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sw_engine: stop-opacity value should be interpolated between stops

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The opacity value is interpolated as are all color channels.
This commit is contained in:
Mira Grudzinska 2021-06-30 00:21:48 +02:00 • committed by Hermet Park
parent 3086f28b55
commit ac95433b53
1 changed files with 14 additions and 12 deletions
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26
src/lib/sw_engine/tvgSwFill.cpp
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@ -49,11 +49,11 @@ static bool _updateColorTable(SwFill* fill, const Fill* fdata, const SwSurface*
auto a = (pColors->a * opacity) / 255;
if (a < 255) fill->translucent = true;
auto r = ALPHA_MULTIPLY(pColors->r, a);
auto g = ALPHA_MULTIPLY(pColors->g, a);
auto b = ALPHA_MULTIPLY(pColors->b, a);
auto r = pColors->r;
auto g = pColors->g;
auto b = pColors->b;
auto rgba = surface->blender.join(r, g, b, a);
auto inc = 1.0f / static_cast<float>(GRADIENT_STOP_SIZE);
auto pos = 1.5f * inc;
uint32_t i = 0;
@ -70,30 +70,32 @@ static bool _updateColorTable(SwFill* fill, const Fill* fdata, const SwSurface*
auto curr = colors + j;
auto next = curr + 1;
auto delta = 1.0f / (next->offset - curr->offset);
a = (next->a * opacity) / 255;
auto a2 = (next->a * opacity) / 255;
if (!fill->translucent && a < 255) fill->translucent = true;
auto r = ALPHA_MULTIPLY(next->r, a);
auto g = ALPHA_MULTIPLY(next->g, a);
auto b = ALPHA_MULTIPLY(next->b, a);
auto rgba2 = surface->blender.join(r, g, b, a);
auto rgba2 = surface->blender.join(next->r, next->g, next->b, a2);
while (pos < next->offset && i < GRADIENT_STOP_SIZE) {
auto t = (pos - curr->offset) * delta;
auto dist = static_cast<int32_t>(256 * t);
auto dist2 = 256 - dist;
fill->ctable[i] = COLOR_INTERPOLATE(rgba, dist2, rgba2, dist);
auto color = COLOR_INTERPOLATE(rgba, dist2, rgba2, dist);
uint8_t a = color >> 24;
fill->ctable[i] = ALPHA_BLEND(color | 0xff000000, a);
++i;
pos += inc;
}
rgba = rgba2;
a = a2;
}
rgba = ALPHA_BLEND(rgba | 0xff000000, a);
for (; i < GRADIENT_STOP_SIZE; ++i)
fill->ctable[i] = rgba;
//Make sure the lat color stop is represented at the end of the table
//Make sure the last color stop is represented at the end of the table
fill->ctable[GRADIENT_STOP_SIZE - 1] = rgba;
return true;