RenderEngine: draw A8 buffers with a color filter
The A8 buffer was created to behave as a mask - when alpha is 0, the
output should be black. If alpha is 255, the original content should be
shown. Alpha in between should blend with black. This is how the DPU
treats the alpha.
By default, Skia draws an A8 buffer as coverage - the SkPaint's color
(in this case, the default of black) is drawn with the alpha in the
buffer. This is the inverse of what we want. Use a color matrix color
filter to inverse it.
Add a test to verify this works as intended. Update
allocateAndFillSourceBuffer to fill more than the first pixel, so I can
use it in my test. (All existing callers use pass in a size of 1x1, so
they are unaffected.)
Bug: 215706351
Bug: 216146341
Test: librenderengine_test
Change-Id: I340de485fd62bea12a5a097f09073c4f7d58fa90
diff --git a/libs/renderengine/tests/RenderEngineTest.cpp b/libs/renderengine/tests/RenderEngineTest.cpp
index 2a25b0b..612a0aa 100644
--- a/libs/renderengine/tests/RenderEngineTest.cpp
+++ b/libs/renderengine/tests/RenderEngineTest.cpp
@@ -218,14 +218,35 @@
uint8_t* pixels;
buffer->getBuffer()->lock(GRALLOC_USAGE_SW_READ_OFTEN | GRALLOC_USAGE_SW_WRITE_OFTEN,
reinterpret_cast<void**>(&pixels));
- pixels[0] = color.r;
- pixels[1] = color.g;
- pixels[2] = color.b;
- pixels[3] = color.a;
+ for (uint32_t j = 0; j < height; j++) {
+ uint8_t* dst = pixels + (buffer->getBuffer()->getStride() * j * 4);
+ for (uint32_t i = 0; i < width; i++) {
+ dst[0] = color.r;
+ dst[1] = color.g;
+ dst[2] = color.b;
+ dst[3] = color.a;
+ dst += 4;
+ }
+ }
buffer->getBuffer()->unlock();
return buffer;
}
+ std::shared_ptr<renderengine::ExternalTexture> allocateR8Buffer(int width, int height) {
+ auto buffer = new GraphicBuffer(width, height, android::PIXEL_FORMAT_R_8, 1,
+ GRALLOC_USAGE_SW_READ_OFTEN | GRALLOC_USAGE_SW_WRITE_OFTEN |
+ GRALLOC_USAGE_HW_TEXTURE,
+ "r8");
+ if (buffer->initCheck() != 0) {
+ // Devices are not required to support R8.
+ return nullptr;
+ }
+ return std::make_shared<
+ renderengine::impl::ExternalTexture>(std::move(buffer), *mRE,
+ renderengine::impl::ExternalTexture::Usage::
+ READABLE);
+ }
+
RenderEngineTest() {
const ::testing::TestInfo* const test_info =
::testing::UnitTest::GetInstance()->current_test_info();
@@ -2541,6 +2562,66 @@
expectBufferColor(Rect(kGreyLevels, 1), generator, 2);
}
+
+TEST_P(RenderEngineTest, r8_behaves_as_mask) {
+ if (GetParam()->type() == renderengine::RenderEngine::RenderEngineType::GLES) {
+ return;
+ }
+
+ initializeRenderEngine();
+
+ const auto r8Buffer = allocateR8Buffer(2, 1);
+ if (!r8Buffer) {
+ return;
+ }
+ {
+ uint8_t* pixels;
+ r8Buffer->getBuffer()->lock(GRALLOC_USAGE_SW_READ_OFTEN | GRALLOC_USAGE_SW_WRITE_OFTEN,
+ reinterpret_cast<void**>(&pixels));
+ // This will be drawn on top of a green buffer. We'll verify that 255
+ // results in keeping the original green and 0 results in black.
+ pixels[0] = 0;
+ pixels[1] = 255;
+ r8Buffer->getBuffer()->unlock();
+ }
+
+ const auto rect = Rect(0, 0, 2, 1);
+ const renderengine::DisplaySettings display{
+ .physicalDisplay = rect,
+ .clip = rect,
+ .outputDataspace = ui::Dataspace::SRGB,
+ };
+
+ const auto greenBuffer = allocateAndFillSourceBuffer(2, 1, ubyte4(0, 255, 0, 255));
+ const renderengine::LayerSettings greenLayer{
+ .geometry.boundaries = rect.toFloatRect(),
+ .source =
+ renderengine::PixelSource{
+ .buffer =
+ renderengine::Buffer{
+ .buffer = greenBuffer,
+ },
+ },
+ .alpha = 1.0f,
+ };
+ const renderengine::LayerSettings r8Layer{
+ .geometry.boundaries = rect.toFloatRect(),
+ .source =
+ renderengine::PixelSource{
+ .buffer =
+ renderengine::Buffer{
+ .buffer = r8Buffer,
+ },
+ },
+ .alpha = 1.0f,
+ };
+
+ std::vector<renderengine::LayerSettings> layers{greenLayer, r8Layer};
+ invokeDraw(display, layers);
+
+ expectBufferColor(Rect(0, 0, 1, 1), 0, 0, 0, 255);
+ expectBufferColor(Rect(1, 0, 2, 1), 0, 255, 0, 255);
+}
} // namespace renderengine
} // namespace android