Fix rounded corner scission clipping

In cases where the corner radius is too big, the middle section that's
rendered without blending might have negative size, causing drawing
artifacts.

Test: manual, by slowing down app launch animation
Fixes: 141612402
Change-Id: I901e6b77791207360d06dea30496b7cbb65041c4

1 files changed, 8 insertions, 5 deletions

diff --git a/libs/renderengine/gl/GLESRenderEngine.cpp b/libs/renderengine/gl/GLESRenderEngine.cpp
index dd4c55d8a7..f39f0663ac 100644
--- a/libs/renderengine/gl/GLESRenderEngine.cpp
+++ b/libs/renderengine/gl/GLESRenderEngine.cpp
@@ -827,11 +827,14 @@ void GLESRenderEngine::handleRoundedCorners(const DisplaySettings& display,
     drawMesh(mesh);
 
     // The middle part of the layer can turn off blending.
-    const Rect middleRect(bounds.left, bounds.top + radius, bounds.right, bounds.bottom - radius);
-    setScissor(middleRect);
-    mState.cornerRadius = 0.0;
-    disableBlending();
-    drawMesh(mesh);
+    if (topRect.bottom < bottomRect.top) {
+        const Rect middleRect(bounds.left, bounds.top + radius, bounds.right,
+                              bounds.bottom - radius);
+        setScissor(middleRect);
+        mState.cornerRadius = 0.0;
+        disableBlending();
+        drawMesh(mesh);
+    }
     disableScissor();
 }