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Only unpremultiply ARGB32 data. Call png_write_info() *before* we set up the write conversion... it doesn't work after.

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This commit is contained in:
Owen Taylor 2005-06-23 12:58:49 +00:00
parent 3b20ab66b8
commit ff27263f39
2 changed files with 42 additions and 11 deletions
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6
ChangeLog
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@ -1,3 +1,9 @@
2005-05-17 Owen Taylor <otaylor@redhat.com>
* src/cairo-png.c (write_png): Only unpremultiply ARGB32 data.
Call png_write_info() *before* we set up the write conversion...
it doesn't work after.
2005-06-23 Carl Worth <cworth@cworth.org>
* ROADMAP: Add workaround for Render's overlapping source/dest bug

47
src/cairo-png.c
View file

@ -38,6 +38,7 @@
#include <png.h>
#include "cairoint.h"
/* Unpremultiplies data and converts native endian ARGB => RGBA bytes */
static void
unpremultiply_data (png_structp png, png_row_infop row_info, png_bytep data)
{
@ -53,14 +54,33 @@ unpremultiply_data (png_structp png, png_row_infop row_info, png_bytep data)
if (alpha == 0) {
b[0] = b[1] = b[2] = b[3] = 0;
} else {
b[0] = (((pixel & 0x0000ff) >> 0) * 255 + alpha / 2) / alpha;
b[0] = (((pixel & 0xff0000) >> 16) * 255 + alpha / 2) / alpha;
b[1] = (((pixel & 0x00ff00) >> 8) * 255 + alpha / 2) / alpha;
b[2] = (((pixel & 0xff0000) >> 16) * 255 + alpha / 2) / alpha;
b[2] = (((pixel & 0x0000ff) >> 0) * 255 + alpha / 2) / alpha;
b[3] = alpha;
}
}
}
/* Converts native endian xRGB => RGBx bytes */
static void
convert_data_to_bytes (png_structp png, png_row_infop row_info, png_bytep data)
{
int i;
for (i = 0; i < row_info->rowbytes; i += 4) {
uint8_t *b = &data[i];
uint32_t pixel;
memcpy (&pixel, b, sizeof (uint32_t));
b[0] = (pixel & 0xff0000) >> 16;
b[1] = (pixel & 0x00ff00) >> 8;
b[2] = (pixel & 0x0000ff) >> 0;
b[3] = 0;
}
}
static cairo_status_t
write_png (cairo_surface_t *surface,
png_rw_ptr write_func,
@ -153,14 +173,19 @@ write_png (cairo_surface_t *surface,
png_convert_from_time_t (&pt, time (NULL));
png_set_tIME (png, info, &pt);
png_set_write_user_transform_fn (png, unpremultiply_data);
if (image->format == CAIRO_FORMAT_ARGB32 ||
image->format == CAIRO_FORMAT_RGB24)
png_set_bgr (png);
/* We have to call png_write_info() before setting up the write
* transformation, since it stores data internally in 'png'
* that is needed for the write transformation functions to work.
*/
png_write_info (png, info);
if (image->format == CAIRO_FORMAT_ARGB32)
png_set_write_user_transform_fn (png, unpremultiply_data);
else if (image->format == CAIRO_FORMAT_RGB24)
png_set_write_user_transform_fn (png, convert_data_to_bytes);
if (image->format == CAIRO_FORMAT_RGB24)
png_set_filler (png, 0, PNG_FILLER_AFTER);
png_write_info (png, info);
png_write_image (png, rows);
png_write_end (png, info);
@ -262,6 +287,7 @@ cairo_surface_write_to_png_stream (cairo_surface_t *surface,
return write_png (surface, stream_write_func, &png_closure);
}
/* Premultiplies data and converts RGBA bytes => native endian */
static void
premultiply_data (png_structp png,
png_row_infop row_info,
@ -271,9 +297,9 @@ premultiply_data (png_structp png,
for (i = 0; i < row_info->rowbytes; i += 4) {
uint8_t *base = &data[i];
uint8_t blue = base[0];
uint8_t red = base[0];
uint8_t green = base[1];
uint8_t red = base[2];
uint8_t blue = base[2];
uint8_t alpha = base[3];
uint32_t p;
@ -352,7 +378,6 @@ read_png (png_rw_ptr read_func,
if (interlace != PNG_INTERLACE_NONE)
png_set_interlace_handling (png);
png_set_bgr (png);
png_set_filler (png, 0xff, PNG_FILLER_AFTER);
png_set_read_user_transform_fn (png, premultiply_data);