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Do a better job of enforcing the semantics of the setRequireUnpremultipliedColors flag

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R=scroggo@google.com, halcanary@google.com, robertphillips@google.com

Author: krajcevski@google.com

Review URL: https://codereview.chromium.org/322813005
This commit is contained in:
krajcevski 2014-06-10 09:17:48 -07:00 committed by Commit bot
parent 074fe9df94
commit 3b570c6b02
1 changed files with 32 additions and 17 deletions
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45
src/images/SkImageDecoder_ktx.cpp
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@ -67,12 +67,30 @@ bool SkKTXImageDecoder::onDecode(SkStream* stream, SkBitmap* bm, Mode mode) {
return false;
}
// Set a flag if our source is premultiplied alpha
const SkString premulKey("KTXPremultipliedAlpha");
const bool bSrcIsPremul = ktxFile.getValueForKey(premulKey) == SkString("True");
// Setup the sampler...
SkScaledBitmapSampler sampler(width, height, this->getSampleSize());
// Determine the alpha of the bitmap...
SkAlphaType alphaType = kOpaque_SkAlphaType;
if (ktxFile.isRGBA8()) {
if (this->getRequireUnpremultipliedColors()) {
alphaType = kUnpremul_SkAlphaType;
// If the client wants unpremul colors and we only have
// premul, then we cannot honor their wish.
if (bSrcIsPremul) {
return false;
}
} else {
alphaType = kPremul_SkAlphaType;
}
}
// Set the config...
bm->setInfo(SkImageInfo::MakeN32(sampler.scaledWidth(), sampler.scaledHeight(),
ktxFile.isRGBA8()? kPremul_SkAlphaType : kOpaque_SkAlphaType));
bm->setInfo(SkImageInfo::MakeN32(sampler.scaledWidth(), sampler.scaledHeight(), alphaType));
if (SkImageDecoder::kDecodeBounds_Mode == mode) {
return true;
}
@ -134,17 +152,19 @@ bool SkKTXImageDecoder::onDecode(SkStream* stream, SkBitmap* bm, Mode mode) {
} else if (ktxFile.isRGBA8()) {
// Uncompressed RGBA data
// If we know that the image contains premultiplied alpha, then
// don't premultiply it upon decoding.
bool setRequireUnpremul = false;
const SkString premulKey("KTXPremultipliedAlpha");
if (ktxFile.getValueForKey(premulKey) == SkString("True")) {
this->setRequireUnpremultipliedColors(true);
setRequireUnpremul = true;
// we need to turn off the premultiplier
SkScaledBitmapSampler::Options opts (*this);
if (bSrcIsPremul) {
SkASSERT(bm->alphaType() == kPremul_SkAlphaType);
SkASSERT(!this->getRequireUnpremultipliedColors());
opts.fPremultiplyAlpha = false;
}
// Uncompressed RGBA data
if (!sampler.begin(bm, SkScaledBitmapSampler::kRGBA, *this)) {
if (!sampler.begin(bm, SkScaledBitmapSampler::kRGBA, opts)) {
return false;
}
@ -158,11 +178,6 @@ bool SkKTXImageDecoder::onDecode(SkStream* stream, SkBitmap* bm, Mode mode) {
srcRow += sampler.srcDY() * srcRowBytes;
}
// Reset this in case the decoder needs to be used again.
if (setRequireUnpremul) {
this->setRequireUnpremultipliedColors(false);
}
return true;
}