Merge "Changed luma calculation to an approximation method. Test: Manually flashed" (5941e11f) · Commits · e / os / platform_frameworks_native

services/surfaceflinger/RegionSamplingThread.cpp

+9 −26

Original line number	Diff line number	Diff line
		@@ -268,16 +268,6 @@ void RegionSamplingThread::binderDied(const wp<IBinder>& who) {
		mDescriptors.erase(who);
		}

		namespace {
		// Using Rec. 709 primaries
		inline float getLuma(float r, float g, float b) {
		constexpr auto rec709_red_primary = 0.2126f;
		constexpr auto rec709_green_primary = 0.7152f;
		constexpr auto rec709_blue_primary = 0.0722f;
		return rec709_red_primary * r + rec709_green_primary * g + rec709_blue_primary * b;
		}
		} // anonymous namespace

		float sampleArea(const uint32_t* data, int32_t width, int32_t height, int32_t stride,
		uint32_t orientation, const Rect& sample_area) {
		if (!sample_area.isValid() \|\| (sample_area.getWidth() > width) \|\|
		@@ -298,30 +288,23 @@ float sampleArea(const uint32_t* data, int32_t width, int32_t height, int32_t st
		std::swap(area.left, area.right);
		}

		std::array<int32_t, 256> brightnessBuckets = {};
		const int32_t majoritySampleNum = area.getWidth() * area.getHeight() / 2;
		const uint32_t pixelCount = (area.bottom - area.top) * (area.right - area.left);
		uint32_t accumulatedLuma = 0;

		// Calculates luma with approximation of Rec. 709 primaries
		for (int32_t row = area.top; row < area.bottom; ++row) {
		const uint32_t* rowBase = data + row * stride;
		for (int32_t column = area.left; column < area.right; ++column) {
		uint32_t pixel = rowBase[column];
		const float r = pixel & 0xFF;
		const float g = (pixel >> 8) & 0xFF;
		const float b = (pixel >> 16) & 0xFF;
		const uint8_t luma = std::round(getLuma(r, g, b));
		++brightnessBuckets[luma];
		if (brightnessBuckets[luma] > majoritySampleNum) return luma / 255.0f;
		const uint32_t r = pixel & 0xFF;
		const uint32_t g = (pixel >> 8) & 0xFF;
		const uint32_t b = (pixel >> 16) & 0xFF;
		const uint32_t luma = (r * 7 + b * 2 + g * 23) >> 5;
		accumulatedLuma += luma;
		}
		}

		int32_t accumulated = 0;
		size_t bucket = 0;
		for (; bucket < brightnessBuckets.size(); bucket++) {
		accumulated += brightnessBuckets[bucket];
		if (accumulated > majoritySampleNum) break;
		}

		return bucket / 255.0f;
		return accumulatedLuma / (255.0f * pixelCount);
		}

		std::vector<float> RegionSamplingThread::sampleBuffer(

services/surfaceflinger/tests/unittests/RegionSamplingTest.cpp

+3 −3

Original line number	Diff line number	Diff line
		@@ -69,16 +69,16 @@ TEST_F(RegionSamplingTest, calculate_mean_mixed_values) {
		n++;
		return pixel;
		});

		EXPECT_THAT(sampleArea(buffer.data(), kWidth, kHeight, kStride, kOrientation, whole_area),
		testing::FloatNear(0.083f, 0.01f));
		testing::FloatNear(0.16f, 0.01f));
		}

		TEST_F(RegionSamplingTest, bimodal_tiebreaker) {
		std::generate(buffer.begin(), buffer.end(),
		[n = 0]() mutable { return (n++ % 2) ? kBlack : kWhite; });
		// presently there's no tiebreaking strategy in place, accept either of the means
		EXPECT_THAT(sampleArea(buffer.data(), kWidth, kHeight, kStride, kOrientation, whole_area),
		testing::AnyOf(testing::FloatEq(1.0), testing::FloatEq(0.0f)));
		testing::FloatEq(0.5f));
		}

		TEST_F(RegionSamplingTest, bounds_checking) {