Quick reject empty paths

bug:7260035

Adding a circle of radius 0 to a path is a no-op in skia, so detect
this case both in the PathRenderer, and in quickReject().

Change-Id: I7a172db49a5d5351b4734b39d4e4ca6379658096

Author: ChrisCraik

libs/hwui/OpenGLRenderer.cpp

@@ -1265,7 +1265,7 @@ bool OpenGLRenderer::quickRejectPreStroke(float left, float top, float right, fl
 }
 
 bool OpenGLRenderer::quickReject(float left, float top, float right, float bottom) {
-    if (mSnapshot->isIgnored()) {
+    if (mSnapshot->isIgnored() || bottom <= top || right <= left) {
         return true;
     }
 
@@ -1951,6 +1951,11 @@ void OpenGLRenderer::drawConvexPath(const SkPath& path, SkPaint* paint) {
     // TODO: try clipping large paths to viewport
     PathRenderer::convexPathVertices(path, paint, mSnapshot->transform, vertexBuffer);
 
+    if (!vertexBuffer.getSize()) {
+        // no vertices to draw
+        return;
+    }
+
     setupDraw();
     setupDrawNoTexture();
     if (isAA) setupDrawAA();

libs/hwui/PathRenderer.cpp

@@ -323,6 +323,11 @@ void PathRenderer::convexPathVertices(const SkPath &path, const SkPaint* paint,
     convexPathPerimeterVertices(path, threshInvScaleX * threshInvScaleX,
             threshInvScaleY * threshInvScaleY, tempVertices);
 
+    if (!tempVertices.size()) {
+        // path was empty, return without allocating vertex buffer
+        return;
+    }
+
 #if VERTEX_DEBUG
     for (unsigned int i = 0; i < tempVertices.size(); i++) {
         ALOGD("orig path: point at %f %f", tempVertices[i].position[0], tempVertices[i].position[1]);