diff options
Diffstat (limited to 'src/cairo-png.c')
| -rw-r--r-- | src/cairo-png.c | 49 |
1 files changed, 37 insertions, 12 deletions
diff --git a/src/cairo-png.c b/src/cairo-png.c index d7297848d..532054e51 100644 --- a/src/cairo-png.c +++ b/src/cairo-png.c @@ -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); @@ -383,7 +408,7 @@ read_png (png_rw_ptr read_func, BAIL: free (row_pointers); free (data); - png_destroy_read_struct (&png, NULL, NULL); + png_destroy_read_struct (&png, &info, NULL); return surface; } |