diff --git a/libs/hwui/Android.mk b/libs/hwui/Android.mk
index 7b59bf2..a630ea1 100644
--- a/libs/hwui/Android.mk
+++ b/libs/hwui/Android.mk
@@ -30,6 +30,7 @@
 		PatchCache.cpp \
 		PathCache.cpp \
 		PathTessellator.cpp \
+		PixelBuffer.cpp \
 		Program.cpp \
 		ProgramCache.cpp \
 		RenderBufferCache.cpp \
diff --git a/libs/hwui/Caches.cpp b/libs/hwui/Caches.cpp
index 57d1a4f..a381a68 100644
--- a/libs/hwui/Caches.cpp
+++ b/libs/hwui/Caches.cpp
@@ -70,6 +70,7 @@
     mCurrentPositionPointer = this;
     mCurrentPositionStride = 0;
     mCurrentTexCoordsPointer = this;
+    mCurrentPixelBuffer = 0;
 
     mTexCoordsArrayEnabled = false;
 
@@ -366,6 +367,28 @@
 }
 
 ///////////////////////////////////////////////////////////////////////////////
+// PBO
+///////////////////////////////////////////////////////////////////////////////
+
+bool Caches::bindPixelBuffer(const GLuint buffer) {
+    if (mCurrentPixelBuffer != buffer) {
+        glBindBuffer(GL_PIXEL_UNPACK_BUFFER, buffer);
+        mCurrentPixelBuffer = buffer;
+        return true;
+    }
+    return false;
+}
+
+bool Caches::unbindPixelBuffer() {
+    if (mCurrentPixelBuffer) {
+        glBindBuffer(GL_PIXEL_UNPACK_BUFFER, 0);
+        mCurrentPixelBuffer = 0;
+        return true;
+    }
+    return false;
+}
+
+///////////////////////////////////////////////////////////////////////////////
 // Meshes and textures
 ///////////////////////////////////////////////////////////////////////////////
 
diff --git a/libs/hwui/Caches.h b/libs/hwui/Caches.h
index 63836c1..91b938b 100644
--- a/libs/hwui/Caches.h
+++ b/libs/hwui/Caches.h
@@ -176,6 +176,16 @@
     bool unbindIndicesBuffer();
 
     /**
+     * Binds the specified buffer as the current GL unpack pixel buffer.
+     */
+    bool bindPixelBuffer(const GLuint buffer);
+
+    /**
+     * Resets the current unpack pixel buffer to 0 (default value.)
+     */
+    bool unbindPixelBuffer();
+
+    /**
      * Binds an attrib to the specified float vertex pointer.
      * Assumes a stride of gMeshStride and a size of 2.
      */
@@ -307,6 +317,7 @@
 
     GLuint mCurrentBuffer;
     GLuint mCurrentIndicesBuffer;
+    GLuint mCurrentPixelBuffer;
     void* mCurrentPositionPointer;
     GLsizei mCurrentPositionStride;
     void* mCurrentTexCoordsPointer;
diff --git a/libs/hwui/DeferredDisplayList.cpp b/libs/hwui/DeferredDisplayList.cpp
index fe51bf9..d5007e1 100644
--- a/libs/hwui/DeferredDisplayList.cpp
+++ b/libs/hwui/DeferredDisplayList.cpp
@@ -21,6 +21,7 @@
 
 #include <utils/Trace.h>
 
+#include "Caches.h"
 #include "Debug.h"
 #include "DisplayListOp.h"
 #include "OpenGLRenderer.h"
@@ -377,6 +378,8 @@
 
 status_t DeferredDisplayList::flush(OpenGLRenderer& renderer, Rect& dirty) {
     ATRACE_NAME("flush drawing commands");
+    Caches::getInstance().fontRenderer->endPrecaching();
+
     status_t status = DrawGlInfo::kStatusDone;
 
     if (isEmpty()) return status; // nothing to flush
diff --git a/libs/hwui/FontRenderer.cpp b/libs/hwui/FontRenderer.cpp
index 44dc731..6894ef9 100644
--- a/libs/hwui/FontRenderer.cpp
+++ b/libs/hwui/FontRenderer.cpp
@@ -33,6 +33,7 @@
 #include "Debug.h"
 #include "Extensions.h"
 #include "FontRenderer.h"
+#include "PixelBuffer.h"
 #include "Rect.h"
 
 namespace android {
@@ -133,26 +134,13 @@
     for (uint32_t i = 0; i < mCacheTextures.size(); i++) {
         mCacheTextures[i]->init();
     }
-
-#if DEBUG_FONT_RENDERER
-    uint16_t totalGlyphs = 0;
-    for (uint32_t i = 0; i < mCacheTextures.size(); i++) {
-        totalGlyphs += mCacheTextures[i]->getGlyphCount();
-        // Erase caches, just as a debugging facility
-        if (mCacheTextures[i]->getTexture()) {
-            memset(mCacheTextures[i]->getTexture(), 0,
-                    mCacheTextures[i]->getWidth() * mCacheTextures[i]->getHeight());
-        }
-    }
-    ALOGD("Flushing caches: glyphs cached = %d", totalGlyphs);
-#endif
 }
 
 void FontRenderer::flushLargeCaches() {
     // Start from 1; don't deallocate smallest/default texture
     for (uint32_t i = 1; i < mCacheTextures.size(); i++) {
         CacheTexture* cacheTexture = mCacheTextures[i];
-        if (cacheTexture->getTexture()) {
+        if (cacheTexture->getPixelBuffer()) {
             cacheTexture->init();
             LruCache<Font::FontDescription, Font*>::Iterator it(mActiveFonts);
             while (it.next()) {
@@ -226,7 +214,7 @@
 
     uint32_t cacheWidth = cacheTexture->getWidth();
 
-    if (!cacheTexture->getTexture()) {
+    if (!cacheTexture->getPixelBuffer()) {
         Caches::getInstance().activeTexture(0);
         // Large-glyph texture memory is allocated only as needed
         cacheTexture->allocateTexture();
@@ -239,7 +227,7 @@
     // or anti-aliased (8 bits per pixel)
     SkMask::Format format = static_cast<SkMask::Format>(glyph.fMaskFormat);
 
-    uint8_t* cacheBuffer = cacheTexture->getTexture();
+    uint8_t* cacheBuffer = cacheTexture->getPixelBuffer()->map();
     uint32_t cacheX = 0, bX = 0, cacheY = 0, bY = 0;
 
     // Copy the glyph image, taking the mask format into account
@@ -377,56 +365,36 @@
     Caches& caches = Caches::getInstance();
     GLuint lastTextureId = 0;
 
-    // OpenGL ES 3.0+ lets us specify the row length for unpack operations such
-    // as glTexSubImage2D(). This allows us to upload a sub-rectangle of a texture.
-    // With OpenGL ES 2.0 we have to upload entire stripes instead.
-    const bool hasUnpackRowLength = Extensions::getInstance().getMajorGlVersion() >= 3;
+    bool resetPixelStore = false;
     glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
 
     // Iterate over all the cache textures and see which ones need to be updated
     for (uint32_t i = 0; i < mCacheTextures.size(); i++) {
         CacheTexture* cacheTexture = mCacheTextures[i];
-        if (cacheTexture->isDirty() && cacheTexture->getTexture()) {
-            const Rect* dirtyRect = cacheTexture->getDirtyRect();
-            uint32_t x = hasUnpackRowLength ? dirtyRect->left : 0;
-            uint32_t y = dirtyRect->top;
-            uint32_t width = cacheTexture->getWidth();
-            uint32_t height = dirtyRect->getHeight();
-            void* textureData = cacheTexture->getTexture() + y * width + x;
-
+        if (cacheTexture->isDirty() && cacheTexture->getPixelBuffer()) {
             if (cacheTexture->getTextureId() != lastTextureId) {
                 lastTextureId = cacheTexture->getTextureId();
                 caches.activeTexture(0);
                 glBindTexture(GL_TEXTURE_2D, lastTextureId);
-
-                // The unpack row length only needs to be specified when a new
-                // texture is bound
-                if (hasUnpackRowLength) {
-                    glPixelStorei(GL_UNPACK_ROW_LENGTH, width);
-                }
             }
 
-            // If we can upload a sub-rectangle, use the dirty rect width
-            // instead of the width of the entire texture
-            if (hasUnpackRowLength) {
-                width = dirtyRect->getWidth();
+            if (cacheTexture->upload()) {
+                resetPixelStore = true;
             }
 
 #if DEBUG_FONT_RENDERER
             ALOGD("glTexSubimage for cacheTexture %d: x, y, width height = %d, %d, %d, %d",
                     i, x, y, width, height);
 #endif
-
-            glTexSubImage2D(GL_TEXTURE_2D, 0, x, y, width, height,
-                    GL_ALPHA, GL_UNSIGNED_BYTE, textureData);
-
-            cacheTexture->setDirty(false);
         }
     }
 
+    // Unbind any PBO we might have used to update textures
+    caches.unbindPixelBuffer();
+
     // Reset to default unpack row length to avoid affecting texture
     // uploads in other parts of the renderer
-    if (hasUnpackRowLength) {
+    if (resetPixelStore) {
         glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
     }
 
@@ -539,13 +507,14 @@
         uint32_t startIndex, uint32_t len, int numGlyphs, uint32_t radius, const float* positions) {
     checkInit();
 
+    DropShadow image;
+    image.width = 0;
+    image.height = 0;
+    image.image = NULL;
+    image.penX = 0;
+    image.penY = 0;
+
     if (!mCurrentFont) {
-        DropShadow image;
-        image.width = 0;
-        image.height = 0;
-        image.image = NULL;
-        image.penX = 0;
-        image.penY = 0;
         return image;
     }
 
@@ -559,6 +528,11 @@
     uint32_t paddedWidth = (uint32_t) (bounds.right - bounds.left) + 2 * radius;
     uint32_t paddedHeight = (uint32_t) (bounds.top - bounds.bottom) + 2 * radius;
 
+    uint32_t maxSize = Caches::getInstance().maxTextureSize;
+    if (paddedWidth > maxSize || paddedHeight > maxSize) {
+        return image;
+    }
+
     // Align buffers for renderscript usage
     if (paddedWidth & (RS_CPU_ALLOCATION_ALIGNMENT - 1)) {
         paddedWidth += RS_CPU_ALLOCATION_ALIGNMENT - paddedWidth % RS_CPU_ALLOCATION_ALIGNMENT;
@@ -578,10 +552,12 @@
         mCurrentFont->render(paint, text, startIndex, len, numGlyphs, penX, penY,
                 Font::BITMAP, dataBuffer, paddedWidth, paddedHeight, NULL, positions);
 
+        // Unbind any PBO we might have used
+        Caches::getInstance().unbindPixelBuffer();
+
         blurImage(&dataBuffer, paddedWidth, paddedHeight, radius);
     }
 
-    DropShadow image;
     image.width = paddedWidth;
     image.height = paddedHeight;
     image.image = dataBuffer;
@@ -612,6 +588,10 @@
     font->precache(paint, text, numGlyphs);
 }
 
+void FontRenderer::endPrecaching() {
+    checkTextureUpdate();
+}
+
 bool FontRenderer::renderPosText(SkPaint* paint, const Rect* clip, const char *text,
         uint32_t startIndex, uint32_t len, int numGlyphs, int x, int y,
         const float* positions, Rect* bounds, Functor* functor) {
@@ -690,5 +670,16 @@
     *image = outImage;
 }
 
+uint32_t FontRenderer::getCacheSize() const {
+    uint32_t size = 0;
+    for (uint32_t i = 0; i < mCacheTextures.size(); i++) {
+        CacheTexture* cacheTexture = mCacheTextures[i];
+        if (cacheTexture && cacheTexture->getPixelBuffer()) {
+            size += cacheTexture->getPixelBuffer()->getSize();
+        }
+    }
+    return size;
+}
+
 }; // namespace uirenderer
 }; // namespace android
diff --git a/libs/hwui/FontRenderer.h b/libs/hwui/FontRenderer.h
index 1da3b6c..348b7e3 100644
--- a/libs/hwui/FontRenderer.h
+++ b/libs/hwui/FontRenderer.h
@@ -61,6 +61,7 @@
     void setFont(SkPaint* paint, const mat4& matrix);
 
     void precache(SkPaint* paint, const char* text, int numGlyphs, const mat4& matrix);
+    void endPrecaching();
 
     // bounds is an out parameter
     bool renderPosText(SkPaint* paint, const Rect* clip, const char *text, uint32_t startIndex,
@@ -95,16 +96,7 @@
         mLinearFiltering = linearFiltering;
     }
 
-    uint32_t getCacheSize() const {
-        uint32_t size = 0;
-        for (uint32_t i = 0; i < mCacheTextures.size(); i++) {
-            CacheTexture* cacheTexture = mCacheTextures[i];
-            if (cacheTexture && cacheTexture->getTexture()) {
-                size += cacheTexture->getWidth() * cacheTexture->getHeight();
-            }
-        }
-        return size;
-    }
+    uint32_t getCacheSize() const;
 
 private:
     friend class Font;
diff --git a/libs/hwui/GammaFontRenderer.cpp b/libs/hwui/GammaFontRenderer.cpp
index bd0a4b3..06d2aad 100644
--- a/libs/hwui/GammaFontRenderer.cpp
+++ b/libs/hwui/GammaFontRenderer.cpp
@@ -129,6 +129,12 @@
     }
 }
 
+void ShaderGammaFontRenderer::endPrecaching() {
+    if (mRenderer) {
+        mRenderer->endPrecaching();
+    }
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 // Lookup-based renderer
 ///////////////////////////////////////////////////////////////////////////////
@@ -146,6 +152,12 @@
     mRenderer = NULL;
 }
 
+void LookupGammaFontRenderer::endPrecaching() {
+    if (mRenderer) {
+        mRenderer->endPrecaching();
+    }
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 // Lookup-based renderer, using 3 different correction tables
 ///////////////////////////////////////////////////////////////////////////////
@@ -177,6 +189,14 @@
     }
 }
 
+void Lookup3GammaFontRenderer::endPrecaching() {
+    for (int i = 0; i < kGammaCount; i++) {
+        if (mRenderers[i]) {
+            mRenderers[i]->endPrecaching();
+        }
+    }
+}
+
 void Lookup3GammaFontRenderer::clear() {
     for (int i = 0; i < kGammaCount; i++) {
         delete mRenderers[i];
diff --git a/libs/hwui/GammaFontRenderer.h b/libs/hwui/GammaFontRenderer.h
index 5c1860e..bbfa66d 100644
--- a/libs/hwui/GammaFontRenderer.h
+++ b/libs/hwui/GammaFontRenderer.h
@@ -40,6 +40,8 @@
     virtual void describe(ProgramDescription& description, const SkPaint* paint) const = 0;
     virtual void setupProgram(ProgramDescription& description, Program* program) const = 0;
 
+    virtual void endPrecaching() = 0;
+
     static GammaFontRenderer* createRenderer();
 
 protected:
@@ -86,6 +88,8 @@
     void describe(ProgramDescription& description, const SkPaint* paint) const;
     void setupProgram(ProgramDescription& description, Program* program) const;
 
+    void endPrecaching();
+
 private:
     ShaderGammaFontRenderer(bool multiGamma);
 
@@ -134,6 +138,8 @@
     void setupProgram(ProgramDescription& description, Program* program) const {
     }
 
+    void endPrecaching();
+
 private:
     LookupGammaFontRenderer();
 
@@ -171,6 +177,8 @@
     void setupProgram(ProgramDescription& description, Program* program) const {
     }
 
+    void endPrecaching();
+
 private:
     Lookup3GammaFontRenderer();
 
diff --git a/libs/hwui/OpenGLRenderer.cpp b/libs/hwui/OpenGLRenderer.cpp
index e18d922..dcd1eb8 100644
--- a/libs/hwui/OpenGLRenderer.cpp
+++ b/libs/hwui/OpenGLRenderer.cpp
@@ -2644,6 +2644,9 @@
     mCaches.dropShadowCache.setFontRenderer(fontRenderer);
     const ShadowTexture* shadow = mCaches.dropShadowCache.get(
             paint, text, bytesCount, count, mDrawModifiers.mShadowRadius, positions);
+    // If the drop shadow exceeds the max texture size or couldn't be
+    // allocated, skip drawing
+    if (!shadow) return;
     const AutoTexture autoCleanup(shadow);
 
     const float sx = x - shadow->left + mDrawModifiers.mShadowDx;
diff --git a/libs/hwui/PixelBuffer.cpp b/libs/hwui/PixelBuffer.cpp
new file mode 100644
index 0000000..8280370
--- /dev/null
+++ b/libs/hwui/PixelBuffer.cpp
@@ -0,0 +1,163 @@
+/*
+ * Copyright (C) 2013 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define LOG_TAG "OpenGLRenderer"
+
+#include <utils/Log.h>
+
+#include "Caches.h"
+#include "Extensions.h"
+#include "PixelBuffer.h"
+#include "Properties.h"
+
+namespace android {
+namespace uirenderer {
+
+///////////////////////////////////////////////////////////////////////////////
+// CPU pixel buffer
+///////////////////////////////////////////////////////////////////////////////
+
+class CpuPixelBuffer: public PixelBuffer {
+public:
+    CpuPixelBuffer(GLenum format, uint32_t width, uint32_t height);
+    ~CpuPixelBuffer();
+
+    uint8_t* map(AccessMode mode = kAccessMode_ReadWrite);
+    void unmap();
+
+    uint8_t* getMappedPointer() const;
+
+    void upload(uint32_t x, uint32_t y, uint32_t width, uint32_t height, int offset);
+
+private:
+    uint8_t* mBuffer;
+};
+
+CpuPixelBuffer::CpuPixelBuffer(GLenum format, uint32_t width, uint32_t height):
+        PixelBuffer(format, width, height) {
+    mBuffer = new uint8_t[width * height * formatSize(format)];
+}
+
+CpuPixelBuffer::~CpuPixelBuffer() {
+    delete[] mBuffer;
+}
+
+uint8_t* CpuPixelBuffer::map(AccessMode mode) {
+    if (mAccessMode == kAccessMode_None) {
+        mAccessMode = mode;
+    }
+    return mBuffer;
+}
+
+void CpuPixelBuffer::unmap() {
+    mAccessMode = kAccessMode_None;
+}
+
+uint8_t* CpuPixelBuffer::getMappedPointer() const {
+    return mAccessMode == kAccessMode_None ? NULL : mBuffer;
+}
+
+void CpuPixelBuffer::upload(uint32_t x, uint32_t y, uint32_t width, uint32_t height, int offset) {
+    glTexSubImage2D(GL_TEXTURE_2D, 0, x, y, width, height,
+            mFormat, GL_UNSIGNED_BYTE, mBuffer + offset);
+}
+
+///////////////////////////////////////////////////////////////////////////////
+// GPU pixel buffer
+///////////////////////////////////////////////////////////////////////////////
+
+class GpuPixelBuffer: public PixelBuffer {
+public:
+    GpuPixelBuffer(GLenum format, uint32_t width, uint32_t height);
+    ~GpuPixelBuffer();
+
+    uint8_t* map(AccessMode mode = kAccessMode_ReadWrite);
+    void unmap();
+
+    uint8_t* getMappedPointer() const;
+
+    void upload(uint32_t x, uint32_t y, uint32_t width, uint32_t height, int offset);
+
+private:
+    GLuint mBuffer;
+    uint8_t* mMappedPointer;
+    Caches& mCaches;
+};
+
+GpuPixelBuffer::GpuPixelBuffer(GLenum format, uint32_t width, uint32_t height):
+        PixelBuffer(format, width, height), mMappedPointer(0), mCaches(Caches::getInstance()) {
+    glGenBuffers(1, &mBuffer);
+    mCaches.bindPixelBuffer(mBuffer);
+    glBufferData(GL_PIXEL_UNPACK_BUFFER, getSize(), NULL, GL_DYNAMIC_DRAW);
+    mCaches.unbindPixelBuffer();
+}
+
+GpuPixelBuffer::~GpuPixelBuffer() {
+    glDeleteBuffers(1, &mBuffer);
+}
+
+uint8_t* GpuPixelBuffer::map(AccessMode mode) {
+    if (mAccessMode == kAccessMode_None) {
+        mCaches.bindPixelBuffer(mBuffer);
+        mMappedPointer = (uint8_t*) glMapBufferRange(GL_PIXEL_UNPACK_BUFFER, 0, getSize(), mode);
+        mAccessMode = mode;
+    }
+
+    return mMappedPointer;
+}
+
+void GpuPixelBuffer::unmap() {
+    if (mAccessMode != kAccessMode_None) {
+        if (mMappedPointer) {
+            mCaches.bindPixelBuffer(mBuffer);
+            glUnmapBuffer(GL_PIXEL_UNPACK_BUFFER);
+        }
+        mAccessMode = kAccessMode_None;
+        mMappedPointer = NULL;
+    }
+}
+
+uint8_t* GpuPixelBuffer::getMappedPointer() const {
+    return mMappedPointer;
+}
+
+void GpuPixelBuffer::upload(uint32_t x, uint32_t y, uint32_t width, uint32_t height, int offset) {
+    // If the buffer is not mapped, unmap() will not bind it
+    mCaches.bindPixelBuffer(mBuffer);
+    unmap();
+    glTexSubImage2D(GL_TEXTURE_2D, 0, x, y, width, height, mFormat,
+            GL_UNSIGNED_BYTE, (void*) offset);
+}
+
+///////////////////////////////////////////////////////////////////////////////
+// Factory
+///////////////////////////////////////////////////////////////////////////////
+
+PixelBuffer* PixelBuffer::create(GLenum format, uint32_t width, uint32_t height, BufferType type) {
+    bool gpuBuffer = type == kBufferType_Auto && Extensions::getInstance().getMajorGlVersion() >= 3;
+    if (gpuBuffer) {
+        char property[PROPERTY_VALUE_MAX];
+        if (property_get(PROPERTY_ENABLE_GPU_PIXEL_BUFFERS, property, "false") > 0) {
+            if (!strcmp(property, "true")) {
+                return new GpuPixelBuffer(format, width, height);
+            }
+        }
+    }
+    return new CpuPixelBuffer(format, width, height);
+}
+
+}; // namespace uirenderer
+}; // namespace android
diff --git a/libs/hwui/PixelBuffer.h b/libs/hwui/PixelBuffer.h
new file mode 100644
index 0000000..32d5417
--- /dev/null
+++ b/libs/hwui/PixelBuffer.h
@@ -0,0 +1,180 @@
+/*
+ * Copyright (C) 2013 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ANDROID_HWUI_PIXEL_BUFFER_H
+#define ANDROID_HWUI_PIXEL_BUFFER_H
+
+#include <GLES3/gl3.h>
+
+namespace android {
+namespace uirenderer {
+
+/**
+ * Represents a pixel buffer. A pixel buffer will be backed either by a
+ * PBO on OpenGL ES 3.0 and higher or by an array of uint8_t on other
+ * versions. If the buffer is backed by a PBO it will of type
+ * GL_PIXEL_UNPACK_BUFFER.
+ *
+ * To read from or write into a PixelBuffer you must first map the
+ * buffer using the map(AccessMode) method. This method returns a
+ * pointer to the beginning of the buffer.
+ *
+ * Before the buffer can be used by the GPU, for instance to upload
+ * a texture, you must first unmap the buffer. To do so, call the
+ * unmap() method.
+ *
+ * Mapping and unmapping a PixelBuffer can have the side effect of
+ * changing the currently active GL_PIXEL_UNPACK_BUFFER. It is
+ * therefore recommended to call Caches::unbindPixelbuffer() after
+ * using a PixelBuffer to upload to a texture.
+ */
+class PixelBuffer {
+public:
+    enum BufferType {
+        kBufferType_Auto,
+        kBufferType_CPU
+    };
+
+    enum AccessMode {
+        kAccessMode_None = 0,
+        kAccessMode_Read = GL_MAP_READ_BIT,
+        kAccessMode_Write = GL_MAP_WRITE_BIT,
+        kAccessMode_ReadWrite = GL_MAP_READ_BIT | GL_MAP_WRITE_BIT
+    };
+
+    /**
+     * Creates a new PixelBuffer object with the specified format and
+     * dimensions. The buffer is immediately allocated.
+     *
+     * The buffer type specifies how the buffer should be allocated.
+     * By default this method will automatically choose whether to allocate
+     * a CPU or GPU buffer.
+     */
+    static PixelBuffer* create(GLenum format, uint32_t width, uint32_t height,
+            BufferType type = kBufferType_Auto);
+
+    virtual ~PixelBuffer() {
+    }
+
+    /**
+     * Returns the format of this render buffer.
+     */
+    GLenum getFormat() const {
+        return mFormat;
+    }
+
+    /**
+     * Maps this before with the specified access mode. This method
+     * returns a pointer to the region of memory where the buffer was
+     * mapped.
+     *
+     * If the buffer is already mapped when this method is invoked,
+     * this method will return the previously mapped pointer. The
+     * access mode can only be changed by calling unmap() first.
+     *
+     * The specified access mode cannot be kAccessMode_None.
+     */
+    virtual uint8_t* map(AccessMode mode = kAccessMode_ReadWrite) = 0;
+
+    /**
+     * Unmaps this buffer, if needed. After the buffer is unmapped,
+     * the pointer previously returned by map() becomes invalid and
+     * should not be used. After calling this method, getMappedPointer()
+     * will always return NULL.
+     */
+    virtual void unmap() = 0;
+
+    /**
+     * Returns the current access mode for this buffer. If the buffer
+     * is not mapped, this method returns kAccessMode_None.
+     */
+    AccessMode getAccessMode() const {
+        return mAccessMode;
+    }
+
+    /**
+     * Returns the currently mapped pointer. Returns NULL if the buffer
+     * is not mapped.
+     */
+    virtual uint8_t* getMappedPointer() const = 0;
+
+    /**
+     * Upload the specified rectangle of this pixe buffer as a
+     * GL_TEXTURE_2D texture. Calling this method will trigger
+     * an unmap() if necessary.
+     */
+    virtual void upload(uint32_t x, uint32_t y, uint32_t width, uint32_t height, int offset) = 0;
+
+    /**
+     * Returns the width of the render buffer in pixels.
+     */
+    uint32_t getWidth() const {
+        return mWidth;
+    }
+
+    /**
+     * Returns the height of the render buffer in pixels.
+     */
+    uint32_t getHeight() const {
+        return mHeight;
+    }
+
+    /**
+     * Returns the size of this pixel buffer in bytes.
+     */
+    uint32_t getSize() const {
+        return mWidth * mHeight * formatSize(mFormat);
+    }
+
+    /**
+     * Returns the number of bytes per pixel in the specified format.
+     *
+     * Supported formats:
+     *      GL_ALPHA
+     *      GL_RGBA
+     */
+    static uint32_t formatSize(GLenum format) {
+        switch (format) {
+            case GL_ALPHA:
+                return 1;
+            case GL_RGBA:
+                return 4;
+        }
+        return 0;
+    }
+
+protected:
+    /**
+     * Creates a new render buffer in the specified format and dimensions.
+     * The format must be GL_ALPHA or GL_RGBA.
+     */
+    PixelBuffer(GLenum format, uint32_t width, uint32_t height):
+            mFormat(format), mWidth(width), mHeight(height), mAccessMode(kAccessMode_None) {
+    }
+
+    GLenum mFormat;
+
+    uint32_t mWidth;
+    uint32_t mHeight;
+
+    AccessMode mAccessMode;
+
+}; // class PixelBuffer
+
+}; // namespace uirenderer
+}; // namespace android
+
+#endif // ANDROID_HWUI_PIXEL_BUFFER_H
diff --git a/libs/hwui/Properties.h b/libs/hwui/Properties.h
index e4b4f3c..6eea00c 100644
--- a/libs/hwui/Properties.h
+++ b/libs/hwui/Properties.h
@@ -25,6 +25,10 @@
  * the OpenGLRenderer.
  */
 
+///////////////////////////////////////////////////////////////////////////////
+// Compile-time properties
+///////////////////////////////////////////////////////////////////////////////
+
 // If turned on, text is interpreted as glyphs instead of UTF-16
 #define RENDER_TEXT_AS_GLYPHS 1
 
@@ -39,6 +43,10 @@
 // to properly implement overdraw debugging
 #define STENCIL_BUFFER_SIZE 8
 
+///////////////////////////////////////////////////////////////////////////////
+// Debug properties
+///////////////////////////////////////////////////////////////////////////////
+
 /**
  * Debug level for app developers. The value is a numeric value defined
  * by the DebugLevel enum below.
@@ -82,6 +90,23 @@
 #define PROPERTY_DEBUG_STENCIL_CLIP "debug.hwui.show_non_rect_clip"
 
 /**
+ * Disables draw operation deferral if set to "true", forcing draw
+ * commands to be issued to OpenGL in order, and processed in sequence
+ * with state-manipulation canvas commands.
+ */
+#define PROPERTY_DISABLE_DRAW_DEFER "debug.hwui.disable_draw_defer"
+
+/**
+ * Used to disable draw operation reordering when deferring draw operations
+ * Has no effect if PROPERTY_DISABLE_DRAW_DEFER is set to "true"
+ */
+#define PROPERTY_DISABLE_DRAW_REORDER "debug.hwui.disable_draw_reorder"
+
+///////////////////////////////////////////////////////////////////////////////
+// Runtime configuration properties
+///////////////////////////////////////////////////////////////////////////////
+
+/**
  * Used to enable/disable scissor optimization. The accepted values are
  * "true" and "false". The default value is "false".
  *
@@ -97,17 +122,10 @@
 #define PROPERTY_DISABLE_SCISSOR_OPTIMIZATION "ro.hwui.disable_scissor_opt"
 
 /**
- * Disables draw operation deferral if set to "true", forcing draw
- * commands to be issued to OpenGL in order, and processed in sequence
- * with state-manipulation canvas commands.
+ * Indicates whether PBOs can be used to back pixel buffers.
+ * Accepted values are "true" and "false".
  */
-#define PROPERTY_DISABLE_DRAW_DEFER "debug.hwui.disable_draw_defer"
-
-/**
- * Used to disable draw operation reordering when deferring draw operations
- * Has no effect if PROPERTY_DISABLE_DRAW_DEFER is set to "true"
- */
-#define PROPERTY_DISABLE_DRAW_REORDER "debug.hwui.disable_draw_reorder"
+#define PROPERTY_ENABLE_GPU_PIXEL_BUFFERS "hwui.use_gpu_pixel_buffers"
 
 // These properties are defined in mega-bytes
 #define PROPERTY_TEXTURE_CACHE_SIZE "ro.hwui.texture_cache_size"
@@ -152,8 +170,9 @@
 // Lumincance threshold above which white gamma correction is applied. Range: [0..255]
 #define PROPERTY_TEXT_WHITE_GAMMA_THRESHOLD "hwui.text_gamma.white_threshold"
 
-// Converts a number of mega-bytes into bytes
-#define MB(s) s * 1024 * 1024
+///////////////////////////////////////////////////////////////////////////////
+// Default property values
+///////////////////////////////////////////////////////////////////////////////
 
 #define DEFAULT_TEXTURE_CACHE_SIZE 24.0f
 #define DEFAULT_LAYER_CACHE_SIZE 16.0f
@@ -170,6 +189,13 @@
 #define DEFAULT_TEXT_BLACK_GAMMA_THRESHOLD 64
 #define DEFAULT_TEXT_WHITE_GAMMA_THRESHOLD 192
 
+///////////////////////////////////////////////////////////////////////////////
+// Misc
+///////////////////////////////////////////////////////////////////////////////
+
+// Converts a number of mega-bytes into bytes
+#define MB(s) s * 1024 * 1024
+
 static DebugLevel readDebugLevel() {
     char property[PROPERTY_VALUE_MAX];
     if (property_get(PROPERTY_DEBUG, property, NULL) > 0) {
diff --git a/libs/hwui/TextDropShadowCache.cpp b/libs/hwui/TextDropShadowCache.cpp
index f1f35bd..6976eaa 100644
--- a/libs/hwui/TextDropShadowCache.cpp
+++ b/libs/hwui/TextDropShadowCache.cpp
@@ -178,6 +178,10 @@
         FontRenderer::DropShadow shadow = mRenderer->renderDropShadow(&paintCopy, text, 0,
                 len, numGlyphs, radius, positions);
 
+        if (!shadow.image) {
+            return NULL;
+        }
+
         texture = new ShadowTexture;
         texture->left = shadow.penX;
         texture->top = shadow.penY;
diff --git a/libs/hwui/font/CacheTexture.cpp b/libs/hwui/font/CacheTexture.cpp
index 577f463..6c5267d 100644
--- a/libs/hwui/font/CacheTexture.cpp
+++ b/libs/hwui/font/CacheTexture.cpp
@@ -18,6 +18,8 @@
 
 #include "CacheTexture.h"
 #include "../Debug.h"
+#include "../Extensions.h"
+#include "../PixelBuffer.h"
 
 namespace android {
 namespace uirenderer {
@@ -111,6 +113,11 @@
             mMesh(NULL), mCurrentQuad(0), mMaxQuadCount(maxQuadCount) {
     mCacheBlocks = new CacheBlock(TEXTURE_BORDER_SIZE, TEXTURE_BORDER_SIZE,
             mWidth - TEXTURE_BORDER_SIZE, mHeight - TEXTURE_BORDER_SIZE, true);
+
+    // OpenGL ES 3.0+ lets us specify the row length for unpack operations such
+    // as glTexSubImage2D(). This allows us to upload a sub-rectangle of a texture.
+    // With OpenGL ES 2.0 we have to upload entire stripes instead.
+    mHasES3 = Extensions::getInstance().getMajorGlVersion() >= 3;
 }
 
 CacheTexture::~CacheTexture() {
@@ -143,7 +150,7 @@
 
 void CacheTexture::releaseTexture() {
     if (mTexture) {
-        delete[] mTexture;
+        delete mTexture;
         mTexture = NULL;
     }
     if (mTextureId) {
@@ -154,6 +161,17 @@
     mCurrentQuad = 0;
 }
 
+void CacheTexture::setLinearFiltering(bool linearFiltering, bool bind) {
+   if (linearFiltering != mLinearFiltering) {
+       mLinearFiltering = linearFiltering;
+
+       const GLenum filtering = linearFiltering ? GL_LINEAR : GL_NEAREST;
+       if (bind) glBindTexture(GL_TEXTURE_2D, getTextureId());
+       glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, filtering);
+       glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, filtering);
+   }
+}
+
 void CacheTexture::allocateMesh() {
     if (!mMesh) {
         mMesh = new TextureVertex[mMaxQuadCount * 4];
@@ -162,7 +180,7 @@
 
 void CacheTexture::allocateTexture() {
     if (!mTexture) {
-        mTexture = new uint8_t[mWidth * mHeight];
+        mTexture = PixelBuffer::create(GL_ALPHA, mWidth, mHeight);
     }
 
     if (!mTextureId) {
@@ -183,6 +201,34 @@
     }
 }
 
+bool CacheTexture::upload() {
+    const Rect& dirtyRect = mDirtyRect;
+
+    uint32_t x = mHasES3 ? dirtyRect.left : 0;
+    uint32_t y = dirtyRect.top;
+    uint32_t width = mHasES3 ? dirtyRect.getWidth() : mWidth;
+    uint32_t height = dirtyRect.getHeight();
+
+    // The unpack row length only needs to be specified when a new
+    // texture is bound
+    if (mHasES3) {
+        glPixelStorei(GL_UNPACK_ROW_LENGTH, mWidth);
+    }
+
+    mTexture->upload(x, y, width, height, y * mWidth + x);
+
+    setDirty(false);
+
+    return mHasES3;
+}
+
+void CacheTexture::setDirty(bool dirty) {
+    mDirty = dirty;
+    if (!dirty) {
+        mDirtyRect.setEmpty();
+    }
+}
+
 bool CacheTexture::fitBitmap(const SkGlyph& glyph, uint32_t* retOriginX, uint32_t* retOriginY) {
     if (glyph.fHeight + TEXTURE_BORDER_SIZE * 2 > mHeight) {
         return false;
diff --git a/libs/hwui/font/CacheTexture.h b/libs/hwui/font/CacheTexture.h
index e7fb474..ddcc836 100644
--- a/libs/hwui/font/CacheTexture.h
+++ b/libs/hwui/font/CacheTexture.h
@@ -30,6 +30,8 @@
 namespace android {
 namespace uirenderer {
 
+class PixelBuffer;
+
 /**
  * CacheBlock is a node in a linked list of current free space areas in a CacheTexture.
  * Using CacheBlocks enables us to pack the cache from top to bottom as well as left to right.
@@ -83,6 +85,10 @@
     void allocateTexture();
     void allocateMesh();
 
+    // Returns true if glPixelStorei(GL_UNPACK_ROW_LENGTH) must be reset
+    // This method will also call setDirty(false)
+    bool upload();
+
     bool fitBitmap(const SkGlyph& glyph, uint32_t* retOriginX, uint32_t* retOriginY);
 
     inline uint16_t getWidth() const {
@@ -97,7 +103,7 @@
         return &mDirtyRect;
     }
 
-    inline uint8_t* getTexture() const {
+    inline PixelBuffer* getPixelBuffer() const {
         return mTexture;
     }
 
@@ -110,13 +116,6 @@
         return mDirty;
     }
 
-    inline void setDirty(bool dirty) {
-        mDirty = dirty;
-        if (!dirty) {
-            mDirtyRect.setEmpty();
-        }
-    }
-
     inline bool getLinearFiltering() const {
         return mLinearFiltering;
     }
@@ -124,16 +123,7 @@
     /**
      * This method assumes that the proper texture unit is active.
      */
-    void setLinearFiltering(bool linearFiltering, bool bind = true) {
-        if (linearFiltering != mLinearFiltering) {
-            mLinearFiltering = linearFiltering;
-
-            const GLenum filtering = linearFiltering ? GL_LINEAR : GL_NEAREST;
-            if (bind) glBindTexture(GL_TEXTURE_2D, getTextureId());
-            glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, filtering);
-            glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, filtering);
-        }
-    }
+    void setLinearFiltering(bool linearFiltering, bool bind = true);
 
     inline uint16_t getGlyphCount() const {
         return mNumGlyphs;
@@ -176,7 +166,9 @@
     }
 
 private:
-    uint8_t* mTexture;
+    void setDirty(bool dirty);
+
+    PixelBuffer* mTexture;
     GLuint mTextureId;
     uint16_t mWidth;
     uint16_t mHeight;
@@ -188,6 +180,7 @@
     uint32_t mMaxQuadCount;
     CacheBlock* mCacheBlocks;
     Rect mDirtyRect;
+    bool mHasES3;
 };
 
 }; // namespace uirenderer
diff --git a/libs/hwui/font/Font.cpp b/libs/hwui/font/Font.cpp
index 02c1aa1..011cfc1 100644
--- a/libs/hwui/font/Font.cpp
+++ b/libs/hwui/font/Font.cpp
@@ -25,11 +25,12 @@
 #include <SkGlyph.h>
 #include <SkUtils.h>
 
-#include "Debug.h"
 #include "FontUtil.h"
 #include "Font.h"
-#include "FontRenderer.h"
-#include "Properties.h"
+#include "../Debug.h"
+#include "../FontRenderer.h"
+#include "../PixelBuffer.h"
+#include "../Properties.h"
 
 namespace android {
 namespace uirenderer {
@@ -200,25 +201,23 @@
             p[3].x(), p[3].y(), u1, v1, glyph->mCacheTexture);
 }
 
-void Font::drawCachedGlyphBitmap(CachedGlyphInfo* glyph, int x, int y,
-        uint8_t* bitmap, uint32_t bitmapW, uint32_t bitmapH, Rect* bounds, const float* pos) {
-    int nPenX = x + glyph->mBitmapLeft;
-    int nPenY = y + glyph->mBitmapTop;
-
-    uint32_t endX = glyph->mStartX + glyph->mBitmapWidth;
-    uint32_t endY = glyph->mStartY + glyph->mBitmapHeight;
+void Font::drawCachedGlyphBitmap(CachedGlyphInfo* glyph, int x, int y, uint8_t* bitmap,
+        uint32_t bitmapWidth, uint32_t bitmapHeight, Rect* bounds, const float* pos) {
+    int dstX = x + glyph->mBitmapLeft;
+    int dstY = y + glyph->mBitmapTop;
 
     CacheTexture* cacheTexture = glyph->mCacheTexture;
-    uint32_t cacheWidth = cacheTexture->getWidth();
-    const uint8_t* cacheBuffer = cacheTexture->getTexture();
 
-    uint32_t cacheX = 0, cacheY = 0;
-    int32_t bX = 0, bY = 0;
-    for (cacheX = glyph->mStartX, bX = nPenX; cacheX < endX; cacheX++, bX++) {
-        for (cacheY = glyph->mStartY, bY = nPenY; cacheY < endY; cacheY++, bY++) {
-            uint8_t tempCol = cacheBuffer[cacheY * cacheWidth + cacheX];
-            bitmap[bY * bitmapW + bX] = tempCol;
-        }
+    uint32_t cacheWidth = cacheTexture->getWidth();
+    uint32_t startY = glyph->mStartY * cacheWidth;
+    uint32_t endY = startY + (glyph->mBitmapHeight * cacheWidth);
+
+    PixelBuffer* pixelBuffer = cacheTexture->getPixelBuffer();
+    const uint8_t* cacheBuffer = pixelBuffer->map();
+
+    for (uint32_t cacheY = startY, bitmapY = dstY * bitmapWidth; cacheY < endY;
+            cacheY += cacheWidth, bitmapY += bitmapWidth) {
+        memcpy(&bitmap[bitmapY + dstX], &cacheBuffer[cacheY + glyph->mStartX], glyph->mBitmapWidth);
     }
 }