Add new property to debug non-rectangular clip operations

This change adds a new property called "debug.hwui.show_stencil_clip"
that accepts the following values:

- "highlight", colorizes in green any drawing command that's tested
  against a non-rectangular clip region
- "region", shows the non-rectangular clip region in blue every time
  it is used
- "hide", default value, nothing is shown

Change-Id: I83c8602310edc4aaeb8b905371cdd185b17d32b5

1 files changed, 14 insertions, 0 deletions

diff --git a/libs/hwui/OpenGLRenderer.cpp b/libs/hwui/OpenGLRenderer.cpp
index 1afeaf0a0444..34d1c983f87d 100644
--- a/libs/hwui/OpenGLRenderer.cpp
+++ b/libs/hwui/OpenGLRenderer.cpp
@@ -1368,6 +1368,12 @@ void OpenGLRenderer::setStencilFromClip() {
             drawRegionRects(*mSnapshot->clipRegion, 0xff000000, SkXfermode::kSrc_Mode, false);
 
             mCaches.stencil.enableTest();
+
+            // Draw the region used to generate the stencil if the appropriate debug
+            // mode is enabled
+            if (mCaches.debugStencilClip == Caches::kStencilShowRegion) {
+                drawRegionRects(*mSnapshot->clipRegion, 0x7f0000ff, SkXfermode::kSrcOver_Mode);
+            }
         } else {
             mCaches.stencil.disable();
         }
@@ -1515,12 +1521,20 @@ void OpenGLRenderer::setupDraw(bool clear) {
         }
         setStencilFromClip();
     }
+
     mDescription.reset();
+
     mSetShaderColor = false;
     mColorSet = false;
     mColorA = mColorR = mColorG = mColorB = 0.0f;
     mTextureUnit = 0;
     mTrackDirtyRegions = true;
+
+    // Enable debug highlight when what we're about to draw is tested against
+    // the stencil buffer and if stencil highlight debugging is on
+    mDescription.hasDebugHighlight = !mCaches.debugOverdraw &&
+            mCaches.debugStencilClip == Caches::kStencilShowHighlight &&
+            mCaches.stencil.isTestEnabled();
 }
 
 void OpenGLRenderer::setupDrawWithTexture(bool isAlpha8) {