root/pngwutil.c
/* [<][>][^][v][top][bottom][index][help] */
DEFINITIONS
This source file includes following definitions.
- png_save_uint_32
- png_save_uint_16
- png_write_sig
- png_write_chunk_header
- png_write_chunk_start
- png_write_chunk_data
- png_write_chunk_end
- png_write_complete_chunk
- png_write_chunk
- png_image_size
- optimize_cmf
- png_deflate_claim
- png_free_buffer_list
- png_text_compress_init
- png_text_compress
- png_write_compressed_data_out
- png_check_keyword
- png_write_IHDR
- png_write_PLTE
- png_compress_IDAT
- png_write_IEND
- png_write_gAMA_fixed
- png_write_sRGB
- png_write_iCCP
- png_write_sPLT
- png_write_sBIT
- png_write_cHRM_fixed
- png_write_tRNS
- png_write_bKGD
- png_write_hIST
- png_write_tEXt
- png_write_zTXt
- png_write_iTXt
- png_write_oFFs
- png_write_pCAL
- png_write_sCAL_s
- png_write_pHYs
- png_write_tIME
- png_write_start_row
- png_write_finish_row
- png_do_write_interlace
- png_write_find_filter
- png_write_filtered_row
/* pngwutil.c - utilities to write a PNG file
*
* Last changed in libpng 1.6.14 [October 23, 2014]
* Copyright (c) 1998-2014 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);
}
/* 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_structrp 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 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().
*/
static void
png_write_chunk_header(png_structrp png_ptr, png_uint_32 chunk_name,
png_uint_32 length)
{
png_byte buf[8];
#if defined(PNG_DEBUG) && (PNG_DEBUG > 0)
PNG_CSTRING_FROM_CHUNK(buf, chunk_name);
png_debug2(0, "Writing %s chunk, length = %lu", buf, (unsigned long)length);
#endif
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_save_uint_32(buf + 4, chunk_name);
png_write_data(png_ptr, buf, 8);
/* Put the chunk name into png_ptr->chunk_name */
png_ptr->chunk_name = chunk_name;
/* Reset the crc and run it over the chunk name */
png_reset_crc(png_ptr);
png_calculate_crc(png_ptr, buf + 4, 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
}
void PNGAPI
png_write_chunk_start(png_structrp png_ptr, png_const_bytep chunk_string,
png_uint_32 length)
{
png_write_chunk_header(png_ptr, PNG_CHUNK_FROM_STRING(chunk_string), length);
}
/* Write the data of a PNG chunk started with png_write_chunk_header().
* 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_header().
*/
void PNGAPI
png_write_chunk_data(png_structrp 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 the user I/O routine alters it.
*/
png_calculate_crc(png_ptr, data, length);
}
}
/* Finish a chunk started with png_write_chunk_header(). */
void PNGAPI
png_write_chunk_end(png_structrp 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);
}
/* 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.
*/
static void
png_write_complete_chunk(png_structrp png_ptr, png_uint_32 chunk_name,
png_const_bytep data, png_size_t length)
{
if (png_ptr == NULL)
return;
/* On 64 bit architectures 'length' may not fit in a png_uint_32. */
if (length > PNG_UINT_31_MAX)
png_error(png_ptr, "length exceeds PNG maximum");
png_write_chunk_header(png_ptr, chunk_name, (png_uint_32)length);
png_write_chunk_data(png_ptr, data, length);
png_write_chunk_end(png_ptr);
}
/* This is the API that calls the internal function above. */
void PNGAPI
png_write_chunk(png_structrp png_ptr, png_const_bytep chunk_string,
png_const_bytep data, png_size_t length)
{
png_write_complete_chunk(png_ptr, PNG_CHUNK_FROM_STRING(chunk_string), data,
length);
}
/* This is used below to find the size of an image to pass to png_deflate_claim,
* so it only needs to be accurate if the size is less than 16384 bytes (the
* point at which a lower LZ window size can be used.)
*/
static png_alloc_size_t
png_image_size(png_structrp png_ptr)
{
/* Only return sizes up to the maximum of a png_uint_32; do this by limiting
* the width and height used to 15 bits.
*/
png_uint_32 h = png_ptr->height;
if (png_ptr->rowbytes < 32768 && h < 32768)
{
if (png_ptr->interlaced)
{
/* Interlacing makes the image larger because of the replication of
* both the filter byte and the padding to a byte boundary.
*/
png_uint_32 w = png_ptr->width;
unsigned int pd = png_ptr->pixel_depth;
png_alloc_size_t cb_base;
int pass;
for (cb_base=0, pass=0; pass<=6; ++pass)
{
png_uint_32 pw = PNG_PASS_COLS(w, pass);
if (pw > 0)
cb_base += (PNG_ROWBYTES(pd, pw)+1) * PNG_PASS_ROWS(h, pass);
}
return cb_base;
}
else
return (png_ptr->rowbytes+1) * h;
}
else
return 0xffffffffU;
}
#ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
/* This is the code to hack the first two bytes of the deflate stream (the
* deflate header) to correct the windowBits value to match the actual data
* size. Note that the second argument is the *uncompressed* size but the
* first argument is the *compressed* data (and it must be deflate
* compressed.)
*/
static void
optimize_cmf(png_bytep data, png_alloc_size_t data_size)
{
/* Optimize the CMF field in the zlib stream. The resultant zlib stream is
* still compliant to the stream specification.
*/
if (data_size <= 16384) /* else windowBits must be 15 */
{
unsigned int z_cmf = data[0]; /* zlib compression method and flags */
if ((z_cmf & 0x0f) == 8 && (z_cmf & 0xf0) <= 0x70)
{
unsigned int z_cinfo;
unsigned int half_z_window_size;
z_cinfo = z_cmf >> 4;
half_z_window_size = 1U << (z_cinfo + 7);
if (data_size <= half_z_window_size) /* else no change */
{
unsigned int tmp;
do
{
half_z_window_size >>= 1;
--z_cinfo;
}
while (z_cinfo > 0 && data_size <= half_z_window_size);
z_cmf = (z_cmf & 0x0f) | (z_cinfo << 4);
data[0] = (png_byte)z_cmf;
tmp = data[1] & 0xe0;
tmp += 0x1f - ((z_cmf << 8) + tmp) % 0x1f;
data[1] = (png_byte)tmp;
}
}
}
}
#else
# define optimize_cmf(dp,dl) ((void)0)
#endif /* PNG_WRITE_OPTIMIZE_CMF_SUPPORTED */
/* Initialize the compressor for the appropriate type of compression. */
static int
png_deflate_claim(png_structrp png_ptr, png_uint_32 owner,
png_alloc_size_t data_size)
{
if (png_ptr->zowner != 0)
{
# if defined(PNG_WARNINGS_SUPPORTED) || defined(PNG_ERROR_TEXT_SUPPORTED)
char msg[64];
PNG_STRING_FROM_CHUNK(msg, owner);
msg[4] = ':';
msg[5] = ' ';
PNG_STRING_FROM_CHUNK(msg+6, png_ptr->zowner);
/* So the message that results is "<chunk> using zstream"; this is an
* internal error, but is very useful for debugging. i18n requirements
* are minimal.
*/
(void)png_safecat(msg, (sizeof msg), 10, " using zstream");
# endif
# if PNG_LIBPNG_BUILD_BASE_TYPE >= PNG_LIBPNG_BUILD_RC
png_warning(png_ptr, msg);
/* Attempt sane error recovery */
if (png_ptr->zowner == png_IDAT) /* don't steal from IDAT */
{
png_ptr->zstream.msg = PNGZ_MSG_CAST("in use by IDAT");
return Z_STREAM_ERROR;
}
png_ptr->zowner = 0;
# else
png_error(png_ptr, msg);
# endif
}
{
int level = png_ptr->zlib_level;
int method = png_ptr->zlib_method;
int windowBits = png_ptr->zlib_window_bits;
int memLevel = png_ptr->zlib_mem_level;
int strategy; /* set below */
int ret; /* zlib return code */
if (owner == png_IDAT)
{
if (png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_STRATEGY)
strategy = png_ptr->zlib_strategy;
else if (png_ptr->do_filter != PNG_FILTER_NONE)
strategy = PNG_Z_DEFAULT_STRATEGY;
else
strategy = PNG_Z_DEFAULT_NOFILTER_STRATEGY;
}
else
{
# ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED
level = png_ptr->zlib_text_level;
method = png_ptr->zlib_text_method;
windowBits = png_ptr->zlib_text_window_bits;
memLevel = png_ptr->zlib_text_mem_level;
strategy = png_ptr->zlib_text_strategy;
# else
/* If customization is not supported the values all come from the
* IDAT values except for the strategy, which is fixed to the
* default. (This is the pre-1.6.0 behavior too, although it was
* implemented in a very different way.)
*/
strategy = Z_DEFAULT_STRATEGY;
# endif
}
/* Adjust 'windowBits' down if larger than 'data_size'; to stop this
* happening just pass 32768 as the data_size parameter. Notice that zlib
* requires an extra 262 bytes in the window in addition to the data to be
* able to see the whole of the data, so if data_size+262 takes us to the
* next windowBits size we need to fix up the value later. (Because even
* though deflate needs the extra window, inflate does not!)
*/
if (data_size <= 16384)
{
/* IMPLEMENTATION NOTE: this 'half_window_size' stuff is only here to
* work round a Microsoft Visual C misbehavior which, contrary to C-90,
* widens the result of the following shift to 64-bits if (and,
* apparently, only if) it is used in a test.
*/
unsigned int half_window_size = 1U << (windowBits-1);
while (data_size + 262 <= half_window_size)
{
half_window_size >>= 1;
--windowBits;
}
}
/* Check against the previous initialized values, if any. */
if ((png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED) &&
(png_ptr->zlib_set_level != level ||
png_ptr->zlib_set_method != method ||
png_ptr->zlib_set_window_bits != windowBits ||
png_ptr->zlib_set_mem_level != memLevel ||
png_ptr->zlib_set_strategy != strategy))
{
if (deflateEnd(&png_ptr->zstream) != Z_OK)
png_warning(png_ptr, "deflateEnd failed (ignored)");
png_ptr->flags &= ~PNG_FLAG_ZSTREAM_INITIALIZED;
}
/* For safety clear out the input and output pointers (currently zlib
* doesn't use them on Init, but it might in the future).
*/
png_ptr->zstream.next_in = NULL;
png_ptr->zstream.avail_in = 0;
png_ptr->zstream.next_out = NULL;
png_ptr->zstream.avail_out = 0;
/* Now initialize if required, setting the new parameters, otherwise just
* to a simple reset to the previous parameters.
*/
if (png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED)
ret = deflateReset(&png_ptr->zstream);
else
{
ret = deflateInit2(&png_ptr->zstream, level, method, windowBits,
memLevel, strategy);
if (ret == Z_OK)
png_ptr->flags |= PNG_FLAG_ZSTREAM_INITIALIZED;
}
/* The return code is from either deflateReset or deflateInit2; they have
* pretty much the same set of error codes.
*/
if (ret == Z_OK)
png_ptr->zowner = owner;
else
png_zstream_error(png_ptr, ret);
return ret;
}
}
/* Clean up (or trim) a linked list of compression buffers. */
void /* PRIVATE */
png_free_buffer_list(png_structrp png_ptr, png_compression_bufferp *listp)
{
png_compression_bufferp list = *listp;
if (list != NULL)
{
*listp = NULL;
do
{
png_compression_bufferp next = list->next;
png_free(png_ptr, list);
list = next;
}
while (list != NULL);
}
}
#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 to allow access to the relevant local variables.
*
* compression_buffer (new in 1.6.0) is just a linked list of zbuffer_size
* temporary buffers. From 1.6.0 it is retained in png_struct so that it will
* be correctly freed in the event of a write error (previous implementations
* just leaked memory.)
*/
typedef struct
{
png_const_bytep input; /* The uncompressed input data */
png_alloc_size_t input_len; /* Its length */
png_uint_32 output_len; /* Final compressed length */
png_byte output[1024]; /* First block of output */
} compression_state;
static void
png_text_compress_init(compression_state *comp, png_const_bytep input,
png_alloc_size_t input_len)
{
comp->input = input;
comp->input_len = input_len;
comp->output_len = 0;
}
/* Compress the data in the compression state input */
static int
png_text_compress(png_structrp png_ptr, png_uint_32 chunk_name,
compression_state *comp, png_uint_32 prefix_len)
{
int ret;
/* To find the length of the output it is necessary to first compress the
* input. The result is buffered rather than using the two-pass algorithm
* that is used on the inflate side; deflate is assumed to be slower and a
* PNG writer is assumed to have more memory available than a PNG reader.
*
* IMPLEMENTATION NOTE: the zlib API deflateBound() can be used to find an
* upper limit on the output size, but it is always bigger than the input
* size so it is likely to be more efficient to use this linked-list
* approach.
*/
ret = png_deflate_claim(png_ptr, chunk_name, comp->input_len);
if (ret != Z_OK)
return ret;
/* Set up the compression buffers, we need a loop here to avoid overflowing a
* uInt. Use ZLIB_IO_MAX to limit the input. The output is always limited
* by the output buffer size, so there is no need to check that. Since this
* is ANSI-C we know that an 'int', hence a uInt, is always at least 16 bits
* in size.
*/
{
png_compression_bufferp *end = &png_ptr->zbuffer_list;
png_alloc_size_t input_len = comp->input_len; /* may be zero! */
png_uint_32 output_len;
/* zlib updates these for us: */
png_ptr->zstream.next_in = PNGZ_INPUT_CAST(comp->input);
png_ptr->zstream.avail_in = 0; /* Set below */
png_ptr->zstream.next_out = comp->output;
png_ptr->zstream.avail_out = (sizeof comp->output);
output_len = png_ptr->zstream.avail_out;
do
{
uInt avail_in = ZLIB_IO_MAX;
if (avail_in > input_len)
avail_in = (uInt)input_len;
input_len -= avail_in;
png_ptr->zstream.avail_in = avail_in;
if (png_ptr->zstream.avail_out == 0)
{
png_compression_buffer *next;
/* Chunk data is limited to 2^31 bytes in length, so the prefix
* length must be counted here.
*/
if (output_len + prefix_len > PNG_UINT_31_MAX)
{
ret = Z_MEM_ERROR;
break;
}
/* Need a new (malloc'ed) buffer, but there may be one present
* already.
*/
next = *end;
if (next == NULL)
{
next = png_voidcast(png_compression_bufferp, png_malloc_base
(png_ptr, PNG_COMPRESSION_BUFFER_SIZE(png_ptr)));
if (next == NULL)
{
ret = Z_MEM_ERROR;
break;
}
/* Link in this buffer (so that it will be freed later) */
next->next = NULL;
*end = next;
}
png_ptr->zstream.next_out = next->output;
png_ptr->zstream.avail_out = png_ptr->zbuffer_size;
output_len += png_ptr->zstream.avail_out;
/* Move 'end' to the next buffer pointer. */
end = &next->next;
}
/* Compress the data */
ret = deflate(&png_ptr->zstream,
input_len > 0 ? Z_NO_FLUSH : Z_FINISH);
/* Claw back input data that was not consumed (because avail_in is
* reset above every time round the loop).
*/
input_len += png_ptr->zstream.avail_in;
png_ptr->zstream.avail_in = 0; /* safety */
}
while (ret == Z_OK);
/* There may be some space left in the last output buffer. This needs to
* be subtracted from output_len.
*/
output_len -= png_ptr->zstream.avail_out;
png_ptr->zstream.avail_out = 0; /* safety */
comp->output_len = output_len;
/* Now double check the output length, put in a custom message if it is
* too long. Otherwise ensure the z_stream::msg pointer is set to
* something.
*/
if (output_len + prefix_len >= PNG_UINT_31_MAX)
{
png_ptr->zstream.msg = PNGZ_MSG_CAST("compressed data too long");
ret = Z_MEM_ERROR;
}
else
png_zstream_error(png_ptr, ret);
/* Reset zlib for another zTXt/iTXt or image data */
png_ptr->zowner = 0;
/* The only success case is Z_STREAM_END, input_len must be 0; if not this
* is an internal error.
*/
if (ret == Z_STREAM_END && input_len == 0)
{
/* Fix up the deflate header, if required */
optimize_cmf(comp->output, comp->input_len);
/* But Z_OK is returned, not Z_STREAM_END; this allows the claim
* function above to return Z_STREAM_END on an error (though it never
* does in the current versions of zlib.)
*/
return Z_OK;
}
else
return ret;
}
}
/* Ship the compressed text out via chunk writes */
static void
png_write_compressed_data_out(png_structrp png_ptr, compression_state *comp)
{
png_uint_32 output_len = comp->output_len;
png_const_bytep output = comp->output;
png_uint_32 avail = (sizeof comp->output);
png_compression_buffer *next = png_ptr->zbuffer_list;
for (;;)
{
if (avail > output_len)
avail = output_len;
png_write_chunk_data(png_ptr, output, avail);
output_len -= avail;
if (output_len == 0 || next == NULL)
break;
avail = png_ptr->zbuffer_size;
output = next->output;
next = next->next;
}
/* This is an internal error; 'next' must have been NULL! */
if (output_len > 0)
png_error(png_ptr, "error writing ancillary chunked compressed data");
}
#endif /* PNG_WRITE_COMPRESSED_TEXT_SUPPORTED */
#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' buffer must be 80 characters in size (for the keyword plus a
* trailing '\0'). If this routine returns 0 then there was no keyword, or a
* valid one could not be generated, and the caller must png_error.
*/
static png_uint_32
png_check_keyword(png_structrp png_ptr, png_const_charp key, png_bytep new_key)
{
png_const_charp orig_key = key;
png_uint_32 key_len = 0;
int bad_character = 0;
int space = 1;
png_debug(1, "in png_check_keyword");
if (key == NULL)
{
*new_key = 0;
return 0;
}
while (*key && key_len < 79)
{
png_byte ch = (png_byte)(0xff & *key++);
if ((ch > 32 && ch <= 126) || (ch >= 161 /*&& ch <= 255*/))
*new_key++ = ch, ++key_len, space = 0;
else if (space == 0)
{
/* A space or an invalid character when one wasn't seen immediately
* before; output just a space.
*/
*new_key++ = 32, ++key_len, space = 1;
/* If the character was not a space then it is invalid. */
if (ch != 32)
bad_character = ch;
}
else if (bad_character == 0)
bad_character = ch; /* just skip it, record the first error */
}
if (key_len > 0 && space) /* trailing space */
{
--key_len, --new_key;
if (bad_character == 0)
bad_character = 32;
}
/* Terminate the keyword */
*new_key = 0;
if (key_len == 0)
return 0;
#ifdef PNG_WARNINGS_SUPPORTED
/* Try to only output one warning per keyword: */
if (*key) /* keyword too long */
png_warning(png_ptr, "keyword truncated");
else if (bad_character != 0)
{
PNG_WARNING_PARAMETERS(p)
png_warning_parameter(p, 1, orig_key);
png_warning_parameter_signed(p, 2, PNG_NUMBER_FORMAT_02x, bad_character);
png_formatted_warning(png_ptr, p, "keyword \"@1\": bad character '0x@2'");
}
#endif /* PNG_WARNINGS_SUPPORTED */
return key_len;
}
#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_structrp png_ptr, png_uint_32 width, png_uint_32 height,
int bit_depth, int color_type, int compression_type, int filter_type,
int interlace_type)
{
png_byte buf[13]; /* Buffer to store the IHDR info */
png_debug(1, "in png_write_IHDR");
/* 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_complete_chunk(png_ptr, png_IHDR, buf, (png_size_t)13);
if ((png_ptr->do_filter) == PNG_NO_FILTERS)
{
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;
}
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_structrp png_ptr, png_const_colorp palette,
png_uint_32 num_pal)
{
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_header(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;
}
/* This is similar to png_text_compress, above, except that it does not require
* all of the data at once and, instead of buffering the compressed result,
* writes it as IDAT chunks. Unlike png_text_compress it *can* png_error out
* because it calls the write interface. As a result it does its own error
* reporting and does not return an error code. In the event of error it will
* just call png_error. The input data length may exceed 32-bits. The 'flush'
* parameter is exactly the same as that to deflate, with the following
* meanings:
*
* Z_NO_FLUSH: normal incremental output of compressed data
* Z_SYNC_FLUSH: do a SYNC_FLUSH, used by png_write_flush
* Z_FINISH: this is the end of the input, do a Z_FINISH and clean up
*
* The routine manages the acquire and release of the png_ptr->zstream by
* checking and (at the end) clearing png_ptr->zowner; it does some sanity
* checks on the 'mode' flags while doing this.
*/
void /* PRIVATE */
png_compress_IDAT(png_structrp png_ptr, png_const_bytep input,
png_alloc_size_t input_len, int flush)
{
if (png_ptr->zowner != png_IDAT)
{
/* First time. Ensure we have a temporary buffer for compression and
* trim the buffer list if it has more than one entry to free memory.
* If 'WRITE_COMPRESSED_TEXT' is not set the list will never have been
* created at this point, but the check here is quick and safe.
*/
if (png_ptr->zbuffer_list == NULL)
{
png_ptr->zbuffer_list = png_voidcast(png_compression_bufferp,
png_malloc(png_ptr, PNG_COMPRESSION_BUFFER_SIZE(png_ptr)));
png_ptr->zbuffer_list->next = NULL;
}
else
png_free_buffer_list(png_ptr, &png_ptr->zbuffer_list->next);
/* It is a terminal error if we can't claim the zstream. */
if (png_deflate_claim(png_ptr, png_IDAT, png_image_size(png_ptr)) != Z_OK)
png_error(png_ptr, png_ptr->zstream.msg);
/* The output state is maintained in png_ptr->zstream, so it must be
* initialized here after the claim.
*/
png_ptr->zstream.next_out = png_ptr->zbuffer_list->output;
png_ptr->zstream.avail_out = png_ptr->zbuffer_size;
}
/* Now loop reading and writing until all the input is consumed or an error
* terminates the operation. The _out values are maintained across calls to
* this function, but the input must be reset each time.
*/
png_ptr->zstream.next_in = PNGZ_INPUT_CAST(input);
png_ptr->zstream.avail_in = 0; /* set below */
for (;;)
{
int ret;
/* INPUT: from the row data */
uInt avail = ZLIB_IO_MAX;
if (avail > input_len)
avail = (uInt)input_len; /* safe because of the check */
png_ptr->zstream.avail_in = avail;
input_len -= avail;
ret = deflate(&png_ptr->zstream, input_len > 0 ? Z_NO_FLUSH : flush);
/* Include as-yet unconsumed input */
input_len += png_ptr->zstream.avail_in;
png_ptr->zstream.avail_in = 0;
/* OUTPUT: write complete IDAT chunks when avail_out drops to zero. Note
* that these two zstream fields are preserved across the calls, therefore
* there is no need to set these up on entry to the loop.
*/
if (png_ptr->zstream.avail_out == 0)
{
png_bytep data = png_ptr->zbuffer_list->output;
uInt size = png_ptr->zbuffer_size;
/* Write an IDAT containing the data then reset the buffer. The
* first IDAT may need deflate header optimization.
*/
# ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
if (!(png_ptr->mode & PNG_HAVE_IDAT) &&
png_ptr->compression_type == PNG_COMPRESSION_TYPE_BASE)
optimize_cmf(data, png_image_size(png_ptr));
# endif
png_write_complete_chunk(png_ptr, png_IDAT, data, size);
png_ptr->mode |= PNG_HAVE_IDAT;
png_ptr->zstream.next_out = data;
png_ptr->zstream.avail_out = size;
/* For SYNC_FLUSH or FINISH it is essential to keep calling zlib with
* the same flush parameter until it has finished output, for NO_FLUSH
* it doesn't matter.
*/
if (ret == Z_OK && flush != Z_NO_FLUSH)
continue;
}
/* The order of these checks doesn't matter much; it just affects which
* possible error might be detected if multiple things go wrong at once.
*/
if (ret == Z_OK) /* most likely return code! */
{
/* If all the input has been consumed then just return. If Z_FINISH
* was used as the flush parameter something has gone wrong if we get
* here.
*/
if (input_len == 0)
{
if (flush == Z_FINISH)
png_error(png_ptr, "Z_OK on Z_FINISH with output space");
return;
}
}
else if (ret == Z_STREAM_END && flush == Z_FINISH)
{
/* This is the end of the IDAT data; any pending output must be
* flushed. For small PNG files we may still be at the beginning.
*/
png_bytep data = png_ptr->zbuffer_list->output;
uInt size = png_ptr->zbuffer_size - png_ptr->zstream.avail_out;
# ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
if (!(png_ptr->mode & PNG_HAVE_IDAT) &&
png_ptr->compression_type == PNG_COMPRESSION_TYPE_BASE)
optimize_cmf(data, png_image_size(png_ptr));
# endif
png_write_complete_chunk(png_ptr, png_IDAT, data, size);
png_ptr->zstream.avail_out = 0;
png_ptr->zstream.next_out = NULL;
png_ptr->mode |= PNG_HAVE_IDAT | PNG_AFTER_IDAT;
png_ptr->zowner = 0; /* Release the stream */
return;
}
else
{
/* This is an error condition. */
png_zstream_error(png_ptr, ret);
png_error(png_ptr, png_ptr->zstream.msg);
}
}
}
/* Write an IEND chunk */
void /* PRIVATE */
png_write_IEND(png_structrp png_ptr)
{
png_debug(1, "in png_write_IEND");
png_write_complete_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_structrp png_ptr, png_fixed_point file_gamma)
{
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_complete_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_structrp png_ptr, int srgb_intent)
{
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_complete_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_structrp png_ptr, png_const_charp name,
png_const_bytep profile)
{
png_uint_32 name_len;
png_uint_32 profile_len;
png_byte new_name[81]; /* 1 byte for the compression byte */
compression_state comp;
png_uint_32 temp;
png_debug(1, "in png_write_iCCP");
/* These are all internal problems: the profile should have been checked
* before when it was stored.
*/
if (profile == NULL)
png_error(png_ptr, "No profile for iCCP chunk"); /* internal error */
profile_len = png_get_uint_32(profile);
if (profile_len < 132)
png_error(png_ptr, "ICC profile too short");
temp = (png_uint_32) (*(profile+8));
if (temp > 3 && (profile_len & 0x03))
png_error(png_ptr, "ICC profile length invalid (not a multiple of 4)");
{
png_uint_32 embedded_profile_len = png_get_uint_32(profile);
if (profile_len != embedded_profile_len)
png_error(png_ptr, "Profile length does not match profile");
}
name_len = png_check_keyword(png_ptr, name, new_name);
if (name_len == 0)
png_error(png_ptr, "iCCP: invalid keyword");
new_name[++name_len] = PNG_COMPRESSION_TYPE_BASE;
/* Make sure we include the NULL after the name and the compression type */
++name_len;
png_text_compress_init(&comp, profile, profile_len);
/* Allow for keyword terminator and compression byte */
if (png_text_compress(png_ptr, png_iCCP, &comp, name_len) != Z_OK)
png_error(png_ptr, png_ptr->zstream.msg);
png_write_chunk_header(png_ptr, png_iCCP, name_len + comp.output_len);
png_write_chunk_data(png_ptr, new_name, name_len);
png_write_compressed_data_out(png_ptr, &comp);
png_write_chunk_end(png_ptr);
}
#endif
#ifdef PNG_WRITE_sPLT_SUPPORTED
/* Write a sPLT chunk */
void /* PRIVATE */
png_write_sPLT(png_structrp png_ptr, png_const_sPLT_tp spalette)
{
png_uint_32 name_len;
png_byte new_name[80];
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");
name_len = png_check_keyword(png_ptr, spalette->name, new_name);
if (name_len == 0)
png_error(png_ptr, "sPLT: invalid keyword");
/* Make sure we include the NULL after the name */
png_write_chunk_header(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, 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, entry_size);
}
#endif
png_write_chunk_end(png_ptr);
}
#endif
#ifdef PNG_WRITE_sBIT_SUPPORTED
/* Write the sBIT chunk */
void /* PRIVATE */
png_write_sBIT(png_structrp png_ptr, png_const_color_8p sbit, int color_type)
{
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_complete_chunk(png_ptr, png_sBIT, buf, size);
}
#endif
#ifdef PNG_WRITE_cHRM_SUPPORTED
/* Write the cHRM chunk */
void /* PRIVATE */
png_write_cHRM_fixed(png_structrp png_ptr, const png_xy *xy)
{
png_byte buf[32];
png_debug(1, "in png_write_cHRM");
/* Each value is saved in 1/100,000ths */
png_save_int_32(buf, xy->whitex);
png_save_int_32(buf + 4, xy->whitey);
png_save_int_32(buf + 8, xy->redx);
png_save_int_32(buf + 12, xy->redy);
png_save_int_32(buf + 16, xy->greenx);
png_save_int_32(buf + 20, xy->greeny);
png_save_int_32(buf + 24, xy->bluex);
png_save_int_32(buf + 28, xy->bluey);
png_write_complete_chunk(png_ptr, png_cHRM, buf, 32);
}
#endif
#ifdef PNG_WRITE_tRNS_SUPPORTED
/* Write the tRNS chunk */
void /* PRIVATE */
png_write_tRNS(png_structrp png_ptr, png_const_bytep trans_alpha,
png_const_color_16p tran, int num_trans, int color_type)
{
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_app_warning(png_ptr,
"Invalid number of transparent colors specified");
return;
}
/* Write the chunk out as it is */
png_write_complete_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_app_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_complete_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_app_warning(png_ptr,
"Ignoring attempt to write 16-bit tRNS chunk when bit_depth is 8");
return;
}
png_write_complete_chunk(png_ptr, png_tRNS, buf, (png_size_t)6);
}
else
{
png_app_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_structrp png_ptr, png_const_color_16p back, int color_type)
{
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_complete_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_complete_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_complete_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_structrp png_ptr, png_const_uint_16p hist, int num_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_header(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
#ifdef PNG_WRITE_tEXt_SUPPORTED
/* Write a tEXt chunk */
void /* PRIVATE */
png_write_tEXt(png_structrp png_ptr, png_const_charp key, png_const_charp text,
png_size_t text_len)
{
png_uint_32 key_len;
png_byte new_key[80];
png_debug(1, "in png_write_tEXt");
key_len = png_check_keyword(png_ptr, key, new_key);
if (key_len == 0)
png_error(png_ptr, "tEXt: invalid keyword");
if (text == NULL || *text == '\0')
text_len = 0;
else
text_len = strlen(text);
if (text_len > PNG_UINT_31_MAX - (key_len+1))
png_error(png_ptr, "tEXt: text too long");
/* Make sure we include the 0 after the key */
png_write_chunk_header(png_ptr, png_tEXt,
(png_uint_32)/*checked above*/(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, new_key, key_len + 1);
if (text_len != 0)
png_write_chunk_data(png_ptr, (png_const_bytep)text, text_len);
png_write_chunk_end(png_ptr);
}
#endif
#ifdef PNG_WRITE_zTXt_SUPPORTED
/* Write a compressed text chunk */
void /* PRIVATE */
png_write_zTXt(png_structrp png_ptr, png_const_charp key, png_const_charp text,
int compression)
{
png_uint_32 key_len;
png_byte new_key[81];
compression_state comp;
png_debug(1, "in png_write_zTXt");
if (compression == PNG_TEXT_COMPRESSION_NONE)
{
png_write_tEXt(png_ptr, key, text, 0);
return;
}
if (compression != PNG_TEXT_COMPRESSION_zTXt)
png_error(png_ptr, "zTXt: invalid compression type");
key_len = png_check_keyword(png_ptr, key, new_key);
if (key_len == 0)
png_error(png_ptr, "zTXt: invalid keyword");
/* Add the compression method and 1 for the keyword separator. */
new_key[++key_len] = PNG_COMPRESSION_TYPE_BASE;
++key_len;
/* Compute the compressed data; do it now for the length */
png_text_compress_init(&comp, (png_const_bytep)text,
text == NULL ? 0 : strlen(text));
if (png_text_compress(png_ptr, png_zTXt, &comp, key_len) != Z_OK)
png_error(png_ptr, png_ptr->zstream.msg);
/* Write start of chunk */
png_write_chunk_header(png_ptr, png_zTXt, key_len + comp.output_len);
/* Write key */
png_write_chunk_data(png_ptr, new_key, key_len);
/* Write the compressed data */
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_structrp png_ptr, int compression, png_const_charp key,
png_const_charp lang, png_const_charp lang_key, png_const_charp text)
{
png_uint_32 key_len, prefix_len;
png_size_t lang_len, lang_key_len;
png_byte new_key[82];
compression_state comp;
png_debug(1, "in png_write_iTXt");
key_len = png_check_keyword(png_ptr, key, new_key);
if (key_len == 0)
png_error(png_ptr, "iTXt: invalid keyword");
/* Set the compression flag */
switch (compression)
{
case PNG_ITXT_COMPRESSION_NONE:
case PNG_TEXT_COMPRESSION_NONE:
compression = new_key[++key_len] = 0; /* no compression */
break;
case PNG_TEXT_COMPRESSION_zTXt:
case PNG_ITXT_COMPRESSION_zTXt:
compression = new_key[++key_len] = 1; /* compressed */
break;
default:
png_error(png_ptr, "iTXt: invalid compression");
}
new_key[++key_len] = PNG_COMPRESSION_TYPE_BASE;
++key_len; /* for the keywod separator */
/* 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, however,
* specifies that the text is UTF-8 and this really doesn't require any
* checking.
*
* The NUL character is forbidden by PNG-1.0 through PNG-1.2 and ISO PNG.
*
* TODO: validate the language tag correctly (see the spec.)
*/
if (lang == NULL) lang = ""; /* empty language is valid */
lang_len = strlen(lang)+1;
if (lang_key == NULL) lang_key = ""; /* may be empty */
lang_key_len = strlen(lang_key)+1;
if (text == NULL) text = ""; /* may be empty */
prefix_len = key_len;
if (lang_len > PNG_UINT_31_MAX-prefix_len)
prefix_len = PNG_UINT_31_MAX;
else
prefix_len = (png_uint_32)(prefix_len + lang_len);
if (lang_key_len > PNG_UINT_31_MAX-prefix_len)
prefix_len = PNG_UINT_31_MAX;
else
prefix_len = (png_uint_32)(prefix_len + lang_key_len);
png_text_compress_init(&comp, (png_const_bytep)text, strlen(text));
if (compression != 0)
{
if (png_text_compress(png_ptr, png_iTXt, &comp, prefix_len) != Z_OK)
png_error(png_ptr, png_ptr->zstream.msg);
}
else
{
if (comp.input_len > PNG_UINT_31_MAX-prefix_len)
png_error(png_ptr, "iTXt: uncompressed text too long");
/* So the string will fit in a chunk: */
comp.output_len = (png_uint_32)/*SAFE*/comp.input_len;
}
png_write_chunk_header(png_ptr, png_iTXt, comp.output_len + prefix_len);
png_write_chunk_data(png_ptr, new_key, key_len);
png_write_chunk_data(png_ptr, (png_const_bytep)lang, lang_len);
png_write_chunk_data(png_ptr, (png_const_bytep)lang_key, lang_key_len);
if (compression != 0)
png_write_compressed_data_out(png_ptr, &comp);
else
png_write_chunk_data(png_ptr, (png_const_bytep)text, comp.input_len);
png_write_chunk_end(png_ptr);
}
#endif
#ifdef PNG_WRITE_oFFs_SUPPORTED
/* Write the oFFs chunk */
void /* PRIVATE */
png_write_oFFs(png_structrp png_ptr, png_int_32 x_offset, png_int_32 y_offset,
int unit_type)
{
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_complete_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_structrp 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_uint_32 purpose_len;
png_size_t units_len, total_len;
png_size_tp params_len;
png_byte buf[10];
png_byte new_purpose[80];
int i;
png_debug1(1, "in png_write_pCAL (%d parameters)", nparams);
if (type >= PNG_EQUATION_LAST)
png_error(png_ptr, "Unrecognized equation type for pCAL chunk");
purpose_len = png_check_keyword(png_ptr, purpose, new_purpose);
if (purpose_len == 0)
png_error(png_ptr, "pCAL: invalid keyword");
++purpose_len; /* terminator */
png_debug1(3, "pCAL purpose length = %d", (int)purpose_len);
units_len = 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_size_tp)png_malloc(png_ptr,
(png_alloc_size_t)(nparams * (sizeof (png_size_t))));
/* 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] = strlen(params[i]) + (i == nparams - 1 ? 0 : 1);
png_debug2(3, "pCAL parameter %d length = %lu", i,
(unsigned long)params_len[i]);
total_len += params_len[i];
}
png_debug1(3, "pCAL total length = %d", (int)total_len);
png_write_chunk_header(png_ptr, png_pCAL, (png_uint_32)total_len);
png_write_chunk_data(png_ptr, new_purpose, purpose_len);
png_save_int_32(buf, X0);
png_save_int_32(buf + 4, X1);
buf[8] = (png_byte)type;
buf[9] = (png_byte)nparams;
png_write_chunk_data(png_ptr, buf, (png_size_t)10);
png_write_chunk_data(png_ptr, (png_const_bytep)units, (png_size_t)units_len);
for (i = 0; i < nparams; i++)
{
png_write_chunk_data(png_ptr, (png_const_bytep)params[i], 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_structrp png_ptr, int unit, png_const_charp width,
png_const_charp height)
{
png_byte buf[64];
png_size_t wlen, hlen, total_len;
png_debug(1, "in png_write_sCAL_s");
wlen = strlen(width);
hlen = 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;
memcpy(buf + 1, width, wlen + 1); /* Append the '\0' here */
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_complete_chunk(png_ptr, png_sCAL, buf, total_len);
}
#endif
#ifdef PNG_WRITE_pHYs_SUPPORTED
/* Write the pHYs chunk */
void /* PRIVATE */
png_write_pHYs(png_structrp png_ptr, png_uint_32 x_pixels_per_unit,
png_uint_32 y_pixels_per_unit,
int unit_type)
{
png_byte buf[9];
png_debug(1, "in png_write_pHYs");
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_complete_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_structrp png_ptr, png_const_timep mod_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_complete_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_structrp png_ptr)
{
#ifdef PNG_WRITE_INTERLACING_SUPPORTED
/* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
/* Start of interlace block */
static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
/* Offset to next interlace block */
static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
/* Start of interlace block in the y direction */
static PNG_CONST png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
/* Offset to next interlace block in the y direction */
static PNG_CONST png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
#endif
png_alloc_size_t buf_size;
int usr_pixel_depth;
png_debug(1, "in png_write_start_row");
usr_pixel_depth = png_ptr->usr_channels * png_ptr->usr_bit_depth;
buf_size = PNG_ROWBYTES(usr_pixel_depth, png_ptr->width) + 1;
/* 1.5.6: added to allow checking in the row write code. */
png_ptr->transformed_pixel_depth = png_ptr->pixel_depth;
png_ptr->maximum_pixel_depth = (png_byte)usr_pixel_depth;
/* Set up row buffer */
png_ptr->row_buf = (png_bytep)png_malloc(png_ptr, buf_size);
png_ptr->row_buf[0] = PNG_FILTER_VALUE_NONE;
#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, 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;
}
}
/* Internal use only. Called when finished processing a row of data. */
void /* PRIVATE */
png_write_finish_row(png_structrp png_ptr)
{
#ifdef PNG_WRITE_INTERLACING_SUPPORTED
/* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
/* Start of interlace block */
static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
/* Offset to next interlace block */
static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
/* Start of interlace block in the y direction */
static PNG_CONST png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
/* Offset to next interlace block in the y direction */
static PNG_CONST png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
#endif
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)
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 */
png_compress_IDAT(png_ptr, NULL, 0, Z_FINISH);
}
#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 */
static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
/* Offset to next interlace block */
static PNG_CONST png_byte 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)
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_structrp png_ptr, png_bytep filtered_row,
png_size_t row_bytes);
#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_structrp 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 = 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, row_info->rowbytes+1);
#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_structrp png_ptr, png_bytep filtered_row,
png_size_t full_row_length/*includes filter byte*/)
{
png_debug(1, "in png_write_filtered_row");
png_debug1(2, "filter = %d", filtered_row[0]);
png_compress_IDAT(png_ptr, filtered_row, full_row_length, Z_NO_FLUSH);
/* 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 */