Skip TransformCanvas calls for FunctorDrawables

Fix issue where attempts to render overscroll content
into the alpha 8 mask would crash if there are WebView
related Functors in the scene.

Provide implementations for getTypeName in SkDrawable instances
of FunctorDrawable.

Fixes: 203960959
Test: manual
Change-Id: Idf321d9bfcbe2b8ba1eb205eadcec95e55865305

1 files changed, 13 insertions, 1 deletions

diff --git a/libs/hwui/pipeline/skia/TransformCanvas.cpp b/libs/hwui/pipeline/skia/TransformCanvas.cpp
index 6777c00c4655..41e36874b862 100644
--- a/libs/hwui/pipeline/skia/TransformCanvas.cpp
+++ b/libs/hwui/pipeline/skia/TransformCanvas.cpp
@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 #include "TransformCanvas.h"
+
+#include "FunctorDrawable.h"
 #include "HolePunch.h"
 #include "SkData.h"
 #include "SkDrawable.h"
@@ -35,7 +37,17 @@ void TransformCanvas::onDrawAnnotation(const SkRect& rect, const char* key, SkDa
 }
 
 void TransformCanvas::onDrawDrawable(SkDrawable* drawable, const SkMatrix* matrix) {
-    drawable->draw(this, matrix);
+    // TransformCanvas filters all drawing commands while maintaining the current
+    // clip stack and transformation. We need to draw most SkDrawables, since their
+    // draw calls may call methods that affect the clip stack and transformation. (Any
+    // actual draw commands will then be filtered out.) But FunctorDrawables are used
+    // as leaf nodes which issue self-contained OpenGL/Vulkan commands. These won't
+    // affect the clip stack + transformation, and in some cases cause problems (e.g. if
+    // the surface only has an alpha channel). See b/203960959
+    const auto* drawableName = drawable->getTypeName();
+    if (drawableName == nullptr || strcmp(drawableName, FunctorDrawable::TYPE_NAME) != 0) {
+        drawable->draw(this, matrix);
+    }
 }
 
 bool TransformCanvas::onFilter(SkPaint& paint) const {