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WASM: Use ARGB8888. Convert into ABGR and unmultiply after sync()

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Wasm needs ABGR STRAIGHT buffer.
As there is a problem using ABGR for loaders, it is better to use ARGB8888.
This patch makes wasm using ARGB8888 and relocate pixels and unmultiply after sync().
This commit is contained in:
Michal Maciola 2021-11-02 18:11:45 +01:00 • committed by Hermet Park
parent c3a29bd648
commit f222124c40
1 changed files with 26 additions and 1 deletions
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27
src/wasm/thorvgwasm.cpp
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@ -128,6 +128,9 @@ public:
mSwCanvas->sync();
//Change ARGB into ABGR and unpremultiply
unpremultiplyBuffer();
return val(typed_memory_view(mWidth * mHeight * 4, mBuffer.get()));
}
@ -216,6 +219,28 @@ private:
}
}
void unpremultiplyBuffer() {
for (uint32_t y = 0; y < mHeight; y++) {
auto buffer = (uint32_t *) mBuffer.get() + mWidth * y;
for (uint32_t x = 0; x < mWidth; ++x) {
uint8_t a = buffer[x] >> 24;
if (a == 255) {
continue;
} else if (a == 0) {
buffer[x] = 0x00ffffff;
} else {
uint16_t b = ((buffer[x] << 8) & 0xff00) / a;
uint16_t g = ((buffer[x]) & 0xff00) / a;
uint16_t r = ((buffer[x] >> 8) & 0xff00) / a;
if (b > 0xff) r = 0xff;
if (g > 0xff) g = 0xff;
if (r > 0xff) b = 0xff;
buffer[x] = (a << 24) | (b << 16) | (g << 8) | (r);
}
}
}
}
void updateSize(int width, int height)
{
if (!mSwCanvas) return;
@ -224,7 +249,7 @@ private:
mWidth = width;
mHeight = height;
mBuffer = make_unique<uint8_t[]>(mWidth * mHeight * 4);
mSwCanvas->target((uint32_t *)mBuffer.get(), mWidth, mWidth, mHeight, SwCanvas::ABGR8888_STRAIGHT);
mSwCanvas->target((uint32_t *)mBuffer.get(), mWidth, mWidth, mHeight, SwCanvas::ARGB8888);
if (mPicture) mPicture->size(width, height);
}