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pngwutil.c
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pngwutil.c
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/* pngwutil.c - utilities to write a PNG file
*
* Last changed in libpng 1.4.8 [July 7, 2011]
* Copyright (c) 1998-2011 Glenn Randers-Pehrson
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
*
* This code is released under the libpng license.
* For conditions of distribution and use, see the disclaimer
* and license in png.h
*/
#define PNG_NO_PEDANTIC_WARNINGS
#include "png.h"
#ifdef PNG_WRITE_SUPPORTED
#include "pngpriv.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 PNGAPI
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);
}
#ifdef PNG_SAVE_INT_32_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 PNGAPI
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 PNGAPI
png_save_uint_16(png_bytep buf, unsigned int i)
{
buf[0] = (png_byte)((i >> 8) & 0xff);
buf[1] = (png_byte)(i & 0xff);
}
/* Simple function to write the signature. If we have already written
* the magic bytes of the signature, or more likely, the PNG stream is
* being embedded into another stream and doesn't need its own signature,
* we should call png_set_sig_bytes() to tell libpng how many of the
* bytes have already been written.
*/
void PNGAPI
png_write_sig(png_structp png_ptr)
{
png_byte png_signature[8] = {137, 80, 78, 71, 13, 10, 26, 10};
#ifdef PNG_IO_STATE_SUPPORTED
/* Inform the I/O callback that the signature is being written */
png_ptr->io_state = PNG_IO_WRITING | PNG_IO_SIGNATURE;
#endif
/* Write the rest of the 8 byte signature */
png_write_data(png_ptr, &png_signature[png_ptr->sig_bytes],
(png_size_t)(8 - png_ptr->sig_bytes));
if (png_ptr->sig_bytes < 3)
png_ptr->mode |= PNG_HAVE_PNG_SIGNATURE;
}
/* Write 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 PNGAPI
png_write_chunk(png_structp png_ptr, png_bytep chunk_name,
png_bytep data, png_size_t length)
{
if (png_ptr == NULL)
return;
png_write_chunk_start(png_ptr, chunk_name, (png_uint_32)length);
png_write_chunk_data(png_ptr, data, (png_size_t)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 PNGAPI
png_write_chunk_start(png_structp png_ptr, png_bytep chunk_name,
png_uint_32 length)
{
png_byte buf[8];
png_debug2(0, "Writing %s chunk, length = %lu", chunk_name,
(unsigned long)length);
if (png_ptr == NULL)
return;
#ifdef PNG_IO_STATE_SUPPORTED
/* Inform the I/O callback that the chunk header is being written.
* PNG_IO_CHUNK_HDR requires a single I/O call.
*/
png_ptr->io_state = PNG_IO_WRITING | PNG_IO_CHUNK_HDR;
#endif
/* Write the length and the chunk name */
png_save_uint_32(buf, length);
png_memcpy(buf + 4, chunk_name, 4);
png_write_data(png_ptr, buf, (png_size_t)8);
/* Put the chunk name into png_ptr->chunk_name */
png_memcpy(png_ptr->chunk_name, chunk_name, 4);
/* Reset the crc and run it over the chunk name */
png_reset_crc(png_ptr);
png_calculate_crc(png_ptr, chunk_name, 4);
#ifdef PNG_IO_STATE_SUPPORTED
/* Inform the I/O callback that chunk data will (possibly) be written.
* PNG_IO_CHUNK_DATA does NOT require a specific number of I/O calls.
*/
png_ptr->io_state = PNG_IO_WRITING | PNG_IO_CHUNK_DATA;
#endif
}
/* 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 PNGAPI
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 (png_ptr == NULL)
return;
if (data != NULL && length > 0)
{
png_write_data(png_ptr, data, length);
/* Update the CRC after writing the data,
* in case that the user I/O routine alters it.
*/
png_calculate_crc(png_ptr, data, length);
}
}
/* Finish a chunk started with png_write_chunk_start(). */
void PNGAPI
png_write_chunk_end(png_structp png_ptr)
{
png_byte buf[4];
if (png_ptr == NULL) return;
#ifdef PNG_IO_STATE_SUPPORTED
/* Inform the I/O callback that the chunk CRC is being written.
* PNG_IO_CHUNK_CRC requires a single I/O function call.
*/
png_ptr->io_state = PNG_IO_WRITING | PNG_IO_CHUNK_CRC;
#endif
/* Write the crc in a single operation */
png_save_uint_32(buf, png_ptr->crc);
png_write_data(png_ptr, buf, (png_size_t)4);
}
#if defined(PNG_WRITE_TEXT_SUPPORTED) || defined(PNG_WRITE_iCCP_SUPPORTED)
/* This pair of functions encapsulates the operation of (a) compressing a
* text string, and (b) issuing it later as a series of chunk data writes.
* The compression_state structure is shared context for these functions
* set up by the caller in order to make the whole mess thread-safe.
*/
typedef struct
{
char *input; /* The uncompressed input data */
int input_len; /* Its length */
int num_output_ptr; /* Number of output pointers used */
int max_output_ptr; /* Size of output_ptr */
png_charpp output_ptr; /* Array of pointers to output */
} compression_state;
/* Compress given text into storage in the png_ptr structure */
static int /* PRIVATE */
png_text_compress(png_structp png_ptr,
png_charp text, png_size_t text_len, int compression,
compression_state *comp)
{
int ret;
comp->num_output_ptr = 0;
comp->max_output_ptr = 0;
comp->output_ptr = NULL;
comp->input = NULL;
comp->input_len = 0;
/* We may just want to pass the text right through */
if (compression == PNG_TEXT_COMPRESSION_NONE)
{
comp->input = text;
comp->input_len = text_len;
return((int)text_len);
}
if (compression >= PNG_TEXT_COMPRESSION_LAST)
{
#ifdef PNG_STDIO_SUPPORTED
char msg[50];
png_snprintf(msg, 50, "Unknown compression type %d", compression);
png_warning(png_ptr, msg);
#else
png_warning(png_ptr, "Unknown compression type");
#endif
}
/* 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 */
/* TODO: the following cast hides a potential overflow problem. */
png_ptr->zstream.avail_in = (uInt)text_len;
/* NOTE: assume zlib doesn't overwrite the input */
png_ptr->zstream.next_in = (Bytef *)text;
png_ptr->zstream.avail_out = png_ptr->zbuf_size;
png_ptr->zstream.next_out = 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))
{
/* Make sure the output array has room */
if (comp->num_output_ptr >= comp->max_output_ptr)
{
int old_max;
old_max = comp->max_output_ptr;
comp->max_output_ptr = comp->num_output_ptr + 4;
if (comp->output_ptr != NULL)
{
png_charpp old_ptr;
old_ptr = comp->output_ptr;
comp->output_ptr = (png_charpp)png_malloc(png_ptr,
(png_alloc_size_t)
(comp->max_output_ptr * png_sizeof(png_charpp)));
png_memcpy(comp->output_ptr, old_ptr, old_max
* png_sizeof(png_charp));
png_free(png_ptr, old_ptr);
}
else
comp->output_ptr = (png_charpp)png_malloc(png_ptr,
(png_alloc_size_t)
(comp->max_output_ptr * png_sizeof(png_charp)));
}
/* Save the data */
comp->output_ptr[comp->num_output_ptr] =
(png_charp)png_malloc(png_ptr,
(png_alloc_size_t)png_ptr->zbuf_size);
png_memcpy(comp->output_ptr[comp->num_output_ptr], png_ptr->zbuf,
png_ptr->zbuf_size);
comp->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)
{
/* Check to see if we need more room */
if (!(png_ptr->zstream.avail_out))
{
/* Check to make sure our output array has room */
if (comp->num_output_ptr >= comp->max_output_ptr)
{
int old_max;
old_max = comp->max_output_ptr;
comp->max_output_ptr = comp->num_output_ptr + 4;
if (comp->output_ptr != NULL)
{
png_charpp old_ptr;
old_ptr = comp->output_ptr;
/* This could be optimized to realloc() */
comp->output_ptr = (png_charpp)png_malloc(png_ptr,
(png_alloc_size_t)(comp->max_output_ptr *
png_sizeof(png_charp)));
png_memcpy(comp->output_ptr, old_ptr,
old_max * png_sizeof(png_charp));
png_free(png_ptr, old_ptr);
}
else
comp->output_ptr = (png_charpp)png_malloc(png_ptr,
(png_alloc_size_t)(comp->max_output_ptr *
png_sizeof(png_charp)));
}
/* Save the data */
comp->output_ptr[comp->num_output_ptr] =
(png_charp)png_malloc(png_ptr,
(png_alloc_size_t)png_ptr->zbuf_size);
png_memcpy(comp->output_ptr[comp->num_output_ptr], png_ptr->zbuf,
png_ptr->zbuf_size);
comp->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;
}
}
else if (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");
}
} while (ret != Z_STREAM_END);
/* Text length is number of buffers plus last buffer */
text_len = png_ptr->zbuf_size * comp->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;
return((int)text_len);
}
/* Ship the compressed text out via chunk writes */
static void /* PRIVATE */
png_write_compressed_data_out(png_structp png_ptr, compression_state *comp)
{
int i;
/* Handle the no-compression case */
if (comp->input)
{
png_write_chunk_data(png_ptr, (png_bytep)comp->input,
(png_size_t)comp->input_len);
return;
}
/* Write saved output buffers, if any */
for (i = 0; i < comp->num_output_ptr; i++)
{
png_write_chunk_data(png_ptr, (png_bytep)comp->output_ptr[i],
(png_size_t)png_ptr->zbuf_size);
png_free(png_ptr, comp->output_ptr[i]);
}
if (comp->max_output_ptr != 0)
png_free(png_ptr, comp->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_size_t)(png_ptr->zbuf_size - png_ptr->zstream.avail_out));
/* Reset zlib for another zTXt/iTXt or image data */
deflateReset(&png_ptr->zstream);
png_ptr->zstream.data_type = Z_BINARY;
}
#endif
/* Write the IHDR chunk, and update the png_struct with the necessary
* information. Note that the rest of this code depends upon this
* information being correct.
*/
void /* PRIVATE */
png_write_IHDR(png_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_IHDR;
int ret;
png_byte buf[13]; /* Buffer to store the IHDR info */
png_debug(1, "in png_write_IHDR");
/* Check that we have valid input data from the application info */
switch (color_type)
{
case PNG_COLOR_TYPE_GRAY:
switch (bit_depth)
{
case 1:
case 2:
case 4:
case 8:
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;
}
/* Write filter_method 64 (intrapixel differencing) only if
* 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and
* 2. Libpng did not write a PNG signature (this filter_method is only
* used in PNG datastreams that are embedded in MNG datastreams) and
* 3. The application called png_permit_mng_features with a mask that
* included PNG_FLAG_MNG_FILTER_64 and
* 4. The filter_method is 64 and
* 5. The color_type is RGB or RGBA
*/
if (
#ifdef PNG_MNG_FEATURES_SUPPORTED
!((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&
((png_ptr->mode&PNG_HAVE_PNG_SIGNATURE) == 0) &&
(color_type == PNG_COLOR_TYPE_RGB ||
color_type == PNG_COLOR_TYPE_RGB_ALPHA) &&
(filter_type == PNG_INTRAPIXEL_DIFFERENCING)) &&
#endif
filter_type != PNG_FILTER_TYPE_BASE)
{
png_warning(png_ptr, "Invalid filter type specified");
filter_type = PNG_FILTER_TYPE_BASE;
}
#ifdef PNG_WRITE_INTERLACING_SUPPORTED
if (interlace_type != PNG_INTERLACE_NONE &&
interlace_type != PNG_INTERLACE_ADAM7)
{
png_warning(png_ptr, "Invalid interlace type specified");
interlace_type = PNG_INTERLACE_ADAM7;
}
#else
interlace_type=PNG_INTERLACE_NONE;
#endif
/* Save the 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;
#ifdef PNG_MNG_FEATURES_SUPPORTED
png_ptr->filter_type = (png_byte)filter_type;
#endif
png_ptr->compression_type = (png_byte)compression_type;
png_ptr->width = width;
png_ptr->height = height;
png_ptr->pixel_depth = (png_byte)(bit_depth * png_ptr->channels);
png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth, width);
/* Set the usr info, so any transformations can modify it */
png_ptr->usr_width = png_ptr->width;
png_ptr->usr_bit_depth = png_ptr->bit_depth;
png_ptr->usr_channels = png_ptr->channels;
/* Pack the header information into the buffer */
png_save_uint_32(buf, width);
png_save_uint_32(buf + 4, height);
buf[8] = (png_byte)bit_depth;
buf[9] = (png_byte)color_type;
buf[10] = (png_byte)compression_type;
buf[11] = (png_byte)filter_type;
buf[12] = (png_byte)interlace_type;
/* Write the chunk */
png_write_chunk(png_ptr, (png_bytep)png_IHDR, buf, (png_size_t)13);
#if defined(PNG_WRITE_APNG_SUPPORTED)
png_ptr->first_frame_width = width;
png_ptr->first_frame_height = height;
#endif
/* 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;
ret = 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);
if (ret != Z_OK)
{
if (ret == Z_VERSION_ERROR) png_error(png_ptr,
"zlib failed to initialize compressor -- version error");
if (ret == Z_STREAM_ERROR) png_error(png_ptr,
"zlib failed to initialize compressor -- stream error");
if (ret == Z_MEM_ERROR) png_error(png_ptr,
"zlib failed to initialize compressor -- mem error");
png_error(png_ptr, "zlib failed to initialize compressor");
}
png_ptr->zstream.next_out = png_ptr->zbuf;
png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
/* libpng is not interested in zstream.data_type */
/* Set it to a predefined value, to avoid its evaluation inside zlib */
png_ptr->zstream.data_type = Z_BINARY;
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 /* PRIVATE */
png_write_PLTE(png_structp png_ptr, png_colorp palette, png_uint_32 num_pal)
{
PNG_PLTE;
png_uint_32 i;
png_colorp pal_ptr;
png_byte buf[3];
png_debug(1, "in png_write_PLTE");
if ((
#ifdef PNG_MNG_FEATURES_SUPPORTED
!(png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE) &&
#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;
}
}
if (!(png_ptr->color_type&PNG_COLOR_MASK_COLOR))
{
png_warning(png_ptr,
"Ignoring request to write a PLTE chunk in grayscale PNG");
return;
}
png_ptr->num_palette = (png_uint_16)num_pal;
png_debug1(3, "num_palette = %d", png_ptr->num_palette);
png_write_chunk_start(png_ptr, (png_bytep)png_PLTE,
(png_uint_32)(num_pal * 3));
#ifdef PNG_POINTER_INDEXING_SUPPORTED
for (i = 0, pal_ptr = palette; i < num_pal; i++, pal_ptr++)
{
buf[0] = pal_ptr->red;
buf[1] = pal_ptr->green;
buf[2] = pal_ptr->blue;
png_write_chunk_data(png_ptr, buf, (png_size_t)3);
}
#else
/* This is a little slower but some buggy compilers need to do this
* instead
*/
pal_ptr=palette;
for (i = 0; i < num_pal; i++)
{
buf[0] = pal_ptr[i].red;
buf[1] = pal_ptr[i].green;
buf[2] = pal_ptr[i].blue;
png_write_chunk_data(png_ptr, buf, (png_size_t)3);
}
#endif
png_write_chunk_end(png_ptr);
png_ptr->mode |= PNG_HAVE_PLTE;
}
/* Write an IDAT chunk */
void /* PRIVATE */
png_write_IDAT(png_structp png_ptr, png_bytep data, png_size_t length)
{
PNG_IDAT;
#if defined(PNG_WRITE_APNG_SUPPORTED)
PNG_fdAT;
#endif
png_debug(1, "in png_write_IDAT");
/* Optimize the CMF field in the zlib stream. */
/* This hack of the zlib stream is compliant to the stream specification. */
if (!(png_ptr->mode & PNG_HAVE_IDAT) &&
png_ptr->compression_type == PNG_COMPRESSION_TYPE_BASE)
{
unsigned int z_cmf = data[0]; /* zlib compression method and flags */
if ((z_cmf & 0x0f) == 8 && (z_cmf & 0xf0) <= 0x70)
{
/* Avoid memory underflows and multiplication overflows.
*
* The conditions below are practically always satisfied;
* however, they still must be checked.
*/
if (length >= 2 &&
png_ptr->height < 16384 && png_ptr->width < 16384)
{
unsigned int z_cinfo;
unsigned int half_z_window_size;
/* Compute the maximum possible length of the datastream */
/* Number of pixels, plus for each row a filter byte
* and possibly a padding byte, so increase the maximum
* size to account for these.
*/
png_uint_32 uncompressed_idat_size = png_ptr->height *
((png_ptr->width *
png_ptr->channels * png_ptr->bit_depth + 15) >> 3);
/* If it's interlaced, each block of 8 rows is sent as up to
* 14 rows, i.e., 6 additional rows, each with a filter byte
* and possibly a padding byte
*/
if (png_ptr->interlaced)
uncompressed_idat_size += ((png_ptr->height + 7)/8) *
(png_ptr->bit_depth < 8 ? 12 : 6);
z_cinfo = z_cmf >> 4;
half_z_window_size = 1 << (z_cinfo + 7);
while (uncompressed_idat_size <= half_z_window_size &&
half_z_window_size >= 256)
{
z_cinfo--;
half_z_window_size >>= 1;
}
z_cmf = (z_cmf & 0x0f) | (z_cinfo << 4);
if (data[0] != (png_byte)z_cmf)
{
data[0] = (png_byte)z_cmf;
data[1] &= 0xe0;
data[1] += (png_byte)(0x1f - ((z_cmf << 8) + data[1]) % 0x1f);
}
}
}
else
png_error(png_ptr,
"Invalid zlib compression method or flags in IDAT");
}
#if defined(PNG_WRITE_APNG_SUPPORTED)
if(png_ptr->num_frames_written == 0)
#endif
png_write_chunk(png_ptr, (png_bytep)png_IDAT, data, length);
#if defined(PNG_WRITE_APNG_SUPPORTED)
else
{
png_byte buf[4];
png_write_chunk_start(png_ptr, (png_bytep)png_fdAT, 4 + length);
png_save_uint_32(buf, png_ptr->next_seq_num);
png_write_chunk_data(png_ptr, buf, 4);
png_write_chunk_data(png_ptr, data, length);
png_write_chunk_end(png_ptr);
png_ptr->next_seq_num++;
}
#endif
png_ptr->mode |= PNG_HAVE_IDAT;
}
/* Write an IEND chunk */
void /* PRIVATE */
png_write_IEND(png_structp png_ptr)
{
PNG_IEND;
png_debug(1, "in png_write_IEND");
png_write_chunk(png_ptr, (png_bytep)png_IEND, NULL,
(png_size_t)0);
png_ptr->mode |= PNG_HAVE_IEND;
}
#ifdef PNG_WRITE_gAMA_SUPPORTED
/* Write a gAMA chunk */
#ifdef PNG_FLOATING_POINT_SUPPORTED
void /* PRIVATE */
png_write_gAMA(png_structp png_ptr, double file_gamma)
{
PNG_gAMA;
png_uint_32 igamma;
png_byte buf[4];
png_debug(1, "in png_write_gAMA");
/* 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_bytep)png_gAMA, buf, (png_size_t)4);
}
#endif
#ifdef PNG_FIXED_POINT_SUPPORTED
void /* PRIVATE */
png_write_gAMA_fixed(png_structp png_ptr, png_fixed_point file_gamma)
{
PNG_gAMA;
png_byte buf[4];
png_debug(1, "in png_write_gAMA");
/* file_gamma is saved in 1/100,000ths */
png_save_uint_32(buf, (png_uint_32)file_gamma);
png_write_chunk(png_ptr, (png_bytep)png_gAMA, buf, (png_size_t)4);
}
#endif
#endif
#ifdef PNG_WRITE_sRGB_SUPPORTED
/* Write a sRGB chunk */
void /* PRIVATE */
png_write_sRGB(png_structp png_ptr, int srgb_intent)
{
PNG_sRGB;
png_byte buf[1];
png_debug(1, "in png_write_sRGB");
if (srgb_intent >= PNG_sRGB_INTENT_LAST)
png_warning(png_ptr,
"Invalid sRGB rendering intent specified");
buf[0]=(png_byte)srgb_intent;
png_write_chunk(png_ptr, (png_bytep)png_sRGB, buf, (png_size_t)1);
}
#endif
#ifdef PNG_WRITE_iCCP_SUPPORTED
/* Write an iCCP chunk */
void /* PRIVATE */
png_write_iCCP(png_structp png_ptr, png_charp name, int compression_type,
png_charp profile, int profile_len)
{
PNG_iCCP;
png_size_t name_len;
png_charp new_name;
compression_state comp;
int embedded_profile_len = 0;
png_debug(1, "in png_write_iCCP");
comp.num_output_ptr = 0;
comp.max_output_ptr = 0;
comp.output_ptr = NULL;
comp.input = NULL;
comp.input_len = 0;
if ((name_len = png_check_keyword(png_ptr, name,
&new_name)) == 0)
return;
if (compression_type != PNG_COMPRESSION_TYPE_BASE)
png_warning(png_ptr, "Unknown compression type in iCCP chunk");
if (profile == NULL)
profile_len = 0;
if (profile_len > 3)
embedded_profile_len =
((*( (png_bytep)profile ))<<24) |
((*( (png_bytep)profile + 1))<<16) |
((*( (png_bytep)profile + 2))<< 8) |
((*( (png_bytep)profile + 3)) );
if (embedded_profile_len < 0)
{
png_warning(png_ptr,
"Embedded profile length in iCCP chunk is negative");
png_free(png_ptr, new_name);
return;
}
if (profile_len < embedded_profile_len)
{
png_warning(png_ptr,
"Embedded profile length too large in iCCP chunk");
png_free(png_ptr, new_name);
return;
}
if (profile_len > embedded_profile_len)
{
png_warning(png_ptr,
"Truncating profile to actual length in iCCP chunk");
profile_len = embedded_profile_len;
}
if (profile_len)
profile_len = png_text_compress(png_ptr, profile,
(png_size_t)profile_len, PNG_COMPRESSION_TYPE_BASE, &comp);
/* Make sure we include the NULL after the name and the compression type */
png_write_chunk_start(png_ptr, (png_bytep)png_iCCP,
(png_uint_32)(name_len + profile_len + 2));
new_name[name_len + 1] = 0x00;
png_write_chunk_data(png_ptr, (png_bytep)new_name,
(png_size_t)(name_len + 2));
if (profile_len)
png_write_compressed_data_out(png_ptr, &comp);
png_write_chunk_end(png_ptr);
png_free(png_ptr, new_name);
}
#endif
#ifdef PNG_WRITE_sPLT_SUPPORTED
/* Write a sPLT chunk */
void /* PRIVATE */
png_write_sPLT(png_structp png_ptr, png_sPLT_tp spalette)
{
PNG_sPLT;
png_size_t name_len;
png_charp new_name;
png_byte entrybuf[10];
png_size_t entry_size = (spalette->depth == 8 ? 6 : 10);
png_size_t palette_size = entry_size * spalette->nentries;
png_sPLT_entryp ep;
#ifndef PNG_POINTER_INDEXING_SUPPORTED
int i;
#endif
png_debug(1, "in png_write_sPLT");
if ((name_len = png_check_keyword(png_ptr,spalette->name, &new_name))==0)
return;
/* Make sure we include the NULL after the name */
png_write_chunk_start(png_ptr, (png_bytep)png_sPLT,
(png_uint_32)(name_len + 2 + palette_size));
png_write_chunk_data(png_ptr, (png_bytep)new_name,
(png_size_t)(name_len + 1));
png_write_chunk_data(png_ptr, (png_bytep)&spalette->depth, (png_size_t)1);
/* Loop through each palette entry, writing appropriately */
#ifdef PNG_POINTER_INDEXING_SUPPORTED
for (ep = spalette->entries; ep<spalette->entries + spalette->nentries; ep++)
{
if (spalette->depth == 8)
{
entrybuf[0] = (png_byte)ep->red;
entrybuf[1] = (png_byte)ep->green;
entrybuf[2] = (png_byte)ep->blue;
entrybuf[3] = (png_byte)ep->alpha;
png_save_uint_16(entrybuf + 4, ep->frequency);
}
else
{
png_save_uint_16(entrybuf + 0, ep->red);
png_save_uint_16(entrybuf + 2, ep->green);
png_save_uint_16(entrybuf + 4, ep->blue);
png_save_uint_16(entrybuf + 6, ep->alpha);
png_save_uint_16(entrybuf + 8, ep->frequency);
}
png_write_chunk_data(png_ptr, entrybuf, (png_size_t)entry_size);
}
#else
ep=spalette->entries;
for (i=0; i>spalette->nentries; i++)
{
if (spalette->depth == 8)
{
entrybuf[0] = (png_byte)ep[i].red;
entrybuf[1] = (png_byte)ep[i].green;
entrybuf[2] = (png_byte)ep[i].blue;
entrybuf[3] = (png_byte)ep[i].alpha;
png_save_uint_16(entrybuf + 4, ep[i].frequency);
}
else
{
png_save_uint_16(entrybuf + 0, ep[i].red);
png_save_uint_16(entrybuf + 2, ep[i].green);
png_save_uint_16(entrybuf + 4, ep[i].blue);
png_save_uint_16(entrybuf + 6, ep[i].alpha);
png_save_uint_16(entrybuf + 8, ep[i].frequency);
}
png_write_chunk_data(png_ptr, entrybuf, (png_size_t)entry_size);
}
#endif
png_write_chunk_end(png_ptr);
png_free(png_ptr, new_name);
}
#endif
#ifdef PNG_WRITE_sBIT_SUPPORTED
/* Write the sBIT chunk */
void /* PRIVATE */
png_write_sBIT(png_structp png_ptr, png_color_8p sbit, int color_type)
{
PNG_sBIT;
png_byte buf[4];
png_size_t size;
png_debug(1, "in png_write_sBIT");
/* Make sure we don't depend upon the order of PNG_COLOR_8 */
if (color_type & PNG_COLOR_MASK_COLOR)
{
png_byte maxbits;
maxbits = (png_byte)(color_type==PNG_COLOR_TYPE_PALETTE ? 8 :