| |
| /* pngwutil.c - utilities to write a PNG file |
| * |
| * libpng 1.00 |
| * For conditions of distribution and use, see copyright notice in png.h |
| * Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc. |
| * Copyright (c) 1996, 1997 Andreas Dilger |
| * Copyright (c) 1998, Glenn Randers-Pehrson |
| * March 7, 1998 |
| */ |
| |
| #define PNG_INTERNAL |
| #include "png.h" |
| |
| /* 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 |
| png_save_uint_32(png_bytep buf, png_uint_32 i) |
| { |
| buf[0] = (png_byte)((i >> 24) & 0xff); |
| buf[1] = (png_byte)((i >> 16) & 0xff); |
| buf[2] = (png_byte)((i >> 8) & 0xff); |
| buf[3] = (png_byte)(i & 0xff); |
| } |
| |
| #if defined(PNG_WRITE_pCAL_SUPPORTED) |
| /* The png_save_int_32 function assumes integers are stored in two's |
| * complement format. If this isn't the case, then this routine needs to |
| * be modified to write data in two's complement format. |
| */ |
| void |
| png_save_int_32(png_bytep buf, png_int_32 i) |
| { |
| buf[0] = (png_byte)((i >> 24) & 0xff); |
| buf[1] = (png_byte)((i >> 16) & 0xff); |
| buf[2] = (png_byte)((i >> 8) & 0xff); |
| buf[3] = (png_byte)(i & 0xff); |
| } |
| #endif |
| |
| /* 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 |
| png_save_uint_16(png_bytep buf, unsigned int i) |
| { |
| buf[0] = (png_byte)((i >> 8) & 0xff); |
| buf[1] = (png_byte)(i & 0xff); |
| } |
| |
| /* 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. |
| */ |
| void |
| png_write_chunk(png_structp png_ptr, png_bytep chunk_name, |
| png_bytep data, png_size_t length) |
| { |
| png_write_chunk_start(png_ptr, chunk_name, (png_uint_32)length); |
| png_write_chunk_data(png_ptr, data, length); |
| png_write_chunk_end(png_ptr); |
| } |
| |
| /* 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(). |
| */ |
| void |
| png_write_chunk_start(png_structp png_ptr, png_bytep chunk_name, |
| png_uint_32 length) |
| { |
| png_byte buf[4]; |
| png_debug2(0, "Writing %s chunk (%d bytes)\n", chunk_name, length); |
| |
| /* write the length */ |
| png_save_uint_32(buf, length); |
| png_write_data(png_ptr, buf, (png_size_t)4); |
| |
| /* write the chunk name */ |
| png_write_data(png_ptr, chunk_name, (png_size_t)4); |
| /* reset the crc and run it over the chunk name */ |
| png_reset_crc(png_ptr); |
| png_calculate_crc(png_ptr, chunk_name, (png_size_t)4); |
| } |
| |
| /* Write the data of a PNG chunk started with png_write_chunk_start(). |
| * 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_start(). |
| */ |
| void |
| png_write_chunk_data(png_structp png_ptr, png_bytep data, png_size_t length) |
| { |
| /* write the data, and run the CRC over it */ |
| if (data != NULL && length > 0) |
| { |
| png_calculate_crc(png_ptr, data, length); |
| png_write_data(png_ptr, data, length); |
| } |
| } |
| |
| /* Finish a chunk started with png_write_chunk_start(). */ |
| void |
| png_write_chunk_end(png_structp png_ptr) |
| { |
| png_byte buf[4]; |
| |
| /* write the crc */ |
| png_save_uint_32(buf, png_ptr->crc); |
| |
| png_write_data(png_ptr, buf, (png_size_t)4); |
| } |
| |
| /* 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 |
| png_write_sig(png_structp png_ptr) |
| { |
| /* write the rest of the 8 byte signature */ |
| png_write_data(png_ptr, &png_sig[png_ptr->sig_bytes], |
| (png_size_t)8 - png_ptr->sig_bytes); |
| } |
| |
| /* 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 |
| png_write_IHDR(png_structp 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\n"); |
| /* 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: |
| case 16: png_ptr->channels = 1; break; |
| default: png_error(png_ptr,"Invalid bit depth for grayscale image"); |
| } |
| break; |
| case PNG_COLOR_TYPE_RGB: |
| if (bit_depth != 8 && bit_depth != 16) |
| 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: |
| if (bit_depth != 8 && bit_depth != 16) |
| 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; |
| } |
| |
| if (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 off the relevent information */ |
| png_ptr->bit_depth = (png_byte)bit_depth; |
| png_ptr->color_type = (png_byte)color_type; |
| png_ptr->interlaced = (png_byte)interlace_type; |
| png_ptr->width = width; |
| png_ptr->height = height; |
| |
| png_ptr->pixel_depth = (png_byte)(bit_depth * png_ptr->channels); |
| png_ptr->rowbytes = ((width * (png_size_t)png_ptr->pixel_depth + 7) >> 3); |
| /* 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_chunk(png_ptr, png_IHDR, buf, (png_size_t)13); |
| |
| /* initialize zlib with PNG info */ |
| png_ptr->zstream.zalloc = png_zalloc; |
| png_ptr->zstream.zfree = png_zfree; |
| png_ptr->zstream.opaque = (voidpf)png_ptr; |
| if (!(png_ptr->do_filter)) |
| { |
| 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; |
| } |
| if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_STRATEGY)) |
| { |
| if (png_ptr->do_filter != PNG_FILTER_NONE) |
| png_ptr->zlib_strategy = Z_FILTERED; |
| else |
| png_ptr->zlib_strategy = Z_DEFAULT_STRATEGY; |
| } |
| if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_LEVEL)) |
| png_ptr->zlib_level = Z_DEFAULT_COMPRESSION; |
| if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_MEM_LEVEL)) |
| png_ptr->zlib_mem_level = 8; |
| if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_WINDOW_BITS)) |
| png_ptr->zlib_window_bits = 15; |
| if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_METHOD)) |
| png_ptr->zlib_method = 8; |
| deflateInit2(&png_ptr->zstream, png_ptr->zlib_level, |
| png_ptr->zlib_method, png_ptr->zlib_window_bits, |
| png_ptr->zlib_mem_level, png_ptr->zlib_strategy); |
| png_ptr->zstream.next_out = png_ptr->zbuf; |
| png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size; |
| |
| png_ptr->mode = PNG_HAVE_IHDR; |
| } |
| |
| /* 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 convient |
| * structure. |
| */ |
| void |
| png_write_PLTE(png_structp png_ptr, png_colorp palette, png_uint_32 num_pal) |
| { |
| png_uint_32 i; |
| png_colorp pal_ptr; |
| png_byte buf[3]; |
| |
| png_debug(1, "in png_write_PLTE\n"); |
| if (num_pal == 0 || num_pal > 256) |
| { |
| 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; |
| } |
| } |
| |
| png_ptr->num_palette = (png_uint_16)num_pal; |
| png_debug1(3, "num_palette = %d\n", png_ptr->num_palette); |
| |
| png_write_chunk_start(png_ptr, png_PLTE, num_pal * 3); |
| 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); |
| } |
| png_write_chunk_end(png_ptr); |
| png_ptr->mode |= PNG_HAVE_PLTE; |
| } |
| |
| /* write an IDAT chunk */ |
| void |
| png_write_IDAT(png_structp png_ptr, png_bytep data, png_size_t length) |
| { |
| png_debug(1, "in png_write_IDAT\n"); |
| png_write_chunk(png_ptr, png_IDAT, data, length); |
| png_ptr->mode |= PNG_HAVE_IDAT; |
| } |
| |
| /* write an IEND chunk */ |
| void |
| png_write_IEND(png_structp png_ptr) |
| { |
| png_debug(1, "in png_write_IEND\n"); |
| png_write_chunk(png_ptr, png_IEND, NULL, (png_size_t)0); |
| png_ptr->mode |= PNG_HAVE_IEND; |
| } |
| |
| #if defined(PNG_WRITE_gAMA_SUPPORTED) |
| /* write a gAMA chunk */ |
| void |
| png_write_gAMA(png_structp png_ptr, double file_gamma) |
| { |
| png_uint_32 igamma; |
| png_byte buf[4]; |
| |
| png_debug(1, "in png_write_gAMA\n"); |
| /* file_gamma is saved in 1/100,000ths */ |
| igamma = (png_uint_32)(file_gamma * 100000.0 + 0.5); |
| png_save_uint_32(buf, igamma); |
| png_write_chunk(png_ptr, png_gAMA, buf, (png_size_t)4); |
| } |
| #endif |
| |
| #if defined(PNG_WRITE_sRGB_SUPPORTED) |
| /* write a sRGB chunk */ |
| void |
| png_write_sRGB(png_structp png_ptr, int srgb_intent) |
| { |
| png_byte buf[1]; |
| |
| png_debug(1, "in png_write_sRGB\n"); |
| if(srgb_intent >= PNG_sRGB_INTENT_LAST) |
| png_warning(png_ptr, |
| "Invalid sRGB rendering intent specified"); |
| buf[0]=(png_byte)srgb_intent; |
| png_write_chunk(png_ptr, png_sRGB, buf, (png_size_t)1); |
| } |
| #endif |
| |
| #if defined(PNG_WRITE_sBIT_SUPPORTED) |
| /* write the sBIT chunk */ |
| void |
| png_write_sBIT(png_structp png_ptr, png_color_8p sbit, int color_type) |
| { |
| png_byte buf[4]; |
| png_size_t size; |
| |
| png_debug(1, "in png_write_sBIT\n"); |
| /* make sure we don't depend upon the order of PNG_COLOR_8 */ |
| if (color_type & PNG_COLOR_MASK_COLOR) |
| { |
| png_byte maxbits; |
| |
| maxbits = 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) |
| { |
| 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_chunk(png_ptr, png_sBIT, buf, size); |
| } |
| #endif |
| |
| #if defined(PNG_WRITE_cHRM_SUPPORTED) |
| /* write the cHRM chunk */ |
| void |
| png_write_cHRM(png_structp png_ptr, double white_x, double white_y, |
| double red_x, double red_y, double green_x, double green_y, |
| double blue_x, double blue_y) |
| { |
| png_uint_32 itemp; |
| png_byte buf[32]; |
| |
| png_debug(1, "in png_write_cHRM\n"); |
| /* each value is saved int 1/100,000ths */ |
| if (white_x < 0 || white_x > 0.8 || white_y < 0 || white_y > 0.8 || |
| white_x + white_y > 1.0) |
| { |
| png_warning(png_ptr, "Invalid cHRM white point specified"); |
| return; |
| } |
| itemp = (png_uint_32)(white_x * 100000.0 + 0.5); |
| png_save_uint_32(buf, itemp); |
| itemp = (png_uint_32)(white_y * 100000.0 + 0.5); |
| png_save_uint_32(buf + 4, itemp); |
| |
| if (red_x < 0 || red_x > 0.8 || red_y < 0 || red_y > 0.8 || |
| red_x + red_y > 1.0) |
| { |
| png_warning(png_ptr, "Invalid cHRM red point specified"); |
| return; |
| } |
| itemp = (png_uint_32)(red_x * 100000.0 + 0.5); |
| png_save_uint_32(buf + 8, itemp); |
| itemp = (png_uint_32)(red_y * 100000.0 + 0.5); |
| png_save_uint_32(buf + 12, itemp); |
| |
| if (green_x < 0 || green_x > 0.8 || green_y < 0 || green_y > 0.8 || |
| green_x + green_y > 1.0) |
| { |
| png_warning(png_ptr, "Invalid cHRM green point specified"); |
| return; |
| } |
| itemp = (png_uint_32)(green_x * 100000.0 + 0.5); |
| png_save_uint_32(buf + 16, itemp); |
| itemp = (png_uint_32)(green_y * 100000.0 + 0.5); |
| png_save_uint_32(buf + 20, itemp); |
| |
| if (blue_x < 0 || blue_x > 0.8 || blue_y < 0 || blue_y > 0.8 || |
| blue_x + blue_y > 1.0) |
| { |
| png_warning(png_ptr, "Invalid cHRM blue point specified"); |
| return; |
| } |
| itemp = (png_uint_32)(blue_x * 100000.0 + 0.5); |
| png_save_uint_32(buf + 24, itemp); |
| itemp = (png_uint_32)(blue_y * 100000.0 + 0.5); |
| png_save_uint_32(buf + 28, itemp); |
| |
| png_write_chunk(png_ptr, png_cHRM, buf, (png_size_t)32); |
| } |
| #endif |
| |
| #if defined(PNG_WRITE_tRNS_SUPPORTED) |
| /* write the tRNS chunk */ |
| void |
| png_write_tRNS(png_structp png_ptr, png_bytep trans, png_color_16p tran, |
| int num_trans, int color_type) |
| { |
| png_byte buf[6]; |
| |
| png_debug(1, "in png_write_tRNS\n"); |
| if (color_type == PNG_COLOR_TYPE_PALETTE) |
| { |
| if (num_trans <= 0 || num_trans > (int)png_ptr->num_palette) |
| { |
| png_warning(png_ptr,"Invalid number of transparent colors specified"); |
| return; |
| } |
| /* write the chunk out as it is */ |
| png_write_chunk(png_ptr, png_tRNS, trans, (png_size_t)num_trans); |
| } |
| else if (color_type == PNG_COLOR_TYPE_GRAY) |
| { |
| /* one 16 bit value */ |
| png_save_uint_16(buf, tran->gray); |
| png_write_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); |
| png_write_chunk(png_ptr, png_tRNS, buf, (png_size_t)6); |
| } |
| else |
| { |
| png_warning(png_ptr, "Can't write tRNS with an alpha channel"); |
| } |
| } |
| #endif |
| |
| #if defined(PNG_WRITE_bKGD_SUPPORTED) |
| /* write the background chunk */ |
| void |
| png_write_bKGD(png_structp png_ptr, png_color_16p back, int color_type) |
| { |
| png_byte buf[6]; |
| |
| png_debug(1, "in png_write_bKGD\n"); |
| if (color_type == PNG_COLOR_TYPE_PALETTE) |
| { |
| if (back->index > png_ptr->num_palette) |
| { |
| png_warning(png_ptr, "Invalid background palette index"); |
| return; |
| } |
| buf[0] = back->index; |
| png_write_chunk(png_ptr, png_bKGD, buf, (png_size_t)1); |
| } |
| else if (color_type & PNG_COLOR_MASK_COLOR) |
| { |
| png_save_uint_16(buf, back->red); |
| png_save_uint_16(buf + 2, back->green); |
| png_save_uint_16(buf + 4, back->blue); |
| png_write_chunk(png_ptr, png_bKGD, buf, (png_size_t)6); |
| } |
| else |
| { |
| png_save_uint_16(buf, back->gray); |
| png_write_chunk(png_ptr, png_bKGD, buf, (png_size_t)2); |
| } |
| } |
| #endif |
| |
| #if defined(PNG_WRITE_hIST_SUPPORTED) |
| /* write the histogram */ |
| void |
| png_write_hIST(png_structp png_ptr, png_uint_16p hist, int num_hist) |
| { |
| int i; |
| png_byte buf[3]; |
| |
| png_debug(1, "in png_write_hIST\n"); |
| if (num_hist > (int)png_ptr->num_palette) |
| { |
| png_debug2(3, "num_hist = %d, num_palette = %d\n", num_hist, |
| png_ptr->num_palette); |
| png_warning(png_ptr, "Invalid number of histogram entries specified"); |
| return; |
| } |
| |
| png_write_chunk_start(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 |
| |
| #if defined(PNG_WRITE_tEXt_SUPPORTED) || defined(PNG_WRITE_zTXt_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 is allocated to hold the corrected keyword and must be freed |
| * by the calling routine. This avoids problems with trying to write to |
| * static keywords without having to have duplicate copies of the strings. |
| */ |
| png_size_t |
| png_check_keyword(png_structp png_ptr, png_charp key, png_charpp new_key) |
| { |
| png_size_t key_len; |
| png_charp kp, dp; |
| int kflag; |
| |
| png_debug(1, "in png_check_keyword\n"); |
| *new_key = NULL; |
| |
| if (key == NULL || (key_len = png_strlen(key)) == 0) |
| { |
| png_chunk_warning(png_ptr, "zero length keyword"); |
| return ((png_size_t)0); |
| } |
| |
| png_debug1(2, "Keyword to be checked is '%s'\n", key); |
| |
| *new_key = (png_charp)png_malloc(png_ptr, (png_uint_32)(key_len + 1)); |
| |
| /* Replace non-printing characters with a blank and print a warning */ |
| for (kp = key, dp = *new_key; *kp != '\0'; kp++, dp++) |
| { |
| if (*kp < 0x20 || (*kp > 0x7E && (png_byte)*kp < 0xA1)) |
| { |
| #if !defined(PNG_NO_STDIO) |
| char msg[40]; |
| |
| sprintf(msg, "invalid keyword character 0x%02X", *kp); |
| png_chunk_warning(png_ptr, msg); |
| #else |
| png_chunk_warning(png_ptr, "invalid character in keyword"); |
| #endif |
| *dp = ' '; |
| } |
| else |
| { |
| *dp = *kp; |
| } |
| } |
| *dp = '\0'; |
| |
| /* Remove any trailing white space. */ |
| kp = *new_key + key_len - 1; |
| if (*kp == ' ') |
| { |
| png_chunk_warning(png_ptr, "trailing spaces removed from keyword"); |
| |
| while (*kp == ' ') |
| { |
| *(kp--) = '\0'; |
| key_len--; |
| } |
| } |
| |
| /* Remove any leading white space. */ |
| kp = *new_key; |
| if (*kp == ' ') |
| { |
| png_chunk_warning(png_ptr, "leading spaces removed from keyword"); |
| |
| while (*kp == ' ') |
| { |
| kp++; |
| key_len--; |
| } |
| } |
| |
| png_debug1(2, "Checking for multiple internal spaces in '%s'\n", kp); |
| |
| /* Remove multiple internal spaces. */ |
| for (kflag = 0, dp = *new_key; *kp != '\0'; kp++) |
| { |
| if (*kp == ' ' && kflag == 0) |
| { |
| *(dp++) = *kp; |
| kflag = 1; |
| } |
| else if (*kp == ' ') |
| { |
| key_len--; |
| } |
| else |
| { |
| *(dp++) = *kp; |
| kflag = 0; |
| } |
| } |
| *dp = '\0'; |
| |
| if (key_len == 0) |
| { |
| png_chunk_warning(png_ptr, "zero length keyword"); |
| } |
| |
| if (key_len > 79) |
| { |
| png_chunk_warning(png_ptr, "keyword length must be 1 - 79 characters"); |
| new_key[79] = '\0'; |
| key_len = 79; |
| } |
| |
| return (key_len); |
| } |
| #endif |
| |
| #if defined(PNG_WRITE_tEXt_SUPPORTED) |
| /* write a tEXt chunk */ |
| void |
| png_write_tEXt(png_structp png_ptr, png_charp key, png_charp text, |
| png_size_t text_len) |
| { |
| png_size_t key_len; |
| png_charp new_key; |
| |
| png_debug(1, "in png_write_tEXt\n"); |
| if (key == NULL || (key_len = png_check_keyword(png_ptr, key, &new_key))==0) |
| { |
| png_warning(png_ptr, "Empty keyword in tEXt chunk"); |
| return; |
| } |
| |
| if (text == NULL || *text == '\0') |
| text_len = 0; |
| |
| /* make sure we include the 0 after the key */ |
| png_write_chunk_start(png_ptr, png_tEXt, (png_uint_32)key_len+text_len+1); |
| png_write_chunk_data(png_ptr, (png_bytep)new_key, key_len + 1); |
| if (text_len) |
| png_write_chunk_data(png_ptr, (png_bytep)text, text_len); |
| |
| png_write_chunk_end(png_ptr); |
| png_free(png_ptr, new_key); |
| } |
| #endif |
| |
| #if defined(PNG_WRITE_zTXt_SUPPORTED) |
| /* write a compressed text chunk */ |
| void |
| png_write_zTXt(png_structp png_ptr, png_charp key, png_charp text, |
| png_size_t text_len, int compression) |
| { |
| png_size_t key_len; |
| char buf[1]; |
| png_charp new_key; |
| int i, ret; |
| png_charpp output_ptr = NULL; /* array of pointers to output */ |
| int num_output_ptr = 0; /* number of output pointers used */ |
| int max_output_ptr = 0; /* size of output_ptr */ |
| |
| png_debug(1, "in png_write_zTXt\n"); |
| |
| if (key == NULL || (key_len = png_check_keyword(png_ptr, key, &new_key))==0) |
| { |
| png_warning(png_ptr, "Empty keyword in zTXt chunk"); |
| return; |
| } |
| |
| if (text == NULL || *text == '\0' || compression==PNG_TEXT_COMPRESSION_NONE) |
| { |
| png_write_tEXt(png_ptr, new_key, text, (png_size_t)0); |
| png_free(png_ptr, new_key); |
| return; |
| } |
| |
| png_free(png_ptr, new_key); |
| |
| if (compression >= PNG_TEXT_COMPRESSION_LAST) |
| { |
| #if !defined(PNG_NO_STDIO) |
| char msg[50]; |
| sprintf(msg, "Unknown zTXt compression type %d", compression); |
| png_warning(png_ptr, msg); |
| #else |
| png_warning(png_ptr, "Unknown zTXt compression type"); |
| #endif |
| compression = PNG_TEXT_COMPRESSION_zTXt; |
| } |
| |
| /* We can't write the chunk until we find out how much data we have, |
| * which means we need to run the compressor first, and save the |
| * output. This shouldn't be a problem, as the vast majority of |
| * comments should be reasonable, but we will set up an array of |
| * malloc'd pointers to be sure. |
| * |
| * If we knew the application was well behaved, we could simplify this |
| * greatly by assuming we can always malloc an output buffer large |
| * enough to hold the compressed text ((1001 * text_len / 1000) + 12) |
| * and malloc this directly. The only time this would be a bad idea is |
| * if we can't malloc more than 64K and we have 64K of random input |
| * data, or if the input string is incredibly large (although this |
| * wouldn't cause a failure, just a slowdown due to swapping). |
| */ |
| |
| /* set up the compression buffers */ |
| png_ptr->zstream.avail_in = (uInt)text_len; |
| png_ptr->zstream.next_in = (Bytef *)text; |
| png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size; |
| png_ptr->zstream.next_out = (Bytef *)png_ptr->zbuf; |
| |
| /* this is the same compression loop as in png_write_row() */ |
| do |
| { |
| /* compress the data */ |
| ret = deflate(&png_ptr->zstream, Z_NO_FLUSH); |
| if (ret != Z_OK) |
| { |
| /* error */ |
| if (png_ptr->zstream.msg != NULL) |
| png_error(png_ptr, png_ptr->zstream.msg); |
| else |
| png_error(png_ptr, "zlib error"); |
| } |
| /* check to see if we need more room */ |
| if (!png_ptr->zstream.avail_out && png_ptr->zstream.avail_in) |
| { |
| /* make sure the output array has room */ |
| if (num_output_ptr >= max_output_ptr) |
| { |
| int old_max; |
| |
| old_max = max_output_ptr; |
| max_output_ptr = num_output_ptr + 4; |
| if (output_ptr != NULL) |
| { |
| png_charpp old_ptr; |
| |
| old_ptr = output_ptr; |
| output_ptr = (png_charpp)png_malloc(png_ptr, |
| (png_uint_32)(max_output_ptr * sizeof (png_charpp))); |
| png_memcpy(output_ptr, old_ptr, old_max * sizeof (png_charp)); |
| png_free(png_ptr, old_ptr); |
| } |
| else |
| output_ptr = (png_charpp)png_malloc(png_ptr, |
| (png_uint_32)(max_output_ptr * sizeof (png_charp))); |
| } |
| |
| /* save the data */ |
| output_ptr[num_output_ptr] = (png_charp)png_malloc(png_ptr, |
| (png_uint_32)png_ptr->zbuf_size); |
| png_memcpy(output_ptr[num_output_ptr], png_ptr->zbuf, |
| png_ptr->zbuf_size); |
| num_output_ptr++; |
| |
| /* and reset the buffer */ |
| png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size; |
| png_ptr->zstream.next_out = png_ptr->zbuf; |
| } |
| /* continue until we don't have anymore to compress */ |
| } while (png_ptr->zstream.avail_in); |
| |
| /* finish the compression */ |
| do |
| { |
| /* tell zlib we are finished */ |
| ret = deflate(&png_ptr->zstream, Z_FINISH); |
| if (ret != Z_OK && ret != Z_STREAM_END) |
| { |
| /* we got an error */ |
| if (png_ptr->zstream.msg != NULL) |
| png_error(png_ptr, png_ptr->zstream.msg); |
| else |
| png_error(png_ptr, "zlib error"); |
| } |
| |
| /* check to see if we need more room */ |
| if (!(png_ptr->zstream.avail_out) && ret == Z_OK) |
| { |
| /* check to make sure our output array has room */ |
| if (num_output_ptr >= max_output_ptr) |
| { |
| int old_max; |
| |
| old_max = max_output_ptr; |
| max_output_ptr = num_output_ptr + 4; |
| if (output_ptr != NULL) |
| { |
| png_charpp old_ptr; |
| |
| old_ptr = output_ptr; |
| /* This could be optimized to realloc() */ |
| output_ptr = (png_charpp)png_malloc(png_ptr, |
| (png_uint_32)(max_output_ptr * sizeof (png_charpp))); |
| png_memcpy(output_ptr, old_ptr, old_max * sizeof (png_charp)); |
| png_free(png_ptr, old_ptr); |
| } |
| else |
| output_ptr = (png_charpp)png_malloc(png_ptr, |
| (png_uint_32)(max_output_ptr * sizeof (png_charp))); |
| } |
| |
| /* save off the data */ |
| output_ptr[num_output_ptr] = (png_charp)png_malloc(png_ptr, |
| (png_uint_32)png_ptr->zbuf_size); |
| png_memcpy(output_ptr[num_output_ptr], png_ptr->zbuf, |
| png_ptr->zbuf_size); |
| num_output_ptr++; |
| |
| /* and reset the buffer pointers */ |
| png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size; |
| png_ptr->zstream.next_out = png_ptr->zbuf; |
| } |
| } while (ret != Z_STREAM_END); |
| |
| /* text length is number of buffers plus last buffer */ |
| text_len = png_ptr->zbuf_size * num_output_ptr; |
| if (png_ptr->zstream.avail_out < png_ptr->zbuf_size) |
| text_len += png_ptr->zbuf_size - (png_size_t)png_ptr->zstream.avail_out; |
| |
| /* write start of chunk */ |
| png_write_chunk_start(png_ptr, png_zTXt, (png_uint_32)(key_len+text_len+2)); |
| /* write key */ |
| png_write_chunk_data(png_ptr, (png_bytep)key, key_len + 1); |
| buf[0] = (png_byte)compression; |
| /* write compression */ |
| png_write_chunk_data(png_ptr, (png_bytep)buf, (png_size_t)1); |
| |
| /* write saved output buffers, if any */ |
| for (i = 0; i < num_output_ptr; i++) |
| { |
| png_write_chunk_data(png_ptr,(png_bytep)output_ptr[i],png_ptr->zbuf_size); |
| png_free(png_ptr, output_ptr[i]); |
| } |
| if (max_output_ptr != 0) |
| png_free(png_ptr, output_ptr); |
| /* write anything left in zbuf */ |
| if (png_ptr->zstream.avail_out < (png_uint_32)png_ptr->zbuf_size) |
| png_write_chunk_data(png_ptr, png_ptr->zbuf, |
| png_ptr->zbuf_size - png_ptr->zstream.avail_out); |
| /* close the chunk */ |
| png_write_chunk_end(png_ptr); |
| |
| /* reset zlib for another zTXt or the image data */ |
| deflateReset(&png_ptr->zstream); |
| } |
| #endif |
| |
| |
| #if defined(PNG_WRITE_oFFs_SUPPORTED) |
| /* write the oFFs chunk */ |
| void |
| png_write_oFFs(png_structp png_ptr, png_uint_32 x_offset, |
| png_uint_32 y_offset, |
| int unit_type) |
| { |
| png_byte buf[9]; |
| |
| png_debug(1, "in png_write_oFFs\n"); |
| if (unit_type >= PNG_OFFSET_LAST) |
| png_warning(png_ptr, "Unrecognized unit type for oFFs chunk"); |
| |
| png_save_uint_32(buf, x_offset); |
| png_save_uint_32(buf + 4, y_offset); |
| buf[8] = (png_byte)unit_type; |
| |
| png_write_chunk(png_ptr, png_oFFs, buf, (png_size_t)9); |
| } |
| #endif |
| |
| #if defined(PNG_WRITE_pCAL_SUPPORTED) |
| /* write the pCAL chunk (png-scivis-19970203) */ |
| void |
| png_write_pCAL(png_structp png_ptr, png_charp purpose, png_int_32 X0, |
| png_int_32 X1, int type, int nparams, png_charp units, png_charpp params) |
| { |
| png_size_t purpose_len, units_len, total_len; |
| png_uint_32p params_len; |
| png_byte buf[10]; |
| png_charp new_purpose; |
| int i; |
| |
| png_debug1(1, "in png_write_pCAL (%d parameters)\n", nparams); |
| if (type >= PNG_EQUATION_LAST) |
| png_warning(png_ptr, "Unrecognized equation type for pCAL chunk"); |
| |
| purpose_len = png_check_keyword(png_ptr, purpose, &new_purpose) + 1; |
| png_debug1(3, "pCAL purpose length = %d\n", purpose_len); |
| units_len = png_strlen(units) + (nparams == 0 ? 0 : 1); |
| png_debug1(3, "pCAL units length = %d\n", units_len); |
| total_len = purpose_len + units_len + 10; |
| |
| params_len = (png_uint_32p)png_malloc(png_ptr, (png_uint_32)(nparams |
| *sizeof(png_uint_32))); |
| |
| /* 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] = png_strlen(params[i]) + (i == nparams - 1 ? 0 : 1); |
| png_debug2(3, "pCAL parameter %d length = %d\n", i, params_len[i]); |
| total_len += (png_size_t)params_len[i]; |
| } |
| |
| png_debug1(3, "pCAL total length = %d\n", total_len); |
| png_write_chunk_start(png_ptr, png_pCAL, (png_uint_32)total_len); |
| png_write_chunk_data(png_ptr, (png_bytep)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_bytep)units, (png_size_t)units_len); |
| |
| png_free(png_ptr, new_purpose); |
| |
| for (i = 0; i < nparams; i++) |
| { |
| png_write_chunk_data(png_ptr, (png_bytep)params[i], |
| (png_size_t)params_len[i]); |
| } |
| |
| png_free(png_ptr, params_len); |
| png_write_chunk_end(png_ptr); |
| } |
| #endif |
| |
| #if defined(PNG_WRITE_pHYs_SUPPORTED) |
| /* write the pHYs chunk */ |
| void |
| png_write_pHYs(png_structp 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\n"); |
| 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_chunk(png_ptr, png_pHYs, buf, (png_size_t)9); |
| } |
| #endif |
| |
| #if defined(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 |
| png_write_tIME(png_structp png_ptr, png_timep mod_time) |
| { |
| png_byte buf[7]; |
| |
| png_debug(1, "in png_write_tIME\n"); |
| 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_chunk(png_ptr, png_tIME, buf, (png_size_t)7); |
| } |
| #endif |
| |
| /* initializes the row writing capability of libpng */ |
| void |
| png_write_start_row(png_structp png_ptr) |
| { |
| png_size_t buf_size; |
| |
| png_debug(1, "in png_write_start_row\n"); |
| buf_size = (png_size_t)(((png_ptr->width * png_ptr->usr_channels * |
| png_ptr->usr_bit_depth + 7) >> 3) + 1); |
| |
| /* set up row buffer */ |
| png_ptr->row_buf = (png_bytep)png_malloc(png_ptr, (png_uint_32)buf_size); |
| png_ptr->row_buf[0] = PNG_FILTER_VALUE_NONE; |
| |
| /* set up filtering buffer, if using this filter */ |
| if (png_ptr->do_filter & PNG_FILTER_SUB) |
| { |
| png_ptr->sub_row = (png_bytep)png_malloc(png_ptr, |
| (png_ptr->rowbytes + 1)); |
| png_ptr->sub_row[0] = PNG_FILTER_VALUE_SUB; |
| } |
| |
| /* We only need to keep the previous row if we are using one of these. */ |
| if (png_ptr->do_filter & (PNG_FILTER_AVG | PNG_FILTER_UP | PNG_FILTER_PAETH)) |
| { |
| /* set up previous row buffer */ |
| png_ptr->prev_row = (png_bytep)png_malloc(png_ptr, (png_uint_32)buf_size); |
| png_memset(png_ptr->prev_row, 0, buf_size); |
| |
| if (png_ptr->do_filter & PNG_FILTER_UP) |
| { |
| png_ptr->up_row = (png_bytep )png_malloc(png_ptr, |
| (png_ptr->rowbytes + 1)); |
| png_ptr->up_row[0] = PNG_FILTER_VALUE_UP; |
| } |
| |
| if (png_ptr->do_filter & PNG_FILTER_AVG) |
| { |
| png_ptr->avg_row = (png_bytep)png_malloc(png_ptr, |
| (png_ptr->rowbytes + 1)); |
| png_ptr->avg_row[0] = PNG_FILTER_VALUE_AVG; |
| } |
| |
| if (png_ptr->do_filter & PNG_FILTER_PAETH) |
| { |
| png_ptr->paeth_row = (png_bytep )png_malloc(png_ptr, |
| (png_ptr->rowbytes + 1)); |
| png_ptr->paeth_row[0] = PNG_FILTER_VALUE_PAETH; |
| } |
| } |
| |
| #ifdef PNG_WRITE_INTERLACING_SUPPORTED |
| /* if interlaced, we need to set up width and height of pass */ |
| if (png_ptr->interlaced) |
| { |
| if (!(png_ptr->transformations & PNG_INTERLACE)) |
| { |
| 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; |
| } |
| png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size; |
| png_ptr->zstream.next_out = png_ptr->zbuf; |
| } |
| |
| /* Internal use only. Called when finished processing a row of data. */ |
| void |
| png_write_finish_row(png_structp png_ptr) |
| { |
| int ret; |
| |
| png_debug(1, "in png_write_finish_row\n"); |
| /* 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) |
| { |
| png_ptr->row_number = 0; |
| if (png_ptr->transformations & PNG_INTERLACE) |
| { |
| 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) |
| 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) |
| png_memset(png_ptr->prev_row, 0, |
| (png_size_t) (((png_uint_32)png_ptr->usr_channels * |
| (png_uint_32)png_ptr->usr_bit_depth * |
| png_ptr->width + 7) >> 3) + 1); |
| return; |
| } |
| } |
| #endif |
| |
| /* if we get here, we've just written the last row, so we need |
| to flush the compressor */ |
| do |
| { |
| /* tell the compressor we are done */ |
| ret = deflate(&png_ptr->zstream, Z_FINISH); |
| /* check for an error */ |
| if (ret != Z_OK && ret != Z_STREAM_END) |
| { |
| if (png_ptr->zstream.msg != NULL) |
| png_error(png_ptr, png_ptr->zstream.msg); |
| else |
| png_error(png_ptr, "zlib error"); |
| } |
| /* check to see if we need more room */ |
| if (!(png_ptr->zstream.avail_out) && ret == Z_OK) |
| { |
| png_write_IDAT(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size); |
| png_ptr->zstream.next_out = png_ptr->zbuf; |
| png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size; |
| } |
| } while (ret != Z_STREAM_END); |
| |
| /* write any extra space */ |
| if (png_ptr->zstream.avail_out < png_ptr->zbuf_size) |
| { |
| png_write_IDAT(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size - |
| png_ptr->zstream.avail_out); |
| } |
| |
| deflateReset(&png_ptr->zstream); |
| } |
| |
| #if defined(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 |
| png_do_write_interlace(png_row_infop row_info, png_bytep row, int pass) |
| { |
| png_debug(1, "in png_do_write_interlace\n"); |
| /* we don't have to do anything on the last pass (6) */ |
| #if defined(PNG_USELESS_TESTS_SUPPORTED) |
| if (row != NULL && row_info != NULL && pass < 6) |
| #else |
| if (pass < 6) |
| #endif |
| { |
| /* each pixel depth is handled seperately */ |
| switch (row_info->pixel_depth) |
| { |
| case 1: |
| { |
| png_bytep sp; |
| png_bytep dp; |
| int shift; |
| int d; |
| int value; |
| png_uint_32 i; |
| |
| dp = row; |
| d = 0; |
| shift = 7; |
| for (i = png_pass_start[pass]; i < row_info->width; |
| i += png_pass_inc[pass]) |
| { |
| sp = row + (png_size_t)(i >> 3); |
| value = (int)(*sp >> (7 - (int)(i & 7))) & 0x1; |
| 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; |
| int shift; |
| int d; |
| int value; |
| png_uint_32 i; |
| |
| dp = row; |
| shift = 6; |
| d = 0; |
| for (i = png_pass_start[pass]; i < row_info->width; |
| i += png_pass_inc[pass]) |
| { |
| sp = row + (png_size_t)(i >> 2); |
| value = (*sp >> ((3 - (int)(i & 3)) << 1)) & 0x3; |
| 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; |
| int shift; |
| int d; |
| int value; |
| png_uint_32 i; |
| |
| dp = row; |
| shift = 4; |
| d = 0; |
| for (i = png_pass_start[pass]; i < row_info->width; |
| i += png_pass_inc[pass]) |
| { |
| sp = row + (png_size_t)(i >> 1); |
| value = (*sp >> ((1 - (int)(i & 1)) << 2)) & 0xf; |
| 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_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_info->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) |
| png_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 = ((row_info->width * |
| row_info->pixel_depth + 7) >> 3); |
| } |
| } |
| #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. |
| */ |
| #define PNG_MAXSUM (~((png_uint_32)0) >> 1) |
| #define PNG_HISHIFT 10 |
| #define PNG_LOMASK ((png_uint_32)0xffffL) |
| #define PNG_HIMASK ((png_uint_32)(~PNG_LOMASK >> PNG_HISHIFT)) |
| void |
| png_write_find_filter(png_structp png_ptr, png_row_infop row_info) |
| { |
| png_bytep prev_row, best_row, row_buf; |
| png_uint_32 mins, bpp; |
| |
| png_debug(1, "in png_write_find_filter\n"); |
| /* find out how many bytes offset each pixel is */ |
| bpp = (row_info->pixel_depth + 7) / 8; |
| |
| prev_row = png_ptr->prev_row; |
| best_row = row_buf = png_ptr->row_buf; |
| mins = PNG_MAXSUM; |
| |
| /* 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 minumum sum of absolute differences" |
| * (experimental and can in theory improve compression), and the "zlib |
| * predictive" method (not implemented in libpng 0.95), which does test |
| * compressions of lines using different filter methods, and then chooses |
| * the (series of) filter(s) which give minimum compressed data size (VERY |
| * computationally expensive). |
| */ |
| |
| /* 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. |
| */ |
| if (png_ptr->do_filter & PNG_FILTER_NONE && |
| png_ptr->do_filter != PNG_FILTER_NONE) |
| { |
| png_bytep rp; |
| png_uint_32 sum = 0; |
| png_uint_32 i; |
| int v; |
| |
| for (i = 0, rp = row_buf + 1; i < row_info->rowbytes; i++, rp++) |
| { |
| v = *rp; |
| sum += (v < 128) ? v : 256 - v; |
| } |
| |
| #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED) |
| if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED) |
| { |
| png_uint_32 sumhi, sumlo; |
| sumlo = sum & PNG_LOMASK; |
| sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK; /* Gives us some footroom */ |
| |
| /* Reduce the sum if we match any of the previous rows */ |
| for (i = 0; i < (png_uint_32)png_ptr->num_prev_filters; i++) |
| { |
| if (png_ptr->prev_filters[i] == PNG_FILTER_NONE) |
| { |
| sumlo = (sumlo * png_ptr->filter_weights[i]) >> |
| PNG_WEIGHT_SHIFT; |
| sumhi = (sumhi * png_ptr->filter_weights[i]) >> |
| PNG_WEIGHT_SHIFT; |
| } |
| } |
| |
| /* Factor in the cost of this filter (this is here for completeness, |
| * but it makes no sense to have a "cost" for the NONE filter, as |
| * it has the minimum possible computational cost - none). |
| */ |
| sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_NONE]) >> |
| PNG_COST_SHIFT; |
| sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_NONE]) >> |
| PNG_COST_SHIFT; |
| |
| if (sumhi > PNG_HIMASK) |
| sum = PNG_MAXSUM; |
| else |
| sum = (sumhi << PNG_HISHIFT) + sumlo; |
| } |
| #endif |
| mins = sum; |
| } |
| |
| /* sub filter */ |
| if (png_ptr->do_filter & PNG_FILTER_SUB) |
| { |
| png_bytep rp, dp, lp; |
| png_uint_32 sum = 0, lmins = mins; |
| png_uint_32 i; |
| int v; |
| |
| #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED) |
| /* We temporarily increase the "minumum sum" by the factor we |
| * would reduce the sum of this filter, so that we can do the |
| * early exit comparison without scaling the sum each time. |
| */ |
| if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED) |
| { |
| png_uint_32 lmhi, lmlo; |
| lmlo = lmins & PNG_LOMASK; |
| lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK; |
| |
| for (i = 0; i < (png_uint_32)png_ptr->num_prev_filters; i++) |
| { |
| if (png_ptr->prev_filters[i] == PNG_FILTER_VALUE_SUB) |
| { |
| lmlo = (lmlo * png_ptr->inv_filter_weights[i]) >> |
| PNG_WEIGHT_SHIFT; |
| lmhi = (lmhi * png_ptr->inv_filter_weights[i]) >> |
| PNG_WEIGHT_SHIFT; |
| } |
| } |
| |
| lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >> |
| PNG_COST_SHIFT; |
| lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >> |
| PNG_COST_SHIFT; |
| |
| if (lmhi > PNG_HIMASK) |
| lmins = PNG_MAXSUM; |
| else |
| lmins = (lmhi << PNG_HISHIFT) + lmlo; |
| } |
| #endif |
| |
| for (i = 0, rp = row_buf + 1, dp = png_ptr->sub_row + 1; i < bpp; |
| i++, rp++, dp++) |
| { |
| v = *dp = *rp; |
| |
| sum += (v < 128) ? v : 256 - v; |
| } |
| for (lp = row_buf + 1; i < row_info->rowbytes; |
| 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; |
| } |
| |
| #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED) |
| if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED) |
| { |
| png_uint_32 sumhi, sumlo; |
| sumlo = sum & PNG_LOMASK; |
| sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK; |
| |
| for (i = 0; i < (png_uint_32)png_ptr->num_prev_filters; i++) |
| { |
| if (png_ptr->prev_filters[i] == PNG_FILTER_VALUE_SUB) |
| { |
| sumlo = (sumlo * png_ptr->inv_filter_weights[i]) >> |
| PNG_WEIGHT_SHIFT; |
| sumhi = (sumhi * png_ptr->inv_filter_weights[i]) >> |
| PNG_WEIGHT_SHIFT; |
| } |
| } |
| |
| sumlo = (sumlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >> |
| PNG_COST_SHIFT; |
| sumhi = (sumhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >> |
| PNG_COST_SHIFT; |
| |
| if (sumhi > PNG_HIMASK) |
| sum = PNG_MAXSUM; |
| else |
| sum = (sumhi << PNG_HISHIFT) + sumlo; |
| } |
| #endif |
| |
| if (sum < mins) |
| { |
| mins = sum; |
| best_row = png_ptr->sub_row; |
| } |
| } |
| |
| /* up filter */ |
| if (png_ptr->do_filter & PNG_FILTER_UP) |
| { |
| png_bytep rp, dp, pp; |
| png_uint_32 sum = 0, lmins = mins; |
| png_uint_32 i; |
| int v; |
| |
| #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED) |
| if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED) |
| { |
| png_uint_32 lmhi, lmlo; |
| lmlo = lmins & PNG_LOMASK; |
| lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK; |
| |
| for (i = 0; i < (png_uint_32)png_ptr->num_prev_filters; i++) |
| { |
| if (png_ptr->prev_filters[i] == PNG_FILTER_VALUE_UP) |
| { |
| lmlo = (lmlo * png_ptr->inv_filter_weights[i]) >> |
| PNG_WEIGHT_SHIFT; |
| lmhi = (lmhi * png_ptr->inv_filter_weights[i]) >> |
| PNG_WEIGHT_SHIFT; |
| } |
| } |
| |
| lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_UP]) >> |
| PNG_COST_SHIFT; |
| lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_UP]) >> |
| PNG_COST_SHIFT; |
| |
| if (lmhi > PNG_HIMASK) |
| lmins = PNG_MAXSUM; |
| else |
| lmins = (lmhi << PNG_HISHIFT) + lmlo; |
| } |
| #endif |
| |
| for (i = 0, rp = row_buf + 1, dp = png_ptr->up_row + 1, |
| pp = prev_row + 1; i < row_info->rowbytes; |
| 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; |
| } |
| |
| #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED) |
| if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED) |
| { |
| png_uint_32 sumhi, sumlo; |
| sumlo = sum & PNG_LOMASK; |
| sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK; |
| |
| for (i = 0; i < (png_uint_32)png_ptr->num_prev_filters; i++) |
| { |
| if (png_ptr->prev_filters[i] == PNG_FILTER_UP) |
| { |
| sumlo = (sumlo * png_ptr->filter_weights[i]) >> |
| PNG_WEIGHT_SHIFT; |
| sumhi = (sumhi * png_ptr->filter_weights[i]) >> |
| PNG_WEIGHT_SHIFT; |
| } |
| } |
| |
| sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_UP]) >> |
| PNG_COST_SHIFT; |
| sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_UP]) >> |
| PNG_COST_SHIFT; |
| |
| if (sumhi > PNG_HIMASK) |
| sum = PNG_MAXSUM; |
| else |
| sum = (sumhi << PNG_HISHIFT) + sumlo; |
| } |
| #endif |
| |
| if (sum < mins) |
| { |
| mins = sum; |
| best_row = png_ptr->up_row; |
| } |
| } |
| |
| /* avg filter */ |
| if (png_ptr->do_filter & PNG_FILTER_AVG) |
| { |
| png_bytep rp, dp, pp, lp; |
| png_uint_32 sum = 0, lmins = mins; |
| png_uint_32 i; |
| int v; |
| |
| #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED) |
| if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED) |
| { |
| png_uint_32 lmhi, lmlo; |
| lmlo = lmins & PNG_LOMASK; |
| lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK; |
| |
| for (i = 0; i < (png_uint_32)png_ptr->num_prev_filters; i++) |
| { |
| if (png_ptr->prev_filters[i] == PNG_FILTER_VALUE_AVG) |
| { |
| lmlo = (lmlo * png_ptr->inv_filter_weights[i]) >> |
| PNG_WEIGHT_SHIFT; |
| lmhi = (lmhi * png_ptr->inv_filter_weights[i]) >> |
| PNG_WEIGHT_SHIFT; |
| } |
| } |
| |
| lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_AVG]) >> |
| PNG_COST_SHIFT; |
| lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_AVG]) >> |
| PNG_COST_SHIFT; |
| |
| if (lmhi > PNG_HIMASK) |
| lmins = PNG_MAXSUM; |
| else |
| lmins = (lmhi << PNG_HISHIFT) + lmlo; |
| } |
| #endif |
| |
| for (i = 0, rp = row_buf + 1, dp = png_ptr->avg_row + 1, |
| pp = prev_row + 1; i < bpp; i++, rp++, pp++, dp++) |
| { |
| v = *dp = (png_byte)(((int)*rp - ((int)*pp / 2)) & 0xff); |
| |
| sum += (v < 128) ? v : 256 - v; |
| } |
| for (lp = row_buf + 1; i < row_info->rowbytes; |
| i++, rp++, pp++, lp++, dp++) |
| { |
| 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; |
| } |
| |
| #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED) |
| if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED) |
| { |
| png_uint_32 sumhi, sumlo; |
| sumlo = sum & PNG_LOMASK; |
| sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK; |
| |
| for (i = 0; i < png_ptr->num_prev_filters; i++) |
| { |
| if (png_ptr->prev_filters[i] == PNG_FILTER_NONE) |
| { |
| sumlo = (sumlo * png_ptr->filter_weights[i]) >> |
| PNG_WEIGHT_SHIFT; |
| sumhi = (sumhi * png_ptr->filter_weights[i]) >> |
| PNG_WEIGHT_SHIFT; |
| } |
| } |
| |
| sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_AVG]) >> |
| PNG_COST_SHIFT; |
| sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_AVG]) >> |
| PNG_COST_SHIFT; |
| |
| if (sumhi > PNG_HIMASK) |
| sum = PNG_MAXSUM; |
| else |
| sum = (sumhi << PNG_HISHIFT) + sumlo; |
| } |
| #endif |
| |
| if (sum < mins) |
| { |
| mins = sum; |
| best_row = png_ptr->avg_row; |
| } |
| } |
| |
| /* Paeth filter */ |
| if (png_ptr->do_filter & PNG_FILTER_PAETH) |
| { |
| png_bytep rp, dp, pp, cp, lp; |
| png_uint_32 sum = 0, lmins = mins; |
| png_uint_32 i; |
| int v; |
| |
| #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED) |
| if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED) |
| { |
| png_uint_32 lmhi, lmlo; |
| lmlo = lmins & PNG_LOMASK; |
| lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK; |
| |
| for (i = 0; i < png_ptr->num_prev_filters; i++) |
| { |
| if (png_ptr->prev_filters[i] == PNG_FILTER_VALUE_PAETH) |
| { |
| lmlo = (lmlo * png_ptr->inv_filter_weights[i]) >> |
| PNG_WEIGHT_SHIFT; |
| lmhi = (lmhi * png_ptr->inv_filter_weights[i]) >> |
| PNG_WEIGHT_SHIFT; |
| } |
| } |
| |
| lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_PAETH]) >> |
| PNG_COST_SHIFT; |
| lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_PAETH]) >> |
| PNG_COST_SHIFT; |
| |
| if (lmhi > PNG_HIMASK) |
| lmins = PNG_MAXSUM; |
| else |
| lmins = (lmhi << PNG_HISHIFT) + lmlo; |
| } |
| #endif |
| |
| for (i = 0, rp = row_buf + 1, dp = png_ptr->paeth_row + 1, |
| pp = prev_row + 1; (unsigned)i < bpp; i++, rp++, pp++, dp++) |
| { |
| v = *dp = (png_byte)(((int)*rp - (int)*pp) & 0xff); |
| |
| sum += (v < 128) ? v : 256 - v; |
| } |
| for (lp = row_buf + 1, cp = prev_row + 1; i < row_info->rowbytes; |
| i++, rp++, pp++, lp++, dp++, cp++) |
| { |
| int a, b, c, pa, pb, pc, p; |
| |
| b = *pp; |
| c = *cp; |
| a = *lp; |
| |
| p = a + b - c; |
| pa = abs(p - a); |
| pb = abs(p - b); |
| pc = abs(p - c); |
| |
| if (pa <= pb && pa <= pc) |
| p = a; |
| else if (pb <= pc) |
| p = b; |
| else |
| p = 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; |
| } |
| |
| #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED) |
| if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED) |
| { |
| png_uint_32 sumhi, sumlo; |
| sumlo = sum & PNG_LOMASK; |
| sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK; |
| |
| for (i = 0; i < png_ptr->num_prev_filters; i++) |
| { |
| if (png_ptr->prev_filters[i] == PNG_FILTER_PAETH) |
| { |
| sumlo = (sumlo * png_ptr->filter_weights[i]) >> |
| PNG_WEIGHT_SHIFT; |
| sumhi = (sumhi * png_ptr->filter_weights[i]) >> |
| PNG_WEIGHT_SHIFT; |
| } |
| } |
| |
| sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_PAETH]) >> |
| PNG_COST_SHIFT; |
| sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_PAETH]) >> |
| PNG_COST_SHIFT; |
| |
| if (sumhi > PNG_HIMASK) |
| sum = PNG_MAXSUM; |
| else |
| sum = (sumhi << PNG_HISHIFT) + sumlo; |
| } |
| #endif |
| |
| if (sum < mins) |
| { |
| best_row = png_ptr->paeth_row; |
| } |
| } |
| |
| /* Do the actual writing of the filtered row data from the chosen filter. */ |
| png_write_filtered_row(png_ptr, best_row); |
| |
| #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED) |
| /* Save the type of filter we picked this time for future calculations */ |
| if (png_ptr->num_prev_filters > 0) |
| { |
| int i; |
| |
| for (i = 1; i < (int)png_ptr->num_prev_filters; i++) |
| { |
| png_ptr->prev_filters[i] = png_ptr->prev_filters[i - 1]; |
| } |
| png_ptr->prev_filters[i] = best_row[0]; |
| } |
| #endif |
| } |
| |
| |
| /* Do the actual writing of a previously filtered row. */ |
| void |
| png_write_filtered_row(png_structp png_ptr, png_bytep filtered_row) |
| { |
| png_debug(1, "in png_write_filtered_row\n"); |
| png_debug1(2, "filter = %d\n", filtered_row[0]); |
| /* set up the zlib input buffer */ |
| png_ptr->zstream.next_in = filtered_row; |
| png_ptr->zstream.avail_in = (uInt)png_ptr->row_info.rowbytes + 1; |
| /* repeat until we have compressed all the data */ |
| do |
| { |
| int ret; /* return of zlib */ |
| |
| /* compress the data */ |
| ret = deflate(&png_ptr->zstream, Z_NO_FLUSH); |
| /* check for compression errors */ |
| if (ret != Z_OK) |
| { |
| if (png_ptr->zstream.msg != NULL) |
| png_error(png_ptr, png_ptr->zstream.msg); |
| else |
| png_error(png_ptr, "zlib error"); |
| } |
| |
| /* see if it is time to write another IDAT */ |
| if (!(png_ptr->zstream.avail_out)) |
| { |
| /* write the IDAT and reset the zlib output buffer */ |
| png_write_IDAT(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size); |
| png_ptr->zstream.next_out = png_ptr->zbuf; |
| png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size; |
| } |
| /* repeat until all data has been compressed */ |
| } while (png_ptr->zstream.avail_in); |
| |
| /* 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; |
| } |
| |
| /* finish row - updates counters and flushes zlib if last row */ |
| png_write_finish_row(png_ptr); |
| |
| #if defined(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 /* PNG_WRITE_FLUSH_SUPPORTED */ |
| } |