diff --git a/services/surfaceflinger/DisplayHardware/HWComposer.cpp b/services/surfaceflinger/DisplayHardware/HWComposer.cpp
index 65763db..ce63ee7 100644
--- a/services/surfaceflinger/DisplayHardware/HWComposer.cpp
+++ b/services/surfaceflinger/DisplayHardware/HWComposer.cpp
@@ -43,6 +43,19 @@
 namespace android {
 // ---------------------------------------------------------------------------
 
+struct HWComposer::cb_context {
+    struct callbacks : public hwc_procs_t {
+        // these are here to facilitate the transition when adding
+        // new callbacks (an implementation can check for NULL before
+        // calling a new callback).
+        void (*zero[4])(void);
+    };
+    callbacks procs;
+    HWComposer* hwc;
+};
+
+// ---------------------------------------------------------------------------
+
 HWComposer::HWComposer(
         const sp<SurfaceFlinger>& flinger,
         EventHandler& handler,
@@ -51,6 +64,7 @@
       mModule(0), mHwc(0), mList(0), mCapacity(0),
       mNumOVLayers(0), mNumFBLayers(0),
       mDpy(EGL_NO_DISPLAY), mSur(EGL_NO_SURFACE),
+      mCBContext(new cb_context),
       mEventHandler(handler),
       mRefreshPeriod(refreshPeriod),
       mVSyncCount(0), mDebugForceFakeVSync(false)
@@ -68,11 +82,11 @@
                 HWC_HARDWARE_COMPOSER, strerror(-err));
         if (err == 0) {
             if (mHwc->registerProcs) {
-                mCBContext.hwc = this;
-                mCBContext.procs.invalidate = &hook_invalidate;
-                mCBContext.procs.vsync = &hook_vsync;
-                mHwc->registerProcs(mHwc, &mCBContext.procs);
-                memset(mCBContext.procs.zero, 0, sizeof(mCBContext.procs.zero));
+                mCBContext->hwc = this;
+                mCBContext->procs.invalidate = &hook_invalidate;
+                mCBContext->procs.vsync = &hook_vsync;
+                mHwc->registerProcs(mHwc, &mCBContext->procs);
+                memset(mCBContext->procs.zero, 0, sizeof(mCBContext->procs.zero));
             }
             if (mHwc->common.version >= HWC_DEVICE_API_VERSION_0_3) {
                 if (mDebugForceFakeVSync) {
@@ -102,6 +116,7 @@
     if (mHwc) {
         hwc_close(mHwc);
     }
+    delete mCBContext;
 }
 
 status_t HWComposer::initCheck() const {
@@ -230,10 +245,117 @@
     return mList ? mList->numHwLayers : 0;
 }
 
-hwc_layer_t* HWComposer::getLayers() const {
-    return mList ? mList->hwLayers : 0;
+/*
+ * Helper template to implement a concrete HWCLayer
+ * This holds the pointer to the concrete hwc layer type
+ * and implements the "iterable" side of HWCLayer.
+ */
+template<typename CONCRETE, typename HWCTYPE>
+class Iterable : public HWComposer::HWCLayer {
+protected:
+    HWCTYPE* const mLayerList;
+    HWCTYPE* mCurrentLayer;
+    Iterable(HWCTYPE* layer) : mLayerList(layer), mCurrentLayer(layer) { }
+    inline HWCTYPE const * getLayer() const { return mCurrentLayer; }
+    inline HWCTYPE* getLayer() { return mCurrentLayer; }
+    virtual ~Iterable() { }
+private:
+    // returns a copy of ourselves
+    virtual HWComposer::HWCLayer* dup() {
+        return new CONCRETE( static_cast<const CONCRETE&>(*this) );
+    }
+    virtual status_t setLayer(size_t index) {
+        mCurrentLayer = &mLayerList[index];
+        return NO_ERROR;
+    }
+};
+
+/*
+ * Concrete implementation of HWCLayer for HWC_DEVICE_API_VERSION_0_3
+ * This implements the HWCLayer side of HWCIterableLayer.
+ */
+class HWCLayerVersion03 : public Iterable<HWCLayerVersion03, hwc_layer_t> {
+public:
+    HWCLayerVersion03(hwc_layer_t* layer)
+        : Iterable<HWCLayerVersion03, hwc_layer_t>(layer) { }
+
+    virtual int32_t getCompositionType() const {
+        return getLayer()->compositionType;
+    }
+    virtual uint32_t getHints() const {
+        return getLayer()->hints;
+    }
+
+    virtual void setDefaultState() {
+        getLayer()->compositionType = HWC_FRAMEBUFFER;
+        getLayer()->hints = 0;
+        getLayer()->flags = HWC_SKIP_LAYER;
+        getLayer()->transform = 0;
+        getLayer()->blending = HWC_BLENDING_NONE;
+        getLayer()->visibleRegionScreen.numRects = 0;
+        getLayer()->visibleRegionScreen.rects = NULL;
+    }
+    virtual void setSkip(bool skip) {
+        if (skip) {
+            getLayer()->flags |= HWC_SKIP_LAYER;
+        } else {
+            getLayer()->flags &= ~HWC_SKIP_LAYER;
+        }
+    }
+    virtual void setBlending(uint32_t blending) {
+        getLayer()->blending = blending;
+    }
+    virtual void setTransform(uint32_t transform) {
+        getLayer()->transform = transform;
+    }
+    virtual void setFrame(const Rect& frame) {
+        reinterpret_cast<Rect&>(getLayer()->displayFrame) = frame;
+    }
+    virtual void setCrop(const Rect& crop) {
+        reinterpret_cast<Rect&>(getLayer()->sourceCrop) = crop;
+    }
+    virtual void setVisibleRegionScreen(const Region& reg) {
+        getLayer()->visibleRegionScreen.rects =
+                reinterpret_cast<hwc_rect_t const *>(
+                        reg.getArray(&getLayer()->visibleRegionScreen.numRects));
+    }
+    virtual void setBuffer(const sp<GraphicBuffer>& buffer) {
+        if (buffer == 0 || buffer->handle == 0) {
+            getLayer()->compositionType = HWC_FRAMEBUFFER;
+            getLayer()->flags |= HWC_SKIP_LAYER;
+            getLayer()->handle = 0;
+        } else {
+            getLayer()->handle = buffer->handle;
+        }
+    }
+};
+
+/*
+ * returns an iterator initialized at a given index in the layer list
+ */
+HWComposer::LayerListIterator HWComposer::getLayerIterator(size_t index) {
+    if (!mList || index > mList->numHwLayers) {
+        return LayerListIterator();
+    }
+    return LayerListIterator(new HWCLayerVersion03(mList->hwLayers), index);
 }
 
+/*
+ * returns an iterator on the beginning of the layer list
+ */
+HWComposer::LayerListIterator HWComposer::begin() {
+    return getLayerIterator(0);
+}
+
+/*
+ * returns an iterator on the end of the layer list
+ */
+HWComposer::LayerListIterator HWComposer::end() {
+    return getLayerIterator(getNumLayers());
+}
+
+
+
 void HWComposer::dump(String8& result, char* buffer, size_t SIZE,
         const Vector< sp<LayerBase> >& visibleLayersSortedByZ) const {
     if (mHwc && mList) {
diff --git a/services/surfaceflinger/DisplayHardware/HWComposer.h b/services/surfaceflinger/DisplayHardware/HWComposer.h
index aada3cd..cafa247 100644
--- a/services/surfaceflinger/DisplayHardware/HWComposer.h
+++ b/services/surfaceflinger/DisplayHardware/HWComposer.h
@@ -22,7 +22,7 @@
 
 #include <EGL/egl.h>
 
-#include <hardware/hwcomposer.h>
+#include <hardware/hwcomposer_defs.h>
 
 #include <utils/StrongPointer.h>
 #include <utils/Vector.h>
@@ -31,12 +31,17 @@
                            const struct timespec *request,
                            struct timespec *remain);
 
+struct hwc_composer_device;
+struct hwc_layer_list;
+struct hwc_procs;
+
 namespace android {
 // ---------------------------------------------------------------------------
 
 class String8;
 class SurfaceFlinger;
 class LayerBase;
+class GraphicBuffer;
 
 class HWComposer
 {
@@ -57,9 +62,6 @@
     // tells the HAL what the framebuffer is
     void setFrameBuffer(EGLDisplay dpy, EGLSurface sur);
 
-    // create a work list for numLayers layer. sets HWC_GEOMETRY_CHANGED.
-    status_t createWorkList(size_t numLayers);
-
     // Asks the HAL what it can do
     status_t prepare() const;
 
@@ -72,14 +74,109 @@
     // release hardware resources
     status_t release() const;
 
+    // create a work list for numLayers layer. sets HWC_GEOMETRY_CHANGED.
+    status_t createWorkList(size_t numLayers);
+
     // get the layer array created by createWorkList()
     size_t getNumLayers() const;
-    hwc_layer_t* getLayers() const;
 
     // get number of layers of the given type as updated in prepare().
     // type is HWC_OVERLAY or HWC_FRAMEBUFFER
     size_t getLayerCount(int type) const;
 
+    // needed forward declarations
+    class LayerListIterator;
+
+    /*
+     * Interface to hardware composer's layers functionality.
+     * This abstracts the HAL interface to layers which can evolve in
+     * incompatible ways from one release to another.
+     * The idea is that we could extend this interface as we add
+     * features to h/w composer.
+     */
+    class HWCLayerInterface {
+    protected:
+        virtual ~HWCLayerInterface() { }
+    public:
+        virtual int32_t getCompositionType() const = 0;
+        virtual uint32_t getHints() const = 0;
+        virtual void setDefaultState() = 0;
+        virtual void setSkip(bool skip) = 0;
+        virtual void setBlending(uint32_t blending) = 0;
+        virtual void setTransform(uint32_t transform) = 0;
+        virtual void setFrame(const Rect& frame) = 0;
+        virtual void setCrop(const Rect& crop) = 0;
+        virtual void setVisibleRegionScreen(const Region& reg) = 0;
+        virtual void setBuffer(const sp<GraphicBuffer>& buffer) = 0;
+    };
+
+    /*
+     * Interface used to implement an iterator to a list
+     * of HWCLayer.
+     */
+    class HWCLayer : public HWCLayerInterface {
+        friend class LayerListIterator;
+        // select the layer at the given index
+        virtual status_t setLayer(size_t index) = 0;
+        virtual HWCLayer* dup() = 0;
+        static HWCLayer* copy(HWCLayer *rhs) {
+            return rhs ? rhs->dup() : NULL;
+        }
+    protected:
+        virtual ~HWCLayer() { }
+    };
+
+    /*
+     * Iterator through a HWCLayer list.
+     * This behaves more or less like a forward iterator.
+     */
+    class LayerListIterator {
+        friend struct HWComposer;
+        HWCLayer* const mLayerList;
+        size_t mIndex;
+
+        LayerListIterator() : mLayerList(NULL), mIndex(0) { }
+
+        LayerListIterator(HWCLayer* layer, size_t index)
+            : mLayerList(layer), mIndex(index) { }
+
+        // we don't allow assignment, because we don't need it for now
+        LayerListIterator& operator = (const LayerListIterator& rhs);
+
+    public:
+        // copy operators
+        LayerListIterator(const LayerListIterator& rhs)
+            : mLayerList(HWCLayer::copy(rhs.mLayerList)), mIndex(rhs.mIndex) {
+        }
+
+        ~LayerListIterator() { delete mLayerList; }
+
+        // pre-increment
+        LayerListIterator& operator++() {
+            mLayerList->setLayer(++mIndex);
+            return *this;
+        }
+
+        // dereference
+        HWCLayerInterface& operator * () { return *mLayerList; }
+        HWCLayerInterface* operator -> () { return mLayerList; }
+
+        // comparison
+        bool operator == (const LayerListIterator& rhs) const {
+            return mIndex == rhs.mIndex;
+        }
+        bool operator != (const LayerListIterator& rhs) const {
+            return !operator==(rhs);
+        }
+    };
+
+    // Returns an iterator to the beginning of the layer list
+    LayerListIterator begin();
+
+    // Returns an iterator to the end of the layer list
+    LayerListIterator end();
+
+
     // Events handling ---------------------------------------------------------
 
     enum {
@@ -111,18 +208,9 @@
             const Vector< sp<LayerBase> >& visibleLayersSortedByZ) const;
 
 private:
+    LayerListIterator getLayerIterator(size_t index);
 
-    struct callbacks : public hwc_procs_t {
-        // these are here to facilitate the transition when adding
-        // new callbacks (an implementation can check for NULL before
-        // calling a new callback).
-        void (*zero[4])(void);
-    };
-
-    struct cb_context {
-        callbacks procs;
-        HWComposer* hwc;
-    };
+    struct cb_context;
 
     static void hook_invalidate(struct hwc_procs* procs);
     static void hook_vsync(struct hwc_procs* procs, int dpy, int64_t timestamp);
@@ -132,14 +220,14 @@
 
     sp<SurfaceFlinger>      mFlinger;
     hw_module_t const*      mModule;
-    hwc_composer_device_t*  mHwc;
-    hwc_layer_list_t*       mList;
+    struct hwc_composer_device*  mHwc;
+    struct hwc_layer_list*  mList;
     size_t                  mCapacity;
     mutable size_t          mNumOVLayers;
     mutable size_t          mNumFBLayers;
-    hwc_display_t           mDpy;
-    hwc_surface_t           mSur;
-    cb_context              mCBContext;
+    EGLDisplay              mDpy;
+    EGLSurface              mSur;
+    cb_context*             mCBContext;
     EventHandler&           mEventHandler;
     nsecs_t                 mRefreshPeriod;
     size_t                  mVSyncCount;
@@ -147,7 +235,6 @@
     bool                    mDebugForceFakeVSync;
 };
 
-
 // ---------------------------------------------------------------------------
 }; // namespace android