commit cf3d95cdec56bea16b9b0f463d4b59377f8720cf
author Leon Scroggins III <scroggo@google.com> Fri Mar 19 13:06:32 2021 -0400
committer Leon Scroggins <scroggo@google.com> Mon Mar 22 14:37:53 2021 +0000
tree 780a6e8fe98c64fbdf6c14980304b76bef88b2d8
parent d5ecb64ef43ea1e6fb85c1abe2bd9d679bc3df9b

SkiaRE: respect disableBlending

Fixes: 182617606
Test: atest librenderengine_test
      RenderEngineTest#testClear
      RenderEngineTest#testDisableBlendingBuffer

When drawing an image or a solid color, use SkBlendMode::kSrc to
avoid blending with other layers. Assert that disableBlending is not
combined with a shadow, since our existing API does not support that.
Continue to ignore disableBlending with blur, which we do not expect
to see as input.

Add RenderEngineTest#testClear and #testDisableBlendingBuffer to verify
the fix.

Change-Id: Ie12cbf497ecb6b71a9b4b625710161fce2b06ee4

libs/renderengine/skia/SkiaGLRenderEngine.cpp

diff --git a/libs/renderengine/skia/SkiaGLRenderEngine.cpp b/libs/renderengine/skia/SkiaGLRenderEngine.cpp
index f76bfa2..908aae3 100644
--- a/libs/renderengine/skia/SkiaGLRenderEngine.cpp
+++ b/libs/renderengine/skia/SkiaGLRenderEngine.cpp
@@ -797,6 +797,8 @@
             const auto rect = layer->geometry.roundedCornersRadius > 0
                     ? getSkRect(layer->geometry.roundedCornersCrop)
                     : bounds;
+            // This would require a new parameter/flag to SkShadowUtils::DrawShadow
+            LOG_ALWAYS_FATAL_IF(layer->disableBlending, "Cannot disableBlending with a shadow");
             drawShadow(canvas, rect, layer->geometry.roundedCornersRadius, layer->shadow);
             continue;
         }
@@ -806,7 +808,7 @@
                  needsToneMapping(layer->sourceDataspace, display.outputDataspace));
 
         // quick abort from drawing the remaining portion of the layer
-        if (layer->alpha == 0 && !requiresLinearEffect &&
+        if (layer->alpha == 0 && !requiresLinearEffect && !layer->disableBlending &&
             (!displayColorTransform || displayColorTransform->isAlphaUnchanged())) {
             continue;
         }
@@ -912,6 +914,10 @@
                                                       requiresLinearEffect));
         }
 
+        if (layer->disableBlending) {
+            paint.setBlendMode(SkBlendMode::kSrc);
+        }
+
         paint.setColorFilter(displayColorTransform);
 
         if (layer->geometry.roundedCornersRadius > 0) {