📄 pngrtran.c
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info_ptr->channels++;
#if defined(PNG_READ_FILLER_SUPPORTED)
/* STRIP_ALPHA and FILLER allowed: MASK_ALPHA bit stripped above */
if ((png_ptr->transformations & PNG_FILLER) &&
((info_ptr->color_type == PNG_COLOR_TYPE_RGB) ||
(info_ptr->color_type == PNG_COLOR_TYPE_GRAY)))
{
info_ptr->channels++;
/* if adding a true alpha channel not just filler */
#if !defined(PNG_1_0_X)
if (png_ptr->transformations & PNG_ADD_ALPHA)
info_ptr->color_type |= PNG_COLOR_MASK_ALPHA;
#endif
}
#endif
#if defined(PNG_USER_TRANSFORM_PTR_SUPPORTED) && \
defined(PNG_READ_USER_TRANSFORM_SUPPORTED)
if(png_ptr->transformations & PNG_USER_TRANSFORM)
{
if(info_ptr->bit_depth < png_ptr->user_transform_depth)
info_ptr->bit_depth = png_ptr->user_transform_depth;
if(info_ptr->channels < png_ptr->user_transform_channels)
info_ptr->channels = png_ptr->user_transform_channels;
}
#endif
info_ptr->pixel_depth = (png_byte)(info_ptr->channels *
info_ptr->bit_depth);
info_ptr->rowbytes = PNG_ROWBYTES(info_ptr->pixel_depth,info_ptr->width);
#if !defined(PNG_READ_EXPAND_SUPPORTED)
if(png_ptr)
return;
#endif
}
/* Transform the row. The order of transformations is significant,
* and is very touchy. If you add a transformation, take care to
* decide how it fits in with the other transformations here.
*/
void /* PRIVATE */
png_do_read_transformations(png_structp png_ptr)
{
png_debug(1, "in png_do_read_transformations\n");
#if !defined(PNG_USELESS_TESTS_SUPPORTED)
if (png_ptr->row_buf == NULL)
{
#if !defined(PNG_NO_STDIO) && !defined(_WIN32_WCE)
char msg[50];
sprintf(msg, "NULL row buffer for row %ld, pass %d", png_ptr->row_number,
png_ptr->pass);
png_error(png_ptr, msg);
#else
png_error(png_ptr, "NULL row buffer");
#endif
}
#endif
#if defined(PNG_READ_EXPAND_SUPPORTED)
if (png_ptr->transformations & PNG_EXPAND)
{
if (png_ptr->row_info.color_type == PNG_COLOR_TYPE_PALETTE)
{
png_do_expand_palette(&(png_ptr->row_info), png_ptr->row_buf + 1,
png_ptr->palette, png_ptr->trans, png_ptr->num_trans);
}
else
{
if (png_ptr->num_trans)
png_do_expand(&(png_ptr->row_info), png_ptr->row_buf + 1,
&(png_ptr->trans_values));
else
png_do_expand(&(png_ptr->row_info), png_ptr->row_buf + 1,
NULL);
}
}
#endif
#if defined(PNG_READ_STRIP_ALPHA_SUPPORTED)
if (png_ptr->flags & PNG_FLAG_STRIP_ALPHA)
png_do_strip_filler(&(png_ptr->row_info), png_ptr->row_buf + 1,
PNG_FLAG_FILLER_AFTER | (png_ptr->flags & PNG_FLAG_STRIP_ALPHA));
#endif
#if defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
if (png_ptr->transformations & PNG_RGB_TO_GRAY)
{
int rgb_error =
png_do_rgb_to_gray(png_ptr, &(png_ptr->row_info), png_ptr->row_buf + 1);
if(rgb_error)
{
png_ptr->rgb_to_gray_status=1;
if(png_ptr->transformations == PNG_RGB_TO_GRAY_WARN)
png_warning(png_ptr, "png_do_rgb_to_gray found nongray pixel");
if(png_ptr->transformations == PNG_RGB_TO_GRAY_ERR)
png_error(png_ptr, "png_do_rgb_to_gray found nongray pixel");
}
}
#endif
/*
From Andreas Dilger e-mail to png-implement, 26 March 1998:
In most cases, the "simple transparency" should be done prior to doing
gray-to-RGB, or you will have to test 3x as many bytes to check if a
pixel is transparent. You would also need to make sure that the
transparency information is upgraded to RGB.
To summarize, the current flow is:
- Gray + simple transparency -> compare 1 or 2 gray bytes and composite
with background "in place" if transparent,
convert to RGB if necessary
- Gray + alpha -> composite with gray background and remove alpha bytes,
convert to RGB if necessary
To support RGB backgrounds for gray images we need:
- Gray + simple transparency -> convert to RGB + simple transparency, compare
3 or 6 bytes and composite with background
"in place" if transparent (3x compare/pixel
compared to doing composite with gray bkgrnd)
- Gray + alpha -> convert to RGB + alpha, composite with background and
remove alpha bytes (3x float operations/pixel
compared with composite on gray background)
Greg's change will do this. The reason it wasn't done before is for
performance, as this increases the per-pixel operations. If we would check
in advance if the background was gray or RGB, and position the gray-to-RGB
transform appropriately, then it would save a lot of work/time.
*/
#if defined(PNG_READ_GRAY_TO_RGB_SUPPORTED)
/* if gray -> RGB, do so now only if background is non-gray; else do later
* for performance reasons */
if ((png_ptr->transformations & PNG_GRAY_TO_RGB) &&
!(png_ptr->mode & PNG_BACKGROUND_IS_GRAY))
png_do_gray_to_rgb(&(png_ptr->row_info), png_ptr->row_buf + 1);
#endif
#if defined(PNG_READ_BACKGROUND_SUPPORTED)
if ((png_ptr->transformations & PNG_BACKGROUND) &&
((png_ptr->num_trans != 0 ) ||
(png_ptr->color_type & PNG_COLOR_MASK_ALPHA)))
png_do_background(&(png_ptr->row_info), png_ptr->row_buf + 1,
&(png_ptr->trans_values), &(png_ptr->background)
#if defined(PNG_READ_GAMMA_SUPPORTED)
, &(png_ptr->background_1),
png_ptr->gamma_table, png_ptr->gamma_from_1,
png_ptr->gamma_to_1, png_ptr->gamma_16_table,
png_ptr->gamma_16_from_1, png_ptr->gamma_16_to_1,
png_ptr->gamma_shift
#endif
);
#endif
#if defined(PNG_READ_GAMMA_SUPPORTED)
if ((png_ptr->transformations & PNG_GAMMA) &&
#if defined(PNG_READ_BACKGROUND_SUPPORTED)
!((png_ptr->transformations & PNG_BACKGROUND) &&
((png_ptr->num_trans != 0) ||
(png_ptr->color_type & PNG_COLOR_MASK_ALPHA))) &&
#endif
(png_ptr->color_type != PNG_COLOR_TYPE_PALETTE))
png_do_gamma(&(png_ptr->row_info), png_ptr->row_buf + 1,
png_ptr->gamma_table, png_ptr->gamma_16_table,
png_ptr->gamma_shift);
#endif
#if defined(PNG_READ_16_TO_8_SUPPORTED)
if (png_ptr->transformations & PNG_16_TO_8)
png_do_chop(&(png_ptr->row_info), png_ptr->row_buf + 1);
#endif
#if defined(PNG_READ_DITHER_SUPPORTED)
if (png_ptr->transformations & PNG_DITHER)
{
png_do_dither((png_row_infop)&(png_ptr->row_info), png_ptr->row_buf + 1,
png_ptr->palette_lookup, png_ptr->dither_index);
if(png_ptr->row_info.rowbytes == (png_uint_32)0)
png_error(png_ptr, "png_do_dither returned rowbytes=0");
}
#endif
#if defined(PNG_READ_INVERT_SUPPORTED)
if (png_ptr->transformations & PNG_INVERT_MONO)
png_do_invert(&(png_ptr->row_info), png_ptr->row_buf + 1);
#endif
#if defined(PNG_READ_SHIFT_SUPPORTED)
if (png_ptr->transformations & PNG_SHIFT)
png_do_unshift(&(png_ptr->row_info), png_ptr->row_buf + 1,
&(png_ptr->shift));
#endif
#if defined(PNG_READ_PACK_SUPPORTED)
if (png_ptr->transformations & PNG_PACK)
png_do_unpack(&(png_ptr->row_info), png_ptr->row_buf + 1);
#endif
#if defined(PNG_READ_BGR_SUPPORTED)
if (png_ptr->transformations & PNG_BGR)
png_do_bgr(&(png_ptr->row_info), png_ptr->row_buf + 1);
#endif
#if defined(PNG_READ_PACKSWAP_SUPPORTED)
if (png_ptr->transformations & PNG_PACKSWAP)
png_do_packswap(&(png_ptr->row_info), png_ptr->row_buf + 1);
#endif
#if defined(PNG_READ_GRAY_TO_RGB_SUPPORTED)
/* if gray -> RGB, do so now only if we did not do so above */
if ((png_ptr->transformations & PNG_GRAY_TO_RGB) &&
(png_ptr->mode & PNG_BACKGROUND_IS_GRAY))
png_do_gray_to_rgb(&(png_ptr->row_info), png_ptr->row_buf + 1);
#endif
#if defined(PNG_READ_FILLER_SUPPORTED)
if (png_ptr->transformations & PNG_FILLER)
png_do_read_filler(&(png_ptr->row_info), png_ptr->row_buf + 1,
(png_uint_32)png_ptr->filler, png_ptr->flags);
#endif
#if defined(PNG_READ_INVERT_ALPHA_SUPPORTED)
if (png_ptr->transformations & PNG_INVERT_ALPHA)
png_do_read_invert_alpha(&(png_ptr->row_info), png_ptr->row_buf + 1);
#endif
#if defined(PNG_READ_SWAP_ALPHA_SUPPORTED)
if (png_ptr->transformations & PNG_SWAP_ALPHA)
png_do_read_swap_alpha(&(png_ptr->row_info), png_ptr->row_buf + 1);
#endif
#if defined(PNG_READ_SWAP_SUPPORTED)
if (png_ptr->transformations & PNG_SWAP_BYTES)
png_do_swap(&(png_ptr->row_info), png_ptr->row_buf + 1);
#endif
#if defined(PNG_READ_USER_TRANSFORM_SUPPORTED)
if (png_ptr->transformations & PNG_USER_TRANSFORM)
{
if(png_ptr->read_user_transform_fn != NULL)
(*(png_ptr->read_user_transform_fn)) /* user read transform function */
(png_ptr, /* png_ptr */
&(png_ptr->row_info), /* row_info: */
/* png_uint_32 width; width of row */
/* png_uint_32 rowbytes; number of bytes in row */
/* png_byte color_type; color type of pixels */
/* png_byte bit_depth; bit depth of samples */
/* png_byte channels; number of channels (1-4) */
/* png_byte pixel_depth; bits per pixel (depth*channels) */
png_ptr->row_buf + 1); /* start of pixel data for row */
#if defined(PNG_USER_TRANSFORM_PTR_SUPPORTED)
if(png_ptr->user_transform_depth)
png_ptr->row_info.bit_depth = png_ptr->user_transform_depth;
if(png_ptr->user_transform_channels)
png_ptr->row_info.channels = png_ptr->user_transform_channels;
#endif
png_ptr->row_info.pixel_depth = (png_byte)(png_ptr->row_info.bit_depth *
png_ptr->row_info.channels);
png_ptr->row_info.rowbytes = PNG_ROWBYTES(png_ptr->row_info.pixel_depth,
png_ptr->row_info.width);
}
#endif
}
#if defined(PNG_READ_PACK_SUPPORTED)
/* Unpack pixels of 1, 2, or 4 bits per pixel into 1 byte per pixel,
* without changing the actual values. Thus, if you had a row with
* a bit depth of 1, you would end up with bytes that only contained
* the numbers 0 or 1. If you would rather they contain 0 and 255, use
* png_do_shift() after this.
*/
void /* PRIVATE */
png_do_unpack(png_row_infop row_info, png_bytep row)
{
png_debug(1, "in png_do_unpack\n");
#if defined(PNG_USELESS_TESTS_SUPPORTED)
if (row != NULL && row_info != NULL && row_info->bit_depth < 8)
#else
if (row_info->bit_depth < 8)
#endif
{
png_uint_32 i;
png_uint_32 row_width=row_info->width;
switch (row_info->bit_depth)
{
case 1:
{
png_bytep sp = row + (png_size_t)((row_width - 1) >> 3);
png_bytep dp = row + (png_size_t)row_width - 1;
png_uint_32 shift = 7 - (int)((row_width + 7) & 0x07);
for (i = 0; i < row_width; i++)
{
*dp = (png_byte)((*sp >> shift) & 0x01);
if (shift == 7)
{
shift = 0;
sp--;
}
else
shift++;
dp--;
}
break;
}
case 2:
{
png_bytep sp = row + (png_size_t)((row_width - 1) >> 2);
png_bytep dp = row + (png_size_t)row_width - 1;
png_uint_32 shift = (int)((3 - ((row_width + 3) & 0x03)) << 1);
for (i = 0; i < row_width; i++)
{
*dp = (png_byte)((*sp >> shift) & 0x03);
if (shift == 6)
{
shift = 0;
sp--;
}
else
shift += 2;
dp--;
}
break;
}
case 4:
{
png_bytep sp = row + (png_size_t)((row_width - 1) >> 1);
png_bytep dp = row + (png_size_t)row_width - 1;
png_uint_32 shift = (int)((1 - ((row_width + 1) & 0x01)) << 2);
for (i = 0; i < row_width; i++)
{
*dp = (png_byte)((*sp >> shift) & 0x0f);
if (shift == 4)
{
shift = 0;
sp--;
}
else
shift = 4;
dp--;
}
break;
}
}
row_info->bit_depth = 8;
row_info->pixel_depth = (png_byte)(8 * row_info->channels);
row_info->rowbytes = row_width * row_info->channels;
}
}
#endif
#if defined(PNG_READ_SHIFT_SUPPORTED)
/* Reverse the effects of png_do_shift. This routine merely shifts the
* pixels back to their significant bits values. Thus, if you have
* a row of bit depth 8, but only 5 are significant, this will shift
* the values back to 0 through 31.
*/
void /* PRIVATE */
png_do_unshift(png_row_infop row_info, png_bytep row, png_color_8p sig_bits)
{
png_debug(1, "in png_do_unshift\n");
if (
#if defined(PNG_USELESS_TESTS_SUPPORTED)
row != NULL && row_info != NULL && sig_bits != NULL &&
#endif
row_info->color_type != PNG_COLOR_TYPE_PALETTE)
{
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