diff --git a/libs/hwui/OpenGLRenderer.cpp b/libs/hwui/OpenGLRenderer.cpp
index 5edaa46..9f337ff0 100644
--- a/libs/hwui/OpenGLRenderer.cpp
+++ b/libs/hwui/OpenGLRenderer.cpp
@@ -237,33 +237,43 @@
     glBlendEquation(GL_FUNC_ADD);
 }
 
+void OpenGLRenderer::detachFunctor(Functor* functor) {
+    mFunctors.remove(functor);
+}
+
+void OpenGLRenderer::attachFunctor(Functor* functor) {
+    mFunctors.add(functor);
+}
+
 status_t OpenGLRenderer::invokeFunctors(Rect& dirty) {
     status_t result = DrawGlInfo::kStatusDone;
-
-    Vector<Functor*> functors(mFunctors);
-    mFunctors.clear();
-
-    DrawGlInfo info;
-    info.clipLeft = 0;
-    info.clipTop = 0;
-    info.clipRight = 0;
-    info.clipBottom = 0;
-    info.isLayer = false;
-    info.width = 0;
-    info.height = 0;
-    memset(info.transform, 0, sizeof(float) * 16);
-
     size_t count = functors.size();
-    for (size_t i = 0; i < count; i++) {
-        Functor* f = functors.itemAt(i);
-        result |= (*f)(DrawGlInfo::kModeProcess, &info);
 
-        if (result != DrawGlInfo::kStatusDone) {
-            Rect localDirty(info.dirtyLeft, info.dirtyTop, info.dirtyRight, info.dirtyBottom);
-            dirty.unionWith(localDirty);
+    if (count > 0) {
+        SortedVector<Functor*> functors(mFunctors);
+        mFunctors.clear();
 
-            if (result & DrawGlInfo::kStatusInvoke) {
-                mFunctors.push(f);
+        DrawGlInfo info;
+        info.clipLeft = 0;
+        info.clipTop = 0;
+        info.clipRight = 0;
+        info.clipBottom = 0;
+        info.isLayer = false;
+        info.width = 0;
+        info.height = 0;
+        memset(info.transform, 0, sizeof(float) * 16);
+
+        for (size_t i = 0; i < count; i++) {
+            Functor* f = functors.itemAt(i);
+            result |= (*f)(DrawGlInfo::kModeProcess, &info);
+
+            if (result != DrawGlInfo::kStatusDone) {
+                Rect localDirty(info.dirtyLeft, info.dirtyTop, info.dirtyRight, info.dirtyBottom);
+                dirty.unionWith(localDirty);
+
+                if (result & DrawGlInfo::kStatusInvoke) {
+                    mFunctors.add(f);
+                }
             }
         }
     }
@@ -305,7 +315,7 @@
         dirty.unionWith(localDirty);
 
         if (result & DrawGlInfo::kStatusInvoke) {
-            mFunctors.push(functor);
+            mFunctors.add(functor);
         }
     }