MediaPlayer setDisplay

flow: 

setDisplay(MediaPlayer .java)>>_setVideoSurface(android.media.MediaPlayer.cpp)>>setVideoSurface(android.media.MediaPlayer.cpp)

>>setVideoSurfaceTexture(MediaPlayer.cpp)>>setVideoSurfaceTextureAsync(Nuplayer.cpp)

//java
    public void setDisplay(SurfaceHolder sh) {
        mSurfaceHolder = sh;
        Surface surface;
        if (sh != null) {
            surface = sh.getSurface();
        } else {
            surface = null;
        }
        _setVideoSurface(surface);
        updateSurfaceScreenOn();
    }


    private native void _setVideoSurface(Surface surface);
//jni
static void
android_media_MediaPlayer_setVideoSurface(JNIEnv *env, jobject thiz, jobject jsurface)
{
    setVideoSurface(env, thiz, jsurface, true /* mediaPlayerMustBeAlive */);
}


static void
setVideoSurface(JNIEnv *env, jobject thiz, jobject jsurface, jboolean mediaPlayerMustBeAlive)
{
    sp<MediaPlayer> mp = getMediaPlayer(env, thiz);
    if (mp == NULL) {
        if (mediaPlayerMustBeAlive) {
            jniThrowException(env, "java/lang/IllegalStateException", NULL);
        }
        return;
    }


    decVideoSurfaceRef(env, thiz);


    sp<IGraphicBufferProducer> new_st;
    if (jsurface) {
        sp<Surface> surface(android_view_Surface_getSurface(env, jsurface));
        if (surface != NULL) {
            new_st = surface->getIGraphicBufferProducer();
            if (new_st == NULL) {
                jniThrowException(env, "java/lang/IllegalArgumentException",
                    "The surface does not have a binding SurfaceTexture!");
                return;
            }
            new_st->incStrong((void*)decVideoSurfaceRef);
        } else {
            jniThrowException(env, "java/lang/IllegalArgumentException",
                    "The surface has been released");
            return;
        }
    }


    env->SetLongField(thiz, fields.surface_texture, (jlong)new_st.get());


    // This will fail if the media player has not been initialized yet. This
    // can be the case if setDisplay() on MediaPlayer.java has been called
    // before setDataSource(). The redundant call to setVideoSurfaceTexture()
    // in prepare/prepareAsync covers for this case.
    mp->setVideoSurfaceTexture(new_st);
}


//c++
status_t MediaPlayer::setVideoSurfaceTexture(
        const sp<IGraphicBufferProducer>& bufferProducer)
{
    ALOGV("setVideoSurfaceTexture");
    Mutex::Autolock _l(mLock);
    if (mPlayer == 0) return NO_INIT;
    return mPlayer->setVideoSurfaceTexture(bufferProducer);
}


void NuPlayer::setVideoSurfaceTextureAsync(
        const sp<IGraphicBufferProducer> &bufferProducer) {
    sp<AMessage> msg = new AMessage(kWhatSetVideoNativeWindow, id());


    if (bufferProducer == NULL) {
        msg->setObject("native-window", NULL);
    } else {
        msg->setObject(
                "native-window",
                new NativeWindowWrapper(
                    new Surface(bufferProducer, true /* controlledByApp */)));
    }


    msg->post();
}