/* pngwutil.c - utilities to write a PNG file * * libpng 0.98 * 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 * January 16, 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; } if (interlace_type != PNG_INTERLACE_NONE && interlace_type != PNG_INTERLACE_ADAM7) { png_warning(png_ptr, "Invalid interlace type specified"); interlace_type = PNG_INTERLACE_ADAM7; } /* 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 > 3) 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) { int 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 > 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, png_uint_32 num_hist) { png_uint_32 i; png_byte buf[3]; png_debug(1, "in png_write_hIST\n"); if (num_hist > 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, 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 0; } png_debug1(2, "Keyword to be checked is '%s'\n", key); *new_key = (png_charp)png_malloc(png_ptr, 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, 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, max_output_ptr * sizeof (png_charp)); } /* save the data */ output_ptr[num_output_ptr] = png_malloc(png_ptr, 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, 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, max_output_ptr * sizeof (png_charp)); } /* save off the data */ output_ptr[num_output_ptr] = png_malloc(png_ptr, 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, 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, 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, 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, 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; } } /* 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 { 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; /* 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; } } /* 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 + 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)(~0x0UL >> 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_size_t 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_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_size_t 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_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_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_size_t 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_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_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_size_t 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_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_size_t 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; 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) { png_byte i; for (i = 1; i < 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 */ }