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Call png_get_channels() to see if image has alpha

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After the png_read_update_info() call, call png_get_channels() to find
out if the image has alpha.

Change-Id: I6fa709418744b4de90d10ff96eaeefe454ffa290
This commit is contained in:
Wan-Teh Chang 2023-06-13 23:24:43 +00:00 committed by James Zern
parent 7f0a341943
commit 8e965ccb0f
1 changed files with 8 additions and 8 deletions
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16
imageio/pngdec.c
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@ -235,7 +235,7 @@ int ReadPNG(const uint8_t* const data, size_t data_size,
volatile png_infop end_info = NULL;
PNGReadContext context = { NULL, 0, 0 };
int color_type, bit_depth, interlaced;
int has_alpha;
int num_channels;
int num_passes;
int p;
volatile int ok = 0;
@ -293,9 +293,6 @@ int ReadPNG(const uint8_t* const data, size_t data_size,
}
if (png_get_valid(png, info, PNG_INFO_tRNS)) {
png_set_tRNS_to_alpha(png);
has_alpha = 1;
} else {
has_alpha = !!(color_type & PNG_COLOR_MASK_ALPHA);
}
// Apply gamma correction if needed.
@ -310,13 +307,16 @@ int ReadPNG(const uint8_t* const data, size_t data_size,
if (!keep_alpha) {
png_set_strip_alpha(png);
has_alpha = 0;
}
num_passes = png_set_interlace_handling(png);
png_read_update_info(png, info);
stride = (int64_t)(has_alpha ? 4 : 3) * width * sizeof(*rgb);
num_channels = png_get_channels(png, info);
if (num_channels != 3 && num_channels != 4) {
goto Error;
}
stride = (int64_t)num_channels * width * sizeof(*rgb);
if (stride != (int)stride ||
!ImgIoUtilCheckSizeArgumentsOverflow(stride, height)) {
goto Error;
@ -341,8 +341,8 @@ int ReadPNG(const uint8_t* const data, size_t data_size,
pic->width = (int)width;
pic->height = (int)height;
ok = has_alpha ? WebPPictureImportRGBA(pic, rgb, (int)stride)
: WebPPictureImportRGB(pic, rgb, (int)stride);
ok = (num_channels == 4) ? WebPPictureImportRGBA(pic, rgb, (int)stride)
: WebPPictureImportRGB(pic, rgb, (int)stride);
if (!ok) {
goto Error;