commit 78dd96d5af20f489f0e8b288617d57774ec284f7
author Romain Guy <romainguy@google.com> Fri May 03 14:24:16 2013 -0700
committer Romain Guy <romainguy@google.com> Fri May 03 17:08:20 2013 -0700
tree 742b702647ae37e196021707fa45cbb8568353e1
parent 927bc7d72048ac90e3b95845699efb479b5589b4

Add an on-screen overdraw counter

The counter can be enabled by setting the system property called
debug.hwui.overdraw to the string "count". If the string is set
to "show", overdraw will be highlighted on screen instead of
printing out a simple counter.

Change-Id: I9a9c970d54bffab43138bbb7682f6c04bc2c40bd

libs/hwui/OpenGLRenderer.cpp

diff --git a/libs/hwui/OpenGLRenderer.cpp b/libs/hwui/OpenGLRenderer.cpp
index 025e9f8..1447eb7 100644
--- a/libs/hwui/OpenGLRenderer.cpp
+++ b/libs/hwui/OpenGLRenderer.cpp
@@ -21,7 +21,6 @@
 #include <sys/types.h>
 
 #include <SkCanvas.h>
-#include <SkPathMeasure.h>
 #include <SkTypeface.h>
 
 #include <utils/Log.h>
@@ -120,6 +119,7 @@
 
     mFirstSnapshot = new Snapshot;
     mFrameStarted = false;
+    mCountOverdraw = false;
 
     mScissorOptimizationDisabled = false;
 }
@@ -222,6 +222,7 @@
 
 status_t OpenGLRenderer::prepareDirty(float left, float top,
         float right, float bottom, bool opaque) {
+
     setupFrameState(left, top, right, bottom, opaque);
 
     // Layer renderers will start the frame immediately
@@ -253,7 +254,7 @@
 }
 
 status_t OpenGLRenderer::clear(float left, float top, float right, float bottom, bool opaque) {
-    if (!opaque) {
+    if (!opaque || mCountOverdraw) {
         mCaches.enableScissor();
         mCaches.setScissor(left, mSnapshot->height - bottom, right - left, bottom - top);
         glClear(GL_COLOR_BUFFER_BIT);
@@ -335,6 +336,10 @@
 #endif
     }
 
+    if (mCountOverdraw) {
+        countOverdraw();
+    }
+
     mFrameStarted = false;
 }
 
@@ -524,6 +529,21 @@
     }
 }
 
+void OpenGLRenderer::countOverdraw() {
+    size_t count = mWidth * mHeight;
+    uint32_t* buffer = new uint32_t[count];
+    glReadPixels(0, 0, mWidth, mHeight, GL_RGBA, GL_UNSIGNED_BYTE, &buffer[0]);
+
+    size_t total = 0;
+    for (size_t i = 0; i < count; i++) {
+        total += buffer[i] & 0xff;
+    }
+
+    mOverdraw = total / float(count);
+
+    delete[] buffer;
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 // Layers
 ///////////////////////////////////////////////////////////////////////////////
@@ -1656,6 +1676,8 @@
     mDescription.hasDebugHighlight = !mCaches.debugOverdraw &&
             mCaches.debugStencilClip == Caches::kStencilShowHighlight &&
             mCaches.stencil.isTestEnabled();
+
+    mDescription.emulateStencil = mCountOverdraw;
 }
 
 void OpenGLRenderer::setupDrawWithTexture(bool isAlpha8) {
@@ -3546,6 +3568,19 @@
 
 void OpenGLRenderer::chooseBlending(bool blend, SkXfermode::Mode mode,
         ProgramDescription& description, bool swapSrcDst) {
+    if (mCountOverdraw) {
+        if (!mCaches.blend) glEnable(GL_BLEND);
+        if (mCaches.lastSrcMode != GL_ONE || mCaches.lastDstMode != GL_ONE) {
+            glBlendFunc(GL_ONE, GL_ONE);
+        }
+
+        mCaches.blend = true;
+        mCaches.lastSrcMode = GL_ONE;
+        mCaches.lastDstMode = GL_ONE;
+
+        return;
+    }
+
     blend = blend || mode != SkXfermode::kSrcOver_Mode;
 
     if (blend) {