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libpng/pngwutil.c
John Bowler b2bee3374c [devel] Make the 16-to-8 scaling accurate. Dividing by 256 with no rounding is 
wrong (high by one) 25% of the time. Dividing by 257 with rounding is
    wrong in 128 out of 65536 cases. Getting the right answer all the time
    without division is easy.
2011-06-10 23:24:58 -05:00

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/* pngwutil.c - utilities to write a PNG file
*
* Last changed in libpng 1.5.3 [(PENDING RELEASE)]
* 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
*/
#include "pngpriv.h"
#ifdef PNG_WRITE_SUPPORTED
#ifdef PNG_WRITE_INT_FUNCTIONS_SUPPORTED
/* Place a 32-bit number into a buffer in PNG byte order. We work
* with unsigned numbers for convenience, although one supported
* ancillary chunk uses signed (two's complement) numbers.
*/
void PNGAPI
png_save_uint_32(png_bytep buf, png_uint_32 i)
{
buf[0] = (png_byte)((i >> 24) & 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. Note that,
* the following works correctly even if png_int_32 has more than 32 bits
* (compare the more complex code required on read for sign extention.)
*/
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);
}
#endif
/* Simple function to write the signature. If we have already written
* the magic bytes of the signature, or more likely, the PNG stream is
* being embedded into another stream and doesn't need its own signature,
* we should call png_set_sig_bytes() to tell libpng how many of the
* bytes have already been written.
*/
void PNGAPI
png_write_sig(png_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_const_bytep chunk_name,
png_const_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_const_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_const_bytep data,
png_size_t length)
{
/* Write the data, and run the CRC over it */
if (png_ptr == NULL)
return;
if (data != NULL && length > 0)
{
png_write_data(png_ptr, data, length);
/* Update the CRC after writing the data,
* in case 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);
}
/* Initialize the compressor for the appropriate type of compression. */
static void
png_zlib_claim(png_structp png_ptr, png_uint_32 state)
{
if (!(png_ptr->zlib_state & PNG_ZLIB_IN_USE))
{
/* If already initialized for 'state' do not re-init. */
if (png_ptr->zlib_state != state)
{
int ret = Z_OK;
png_const_charp who = "-";
/* If actually initialized for another state do a deflateEnd. */
if (png_ptr->zlib_state != PNG_ZLIB_UNINITIALIZED)
{
ret = deflateEnd(&png_ptr->zstream);
who = "end";
png_ptr->zlib_state = PNG_ZLIB_UNINITIALIZED;
}
/* zlib itself detects an incomplete state on deflateEnd */
if (ret == Z_OK) switch (state)
{
# ifdef PNG_WRITE_COMPRESSED_TEXT_SUPPORTED
case PNG_ZLIB_FOR_TEXT:
ret = deflateInit2(&png_ptr->zstream,
png_ptr->zlib_text_level, png_ptr->zlib_text_method,
png_ptr->zlib_text_window_bits,
png_ptr->zlib_text_mem_level, png_ptr->zlib_text_strategy);
who = "text";
break;
# endif
case PNG_ZLIB_FOR_IDAT:
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);
who = "IDAT";
break;
default:
png_error(png_ptr, "invalid zlib state");
}
if (ret == Z_OK)
png_ptr->zlib_state = state;
else /* an error in deflateEnd or deflateInit2 */
{
size_t pos = 0;
char msg[64];
pos = png_safecat(msg, sizeof msg, pos,
"zlib failed to initialize compressor (");
pos = png_safecat(msg, sizeof msg, pos, who);
switch (ret)
{
case Z_VERSION_ERROR:
pos = png_safecat(msg, sizeof msg, pos, ") version error");
break;
case Z_STREAM_ERROR:
pos = png_safecat(msg, sizeof msg, pos, ") stream error");
break;
case Z_MEM_ERROR:
pos = png_safecat(msg, sizeof msg, pos, ") memory error");
break;
default:
pos = png_safecat(msg, sizeof msg, pos, ") unknown error");
break;
}
png_error(png_ptr, msg);
}
}
/* Here on success, claim the zstream: */
png_ptr->zlib_state |= PNG_ZLIB_IN_USE;
}
else
png_error(png_ptr, "zstream already in use (internal error)");
}
/* The opposite: release the stream. It is also reset, this API will warn on
* error but will not fail.
*/
static void
png_zlib_release(png_structp png_ptr)
{
if (png_ptr->zlib_state & PNG_ZLIB_IN_USE)
{
int ret = deflateReset(&png_ptr->zstream);
png_ptr->zlib_state &= ~PNG_ZLIB_IN_USE;
if (ret != Z_OK)
{
png_const_charp err;
PNG_WARNING_PARAMETERS(p)
switch (ret)
{
case Z_VERSION_ERROR:
err = "version";
break;
case Z_STREAM_ERROR:
err = "stream";
break;
case Z_MEM_ERROR:
err = "memory";
break;
default:
err = "unknown";
break;
}
png_warning_parameter_signed(p, 1, PNG_NUMBER_FORMAT_d, ret);
png_warning_parameter(p, 2, err);
if (png_ptr->zstream.msg)
err = png_ptr->zstream.msg;
else
err = "[no zlib message]";
png_warning_parameter(p, 3, err);
png_formatted_warning(png_ptr, p,
"zlib failed to reset compressor: @1(@2): @3");
}
}
else
png_warning(png_ptr, "zstream not in use (internal error)");
}
#ifdef PNG_WRITE_COMPRESSED_TEXT_SUPPORTED
/* This pair of functions encapsulates the operation of (a) compressing a
* text string, and (b) issuing it later as a series of chunk data writes.
* The compression_state structure is shared context for these functions
* set up by the caller in order to make the whole mess thread-safe.
*/
typedef struct
{
png_const_bytep input; /* The uncompressed input data */
png_size_t input_len; /* Its length */
int num_output_ptr; /* Number of output pointers used */
int max_output_ptr; /* Size of output_ptr */
png_bytep *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_const_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 = text_len;
/* We may just want to pass the text right through */
if (compression == PNG_TEXT_COMPRESSION_NONE)
{
comp->input = (png_const_bytep)text;
return((int)text_len);
}
if (compression >= PNG_TEXT_COMPRESSION_LAST)
{
PNG_WARNING_PARAMETERS(p)
png_warning_parameter_signed(p, 1, PNG_NUMBER_FORMAT_d,
compression);
png_formatted_warning(png_ptr, p, "Unknown compression type @1");
}
/* 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).
*/
png_zlib_claim(png_ptr, PNG_ZLIB_FOR_TEXT);
/* 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_bytepp old_ptr;
old_ptr = comp->output_ptr;
comp->output_ptr = (png_bytepp)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_bytepp)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_bytep)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_bytepp old_ptr;
old_ptr = comp->output_ptr;
/* This could be optimized to realloc() */
comp->output_ptr = (png_bytepp)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_bytepp)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_bytep)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, comp->input, comp->input_len);
return;
}
#ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
if (comp->input_len >= 2 && comp->input_len < 16384)
{
unsigned int z_cmf; /* zlib compression method and flags */
/* Optimize the CMF field in the zlib stream. This hack of the zlib
* stream is compliant to the stream specification.
*/
if (comp->num_output_ptr)
z_cmf = comp->output_ptr[0][0];
else
z_cmf = png_ptr->zbuf[0];
if ((z_cmf & 0x0f) == 8 && (z_cmf & 0xf0) <= 0x70)
{
unsigned int z_cinfo;
unsigned int half_z_window_size;
png_size_t uncompressed_text_size = comp->input_len;
z_cinfo = z_cmf >> 4;
half_z_window_size = 1 << (z_cinfo + 7);
while (uncompressed_text_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 (comp->num_output_ptr)
{
if (comp->output_ptr[0][0] != z_cmf)
{
int tmp;
comp->output_ptr[0][0] = (png_byte)z_cmf;
tmp = comp->output_ptr[0][1] & 0xe0;
tmp += 0x1f - ((z_cmf << 8) + tmp) % 0x1f;
comp->output_ptr[0][1] = (png_byte)tmp;
}
}
else
{
int tmp;
png_ptr->zbuf[0] = (png_byte)z_cmf;
tmp = png_ptr->zbuf[1] & 0xe0;
tmp += 0x1f - ((z_cmf << 8) + tmp) % 0x1f;
png_ptr->zbuf[1] = (png_byte)tmp;
}
}
else
png_error(png_ptr,
"Invalid zlib compression method or flags in non-IDAT chunk");
}
#endif /* PNG_WRITE_OPTIMIZE_CMF_SUPPORTED */
/* Write saved output buffers, if any */
for (i = 0; i < comp->num_output_ptr; i++)
{
png_write_chunk_data(png_ptr, 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 */
png_zlib_release(png_ptr);
}
#endif /* PNG_WRITE_COMPRESSED_TEXT_SUPPORTED */
/* 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;
png_byte buf[13]; /* Buffer to store the IHDR info */
png_debug(1, "in png_write_IHDR");
/* Check that we have valid input data from the application info */
switch (color_type)
{
case PNG_COLOR_TYPE_GRAY:
switch (bit_depth)
{
case 1:
case 2:
case 4:
case 8:
#ifdef PNG_WRITE_16BIT_SUPPORTED
case 16:
#endif
png_ptr->channels = 1; break;
default:
png_error(png_ptr,
"Invalid bit depth for grayscale image");
}
break;
case PNG_COLOR_TYPE_RGB:
#ifdef PNG_WRITE_16BIT_SUPPORTED
if (bit_depth != 8 && bit_depth != 16)
#else
if (bit_depth != 8)
#endif
png_error(png_ptr, "Invalid bit depth for RGB image");
png_ptr->channels = 3;
break;
case PNG_COLOR_TYPE_PALETTE:
switch (bit_depth)
{
case 1:
case 2:
case 4:
case 8:
png_ptr->channels = 1;
break;
default:
png_error(png_ptr, "Invalid bit depth for paletted image");
}
break;
case PNG_COLOR_TYPE_GRAY_ALPHA:
if (bit_depth != 8 && bit_depth != 16)
png_error(png_ptr, "Invalid bit depth for grayscale+alpha image");
png_ptr->channels = 2;
break;
case PNG_COLOR_TYPE_RGB_ALPHA:
#ifdef PNG_WRITE_16BIT_SUPPORTED
if (bit_depth != 8 && bit_depth != 16)
#else
if (bit_depth != 8)
#endif
png_error(png_ptr, "Invalid bit depth for RGBA image");
png_ptr->channels = 4;
break;
default:
png_error(png_ptr, "Invalid image color type specified");
}
if (compression_type != PNG_COMPRESSION_TYPE_BASE)
{
png_warning(png_ptr, "Invalid compression type specified");
compression_type = PNG_COMPRESSION_TYPE_BASE;
}
/* Write filter_method 64 (intrapixel differencing) only if
* 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and
* 2. Libpng did not write a PNG signature (this filter_method is only
* used in PNG datastreams that are embedded in MNG datastreams) and
* 3. The application called png_permit_mng_features with a mask that
* included PNG_FLAG_MNG_FILTER_64 and
* 4. The filter_method is 64 and
* 5. The color_type is RGB or RGBA
*/
if (
#ifdef PNG_MNG_FEATURES_SUPPORTED
!((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&
((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_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;
#ifdef PNG_WRITE_COMPRESSED_TEXT_SUPPORTED
#ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED
if (!(png_ptr->flags & PNG_FLAG_ZTXT_CUSTOM_STRATEGY))
png_ptr->zlib_text_strategy = Z_DEFAULT_STRATEGY;
if (!(png_ptr->flags & PNG_FLAG_ZTXT_CUSTOM_LEVEL))
png_ptr->zlib_text_level = png_ptr->zlib_level;
if (!(png_ptr->flags & PNG_FLAG_ZTXT_CUSTOM_MEM_LEVEL))
png_ptr->zlib_text_mem_level = png_ptr->zlib_mem_level;
if (!(png_ptr->flags & PNG_FLAG_ZTXT_CUSTOM_WINDOW_BITS))
png_ptr->zlib_text_window_bits = png_ptr->zlib_window_bits;
if (!(png_ptr->flags & PNG_FLAG_ZTXT_CUSTOM_METHOD))
png_ptr->zlib_text_method = png_ptr->zlib_method;
#else
png_ptr->zlib_text_strategy = Z_DEFAULT_STRATEGY;
png_ptr->zlib_text_level = png_ptr->zlib_level;
png_ptr->zlib_text_mem_level = png_ptr->zlib_mem_level;
png_ptr->zlib_text_window_bits = png_ptr->zlib_window_bits;
png_ptr->zlib_text_method = png_ptr->zlib_method;
#endif /* PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED */
#endif /* PNG_WRITE_COMPRESSED_TEXT_SUPPORTED */
/* Record that the compressor has not yet been initialized. */
png_ptr->zlib_state = PNG_ZLIB_UNINITIALIZED;
png_ptr->mode = PNG_HAVE_IHDR; /* not READY_FOR_ZTXT */
}
/* Write the palette. We are careful not to trust png_color to be in the
* correct order for PNG, so people can redefine it to any convenient
* structure.
*/
void /* PRIVATE */
png_write_PLTE(png_structp png_ptr, png_const_colorp palette,
png_uint_32 num_pal)
{
PNG_PLTE;
png_uint_32 i;
png_const_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_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;
png_debug(1, "in png_write_IDAT");
#ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
if (!(png_ptr->mode & PNG_HAVE_IDAT) &&
png_ptr->compression_type == PNG_COMPRESSION_TYPE_BASE)
{
/* Optimize the CMF field in the zlib stream. This hack of the zlib
* stream is compliant to the stream specification.
*/
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)
{
/* 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.
*/
unsigned int z_cinfo;
unsigned int half_z_window_size;
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] != z_cmf)
{
int tmp;
data[0] = (png_byte)z_cmf;
tmp = data[1] & 0xe0;
tmp += 0x1f - ((z_cmf << 8) + tmp) % 0x1f;
data[1] = (png_byte)tmp;
}
}
}
else
png_error(png_ptr,
"Invalid zlib compression method or flags in IDAT");
}
#endif /* PNG_WRITE_OPTIMIZE_CMF_SUPPORTED */
png_write_chunk(png_ptr, png_IDAT, data, length);
png_ptr->mode |= PNG_HAVE_IDAT;
/* Prior to 1.5.3 this code was replicated in every caller (except at the
* end, where it isn't technically necessary). Since this function has
* flushed the data we can safely reset the zlib output buffer here.
*/
png_ptr->zstream.next_out = png_ptr->zbuf;
png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
}
/* 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_IEND, NULL, (png_size_t)0);
png_ptr->mode |= PNG_HAVE_IEND;
}
#ifdef PNG_WRITE_gAMA_SUPPORTED
/* Write a gAMA chunk */
void /* PRIVATE */
png_write_gAMA_fixed(png_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_gAMA, buf, (png_size_t)4);
}
#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_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_const_charp name, int compression_type,
png_const_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_const_bytep)profile ))<<24) |
((*( (png_const_bytep)profile + 1))<<16) |
((*( (png_const_bytep)profile + 2))<< 8) |
((*( (png_const_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_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)
{
comp.input_len = 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_const_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_sPLT,
(png_uint_32)(name_len + 2 + palette_size));
png_write_chunk_data(png_ptr, (png_bytep)new_name,
(png_size_t)(name_len + 1));
png_write_chunk_data(png_ptr, &spalette->depth, (png_size_t)1);
/* Loop through each palette entry, writing appropriately */
#ifdef PNG_POINTER_INDEXING_SUPPORTED
for (ep = spalette->entries; ep<spalette->entries + spalette->nentries; ep++)
{
if (spalette->depth == 8)
{
entrybuf[0] = (png_byte)ep->red;
entrybuf[1] = (png_byte)ep->green;
entrybuf[2] = (png_byte)ep->blue;
entrybuf[3] = (png_byte)ep->alpha;
png_save_uint_16(entrybuf + 4, ep->frequency);
}
else
{
png_save_uint_16(entrybuf + 0, ep->red);
png_save_uint_16(entrybuf + 2, ep->green);
png_save_uint_16(entrybuf + 4, ep->blue);
png_save_uint_16(entrybuf + 6, ep->alpha);
png_save_uint_16(entrybuf + 8, ep->frequency);
}
png_write_chunk_data(png_ptr, entrybuf, (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_const_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 :
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
#ifdef PNG_WRITE_cHRM_SUPPORTED
/* Write the cHRM chunk */
void /* PRIVATE */
png_write_cHRM_fixed(png_structp png_ptr, png_fixed_point white_x,
png_fixed_point white_y, png_fixed_point red_x, png_fixed_point red_y,
png_fixed_point green_x, png_fixed_point green_y, png_fixed_point blue_x,
png_fixed_point blue_y)
{
PNG_cHRM;
png_byte buf[32];
png_debug(1, "in png_write_cHRM");
/* Each value is saved in 1/100,000ths */
#ifdef PNG_CHECK_cHRM_SUPPORTED
if (png_check_cHRM_fixed(png_ptr, white_x, white_y, red_x, red_y,
green_x, green_y, blue_x, blue_y))
#endif
{
png_save_uint_32(buf, (png_uint_32)white_x);
png_save_uint_32(buf + 4, (png_uint_32)white_y);
png_save_uint_32(buf + 8, (png_uint_32)red_x);
png_save_uint_32(buf + 12, (png_uint_32)red_y);
png_save_uint_32(buf + 16, (png_uint_32)green_x);
png_save_uint_32(buf + 20, (png_uint_32)green_y);
png_save_uint_32(buf + 24, (png_uint_32)blue_x);
png_save_uint_32(buf + 28, (png_uint_32)blue_y);
png_write_chunk(png_ptr, png_cHRM, buf, (png_size_t)32);
}
}
#endif
#ifdef PNG_WRITE_tRNS_SUPPORTED
/* Write the tRNS chunk */
void /* PRIVATE */
png_write_tRNS(png_structp png_ptr, png_const_bytep trans_alpha,
png_const_color_16p tran, int num_trans, int color_type)
{
PNG_tRNS;
png_byte buf[6];
png_debug(1, "in png_write_tRNS");
if (color_type == PNG_COLOR_TYPE_PALETTE)
{
if (num_trans <= 0 || num_trans > (int)png_ptr->num_palette)
{
png_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_alpha, (png_size_t)num_trans);
}
else if (color_type == PNG_COLOR_TYPE_GRAY)
{
/* One 16 bit value */
if (tran->gray >= (1 << png_ptr->bit_depth))
{
png_warning(png_ptr,
"Ignoring attempt to write tRNS chunk out-of-range for bit_depth");
return;
}
png_save_uint_16(buf, tran->gray);
png_write_chunk(png_ptr, png_tRNS, buf, (png_size_t)2);
}
else if (color_type == PNG_COLOR_TYPE_RGB)
{
/* Three 16 bit values */
png_save_uint_16(buf, tran->red);
png_save_uint_16(buf + 2, tran->green);
png_save_uint_16(buf + 4, tran->blue);
#ifdef PNG_WRITE_16BIT_SUPPORTED
if (png_ptr->bit_depth == 8 && (buf[0] | buf[2] | buf[4]))
#else
if (buf[0] | buf[2] | buf[4])
#endif
{
png_warning(png_ptr,
"Ignoring attempt to write 16-bit tRNS chunk when bit_depth is 8");
return;
}
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
#ifdef PNG_WRITE_bKGD_SUPPORTED
/* Write the background chunk */
void /* PRIVATE */
png_write_bKGD(png_structp png_ptr, png_const_color_16p back, int color_type)
{
PNG_bKGD;
png_byte buf[6];
png_debug(1, "in png_write_bKGD");
if (color_type == PNG_COLOR_TYPE_PALETTE)
{
if (
#ifdef PNG_MNG_FEATURES_SUPPORTED
(png_ptr->num_palette ||
(!(png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE))) &&
#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);
#ifdef PNG_WRITE_16BIT_SUPPORTED
if (png_ptr->bit_depth == 8 && (buf[0] | buf[2] | buf[4]))
#else
if (buf[0] | buf[2] | buf[4])
#endif
{
png_warning(png_ptr,
"Ignoring attempt to write 16-bit bKGD chunk when bit_depth is 8");
return;
}
png_write_chunk(png_ptr, png_bKGD, buf, (png_size_t)6);
}
else
{
if (back->gray >= (1 << png_ptr->bit_depth))
{
png_warning(png_ptr,
"Ignoring attempt to write bKGD chunk out-of-range for bit_depth");
return;
}
png_save_uint_16(buf, back->gray);
png_write_chunk(png_ptr, png_bKGD, buf, (png_size_t)2);
}
}
#endif
#ifdef PNG_WRITE_hIST_SUPPORTED
/* Write the histogram */
void /* PRIVATE */
png_write_hIST(png_structp png_ptr, png_const_uint_16p hist, int num_hist)
{
PNG_hIST;
int i;
png_byte buf[3];
png_debug(1, "in png_write_hIST");
if (num_hist > (int)png_ptr->num_palette)
{
png_debug2(3, "num_hist = %d, num_palette = %d", num_hist,
png_ptr->num_palette);
png_warning(png_ptr, "Invalid number of histogram entries specified");
return;
}
png_write_chunk_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_pCAL_SUPPORTED) || \
defined(PNG_WRITE_iCCP_SUPPORTED) || defined(PNG_WRITE_sPLT_SUPPORTED)
/* Check that the tEXt or zTXt keyword is valid per PNG 1.0 specification,
* and if invalid, correct the keyword rather than discarding the entire
* chunk. The PNG 1.0 specification requires keywords 1-79 characters in
* length, forbids leading or trailing whitespace, multiple internal spaces,
* and the non-break space (0x80) from ISO 8859-1. Returns keyword length.
*
* The new_key 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 /* PRIVATE */
png_check_keyword(png_structp png_ptr, png_const_charp key, png_charpp new_key)
{
png_size_t key_len;
png_const_charp ikp;
png_charp kp, dp;
int kflag;
int kwarn=0;
png_debug(1, "in png_check_keyword");
*new_key = NULL;
if (key == NULL || (key_len = png_strlen(key)) == 0)
{
png_warning(png_ptr, "zero length keyword");
return ((png_size_t)0);
}
png_debug1(2, "Keyword to be checked is '%s'", key);
*new_key = (png_charp)png_malloc_warn(png_ptr, (png_uint_32)(key_len + 2));
if (*new_key == NULL)
{
png_warning(png_ptr, "Out of memory while procesing keyword");
return ((png_size_t)0);
}
/* Replace non-printing characters with a blank and print a warning */
for (ikp = key, dp = *new_key; *ikp != '\0'; ikp++, dp++)
{
if ((png_byte)*ikp < 0x20 ||
((png_byte)*ikp > 0x7E && (png_byte)*ikp < 0xA1))
{
PNG_WARNING_PARAMETERS(p)
png_warning_parameter_unsigned(p, 1, PNG_NUMBER_FORMAT_02x,
(png_byte)*ikp);
png_formatted_warning(png_ptr, p, "invalid keyword character 0x@1");
*dp = ' ';
}
else
{
*dp = *ikp;
}
}
*dp = '\0';
/* Remove any trailing white space. */
kp = *new_key + key_len - 1;
if (*kp == ' ')
{
png_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_warning(png_ptr, "leading spaces removed from keyword");
while (*kp == ' ')
{
kp++;
key_len--;
}
}
png_debug1(2, "Checking for multiple internal spaces in '%s'", 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--;
kwarn = 1;
}
else
{
*(dp++) = *kp;
kflag = 0;
}
}
*dp = '\0';
if (kwarn)
png_warning(png_ptr, "extra interior spaces removed from keyword");
if (key_len == 0)
{
png_free(png_ptr, *new_key);
png_warning(png_ptr, "Zero length keyword");
}
if (key_len > 79)
{
png_warning(png_ptr, "keyword length must be 1 - 79 characters");
(*new_key)[79] = '\0';
key_len = 79;
}
return (key_len);
}
#endif
#ifdef PNG_WRITE_tEXt_SUPPORTED
/* Write a tEXt chunk */
void /* PRIVATE */
png_write_tEXt(png_structp png_ptr, png_const_charp key, png_const_charp text,
png_size_t text_len)
{
PNG_tEXt;
png_size_t key_len;
png_charp new_key;
png_debug(1, "in png_write_tEXt");
if ((key_len = png_check_keyword(png_ptr, key, &new_key))==0)
return;
if (text == NULL || *text == '\0')
text_len = 0;
else
text_len = png_strlen(text);
/* 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.
* The NUL character is forbidden by PNG-1.0 through PNG-1.2 and ISO PNG.
*/
png_write_chunk_data(png_ptr, (png_bytep)new_key,
(png_size_t)(key_len + 1));
if (text_len)
png_write_chunk_data(png_ptr, (png_const_bytep)text,
(png_size_t)text_len);
png_write_chunk_end(png_ptr);
png_free(png_ptr, new_key);
}
#endif
#ifdef PNG_WRITE_zTXt_SUPPORTED
/* Write a compressed text chunk */
void /* PRIVATE */
png_write_zTXt(png_structp png_ptr, png_const_charp key, png_const_charp text,
png_size_t text_len, int compression)
{
PNG_zTXt;
png_size_t key_len;
png_byte buf;
png_charp new_key;
compression_state comp;
png_debug(1, "in png_write_zTXt");
comp.num_output_ptr = 0;
comp.max_output_ptr = 0;
comp.output_ptr = NULL;
comp.input = NULL;
comp.input_len = 0;
if ((key_len = png_check_keyword(png_ptr, key, &new_key)) == 0)
{
png_free(png_ptr, new_key);
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;
}
text_len = png_strlen(text);
/* Compute the compressed data; do it now for the length */
text_len = png_text_compress(png_ptr, text, text_len, compression,
&comp);
/* 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)new_key,
(png_size_t)(key_len + 1));
png_free(png_ptr, new_key);
buf = (png_byte)compression;
/* Write compression */
png_write_chunk_data(png_ptr, &buf, (png_size_t)1);
/* Write the compressed data */
comp.input_len = text_len;
png_write_compressed_data_out(png_ptr, &comp);
/* Close the chunk */
png_write_chunk_end(png_ptr);
}
#endif
#ifdef PNG_WRITE_iTXt_SUPPORTED
/* Write an iTXt chunk */
void /* PRIVATE */
png_write_iTXt(png_structp png_ptr, int compression, png_const_charp key,
png_const_charp lang, png_const_charp lang_key, png_const_charp text)
{
PNG_iTXt;
png_size_t lang_len, key_len, lang_key_len, text_len;
png_charp new_lang;
png_charp new_key = NULL;
png_byte cbuf[2];
compression_state comp;
png_debug(1, "in png_write_iTXt");
comp.num_output_ptr = 0;
comp.max_output_ptr = 0;
comp.output_ptr = NULL;
comp.input = NULL;
if ((key_len = png_check_keyword(png_ptr, key, &new_key)) == 0)
return;
if ((lang_len = png_check_keyword(png_ptr, lang, &new_lang)) == 0)
{
png_warning(png_ptr, "Empty language field in iTXt chunk");
new_lang = NULL;
lang_len = 0;
}
if (lang_key == NULL)
lang_key_len = 0;
else
lang_key_len = png_strlen(lang_key);
if (text == NULL)
text_len = 0;
else
text_len = png_strlen(text);
/* Compute the compressed data; do it now for the length */
text_len = png_text_compress(png_ptr, text, text_len, compression - 2,
&comp);
/* Make sure we include the compression flag, the compression byte,
* and the NULs after the key, lang, and lang_key parts
*/
png_write_chunk_start(png_ptr, png_iTXt, (png_uint_32)(
5 /* comp byte, comp flag, terminators for key, lang and lang_key */
+ key_len
+ lang_len
+ lang_key_len
+ text_len));
/* We leave it to the application to meet PNG-1.0 requirements on the
* contents of the text. PNG-1.0 through PNG-1.2 discourage the use of
* any non-Latin-1 characters except for NEWLINE. ISO PNG will forbid them.
* The NUL character is forbidden by PNG-1.0 through PNG-1.2 and ISO PNG.
*/
png_write_chunk_data(png_ptr, (png_bytep)new_key, (png_size_t)(key_len + 1));
/* Set the compression flag */
if (compression == PNG_ITXT_COMPRESSION_NONE ||
compression == PNG_TEXT_COMPRESSION_NONE)
cbuf[0] = 0;
else /* compression == PNG_ITXT_COMPRESSION_zTXt */
cbuf[0] = 1;
/* Set the compression method */
cbuf[1] = 0;
png_write_chunk_data(png_ptr, cbuf, (png_size_t)2);
cbuf[0] = 0;
png_write_chunk_data(png_ptr, (new_lang ? (png_const_bytep)new_lang : cbuf),
(png_size_t)(lang_len + 1));
png_write_chunk_data(png_ptr, (lang_key ? (png_const_bytep)lang_key : cbuf),
(png_size_t)(lang_key_len + 1));
png_write_compressed_data_out(png_ptr, &comp);
png_write_chunk_end(png_ptr);
png_free(png_ptr, new_key);
png_free(png_ptr, new_lang);
}
#endif
#ifdef PNG_WRITE_oFFs_SUPPORTED
/* Write the oFFs chunk */
void /* PRIVATE */
png_write_oFFs(png_structp png_ptr, png_int_32 x_offset, png_int_32 y_offset,
int unit_type)
{
PNG_oFFs;
png_byte buf[9];
png_debug(1, "in png_write_oFFs");
if (unit_type >= PNG_OFFSET_LAST)
png_warning(png_ptr, "Unrecognized unit type for oFFs chunk");
png_save_int_32(buf, x_offset);
png_save_int_32(buf + 4, y_offset);
buf[8] = (png_byte)unit_type;
png_write_chunk(png_ptr, png_oFFs, buf, (png_size_t)9);
}
#endif
#ifdef PNG_WRITE_pCAL_SUPPORTED
/* Write the pCAL chunk (described in the PNG extensions document) */
void /* PRIVATE */
png_write_pCAL(png_structp png_ptr, png_charp purpose, png_int_32 X0,
png_int_32 X1, int type, int nparams, png_const_charp units,
png_charpp params)
{
PNG_pCAL;
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)", 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", (int)purpose_len);
units_len = png_strlen(units) + (nparams == 0 ? 0 : 1);
png_debug1(3, "pCAL units length = %d", (int)units_len);
total_len = purpose_len + units_len + 10;
params_len = (png_uint_32p)png_malloc(png_ptr,
(png_alloc_size_t)(nparams * png_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 = %lu", i,
(unsigned long)params_len[i]);
total_len += (png_size_t)params_len[i];
}
png_debug1(3, "pCAL total length = %d", (int)total_len);
png_write_chunk_start(png_ptr, png_pCAL, (png_uint_32)total_len);
png_write_chunk_data(png_ptr, (png_const_bytep)new_purpose,
(png_size_t)purpose_len);
png_save_int_32(buf, X0);
png_save_int_32(buf + 4, X1);
buf[8] = (png_byte)type;
buf[9] = (png_byte)nparams;
png_write_chunk_data(png_ptr, buf, (png_size_t)10);
png_write_chunk_data(png_ptr, (png_const_bytep)units, (png_size_t)units_len);
png_free(png_ptr, new_purpose);
for (i = 0; i < nparams; i++)
{
png_write_chunk_data(png_ptr, (png_const_bytep)params[i],
(png_size_t)params_len[i]);
}
png_free(png_ptr, params_len);
png_write_chunk_end(png_ptr);
}
#endif
#ifdef PNG_WRITE_sCAL_SUPPORTED
/* Write the sCAL chunk */
void /* PRIVATE */
png_write_sCAL_s(png_structp png_ptr, int unit, png_const_charp width,
png_const_charp height)
{
PNG_sCAL;
png_byte buf[64];
png_size_t wlen, hlen, total_len;
png_debug(1, "in png_write_sCAL_s");
wlen = png_strlen(width);
hlen = png_strlen(height);
total_len = wlen + hlen + 2;
if (total_len > 64)
{
png_warning(png_ptr, "Can't write sCAL (buffer too small)");
return;
}
buf[0] = (png_byte)unit;
png_memcpy(buf + 1, width, wlen + 1); /* Append the '\0' here */
png_memcpy(buf + wlen + 2, height, hlen); /* Do NOT append the '\0' here */
png_debug1(3, "sCAL total length = %u", (unsigned int)total_len);
png_write_chunk(png_ptr, png_sCAL, buf, total_len);
}
#endif
#ifdef PNG_WRITE_pHYs_SUPPORTED
/* Write the pHYs chunk */
void /* PRIVATE */
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_pHYs;
png_byte buf[9];
png_debug(1, "in png_write_pHYs");
if (unit_type >= PNG_RESOLUTION_LAST)
png_warning(png_ptr, "Unrecognized unit type for pHYs chunk");
png_save_uint_32(buf, x_pixels_per_unit);
png_save_uint_32(buf + 4, y_pixels_per_unit);
buf[8] = (png_byte)unit_type;
png_write_chunk(png_ptr, png_pHYs, buf, (png_size_t)9);
}
#endif
#ifdef PNG_WRITE_tIME_SUPPORTED
/* Write the tIME chunk. Use either png_convert_from_struct_tm()
* or png_convert_from_time_t(), or fill in the structure yourself.
*/
void /* PRIVATE */
png_write_tIME(png_structp png_ptr, png_const_timep mod_time)
{
PNG_tIME;
png_byte buf[7];
png_debug(1, "in png_write_tIME");
if (mod_time->month > 12 || mod_time->month < 1 ||
mod_time->day > 31 || mod_time->day < 1 ||
mod_time->hour > 23 || mod_time->second > 60)
{
png_warning(png_ptr, "Invalid time specified for tIME chunk");
return;
}
png_save_uint_16(buf, mod_time->year);
buf[2] = mod_time->month;
buf[3] = mod_time->day;
buf[4] = mod_time->hour;
buf[5] = mod_time->minute;
buf[6] = mod_time->second;
png_write_chunk(png_ptr, png_tIME, buf, (png_size_t)7);
}
#endif
/* Initializes the row writing capability of libpng */
void /* PRIVATE */
png_write_start_row(png_structp png_ptr)
{
#ifdef PNG_WRITE_INTERLACING_SUPPORTED
/* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
/* Start of interlace block */
int png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
/* Offset to next interlace block */
int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
/* Start of interlace block in the y direction */
int png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
/* Offset to next interlace block in the y direction */
int png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
#endif
png_size_t buf_size;
png_debug(1, "in png_write_start_row");
buf_size = (png_size_t)(PNG_ROWBYTES(
png_ptr->usr_channels*png_ptr->usr_bit_depth, png_ptr->width) + 1);
/* Set up row buffer */
png_ptr->row_buf = (png_bytep)png_malloc(png_ptr,
(png_alloc_size_t)buf_size);
png_ptr->row_buf[0] = PNG_FILTER_VALUE_NONE;
#ifdef PNG_WRITE_FILTER_SUPPORTED
/* 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_calloc(png_ptr,
(png_alloc_size_t)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;
}
}
#endif /* PNG_WRITE_FILTER_SUPPORTED */
#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_zlib_claim(png_ptr, PNG_ZLIB_FOR_IDAT);
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 /* PRIVATE */
png_write_finish_row(png_structp png_ptr)
{
#ifdef PNG_WRITE_INTERLACING_SUPPORTED
/* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
/* Start of interlace block */
int png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
/* Offset to next interlace block */
int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
/* Start of interlace block in the y direction */
int png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
/* Offset to next interlace block in the y direction */
int png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
#endif
int ret;
png_debug(1, "in png_write_finish_row");
/* Next row */
png_ptr->row_number++;
/* See if we are done */
if (png_ptr->row_number < png_ptr->num_rows)
return;
#ifdef PNG_WRITE_INTERLACING_SUPPORTED
/* If interlaced, go to next pass */
if (png_ptr->interlaced)
{
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_ROWBYTES(png_ptr->usr_channels*
png_ptr->usr_bit_depth, png_ptr->width)) + 1);
return;
}
}
#endif
/* If we get here, we've just written the last row, so we need
to flush the compressor */
do
{
/* Tell the compressor we are done */
ret = deflate(&png_ptr->zstream, Z_FINISH);
/* Check for an error */
if (ret == Z_OK)
{
/* Check to see if we need more room */
if (!(png_ptr->zstream.avail_out))
{
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;
}
}
else if (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");
}
} 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);
}
png_zlib_release(png_ptr);
png_ptr->zstream.data_type = Z_BINARY;
}
#ifdef PNG_WRITE_INTERLACING_SUPPORTED
/* Pick out the correct pixels for the interlace pass.
* The basic idea here is to go through the row with a source
* pointer and a destination pointer (sp and dp), and copy the
* correct pixels for the pass. As the row gets compacted,
* sp will always be >= dp, so we should never overwrite anything.
* See the default: case for the easiest code to understand.
*/
void /* PRIVATE */
png_do_write_interlace(png_row_infop row_info, png_bytep row, int pass)
{
/* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
/* Start of interlace block */
int png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
/* Offset to next interlace block */
int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
png_debug(1, "in png_do_write_interlace");
/* We don't have to do anything on the last pass (6) */
if (pass < 6)
{
/* Each pixel depth is handled separately */
switch (row_info->pixel_depth)
{
case 1:
{
png_bytep sp;
png_bytep dp;
int shift;
int d;
int value;
png_uint_32 i;
png_uint_32 row_width = row_info->width;
dp = row;
d = 0;
shift = 7;
for (i = png_pass_start[pass]; i < row_width;
i += png_pass_inc[pass])
{
sp = row + (png_size_t)(i >> 3);
value = (int)(*sp >> (7 - (int)(i & 0x07))) & 0x01;
d |= (value << shift);
if (shift == 0)
{
shift = 7;
*dp++ = (png_byte)d;
d = 0;
}
else
shift--;
}
if (shift != 7)
*dp = (png_byte)d;
break;
}
case 2:
{
png_bytep sp;
png_bytep dp;
int shift;
int d;
int value;
png_uint_32 i;
png_uint_32 row_width = row_info->width;
dp = row;
shift = 6;
d = 0;
for (i = png_pass_start[pass]; i < row_width;
i += png_pass_inc[pass])
{
sp = row + (png_size_t)(i >> 2);
value = (*sp >> ((3 - (int)(i & 0x03)) << 1)) & 0x03;
d |= (value << shift);
if (shift == 0)
{
shift = 6;
*dp++ = (png_byte)d;
d = 0;
}
else
shift -= 2;
}
if (shift != 6)
*dp = (png_byte)d;
break;
}
case 4:
{
png_bytep sp;
png_bytep dp;
int shift;
int d;
int value;
png_uint_32 i;
png_uint_32 row_width = row_info->width;
dp = row;
shift = 4;
d = 0;
for (i = png_pass_start[pass]; i < row_width;
i += png_pass_inc[pass])
{
sp = row + (png_size_t)(i >> 1);
value = (*sp >> ((1 - (int)(i & 0x01)) << 2)) & 0x0f;
d |= (value << shift);
if (shift == 0)
{
shift = 4;
*dp++ = (png_byte)d;
d = 0;
}
else
shift -= 4;
}
if (shift != 4)
*dp = (png_byte)d;
break;
}
default:
{
png_bytep sp;
png_bytep dp;
png_uint_32 i;
png_uint_32 row_width = row_info->width;
png_size_t pixel_bytes;
/* Start at the beginning */
dp = row;
/* Find out how many bytes each pixel takes up */
pixel_bytes = (row_info->pixel_depth >> 3);
/* Loop through the row, only looking at the pixels that matter */
for (i = png_pass_start[pass]; i < row_width;
i += png_pass_inc[pass])
{
/* Find out where the original pixel is */
sp = row + (png_size_t)i * pixel_bytes;
/* Move the pixel */
if (dp != sp)
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 = PNG_ROWBYTES(row_info->pixel_depth,
row_info->width);
}
}
#endif
/* This filters the row, chooses which filter to use, if it has not already
* been specified by the application, and then writes the row out with the
* chosen filter.
*/
static void png_write_filtered_row(png_structp png_ptr, png_bytep filtered_row);
#define PNG_MAXSUM (((png_uint_32)(-1)) >> 1)
#define PNG_HISHIFT 10
#define PNG_LOMASK ((png_uint_32)0xffffL)
#define PNG_HIMASK ((png_uint_32)(~PNG_LOMASK >> PNG_HISHIFT))
void /* PRIVATE */
png_write_find_filter(png_structp png_ptr, png_row_infop row_info)
{
png_bytep best_row;
#ifdef PNG_WRITE_FILTER_SUPPORTED
png_bytep prev_row, row_buf;
png_uint_32 mins, bpp;
png_byte filter_to_do = png_ptr->do_filter;
png_size_t row_bytes = row_info->rowbytes;
#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
int num_p_filters = (int)png_ptr->num_prev_filters;
#endif
png_debug(1, "in png_write_find_filter");
#ifndef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
if (png_ptr->row_number == 0 && filter_to_do == PNG_ALL_FILTERS)
{
/* These will never be selected so we need not test them. */
filter_to_do &= ~(PNG_FILTER_UP | PNG_FILTER_PAETH);
}
#endif
/* Find out how many bytes offset each pixel is */
bpp = (row_info->pixel_depth + 7) >> 3;
prev_row = png_ptr->prev_row;
#endif
best_row = png_ptr->row_buf;
#ifdef PNG_WRITE_FILTER_SUPPORTED
row_buf = best_row;
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_size_t i;
int v;
for (i = 0, rp = row_buf + 1; i < row_bytes; i++, rp++)
{
v = *rp;
sum += (v < 128) ? v : 256 - v;
}
#ifdef 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_size_t 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_size_t i;
int v;
#ifdef 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_bytes;
i++, rp++, lp++, dp++)
{
v = *dp = (png_byte)(((int)*rp - (int)*lp) & 0xff);
sum += (v < 128) ? v : 256 - v;
if (sum > lmins) /* We are already worse, don't continue. */
break;
}
#ifdef 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_size_t 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_size_t i;
int v;
#ifdef 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;
}
#ifdef 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_size_t i;
int v;
#ifdef 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;
}
#ifdef 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_size_t 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_size_t i;
int v;
#ifdef 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;
}
#ifdef 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;
}
}
#endif /* PNG_WRITE_FILTER_SUPPORTED */
/* Do the actual writing of the filtered row data from the chosen filter. */
png_write_filtered_row(png_ptr, best_row);
#ifdef PNG_WRITE_FILTER_SUPPORTED
#ifdef 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
#endif /* PNG_WRITE_FILTER_SUPPORTED */
}
/* Do the actual writing of a previously filtered row. */
static void
png_write_filtered_row(png_structp png_ptr, png_bytep filtered_row)
{
png_size_t avail;
png_debug(1, "in png_write_filtered_row");
png_debug1(2, "filter = %d", filtered_row[0]);
/* Set up the zlib input buffer */
png_ptr->zstream.next_in = filtered_row;
png_ptr->zstream.avail_in = 0;
avail = png_ptr->row_info.rowbytes + 1;
/* Repeat until we have compressed all the data */
do
{
int ret; /* Return of zlib */
/* Record the number of bytes available - zlib supports at least 65535
* bytes at one step, depending on the size of the zlib type 'uInt', the
* maximum size zlib can write at once is ZLIB_IO_MAX (from pngpriv.h).
* Use this because on 16 bit systems 'rowbytes' can be up to 65536 (i.e.
* one more than 16 bits) and, in this case 'rowbytes+1' can overflow a
* uInt. ZLIB_IO_MAX can be safely reduced to cause zlib to be called
* with smaller chunks of data.
*/
if (png_ptr->zstream.avail_in == 0)
{
if (avail > ZLIB_IO_MAX)
{
png_ptr->zstream.avail_in = ZLIB_IO_MAX;
avail -= ZLIB_IO_MAX;
}
else
{
/* So this will fit in the available uInt space: */
png_ptr->zstream.avail_in = (uInt)avail;
avail = 0;
}
}
/* 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);
}
/* Repeat until all data has been compressed */
} while (avail > 0 || png_ptr->zstream.avail_in > 0);
/* 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);
#ifdef PNG_WRITE_FLUSH_SUPPORTED
png_ptr->flush_rows++;
if (png_ptr->flush_dist > 0 &&
png_ptr->flush_rows >= png_ptr->flush_dist)
{
png_write_flush(png_ptr);
}
#endif
}
#endif /* PNG_WRITE_SUPPORTED */
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