diff --git a/libhwcomposer/hwc_copybit.cpp b/libhwcomposer/hwc_copybit.cpp
index f819264..6488173 100644
--- a/libhwcomposer/hwc_copybit.cpp
+++ b/libhwcomposer/hwc_copybit.cpp
@@ -2,8 +2,7 @@
  * Copyright (C) 2010 The Android Open Source Project
  * Copyright (C) 2012-2013, The Linux Foundation. All rights reserved.
  *
- * Not a Contribution, Apache license notifications and license are retained
- * for attribution purposes only.
+ * Not a Contribution.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -25,7 +24,9 @@
 #include "hwc_copybit.h"
 #include "comptype.h"
 #include "gr.h"
+#include "cb_utils.h"
 
+using namespace qdutils;
 namespace qhwc {
 
 struct range {
@@ -275,20 +276,18 @@
             close(mRelFd[0]);
             mRelFd[0] = -1;
         }
-
-        //Clear the visible region on the render buffer
-        //XXX: Do this only when needed.
-        hwc_rect_t clearRegion;
-        getNonWormholeRegion(list, clearRegion);
-        clear(renderBuffer, clearRegion);
     } else {
         if(mRelFd[0] >=0) {
             copybit_device_t *copybit = getCopyBitDevice();
             copybit->set_sync(copybit, mRelFd[0]);
         }
-        hwc_rect_t clearRegion = {0,0,0,0};
-        clear(renderBuffer, clearRegion);
     }
+
+    //Clear the transparent or left out region on the render buffer
+    hwc_rect_t clearRegion = {0,0,0,0};
+    if(CBUtils::getuiClearRegion(list, clearRegion, layerProp))
+        clear(renderBuffer, clearRegion);
+
     // numAppLayers-1, as we iterate from 0th layer index with HWC_COPYBIT flag
     for (int i = 0; i <= (ctx->listStats[dpy].numAppLayers-1); i++) {
         hwc_layer_1_t *layer = &list->hwLayers[i];
diff --git a/libqdutils/Android.mk b/libqdutils/Android.mk
index b6bbc47..d514405 100644
--- a/libqdutils/Android.mk
+++ b/libqdutils/Android.mk
@@ -4,13 +4,14 @@
 
 LOCAL_MODULE                  := libqdutils
 LOCAL_MODULE_TAGS             := optional
-LOCAL_SHARED_LIBRARIES        := $(common_libs)
+LOCAL_SHARED_LIBRARIES        := $(common_libs) libui
 LOCAL_C_INCLUDES              := $(common_includes) $(kernel_includes)
 LOCAL_CFLAGS                  := $(common_flags) -DLOG_TAG=\"qdutils\"
 LOCAL_ADDITIONAL_DEPENDENCIES := $(common_deps)
 LOCAL_SRC_FILES               := profiler.cpp mdp_version.cpp \
                                  idle_invalidator.cpp \
-                                 comptype.cpp qd_utils.cpp
+                                 comptype.cpp qd_utils.cpp \
+                                 cb_utils.cpp
 include $(BUILD_SHARED_LIBRARY)
 
 include $(CLEAR_VARS)
diff --git a/libqdutils/cb_utils.cpp b/libqdutils/cb_utils.cpp
new file mode 100644
index 0000000..bc7e5b1
--- /dev/null
+++ b/libqdutils/cb_utils.cpp
@@ -0,0 +1,79 @@
+/* Copyright (c) 2013, The Linux Foundation. All rights reserved.
+* Redistribution and use in source and binary forms, with or without
+* * modification, are permitted provided that the following conditions are
+* met:
+*   * Redistributions of source code must retain the above copyrigh
+*     notice, this list of conditions and the following disclaimer
+*   * Redistributions in binary form must reproduce the above
+*     copyright notice, this list of conditions and the following
+*     disclaimer in the documentation and/or other materials provided
+*     with the distribution.
+*   * Neither the name of The Linux Foundation nor the names of its
+*     contributors may be used to endorse or promote products derived
+*     from this software without specific prior written permission.
+*
+* THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESS OR IMPLIED
+* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT
+* ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS
+* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
+* BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+* * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
+* OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
+* IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+#include "cb_utils.h"
+
+/* get union of two rects into 3rd rect */
+void getUnion(hwc_rect_t& rect1,hwc_rect_t& rect2, hwc_rect_t& irect) {
+    irect.left   = min(rect1.left, rect2.left);
+    irect.top    = min(rect1.top, rect2.top);
+    irect.right  = max(rect1.right, rect2.right);
+    irect.bottom = max(rect1.bottom, rect2.bottom);
+}
+
+using namespace android;
+using namespace qhwc;
+namespace qdutils {
+
+int CBUtils::getuiClearRegion(hwc_display_contents_1_t* list,
+          hwc_rect_t &clearWormholeRect, LayerProp *layerProp) {
+
+    uint32_t last = list->numHwLayers - 1;
+    hwc_rect_t fbFrame = list->hwLayers[last].displayFrame;
+
+    Rect fbFrameRect(fbFrame.left,fbFrame.top,fbFrame.right,fbFrame.bottom);
+    Region wormholeRegion(fbFrameRect);
+
+    for (uint32_t i = 0 ; i < last; i++) {
+        // need to take care only in per pixel blending.
+        // Restrict calculation only for copybit layers.
+        if((list->hwLayers[i].blending != HWC_BLENDING_NONE) ||
+           !(layerProp[i].mFlags & HWC_COPYBIT))
+            continue ;
+        hwc_rect_t displayFrame = list->hwLayers[i].displayFrame;
+        Rect tmpRect(displayFrame.left,displayFrame.top,displayFrame.right,
+        displayFrame.bottom);
+        Region tmpRegion(tmpRect);
+        wormholeRegion.subtractSelf(wormholeRegion.intersect(tmpRegion));
+    }
+    if (wormholeRegion.isEmpty()) {
+        return 0;
+    }
+    //TO DO :- 1. remove union and call clear for each rect.
+    //      :- 2. support swap ract feature.
+    Region::const_iterator it = wormholeRegion.begin();
+    Region::const_iterator const end = wormholeRegion.end();
+    while (it != end) {
+        const Rect& r = *it++;
+        hwc_rect_t tmpWormRect = {r.left,r.top,r.right,r.bottom};
+        getUnion(clearWormholeRect, tmpWormRect, clearWormholeRect);
+
+    }
+    return 1;
+}
+
+}//namespace qdutils
diff --git a/libqdutils/cb_utils.h b/libqdutils/cb_utils.h
new file mode 100644
index 0000000..85dd78f
--- /dev/null
+++ b/libqdutils/cb_utils.h
@@ -0,0 +1,45 @@
+/* Copyright (c) 2013, The Linux Foundation. All rights reserved.
+* Redistribution and use in source and binary forms, with or without
+* * modification, are permitted provided that the following conditions are
+* met:
+*   * Redistributions of source code must retain the above copyrigh
+*     notice, this list of conditions and the following disclaimer
+*   * Redistributions in binary form must reproduce the above
+*     copyright notice, this list of conditions and the following
+*     disclaimer in the documentation and/or other materials provided
+*     with the distribution.
+*   * Neither the name of The Linux Foundation nor the names of its
+*     contributors may be used to endorse or promote products derived
+*     from this software without specific prior written permission.
+*
+* THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESS OR IMPLIED
+* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT
+* ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS
+* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
+* BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+* * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
+* OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
+* IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+
+#ifndef CB_UTIL_H
+#define CB_UTIL_H
+
+#include <ui/Region.h>
+#include "hwc_utils.h"
+
+using namespace qhwc;
+namespace qdutils {
+class CBUtils {
+public:
+static int getuiClearRegion(hwc_display_contents_1_t* list,
+                              hwc_rect_t &clearWormholeRec,
+                                      LayerProp *layerProp);
+};
+}//namespace qdutils
+#endif /* end of include guard: CB_UTIL_H*/
+