mewin/libpng
1
0
Fork 0
mirror of https://git.code.sf.net/p/libpng/code.git synced 2025-07-10 18:04:09 +02:00
Code Issues Projects Releases Wiki Activity
libpng/pngwutil.c
Glenn Randers-Pehrson 33b25bf1a8 Imported from libpng-1.0.4f.tar
2009-04-06 16:04:40 -05:00

2079 lines
62 KiB
C
Raw Blame History

/* pngwutil.c - utilities to write a PNG file
*
* libpng 1.0.4f - October 12, 1999
* 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, 1999 Glenn Randers-Pehrson
*/
#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 convenient
* 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 ((
#ifdef PNG_WRITE_EMPTY_PLTE_SUPPORTED
!png_ptr->empty_plte_permitted &&
#endif
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 1/1000000ths */
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 = (png_byte)(color_type==PNG_COLOR_TYPE_PALETTE ? 8 :
png_ptr->usr_bit_depth);
if (sbit->red == 0 || sbit->red > maxbits ||
sbit->green == 0 || sbit->green > maxbits ||
sbit->blue == 0 || sbit->blue > maxbits)
{
png_warning(png_ptr, "Invalid sBIT depth specified");
return;
}
buf[0] = sbit->red;
buf[1] = sbit->green;
buf[2] = sbit->blue;
size = 3;
}
else
{
if (sbit->gray == 0 || sbit->gray > png_ptr->usr_bit_depth)
{
png_warning(png_ptr, "Invalid sBIT depth specified");
return;
}
buf[0] = sbit->gray;
size = 1;
}
if (color_type & PNG_COLOR_MASK_ALPHA)
{
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 1/1000000ths */
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 (
#ifdef PNG_WRITE_EMPTY_PLTE_SUPPORTED
(!png_ptr->empty_plte_permitted ||
(png_ptr->empty_plte_permitted && png_ptr->num_palette)) &&
#endif
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) || \
defined(PNG_WRITE_pCAL_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);
/*
* We leave it to the application to meet PNG-1.0 requirements on the
* contents of the text. PNG-1.0 through PNG-1.2 discourage the use of
* any non-Latin-1 characters except for NEWLINE. ISO PNG will forbid them.
*/
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 any more 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 separately */
switch (row_info->pixel_depth)
{
case 1:
{
png_bytep sp;
png_bytep dp;
int shift;
int d;
int value;
png_uint_32 i;
png_uint_32 row_width = row_info->width;
dp = row;
d = 0;
shift = 7;
for (i = png_pass_start[pass]; i < row_width;
i += png_pass_inc[pass])
{
sp = row + (png_size_t)(i >> 3);
value = (int)(*sp >> (7 - (int)(i & 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;
png_uint_32 row_width = row_info->width;
dp = row;
shift = 6;
d = 0;
for (i = png_pass_start[pass]; i < row_width;
i += png_pass_inc[pass])
{
sp = row + (png_size_t)(i >> 2);
value = (*sp >> ((3 - (int)(i & 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;
png_uint_32 row_width = row_info->width;
dp = row;
shift = 4;
d = 0;
for (i = png_pass_start[pass]; i < row_width;
i += png_pass_inc[pass])
{
sp = row + (png_size_t)(i >> 1);
value = (*sp >> ((1 - (int)(i & 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_uint_32 row_width = row_info->width;
png_size_t pixel_bytes;
/* start at the beginning */
dp = row;
/* find out how many bytes each pixel takes up */
pixel_bytes = (row_info->pixel_depth >> 3);
/* loop through the row, only looking at the pixels that
matter */
for (i = png_pass_start[pass]; i < row_width;
i += png_pass_inc[pass])
{
/* find out where the original pixel is */
sp = row + (png_size_t)i * pixel_bytes;
/* move the pixel */
if (dp != sp)
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_byte filter_to_do = png_ptr->do_filter;
png_uint_32 row_bytes = row_info->rowbytes;
#if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
int num_p_filters = (int)png_ptr->num_prev_filters;
#endif
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 minimum sum of absolute differences"
* (experimental and can in theory improve compression), and the "zlib
* predictive" method (not implemented yet), which does test compressions
* of lines using different filter methods, and then chooses the
* (series of) filter(s) that give minimum compressed data size (VERY
* computationally expensive).
*
* GRR 980525: consider also
* (1) minimum sum of absolute differences from running average (i.e.,
* keep running sum of non-absolute differences & count of bytes)
* [track dispersion, too? restart average if dispersion too large?]
* (1b) minimum sum of absolute differences from sliding average, probably
* with window size <= deflate window (usually 32K)
* (2) minimum sum of squared differences from zero or running average
* (i.e., ~ root-mean-square approach)
*/
/* We don't need to test the 'no filter' case if this is the only filter
* that has been chosen, as it doesn't actually do anything to the data.
*/
if (filter_to_do & PNG_FILTER_NONE &&
filter_to_do != 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_bytes; 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;
int j;
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 (j = 0; j < num_p_filters; j++)
{
if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_NONE)
{
sumlo = (sumlo * png_ptr->filter_weights[j]) >>
PNG_WEIGHT_SHIFT;
sumhi = (sumhi * png_ptr->filter_weights[j]) >>
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 (filter_to_do == PNG_FILTER_SUB)
/* it's the only filter so no testing is needed */
{
png_bytep rp, lp, dp;
png_uint_32 i;
for (i = 0, rp = row_buf + 1, dp = png_ptr->sub_row + 1; i < bpp;
i++, rp++, dp++)
{
*dp = *rp;
}
for (lp = row_buf + 1; i < row_bytes;
i++, rp++, lp++, dp++)
{
*dp = (png_byte)(((int)*rp - (int)*lp) & 0xff);
}
best_row = png_ptr->sub_row;
}
else if (filter_to_do & 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 "minimum 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)
{
int j;
png_uint_32 lmhi, lmlo;
lmlo = lmins & PNG_LOMASK;
lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
for (j = 0; j < num_p_filters; j++)
{
if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_SUB)
{
lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>
PNG_WEIGHT_SHIFT;
lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>
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)
{
int j;
png_uint_32 sumhi, sumlo;
sumlo = sum & PNG_LOMASK;
sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
for (j = 0; j < num_p_filters; j++)
{
if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_SUB)
{
sumlo = (sumlo * png_ptr->inv_filter_weights[j]) >>
PNG_WEIGHT_SHIFT;
sumhi = (sumhi * png_ptr->inv_filter_weights[j]) >>
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 (filter_to_do == PNG_FILTER_UP)
{
png_bytep rp, dp, pp;
png_uint_32 i;
for (i = 0, rp = row_buf + 1, dp = png_ptr->up_row + 1,
pp = prev_row + 1; i < row_bytes;
i++, rp++, pp++, dp++)
{
*dp = (png_byte)(((int)*rp - (int)*pp) & 0xff);
}
best_row = png_ptr->up_row;
}
else if (filter_to_do & 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)
{
int j;
png_uint_32 lmhi, lmlo;
lmlo = lmins & PNG_LOMASK;
lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
for (j = 0; j < num_p_filters; j++)
{
if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_UP)
{
lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>
PNG_WEIGHT_SHIFT;
lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>
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_bytes; i++)
{
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)
{
int j;
png_uint_32 sumhi, sumlo;
sumlo = sum & PNG_LOMASK;
sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
for (j = 0; j < num_p_filters; j++)
{
if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_UP)
{
sumlo = (sumlo * png_ptr->filter_weights[j]) >>
PNG_WEIGHT_SHIFT;
sumhi = (sumhi * png_ptr->filter_weights[j]) >>
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 (filter_to_do == PNG_FILTER_AVG)
{
png_bytep rp, dp, pp, lp;
png_uint_32 i;
for (i = 0, rp = row_buf + 1, dp = png_ptr->avg_row + 1,
pp = prev_row + 1; i < bpp; i++)
{
*dp++ = (png_byte)(((int)*rp++ - ((int)*pp++ / 2)) & 0xff);
}
for (lp = row_buf + 1; i < row_bytes; i++)
{
*dp++ = (png_byte)(((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2))
& 0xff);
}
best_row = png_ptr->avg_row;
}
else if (filter_to_do & 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)
{
int j;
png_uint_32 lmhi, lmlo;
lmlo = lmins & PNG_LOMASK;
lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
for (j = 0; j < num_p_filters; j++)
{
if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_AVG)
{
lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>
PNG_WEIGHT_SHIFT;
lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>
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++)
{
v = *dp++ = (png_byte)(((int)*rp++ - ((int)*pp++ / 2)) & 0xff);
sum += (v < 128) ? v : 256 - v;
}
for (lp = row_buf + 1; i < row_bytes; i++)
{
v = *dp++ =
(png_byte)(((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2)) & 0xff);
sum += (v < 128) ? v : 256 - v;
if (sum > lmins) /* We are already worse, don't continue. */
break;
}
#if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
{
int j;
png_uint_32 sumhi, sumlo;
sumlo = sum & PNG_LOMASK;
sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
for (j = 0; j < num_p_filters; j++)
{
if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_NONE)
{
sumlo = (sumlo * png_ptr->filter_weights[j]) >>
PNG_WEIGHT_SHIFT;
sumhi = (sumhi * png_ptr->filter_weights[j]) >>
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 (filter_to_do == PNG_FILTER_PAETH)
{
png_bytep rp, dp, pp, cp, lp;
png_uint_32 i;
for (i = 0, rp = row_buf + 1, dp = png_ptr->paeth_row + 1,
pp = prev_row + 1; i < bpp; i++)
{
*dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
}
for (lp = row_buf + 1, cp = prev_row + 1; i < row_bytes; i++)
{
int a, b, c, pa, pb, pc, p;
b = *pp++;
c = *cp++;
a = *lp++;
p = b - c;
pc = a - c;
#ifdef PNG_USE_ABS
pa = abs(p);
pb = abs(pc);
pc = abs(p + pc);
#else
pa = p < 0 ? -p : p;
pb = pc < 0 ? -pc : pc;
pc = (p + pc) < 0 ? -(p + pc) : p + pc;
#endif
p = (pa <= pb && pa <=pc) ? a : (pb <= pc) ? b : c;
*dp++ = (png_byte)(((int)*rp++ - p) & 0xff);
}
best_row = png_ptr->paeth_row;
}
else if (filter_to_do & 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)
{
int j;
png_uint_32 lmhi, lmlo;
lmlo = lmins & PNG_LOMASK;
lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
for (j = 0; j < num_p_filters; j++)
{
if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_PAETH)
{
lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>
PNG_WEIGHT_SHIFT;
lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>
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++)
{
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_bytes; i++)
{
int a, b, c, pa, pb, pc, p;
b = *pp++;
c = *cp++;
a = *lp++;
#ifndef PNG_SLOW_PAETH
p = b - c;
pc = a - c;
#ifdef PNG_USE_ABS
pa = abs(p);
pb = abs(pc);
pc = abs(p + pc);
#else
pa = p < 0 ? -p : p;
pb = pc < 0 ? -pc : pc;
pc = (p + pc) < 0 ? -(p + pc) : p + pc;
#endif
p = (pa <= pb && pa <=pc) ? a : (pb <= pc) ? b : c;
#else /* PNG_SLOW_PAETH */
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;
#endif /* PNG_SLOW_PAETH */
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)
{
int j;
png_uint_32 sumhi, sumlo;
sumlo = sum & PNG_LOMASK;
sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
for (j = 0; j < num_p_filters; j++)
{
if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_PAETH)
{
sumlo = (sumlo * png_ptr->filter_weights[j]) >>
PNG_WEIGHT_SHIFT;
sumhi = (sumhi * png_ptr->filter_weights[j]) >>
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 j;
for (j = 1; j < num_p_filters; j++)
{
png_ptr->prev_filters[j] = png_ptr->prev_filters[j - 1];
}
png_ptr->prev_filters[j] = 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 */
}
Reference in New Issue View Git Blame Copy Permalink