ptr->usr_width = (png_ptr->width + png_pass_inc[0] - 1 - + png_pass_start[0]) / png_pass_inc[0]; + } + + else + { + png_ptr->num_rows = png_ptr->height; + png_ptr->usr_width = png_ptr->width; + } + } + + else +#endif + { + png_ptr->num_rows = png_ptr->height; + png_ptr->usr_width = png_ptr->width; + } +} + +/* Internal use only. Called when finished processing a row of data. */ +void /* PRIVATE */ +png_write_finish_row(png_structrp png_ptr) +{ +#ifdef PNG_WRITE_INTERLACING_SUPPORTED + /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */ + + /* Start of interlace block */ + static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0}; + + /* Offset to next interlace block */ + static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1}; + + /* Start of interlace block in the y direction */ + static PNG_CONST png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1}; + + /* Offset to next interlace block in the y direction */ + static PNG_CONST png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2}; +#endif + + png_debug(1, "in png_write_finish_row"); + + /* Next row */ + png_ptr->row_number++; + + /* See if we are done */ + if (png_ptr->row_number < png_ptr->num_rows) + return; + +#ifdef PNG_WRITE_INTERLACING_SUPPORTED + /* If interlaced, go to next pass */ + if (png_ptr->interlaced != 0) + { + png_ptr->row_number = 0; + if ((png_ptr->transformations & PNG_INTERLACE) != 0) + { + png_ptr->pass++; + } + + else + { + /* Loop until we find a non-zero width or height pass */ + do + { + png_ptr->pass++; + + if (png_ptr->pass >= 7) + break; + + png_ptr->usr_width = (png_ptr->width + + png_pass_inc[png_ptr->pass] - 1 - + png_pass_start[png_ptr->pass]) / + png_pass_inc[png_ptr->pass]; + + png_ptr->num_rows = (png_ptr->height + + png_pass_yinc[png_ptr->pass] - 1 - + png_pass_ystart[png_ptr->pass]) / + png_pass_yinc[png_ptr->pass]; + + if ((png_ptr->transformations & PNG_INTERLACE) != 0) + break; + + } while (png_ptr->usr_width == 0 || png_ptr->num_rows == 0); + + } + + /* Reset the row above the image for the next pass */ + if (png_ptr->pass < 7) + { + if (png_ptr->prev_row != NULL) + memset(png_ptr->prev_row, 0, + (png_size_t)(PNG_ROWBYTES(png_ptr->usr_channels* + png_ptr->usr_bit_depth, png_ptr->width)) + 1); + + return; + } + } +#endif + + /* If we get here, we've just written the last row, so we need + to flush the compressor */ + png_compress_IDAT(png_ptr, NULL, 0, Z_FINISH); +} + +#ifdef PNG_WRITE_INTERLACING_SUPPORTED +/* Pick out the correct pixels for the interlace pass. + * The basic idea here is to go through the row with a source + * pointer and a destination pointer (sp and dp), and copy the + * correct pixels for the pass. As the row gets compacted, + * sp will always be >= dp, so we should never overwrite anything. + * See the default: case for the easiest code to understand. + */ +void /* PRIVATE */ +png_do_write_interlace(png_row_infop row_info, png_bytep row, int pass) +{ + /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */ + + /* Start of interlace block */ + static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0}; + + /* Offset to next interlace block */ + static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1}; + + png_debug(1, "in png_do_write_interlace"); + + /* We don't have to do anything on the last pass (6) */ + if (pass < 6) + { + /* Each pixel depth is handled separately */ + switch (row_info->pixel_depth) + { + case 1: + { + png_bytep sp; + png_bytep dp; + unsigned int shift; + int d; + int value; + png_uint_32 i; + png_uint_32 row_width = row_info->width; + + dp = row; + d = 0; + shift = 7; + + for (i = png_pass_start[pass]; i < row_width; + i += png_pass_inc[pass]) + { + sp = row + (png_size_t)(i >> 3); + value = (int)(*sp >> (7 - (int)(i & 0x07))) & 0x01; + d |= (value << shift); + + if (shift == 0) + { + shift = 7; + *dp++ = (png_byte)d; + d = 0; + } + + else + shift--; + + } + if (shift != 7) + *dp = (png_byte)d; + + break; + } + + case 2: + { + png_bytep sp; + png_bytep dp; + unsigned int shift; + int d; + int value; + png_uint_32 i; + png_uint_32 row_width = row_info->width; + + dp = row; + shift = 6; + d = 0; + + for (i = png_pass_start[pass]; i < row_width; + i += png_pass_inc[pass]) + { + sp = row + (png_size_t)(i >> 2); + value = (*sp >> ((3 - (int)(i & 0x03)) << 1)) & 0x03; + d |= (value << shift); + + if (shift == 0) + { + shift = 6; + *dp++ = (png_byte)d; + d = 0; + } + + else + shift -= 2; + } + if (shift != 6) + *dp = (png_byte)d; + + break; + } + + case 4: + { + png_bytep sp; + png_bytep dp; + unsigned int shift; + int d; + int value; + png_uint_32 i; + png_uint_32 row_width = row_info->width; + + dp = row; + shift = 4; + d = 0; + for (i = png_pass_start[pass]; i < row_width; + i += png_pass_inc[pass]) + { + sp = row + (png_size_t)(i >> 1); + value = (*sp >> ((1 - (int)(i & 0x01)) << 2)) & 0x0f; + d |= (value << shift); + + if (shift == 0) + { + shift = 4; + *dp++ = (png_byte)d; + d = 0; + } + + else + shift -= 4; + } + if (shift != 4) + *dp = (png_byte)d; + + break; + } + + default: + { + png_bytep sp; + png_bytep dp; + png_uint_32 i; + png_uint_32 row_width = row_info->width; + png_size_t pixel_bytes; + + /* Start at the beginning */ + dp = row; + + /* Find out how many bytes each pixel takes up */ + pixel_bytes = (row_info->pixel_depth >> 3); + + /* Loop through the row, only looking at the pixels that matter */ + for (i = png_pass_start[pass]; i < row_width; + i += png_pass_inc[pass]) + { + /* Find out where the original pixel is */ + sp = row + (png_size_t)i * pixel_bytes; + + /* Move the pixel */ + if (dp != sp) + memcpy(dp, sp, pixel_bytes); + + /* Next pixel */ + dp += pixel_bytes; + } + break; + } + } + /* Set new row width */ + row_info->width = (row_info->width + + png_pass_inc[pass] - 1 - + png_pass_start[pass]) / + png_pass_inc[pass]; + + row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, + row_info->width); + } +} +#endif + + +/* This filters the row, chooses which filter to use, if it has not already + * been specified by the application, and then writes the row out with the + * chosen filter. + */ +static void /* PRIVATE */ +png_write_filtered_row(png_structrp png_ptr, png_bytep filtered_row, + png_size_t row_bytes); + +#ifdef PNG_WRITE_FILTER_SUPPORTED +static png_size_t /* PRIVATE */ +png_setup_sub_row(png_structrp png_ptr, const png_uint_32 bpp, + const png_size_t row_bytes, const png_size_t lmins) +{ + png_bytep rp, dp, lp; + png_size_t i; + png_size_t sum = 0; + int v; + + png_ptr->try_row[0] = PNG_FILTER_VALUE_SUB; + + for (i = 0, rp = png_ptr->row_buf + 1, dp = png_ptr->try_row + 1; i < bpp; + i++, rp++, dp++) + { + v = *dp = *rp; + sum += (v < 128) ? v : 256 - v; + } + + for (lp = png_ptr->row_buf + 1; i < row_bytes; + i++, rp++, lp++, dp++) + { + v = *dp = (png_byte)(((int)*rp - (int)*lp) & 0xff); + sum += (v < 128) ? v : 256 - v; + + if (sum > lmins) /* We are already worse, don't continue. */ + break; + } + + return (sum); +} + +static png_size_t /* PRIVATE */ +png_setup_up_row(png_structrp png_ptr, const png_size_t row_bytes, + const png_size_t lmins) +{ + png_bytep rp, dp, pp; + png_size_t i; + png_size_t sum = 0; + int v; + + png_ptr->try_row[0] = PNG_FILTER_VALUE_UP; + + for (i = 0, rp = png_ptr->row_buf + 1, dp = png_ptr->try_row + 1, + pp = png_ptr->prev_row + 1; i < row_bytes; + i++, rp++, pp++, dp++) + { + v = *dp = (png_byte)(((int)*rp - (int)*pp) & 0xff); + sum += (v < 128) ? v : 256 - v; + + if (sum > lmins) /* We are already worse, don't continue. */ + break; + } + + return (sum); +} + +static png_size_t /* PRIVATE */ +png_setup_avg_row(png_structrp png_ptr, const png_uint_32 bpp, + const png_size_t row_bytes, const png_size_t lmins) +{ + png_bytep rp, dp, pp, lp; + png_uint_32 i; + png_size_t sum = 0; + int v; + + png_ptr->try_row[0] = PNG_FILTER_VALUE_AVG; + + for (i = 0, rp = png_ptr->row_buf + 1, dp = png_ptr->try_row + 1, + pp = png_ptr->prev_row + 1; i < bpp; i++) + { + v = *dp++ = (png_byte)(((int)*rp++ - ((int)*pp++ / 2)) & 0xff); + + sum += (v < 128) ? v : 256 - v; + } + + for (lp = png_ptr->row_buf + 1; i < row_bytes; i++) + { + v = *dp++ = (png_byte)(((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2)) + & 0xff); + + sum += (v < 128) ? v : 256 - v; + + if (sum > lmins) /* We are already worse, don't continue. */ + break; + } + + return (sum); +} + +static png_size_t /* PRIVATE */ +png_setup_paeth_row(png_structrp png_ptr, const png_uint_32 bpp, + const png_size_t row_bytes, const png_size_t lmins) +{ + png_bytep rp, dp, pp, cp, lp; + png_size_t i; + png_size_t sum = 0; + int v; + + png_ptr->try_row[0] = PNG_FILTER_VALUE_PAETH; + + for (i = 0, rp = png_ptr->row_buf + 1, dp = png_ptr->try_row + 1, + pp = png_ptr->prev_row + 1; i < bpp; i++) + { + v = *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff); + + sum += (v < 128) ? v : 256 - v; + } + + for (lp = png_ptr->row_buf + 1, cp = png_ptr->prev_row + 1; i < row_bytes; + i++) + { + int a, b, c, pa, pb, pc, p; + + b = *pp++; + c = *cp++; + a = *lp++; + + p = b - c; + pc = a - c; + +#ifdef PNG_USE_ABS + pa = abs(p); + pb = abs(pc); + pc = abs(p + pc); +#else + pa = p < 0 ? -p : p; + pb = pc < 0 ? -pc : pc; + pc = (p + pc) < 0 ? -(p + pc) : p + pc; +#endif + + p = (pa <= pb && pa <=pc) ? a : (pb <= pc) ? b : c; + + v = *dp++ = (png_byte)(((int)*rp++ - p) & 0xff); + + sum += (v < 128) ? v : 256 - v; + + if (sum > lmins) /* We are already worse, don't continue. */ + break; + } + + return (sum); +} +#endif /* WRITE_FILTER */ + +void /* PRIVATE */ +png_write_find_filter(png_structrp png_ptr, png_row_infop row_info) +{ +#ifndef PNG_WRITE_FILTER_SUPPORTED + png_write_filtered_row(png_ptr, png_ptr->row_buf, row_info->rowbytes+1); +#else + png_byte filter_to_do = png_ptr->do_filter; + png_bytep row_buf; + png_bytep best_row; + png_uint_32 bpp; + png_size_t mins; + png_size_t row_bytes = row_info->rowbytes; + + png_debug(1, "in png_write_find_filter"); + + /* Find out how many bytes offset each pixel is */ + bpp = (row_info->pixel_depth + 7) >> 3; + + row_buf = png_ptr->row_buf; + mins = PNG_SIZE_MAX - 256/* so we can detect potential overflow of the + running sum */; + + /* The prediction method we use is to find which method provides the + * smallest value when summing the absolute values of the distances + * from zero, using anything >= 128 as negative numbers. This is known + * as the "minimum sum of absolute differences" heuristic. Other + * heuristics are the "weighted minimum sum of absolute differences" + * (experimental and can in theory improve compression), and the "zlib + * predictive" method (not implemented yet), which does test compressions + * of lines using different filter methods, and then chooses the + * (series of) filter(s) that give minimum compressed data size (VERY + * computationally expensive). + * + * GRR 980525: consider also + * + * (1) minimum sum of absolute differences from running average (i.e., + * keep running sum of non-absolute differences & count of bytes) + * [track dispersion, too? restart average if dispersion too large?] + * + * (1b) minimum sum of absolute differences from sliding average, probably + * with window size <= deflate window (usually 32K) + * + * (2) minimum sum of squared differences from zero or running average + * (i.e., ~ root-mean-square approach) + */ + + + /* We don't need to test the 'no filter' case if this is the only filter + * that has been chosen, as it doesn't actually do anything to the data. + */ + best_row = png_ptr->row_buf; + + + if ((filter_to_do & PNG_FILTER_NONE) != 0 && filter_to_do != PNG_FILTER_NONE) + { + png_bytep rp; + png_size_t sum = 0; + png_size_t i; + int v; + + if (PNG_SIZE_MAX/128 <= row_bytes) + { + for (i = 0, rp = row_buf + 1; i < row_bytes; i++, rp++) + { + /* Check for overflow */ + if (sum > PNG_SIZE_MAX/128 - 256) + break; + + v = *rp; + sum += (v < 128) ? v : 256 - v; + } + } + else /* Overflow is not possible */ + { + for (i = 0, rp = row_buf + 1; i < row_bytes; i++, rp++) + { + v = *rp; + sum += (v < 128) ? v : 256 - v; + } + } + + mins = sum; + } + + /* Sub filter */ + if (filter_to_do == PNG_FILTER_SUB) + /* It's the only filter so no testing is needed */ + { + (void) png_setup_sub_row(png_ptr, bpp, row_bytes, mins); + best_row = png_ptr->try_row; + } + + else if ((filter_to_do & PNG_FILTER_SUB) != 0) + { + png_size_t sum; + png_size_t lmins = mins; + + sum = png_setup_sub_row(png_ptr, bpp, row_bytes, lmins); + + if (sum < mins) + { + mins = sum; + best_row = png_ptr->try_row; + if (png_ptr->tst_row != NULL) + { + png_ptr->try_row = png_ptr->tst_row; + png_ptr->tst_row = best_row; + } + } + } + + /* Up filter */ + if (filter_to_do == PNG_FILTER_UP) + { + (void) png_setup_up_row(png_ptr, row_bytes, mins); + best_row = png_ptr->try_row; + } + + else if ((filter_to_do & PNG_FILTER_UP) != 0) + { + png_size_t sum; + png_size_t lmins = mins; + + sum = png_setup_up_row(png_ptr, row_bytes, lmins); + + if (sum < mins) + { + mins = sum; + best_row = png_ptr->try_row; + if (png_ptr->tst_row != NULL) + { + png_ptr->try_row = png_ptr->tst_row; + png_ptr->tst_row = best_row; + } + } + } + + /* Avg filter */ + if (filter_to_do == PNG_FILTER_AVG) + { + (void) png_setup_avg_row(png_ptr, bpp, row_bytes, mins); + best_row = png_ptr->try_row; + } + + else if ((filter_to_do & PNG_FILTER_AVG) != 0) + { + png_size_t sum; + png_size_t lmins = mins; + + sum= png_setup_avg_row(png_ptr, bpp, row_bytes, lmins); + + if (sum < mins) + { + mins = sum; + best_row = png_ptr->try_row; + if (png_ptr->tst_row != NULL) + { + png_ptr->try_row = png_ptr->tst_row; + png_ptr->tst_row = best_row; + } + } + } + + /* Paeth filter */ + if ((filter_to_do == PNG_FILTER_PAETH) != 0) + { + (void) png_setup_paeth_row(png_ptr, bpp, row_bytes, mins); + best_row = png_ptr->try_row; + } + + else if ((filter_to_do & PNG_FILTER_PAETH) != 0) + { + png_size_t sum; + png_size_t lmins = mins; + + sum = png_setup_paeth_row(png_ptr, bpp, row_bytes, lmins); + + if (sum < mins) + { + best_row = png_ptr->try_row; + if (png_ptr->tst_row != NULL) + { + png_ptr->try_row = png_ptr->tst_row; + png_ptr->tst_row = best_row; + } + } + } + + /* Do the actual writing of the filtered row data from the chosen filter. */ + png_write_filtered_row(png_ptr, best_row, row_info->rowbytes+1); + +#endif /* WRITE_FILTER */ +} + + +/* Do the actual writing of a previously filtered row. */ +static void +png_write_filtered_row(png_structrp png_ptr, png_bytep filtered_row, + png_size_t full_row_length/*includes filter byte*/) +{ + png_debug(1, "in png_write_filtered_row"); + + png_debug1(2, "filter = %d", filtered_row[0]); + + png_compress_IDAT(png_ptr, filtered_row, full_row_length, Z_NO_FLUSH); + +#ifdef PNG_WRITE_FILTER_SUPPORTED + /* Swap the current and previous rows */ + if (png_ptr->prev_row != NULL) + { + png_bytep tptr; + + tptr = png_ptr->prev_row; + png_ptr->prev_row = png_ptr->row_buf; + png_ptr->row_buf = tptr; + } +#endif /* WRITE_FILTER */ + + /* Finish row - updates counters and flushes zlib if last row */ + png_write_finish_row(png_ptr); + +#ifdef PNG_WRITE_FLUSH_SUPPORTED + png_ptr->flush_rows++; + + if (png_ptr->flush_dist > 0 && + png_ptr->flush_rows >= png_ptr->flush_dist) + { + png_write_flush(png_ptr); + } +#endif /* WRITE_FLUSH */ +} +#endif /* WRITE */ |