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Bug 1756803 scaling/premultiply alpha of ImageData r=aosmond

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Two issues:

The result of scaling & premultiply is order critical, the previous order for ImageData was scale > premultiply, the other image sources were premultiplied by default so didn't expose this issue. Reorder in the ImageData and common code paths (the original order followed the w3c spec order of operations - maybe the spec needs amending).

The ImageData path did not set the premultiplied flag of the resulting ImageBitmap correctly so the image would be premultiplied again in PrepareForDrawTarget.

Differential Revision: https://phabricator.services.mozilla.com/D139700
This commit is contained in:
Angus Sawyer
2022-03-18 16:47:26 +00:00
parent 2faa39b193
commit 4c68b4a042
1 changed files with 22 additions and 11 deletions
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33
dom/canvas/ImageBitmap.cpp
View File

@@ -439,7 +439,6 @@ static already_AddRefed<SourceSurface> CreateSurfaceFromRawData(
// Copy the source buffer in the _cropRect_ area into a new SourceSurface.
RefPtr<DataSourceSurface> result =
CropAndCopyDataSourceSurface(dataSurface, cropRect);
if (NS_WARN_IF(!result)) {
return nullptr;
}
@@ -452,17 +451,17 @@ static already_AddRefed<SourceSurface> CreateSurfaceFromRawData(
}
}
if (aOptions.mResizeWidth.WasPassed() || aOptions.mResizeHeight.WasPassed()) {
dataSurface = result->GetDataSurface();
result = ScaleDataSourceSurface(dataSurface, aOptions);
if (aOptions.mPremultiplyAlpha == PremultiplyAlpha::Premultiply) {
result = AlphaPremultiplyDataSourceSurface(result);
if (NS_WARN_IF(!result)) {
return nullptr;
}
}
if (aOptions.mPremultiplyAlpha == PremultiplyAlpha::Premultiply) {
result = AlphaPremultiplyDataSourceSurface(result);
if (aOptions.mResizeWidth.WasPassed() || aOptions.mResizeHeight.WasPassed()) {
dataSurface = result->GetDataSurface();
result = ScaleDataSourceSurface(dataSurface, aOptions);
if (NS_WARN_IF(!result)) {
return nullptr;
}
@@ -928,6 +927,17 @@ already_AddRefed<ImageBitmap> ImageBitmap::CreateImageBitmapInternal(
}
}
if (requiresPremultiply) {
if (!dataSurface) {
dataSurface = surface->GetDataSurface();
}
surface = AlphaPremultiplyDataSourceSurface(dataSurface, true);
if (NS_WARN_IF(!surface)) {
return nullptr;
}
}
// resize if required
if (aOptions.mResizeWidth.WasPassed() || aOptions.mResizeHeight.WasPassed()) {
if (!dataSurface) {
@@ -944,13 +954,12 @@ already_AddRefed<ImageBitmap> ImageBitmap::CreateImageBitmapInternal(
cropRect.SetRect(0, 0, surface->GetSize().width, surface->GetSize().height);
}
if (requiresPremultiply || requiresUnpremultiply) {
if (requiresUnpremultiply) {
if (!dataSurface) {
dataSurface = surface->GetDataSurface();
}
surface =
AlphaPremultiplyDataSourceSurface(dataSurface, requiresPremultiply);
surface = AlphaPremultiplyDataSourceSurface(dataSurface, false);
if (NS_WARN_IF(!surface)) {
return nullptr;
}
@@ -1182,7 +1191,9 @@ already_AddRefed<ImageBitmap> ImageBitmap::CreateInternal(
array.ComputeState();
const SurfaceFormat FORMAT = SurfaceFormat::R8G8B8A8;
// ImageData's underlying data is not alpha-premultiplied.
auto alphaType = gfxAlphaType::NonPremult;
auto alphaType = (aOptions.mPremultiplyAlpha == PremultiplyAlpha::Premultiply)
? gfxAlphaType::Premult
: gfxAlphaType::NonPremult;
const uint32_t BYTES_PER_PIXEL = BytesPerPixel(FORMAT);
const uint32_t imageWidth = aImageData.Width();