Implement SurfaceTexture frame-available callback.

This change implements the onFrameAvailable callback for the
SurfaceTexture java class.  It includes the C++ SurfaceTexture code as
well as the JNI and Java code to enable the callback.

Change-Id: Ifd8b8e7ad46ee70cba6da1c2e96dab8045d1ea30

include/gui/SurfaceTexture.h

@@ -40,6 +40,10 @@ public:
     enum { MIN_BUFFER_SLOTS = 3 };
     enum { NUM_BUFFER_SLOTS = 32 };
 
+    struct FrameAvailableListener : public virtual RefBase {
+        virtual void onFrameAvailable() = 0;
+    };
+
     // tex indicates the name OpenGL texture to which images are to be streamed.
     // This texture name cannot be changed once the SurfaceTexture is created.
     SurfaceTexture(GLuint tex);
@@ -93,6 +97,10 @@ public:
     // functions.
     void getTransformMatrix(float mtx[16]);
 
+    // setFrameAvailableListener sets the listener object that will be notified
+    // when a new frame becomes available.
+    void setFrameAvailableListener(const sp<FrameAvailableListener>& l);
+
 private:
 
     // freeAllBuffers frees the resources (both GraphicBuffer and EGLImage) for
@@ -195,6 +203,11 @@ private:
     // to a buffer, but other processes do.
     Vector<sp<GraphicBuffer> > mAllocdBuffers;
 
+    // mFrameAvailableListener is the listener object that will be called when a
+    // new frame becomes available. If it is not NULL it will be called from
+    // queueBuffer.
+    sp<FrameAvailableListener> mFrameAvailableListener;
+
     // mMutex is the mutex used to prevent concurrent access to the member
     // variables of SurfaceTexture objects. It must be locked whenever the
     // member variables are accessed.

libs/gui/SurfaceTexture.cpp

@@ -166,6 +166,9 @@ status_t SurfaceTexture::queueBuffer(int buf) {
     mLastQueued = buf;
     mLastQueuedCrop = mNextCrop;
     mLastQueuedTransform = mNextTransform;
+    if (mFrameAvailableListener != 0) {
+        mFrameAvailableListener->onFrameAvailable();
+    }
     return OK;
 }
 
@@ -294,6 +297,13 @@ void SurfaceTexture::getTransformMatrix(float mtx[16]) {
     mtxMul(mtx, mtxFlipV, mtxBeforeFlipV);
 }
 
+void SurfaceTexture::setFrameAvailableListener(
+        const sp<FrameAvailableListener>& l) {
+    LOGV("SurfaceTexture::setFrameAvailableListener");
+    Mutex::Autolock lock(mMutex);
+    mFrameAvailableListener = l;
+}
+
 void SurfaceTexture::freeAllBuffers() {
     for (int i = 0; i < NUM_BUFFER_SLOTS; i++) {
         mSlots[i].mGraphicBuffer = 0;