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Merge branch 'fix-png-write-endian' into 'master'

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Read/write 16-bpc PNG data in native endian

Closes #501

See merge request cairo/cairo!230
This commit is contained in:
Uli Schlachter 2021-08-23 16:31:57 +00:00
commit 923715f2e9
1 changed files with 16 additions and 0 deletions
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16
src/cairo-png.c
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@ -407,6 +407,14 @@ write_png (cairo_surface_t *surface,
*/
png_write_info (png, info);
#ifndef WORDS_BIGENDIAN
/* libpng treats 16-bit data as big-endian by default. Swapping the
* byte-order on little endian ensures the native-endian data can be
* provided to png_write_image. This does not affect 8-bit data.
*/
png_set_swap (png);
#endif
if (png_color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
if (clone->format != CAIRO_FORMAT_RGBA128F)
png_set_write_user_transform_fn (png, unpremultiply_data);
@ -702,6 +710,14 @@ read_png (struct png_read_closure_t *png_closure)
png_read_info (png, info);
#ifndef WORDS_BIGENDIAN
/* libpng treats 16-bit data as big-endian by default. Swapping the
* byte-order on little endian ensures the native-endian data can be
* provided to png_read_image. This does not affect 8-bit data.
*/
png_set_swap (png);
#endif
png_get_IHDR (png, info,
&png_width, &png_height, &depth,
&color_type, &interlace, NULL, NULL);