Fix SkShader leak for Gradient VectorDrawable and test

This CL fixes a SkShader leak in VD when applying local matrix
to the shader. Specifically, the usage of newWithLocalMatrix(...)
increments the shader's ref count in every draw() call for
Gradient VectorDrawable, whereas there's no balancing call to
decrement the ref count in draw(). In this CL, we assume
the ownership of the shader returned from newWithLocalMatrix(...)
to ensure the correct ref count management.

Also, add test to verify that shader is no longer being leaked

BUG: 32067647
Test: this CL

Change-Id: Ic15fe46cde06a73d81b44e2d3c56b51907344cc0

1 files changed, 6 insertions, 2 deletions

diff --git a/libs/hwui/VectorDrawable.cpp b/libs/hwui/VectorDrawable.cpp
index 2b7994139641..aeee66106fb3 100644
--- a/libs/hwui/VectorDrawable.cpp
+++ b/libs/hwui/VectorDrawable.cpp
@@ -202,7 +202,9 @@ void FullPath::drawPath(SkCanvas* outCanvas, SkPath& renderPath, float strokeSca
     if (properties.getFillGradient() != nullptr) {
         paint.setColor(applyAlpha(SK_ColorBLACK, properties.getFillAlpha()));
         SkShader* newShader = properties.getFillGradient()->newWithLocalMatrix(matrix);
-        paint.setShader(newShader);
+        // newWithLocalMatrix(...) creates a new SkShader and returns a bare pointer. We need to
+        // remove the extra ref so that the ref count is correctly managed.
+        paint.setShader(newShader)->unref();
         needsFill = true;
     } else if (properties.getFillColor() != SK_ColorTRANSPARENT) {
         paint.setColor(applyAlpha(properties.getFillColor(), properties.getFillAlpha()));
@@ -222,7 +224,9 @@ void FullPath::drawPath(SkCanvas* outCanvas, SkPath& renderPath, float strokeSca
     if (properties.getStrokeGradient() != nullptr) {
         paint.setColor(applyAlpha(SK_ColorBLACK, properties.getStrokeAlpha()));
         SkShader* newShader = properties.getStrokeGradient()->newWithLocalMatrix(matrix);
-        paint.setShader(newShader);
+        // newWithLocalMatrix(...) creates a new SkShader and returns a bare pointer. We need to
+        // remove the extra ref so that the ref count is correctly managed.
+        paint.setShader(newShader)->unref();
         needsStroke = true;
     } else if (properties.getStrokeColor() != SK_ColorTRANSPARENT) {
         paint.setColor(applyAlpha(properties.getStrokeColor(), properties.getStrokeAlpha()));