diff --git a/include/gui/SurfaceTexture.h b/include/gui/SurfaceTexture.h
index ff92e08..cbc15d8 100644
--- a/include/gui/SurfaceTexture.h
+++ b/include/gui/SurfaceTexture.h
@@ -113,8 +113,11 @@
     int mBufferCount;
 
     // mCurrentTexture is the buffer slot index of the buffer that is currently
-    // bound to the OpenGL texture. A value of INVALID_BUFFER_SLOT, indicating
-    // that no buffer is currently bound to the texture.
+    // bound to the OpenGL texture. It is initialized to INVALID_BUFFER_SLOT,
+    // indicating that no buffer slot is currently bound to the texture. Note,
+    // however, that a value of INVALID_BUFFER_SLOT does not necessarily mean
+    // that no buffer is bound to the texture. A call to setBufferCount will
+    // reset mCurrentTexture to INVALID_BUFFER_SLOT.
     int mCurrentTexture;
 
     // mLastQueued is the buffer slot index of the most recently enqueued buffer.
diff --git a/libs/gui/SurfaceTexture.cpp b/libs/gui/SurfaceTexture.cpp
index 9579996..11a48d9 100644
--- a/libs/gui/SurfaceTexture.cpp
+++ b/libs/gui/SurfaceTexture.cpp
@@ -15,6 +15,7 @@
  */
 
 #define LOG_TAG "SurfaceTexture"
+//#define LOG_NDEBUG 0
 
 #define GL_GLEXT_PROTOTYPES
 #define EGL_EGLEXT_PROTOTYPES
@@ -36,21 +37,32 @@
 SurfaceTexture::SurfaceTexture(GLuint tex) :
     mBufferCount(MIN_BUFFER_SLOTS), mCurrentTexture(INVALID_BUFFER_SLOT),
     mLastQueued(INVALID_BUFFER_SLOT), mTexName(tex) {
+    LOGV("SurfaceTexture::SurfaceTexture");
+    for (int i = 0; i < NUM_BUFFER_SLOTS; i++) {
+        mSlots[i].mEglImage = EGL_NO_IMAGE_KHR;
+        mSlots[i].mEglDisplay = EGL_NO_DISPLAY;
+        mSlots[i].mOwnedByClient = false;
+    }
 }
 
 SurfaceTexture::~SurfaceTexture() {
+    LOGV("SurfaceTexture::~SurfaceTexture");
     freeAllBuffers();
 }
 
 status_t SurfaceTexture::setBufferCount(int bufferCount) {
+    LOGV("SurfaceTexture::setBufferCount");
     Mutex::Autolock lock(mMutex);
     freeAllBuffers();
     mBufferCount = bufferCount;
+    mCurrentTexture = INVALID_BUFFER_SLOT;
+    mLastQueued = INVALID_BUFFER_SLOT;
     return OK;
 }
 
 sp<GraphicBuffer> SurfaceTexture::requestBuffer(int buf,
         uint32_t w, uint32_t h, uint32_t format, uint32_t usage) {
+    LOGV("SurfaceTexture::requestBuffer");
     Mutex::Autolock lock(mMutex);
     if (buf < 0 || mBufferCount <= buf) {
         LOGE("requestBuffer: slot index out of range [0, %d]: %d",
@@ -75,6 +87,7 @@
 }
 
 status_t SurfaceTexture::dequeueBuffer(int *buf) {
+    LOGV("SurfaceTexture::dequeueBuffer");
     Mutex::Autolock lock(mMutex);
     int found = INVALID_BUFFER_SLOT;
     for (int i = 0; i < mBufferCount; i++) {
@@ -92,6 +105,7 @@
 }
 
 status_t SurfaceTexture::queueBuffer(int buf) {
+    LOGV("SurfaceTexture::queueBuffer");
     Mutex::Autolock lock(mMutex);
     if (buf < 0 || mBufferCount <= buf) {
         LOGE("queueBuffer: slot index out of range [0, %d]: %d",
@@ -111,6 +125,7 @@
 }
 
 void SurfaceTexture::cancelBuffer(int buf) {
+    LOGV("SurfaceTexture::cancelBuffer");
     Mutex::Autolock lock(mMutex);
     if (buf < 0 || mBufferCount <= buf) {
         LOGE("cancelBuffer: slot index out of range [0, %d]: %d", mBufferCount,
@@ -124,18 +139,21 @@
 }
 
 status_t SurfaceTexture::setCrop(const Rect& reg) {
+    LOGV("SurfaceTexture::setCrop");
     Mutex::Autolock lock(mMutex);
     // XXX: How should we handle crops?
     return OK;
 }
 
 status_t SurfaceTexture::setTransform(uint32_t transform) {
+    LOGV("SurfaceTexture::setTransform");
     Mutex::Autolock lock(mMutex);
     // XXX: How should we handle transforms?
     return OK;
 }
 
 status_t SurfaceTexture::updateTexImage() {
+    LOGV("SurfaceTexture::updateTexImage");
     Mutex::Autolock lock(mMutex);
 
     // We always bind the texture even if we don't update its contents.
diff --git a/opengl/tests/hwc/hwcCommit.cpp b/opengl/tests/hwc/hwcCommit.cpp
index ed74cbe..66ccdae 100644
--- a/opengl/tests/hwc/hwcCommit.cpp
+++ b/opengl/tests/hwc/hwcCommit.cpp
@@ -76,6 +76,7 @@
 #include <cmath>
 #include <cstdlib>
 #include <ctime>
+#include <iomanip>
 #include <istream>
 #include <libgen.h>
 #include <list>
@@ -125,6 +126,7 @@
 const struct hwc_rect defaultDisplayFrame = {0, 0, 100, 100};
 
 // Global Constants
+const uint32_t printFieldWidth = 2;
 const struct searchLimits {
     uint32_t   numOverlays;
     HwcTestDim sourceCrop;
@@ -233,6 +235,8 @@
 static EGLDisplay dpy;
 static EGLSurface surface;
 static EGLint width, height;
+static size_t maxHeadingLen;
+static vector<string> formats;
 
 // Measurements
 struct meas {
@@ -264,6 +268,9 @@
         HwcTestDim vScaleBestDf;
         HwcTestDim vScaleBestSc;
     } sc;
+    vector<uint32_t> overlapBlendNone;
+    vector<uint32_t> overlapBlendPremult;
+    vector<uint32_t> overlapBlendCoverage;
 };
 vector<meas> measurements;
 
@@ -292,9 +299,14 @@
                   const HwcTestDim& dfMin, const HwcTestDim& dfMax,
                   const HwcTestDim& scMin, const HwcTestDim& scMax,
                   HwcTestDim& outBestDf, HwcTestDim& outBestSc);
+uint32_t numOverlapping(uint32_t backgroundFormat, uint32_t foregroundFormat,
+                        uint32_t backgroundBlend, uint32_t foregroundBlend);
 string transformList2str(const list<uint32_t>& transformList);
 string blendList2str(const list<uint32_t>& blendList);
 void init(void);
+void printFormatHeadings(size_t indent);
+void printOverlapLine(size_t indent, const string formatStr,
+                      const vector<uint32_t>& results);
 void printSyntax(const char *cmd);
 
 // Command-line option settings
@@ -332,7 +344,6 @@
     bool    error;
     string  str;
     char cmd[MAXCMD];
-    list<string> formats;
     list<Rectangle> rectList;
 
     testSetLogCatTag(LOG_TAG);
@@ -395,6 +406,13 @@
         }
     }
 
+    // Determine length of longest specified graphic format.
+    // This value is used for output formating
+    for (vector<string>::iterator it = formats.begin();
+         it != formats.end(); ++it) {
+         maxHeadingLen = max(maxHeadingLen, it->length());
+    }
+
     // Stop framework
     rv = snprintf(cmd, sizeof(cmd), "%s", CMD_STOP_FRAMEWORK);
     if (rv >= (signed) sizeof(cmd) - 1) {
@@ -411,7 +429,7 @@
     init();
 
     // For each of the graphic formats
-    for (list<string>::iterator itFormat = formats.begin();
+    for (vector<string>::iterator itFormat = formats.begin();
          itFormat != formats.end(); ++itFormat) {
 
         // Locate hwcTestLib structure that describes this format
@@ -539,8 +557,66 @@
         testPrintI("    VScale Best Source Crop: %s",
                    ((string) measPtr->sc.vScaleBestSc).c_str());
 
+        // Overlap two graphic formats and different blends
+        // Results displayed after all overlap measurments with
+        // current format in the foreground
+        // TODO: make measurments with background blend other than
+        //       none.  All of these measurements are done with a
+        //       background blend of HWC_BLENDING_NONE, with the
+        //       blend type of the foregound being varied.
+        uint32_t foregroundFormat = format->format;
+        for (vector<string>::iterator it = formats.begin();
+             it != formats.end(); ++it) {
+            uint32_t num;
+
+            const struct hwcTestGraphicFormat *backgroundFormatPtr
+                = hwcTestGraphicFormatLookup((*it).c_str());
+            uint32_t backgroundFormat = backgroundFormatPtr->format;
+
+            num = numOverlapping(backgroundFormat, foregroundFormat,
+                                 HWC_BLENDING_NONE, HWC_BLENDING_NONE);
+            measPtr->overlapBlendNone.push_back(num);
+
+            num = numOverlapping(backgroundFormat, foregroundFormat,
+                                 HWC_BLENDING_NONE, HWC_BLENDING_PREMULT);
+            measPtr->overlapBlendPremult.push_back(num);
+
+            num = numOverlapping(backgroundFormat, foregroundFormat,
+                                 HWC_BLENDING_NONE, HWC_BLENDING_COVERAGE);
+            measPtr->overlapBlendCoverage.push_back(num);
+        }
+
     }
 
+    // Display overlap results
+    size_t indent = 2;
+    testPrintI("overlapping blend: none");
+    printFormatHeadings(indent);
+    for (vector<string>::iterator it = formats.begin();
+         it != formats.end(); ++it) {
+        printOverlapLine(indent, *it, measurements[it
+                         - formats.begin()].overlapBlendNone);
+    }
+    testPrintI("");
+
+    testPrintI("overlapping blend: premult");
+    printFormatHeadings(indent);
+    for (vector<string>::iterator it = formats.begin();
+         it != formats.end(); ++it) {
+        printOverlapLine(indent, *it, measurements[it
+                         - formats.begin()].overlapBlendPremult);
+    }
+    testPrintI("");
+
+    testPrintI("overlapping blend: coverage");
+    printFormatHeadings(indent);
+    for (vector<string>::iterator it = formats.begin();
+         it != formats.end(); ++it) {
+        printOverlapLine(indent, *it, measurements[it
+                         - formats.begin()].overlapBlendCoverage);
+    }
+    testPrintI("");
+
     // Start framework
     rv = snprintf(cmd, sizeof(cmd), "%s", CMD_START_FRAMEWORK);
     if (rv >= (signed) sizeof(cmd) - 1) {
@@ -1204,6 +1280,33 @@
     return best;
 }
 
+uint32_t numOverlapping(uint32_t backgroundFormat, uint32_t foregroundFormat,
+                        uint32_t backgroundBlend, uint32_t foregroundBlend)
+{
+    list<Rectangle> rectList;
+
+    Rectangle background(backgroundFormat, startDim, startDim);
+    background.blend = backgroundBlend;
+    rectList.push_back(background);
+
+    // TODO: Handle cases where startDim is so small that adding 5
+    //       causes frames not to overlap.
+    // TODO: Handle cases where startDim is so large that adding 5
+    //       cause a portion or all of the foreground displayFrame
+    //       to be off the display.
+    Rectangle foreground(foregroundFormat, startDim, startDim);
+    foreground.displayFrame.left += 5;
+    foreground.displayFrame.top += 5;
+    foreground.displayFrame.right += 5;
+    foreground.displayFrame.bottom += 5;
+    background.blend = foregroundBlend;
+    rectList.push_back(foreground);
+
+    uint32_t num = numOverlays(rectList);
+
+    return num;
+}
+
 Rectangle::Rectangle(uint32_t graphicFormat, HwcTestDim dfDim,
                      HwcTestDim sDim) :
     format(graphicFormat), transform(defaultTransform),
@@ -1405,6 +1508,45 @@
     hwcTestOpenHwc(&hwcDevice);
 }
 
+void printFormatHeadings(size_t indent)
+{
+    for (size_t row = 0; row <= maxHeadingLen; row++) {
+        ostringstream line;
+        for(vector<string>::iterator it = formats.begin();
+            it != formats.end(); ++it) {
+            if ((maxHeadingLen - row) <= it->length()) {
+                if (row != maxHeadingLen) {
+                    char ch = (*it)[it->length() - (maxHeadingLen - row)];
+                    line << ' ' << setw(printFieldWidth) << ch;
+                } else {
+                    line << ' ' << string(printFieldWidth, '-');
+                }
+            } else {
+               line << ' ' << setw(printFieldWidth) << "";
+            }
+        }
+        testPrintI("%*s%s", indent + maxHeadingLen, "",
+                   line.str().c_str());
+    }
+}
+
+void printOverlapLine(size_t indent, const string formatStr,
+                        const vector<uint32_t>& results)
+{
+    ostringstream line;
+
+    line << setw(indent + maxHeadingLen - formatStr.length()) << "";
+
+    line << formatStr;
+
+    for (vector<uint32_t>::const_iterator it = results.begin();
+         it != results.end(); ++it) {
+        line << ' ' << setw(printFieldWidth) << *it;
+    }
+
+    testPrintI("%s", line.str().c_str());
+}
+
 void printSyntax(const char *cmd)
 {
     testPrintE("  %s [options] [graphicFormat] ...",
diff --git a/opengl/tests/hwc/hwcTestLib.cpp b/opengl/tests/hwc/hwcTestLib.cpp
index a468a92..925405e 100644
--- a/opengl/tests/hwc/hwcTestLib.cpp
+++ b/opengl/tests/hwc/hwcTestLib.cpp
@@ -475,14 +475,14 @@
         testPrintI("      displayFrame: %s",
                    hwcTestRect2str(list->hwLayers[layer].displayFrame).c_str());
         testPrintI("      scaleFactor: [%f, %f]",
-                   (float) (list->hwLayers[layer].displayFrame.right
-                            - list->hwLayers[layer].displayFrame.left)
-                       / (float) (list->hwLayers[layer].sourceCrop.right
-                            - list->hwLayers[layer].sourceCrop.left),
-                   (float) (list->hwLayers[layer].displayFrame.bottom
-                            - list->hwLayers[layer].displayFrame.top)
-                       / (float) (list->hwLayers[layer].sourceCrop.bottom
-                            - list->hwLayers[layer].sourceCrop.top));
+                   (float) (list->hwLayers[layer].sourceCrop.right
+                            - list->hwLayers[layer].sourceCrop.left)
+                       / (float) (list->hwLayers[layer].displayFrame.right
+                            - list->hwLayers[layer].displayFrame.left),
+                   (float) (list->hwLayers[layer].sourceCrop.bottom
+                            - list->hwLayers[layer].sourceCrop.top)
+                       / (float) (list->hwLayers[layer].displayFrame.bottom
+                            - list->hwLayers[layer].displayFrame.top));
     }
 }
 
@@ -494,7 +494,11 @@
  */
 void hwcTestDisplayListPrepareModifiable(hwc_layer_list_t *list)
 {
+    uint32_t numOverlays = 0;
     for (unsigned int layer = 0; layer < list->numHwLayers; layer++) {
+        if (list->hwLayers[layer].compositionType == HWC_OVERLAY) {
+            numOverlays++;
+        }
         testPrintI("    layer %u compositionType: %#x%s%s", layer,
                    list->hwLayers[layer].compositionType,
                    (list->hwLayers[layer].compositionType == HWC_FRAMEBUFFER)
@@ -508,6 +512,7 @@
                    (list->hwLayers[layer].hints & HWC_HINT_CLEAR_FB)
                        ? " CLEAR_FB" : "");
     }
+    testPrintI("    numOverlays: %u", numOverlays);
 }
 
 /*