Merge "Dither HDR content when compositing to an 8-bit target" into tm-dev
diff --git a/libs/renderengine/skia/SkiaGLRenderEngine.cpp b/libs/renderengine/skia/SkiaGLRenderEngine.cpp
index 1665550..df9f8ab 100644
--- a/libs/renderengine/skia/SkiaGLRenderEngine.cpp
+++ b/libs/renderengine/skia/SkiaGLRenderEngine.cpp
@@ -39,6 +39,7 @@
#include <gui/TraceUtils.h>
#include <sync/sync.h>
#include <ui/BlurRegion.h>
+#include <ui/DataspaceUtils.h>
#include <ui/DebugUtils.h>
#include <ui/GraphicBuffer.h>
#include <utils/Trace.h>
@@ -1105,9 +1106,15 @@
.requiresLinearEffect = requiresLinearEffect,
.layerDimmingRatio = layerDimmingRatio}));
- // Turn on dithering when dimming beyond this threshold.
+ // Turn on dithering when dimming beyond this (arbitrary) threshold...
static constexpr float kDimmingThreshold = 0.2f;
- if (layerDimmingRatio <= kDimmingThreshold) {
+ // ...or we're rendering an HDR layer down to an 8-bit target
+ // Most HDR standards require at least 10-bits of color depth for source content, so we
+ // can just extract the transfer function rather than dig into precise gralloc layout.
+ // Furthermore, we can assume that the only 8-bit target we support is RGBA8888.
+ const bool requiresDownsample = isHdrDataspace(layer.sourceDataspace) &&
+ buffer->getPixelFormat() == PIXEL_FORMAT_RGBA_8888;
+ if (layerDimmingRatio <= kDimmingThreshold || requiresDownsample) {
paint.setDither(true);
}
paint.setAlphaf(layer.alpha);