把Android原生的View渲染到OpenGL Texture

http://blog.csdn.net/u010949962/article/details/41865777

最近要把Android 原生的View渲染到OpenGL GLSurfaceView中，起初想到的是截图的方法，也就是把View截取成bitmap后，再把Bitmap渲染到OpenGL中；但是明显这种方法是不可行的，面对一些高速动态更新的View，只有不停的对view 进行截图才能渲染出原生View的效果。

         通过大量的Google终于在国外的网站找到了一个做过类似的先例（链接:http://www.felixjones.co.uk/neo%20website/Android_View/）。不过经过测试该方法只能渲染直接父类为View的view，也就是只能渲染一层View（如progressbar，没不能添加child的view），当该原生Android View包含很多子view时（也就是根View为FramLayout、或者linearLayout之类），无法实时的监听到View动态改变，OpenGL中只能不停的渲染该view，才能渲染出原生View的效果。但是这样一来不同的渲染会耗费大量的资源，降低应用程序的效率。理想中的话，是监听到了该View的内容或者其子view 的内容发生了变化(如：View中的字幕发生滚动)才进行渲染。

        经过接近两周的努力我终于完美地实现了该效果，既然是站在别人的基础上得来的成果，那么该方法就应当被共享，所以产生了此文，不过只支持api 15以上的

步骤一:重写根View

1.设置该View 绘制自己：

setWillNotDraw(false);

 2.监听View的变化，重写View，用ViewTreeObServer来监听，方法如下：

private void addOnPreDrawListener() {

    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {

        final ViewTreeObserver mObserver = getViewTreeObserver();
        if (mObserver != null) {
            mObserver.addOnPreDrawListener(new OnPreDrawListener() {

                @Override
                public boolean onPreDraw() {
                    if (isDirty()) {//View或者子view发生变化
                        invalidate();
                    }
                    return true;
                }
            });
        }
    }
}

 3.重写该View的onDraw方法:

@Override
protected void onDraw(Canvas canvas) {
    try {
        if (mSurface != null) {
            Canvas surfaceCanvas = mSurface.lockCanvas(null);
            super.dispatchDraw(surfaceCanvas);
            mSurface.unlockCanvasAndPost(surfaceCanvas);

            mSurface.release();
            mSurface = null;
            mSurface = new Surface(mSurfaceTexture);
        }
    } catch (OutOfResourcesException e) {
        e.printStackTrace();
    }
}

步骤二：GLSurfaceView.Renderer

class CustomRenderer implements GLSurfaceView.Renderer {
    int glSurfaceTex;
    private final int GL_TEXTURE_EXTERNAL_OES = 0x8D65;
    long currentTime;
    long previousTime;
    boolean b = false;
    int frameCount = 0;
    DirectDrawer mDirectDrawer;
    ActivityManager activityManager;
    MemoryInfo _memoryInfo;


    // Fixed values
    private int TEXTURE_WIDTH = 360;
    private int TEXTURE_HEIGHT = 360;

    Context context;

    private LauncherAppWidgetHostView addedWidgetView;

    private SurfaceTexture surfaceTexture = null;

    private Surface surface;

    float fps;

    public CustomRenderer(Context context, LauncherAppWidgetHostView addedWidgetView, Display mDisplay){
        this.context = context;
        this.addedWidgetView = addedWidgetView;
        TEXTURE_WIDTH = mDisplay.getWidth();
        TEXTURE_HEIGHT = mDisplay.getHeight();
        _memoryInfo = new MemoryInfo();
        activityManager = (ActivityManager) context.getApplicationContext().getSystemService(Context.ACTIVITY_SERVICE);
    }

    @Override
    public void onDrawFrame(GL10 gl) {

        synchronized (this) {
            surfaceTexture.updateTexImage();
        }

        activityManager.getMemoryInfo(_memoryInfo);

        GLES20.glClearColor(0.0f, 0.0f, 1.0f, 1.0f);
        GLES20.glClear(GLES20.GL_DEPTH_BUFFER_BIT | GLES20.GL_COLOR_BUFFER_BIT);
        GLES20.glEnable(GLES20.GL_BLEND);
        GLES20.glBlendFunc(GLES20.GL_ONE, GLES20.GL_ONE_MINUS_SRC_ALPHA);

        float[] mtx = new float[16];
        surfaceTexture.getTransformMatrix(mtx);
        mDirectDrawer.draw(mtx);

        calculateFps();
        //getAppMemorySize();
        //getRunningAppProcessInfo();
        //Log.v("onDrawFrame", "FPS: " + Math.round(fps) + ", availMem: " + Math.round(_memoryInfo.availMem / 1048576) + "MB");
    }

    private void getAppMemorySize(){
        ActivityManager mActivityManager = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
        android.os.Debug.MemoryInfo[] memoryInfos = mActivityManager.getProcessMemoryInfo(new int[]{android.os.Process.myPid()});
        int size = memoryInfos[0].dalvikPrivateDirty;
        Log.w("getAppMemorySize", size / 1024 + " MB");
    }


    private void getRunningAppProcessInfo() {
        ActivityManager  mActivityManager = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);

        //获得系统里正在运行的所有进程
        List<RunningAppProcessInfo> runningAppProcessesList = mActivityManager.getRunningAppProcesses();

        for (RunningAppProcessInfo runningAppProcessInfo : runningAppProcessesList) {
            // 进程ID号
            int pid = runningAppProcessInfo.pid;
            // 用户ID
            int uid = runningAppProcessInfo.uid;
            // 进程名
            String processName = runningAppProcessInfo.processName;
            // 占用的内存
            int[] pids = new int[] {pid};
            Debug.MemoryInfo[] memoryInfo = mActivityManager.getProcessMemoryInfo(pids);
            int memorySize = memoryInfo[0].dalvikPrivateDirty;

            System.out.println("processName="+processName+",currentPid: "+  "pid= " +android.os.Process.myPid()+"----------->"+pid+",uid="+uid+",memorySize="+memorySize+"kb");
        }
    }

    @Override
    public void onSurfaceCreated(GL10 gl, EGLConfig config) {

        surface = null;
        surfaceTexture = null;

        glSurfaceTex = Engine_CreateSurfaceTexture(TEXTURE_WIDTH, TEXTURE_HEIGHT);
        Log.d("GLES20Ext", "glSurfaceTex" + glSurfaceTex);
        if (glSurfaceTex > 0) {
            surfaceTexture = new SurfaceTexture(glSurfaceTex);
            surfaceTexture.setDefaultBufferSize(TEXTURE_WIDTH, TEXTURE_HEIGHT);
            surface = new Surface(surfaceTexture);
            addedWidgetView.setSurface(surface);
            addedWidgetView.setSurfaceTexture(surfaceTexture);
            //addedWidgetView.setSurfaceTexture(surfaceTexture);
            mDirectDrawer = new DirectDrawer(glSurfaceTex);
        }
    }

    float calculateFps() {

        frameCount++;
        if (!b) {
            b = true;
            previousTime = System.currentTimeMillis();
        }
        long intervalTime = System.currentTimeMillis() - previousTime;

        if (intervalTime >= 1000) {
            b = false;
            fps = frameCount / (intervalTime / 1000f);
            frameCount = 0;
            Log.w("calculateFps", "FPS: " + fps);
        }

        return fps;
    }

    int Engine_CreateSurfaceTexture(int width, int height) {
        /*
         * Create our texture. This has to be done each time the surface is
         * created.
         */

        int[] textures = new int[1];
        GLES20.glGenTextures(1, textures, 0);

        glSurfaceTex = textures[0];

        if (glSurfaceTex > 0) {
            GLES20.glBindTexture(GL_TEXTURE_EXTERNAL_OES, glSurfaceTex);

            // Notice the use of GL_TEXTURE_2D for texture creation
            GLES20.glTexImage2D(GLES20.GL_TEXTURE_2D, 0, GLES20.GL_RGB, width, height, 0, GLES20.GL_RGB, GLES20.GL_UNSIGNED_BYTE, null);

            GLES20.glTexParameteri(GL_TEXTURE_EXTERNAL_OES, GLES20.GL_TEXTURE_MIN_FILTER, GLES20.GL_NEAREST);
            GLES20.glTexParameteri(GL_TEXTURE_EXTERNAL_OES, GLES20.GL_TEXTURE_MAG_FILTER, GLES20.GL_NEAREST);

            GLES20.glTexParameteri(GL_TEXTURE_EXTERNAL_OES, GLES20.GL_TEXTURE_WRAP_S, GLES20.GL_CLAMP_TO_EDGE);
            GLES20.glTexParameteri(GL_TEXTURE_EXTERNAL_OES, GLES20.GL_TEXTURE_WRAP_T, GLES20.GL_CLAMP_TO_EDGE);
        }
        return glSurfaceTex;
    }

    @Override
    public void onSurfaceChanged(GL10 gl, int width, int height) {

    }
}

public class DirectDrawer {
   private final String vertexShaderCode =
           "attribute vec4 vPosition;" +
           "attribute vec2 inputTextureCoordinate;" +
           "varying vec2 textureCoordinate;" +
           "void main()" +
           "{"+
               "gl_Position = vPosition;"+
               "textureCoordinate = inputTextureCoordinate;" +
           "}";

   private final String fragmentShaderCode =
           "#extension GL_OES_EGL_image_external : require
"+
           "precision mediump float;" +
           "varying vec2 textureCoordinate;
" +
           "uniform samplerExternalOES s_texture;
" +
           "void main() {" +
           "  gl_FragColor = texture2D( s_texture, textureCoordinate );
" +
           "}";

   private FloatBuffer vertexBuffer, textureVerticesBuffer;
   private ShortBuffer drawListBuffer;
   private final int mProgram;
   private int mPositionHandle;
   private int mTextureCoordHandle;

   private short drawOrder[] = { 0, 1, 2, 0, 2, 3 }; // order to draw vertices

   // number of coordinates per vertex in this array
   private static final int COORDS_PER_VERTEX = 2;

   private final int vertexStride = COORDS_PER_VERTEX * 4; // 4 bytes per vertex

   static float squareCoords[] = {
      -1.0f,  0.0f,
      -1.0f, -2.2f,
       1.0f, -2.2f,
       1.0f,  0.0f,
   };

   static float textureVertices[] = {
        0f,  0f,
        0f,  1f,
        1f,  1f,
        1f,  0f,
   };

   private int texture;

   public DirectDrawer(int texture)
   {
       this.texture = texture;
       // initialize vertex byte buffer for shape coordinates
       ByteBuffer bb = ByteBuffer.allocateDirect(squareCoords.length * 4);
       bb.order(ByteOrder.nativeOrder());
       vertexBuffer = bb.asFloatBuffer();
       vertexBuffer.put(squareCoords);
       vertexBuffer.position(0);

       // initialize byte buffer for the draw list
       ByteBuffer dlb = ByteBuffer.allocateDirect(drawOrder.length * 2);
       dlb.order(ByteOrder.nativeOrder());
       drawListBuffer = dlb.asShortBuffer();
       drawListBuffer.put(drawOrder);
       drawListBuffer.position(0);

       ByteBuffer bb2 = ByteBuffer.allocateDirect(textureVertices.length * 4);
       bb2.order(ByteOrder.nativeOrder());
       textureVerticesBuffer = bb2.asFloatBuffer();
       textureVerticesBuffer.put(textureVertices);
       textureVerticesBuffer.position(0);

       int vertexShader    = loadShader(GLES20.GL_VERTEX_SHADER, vertexShaderCode);
       int fragmentShader  = loadShader(GLES20.GL_FRAGMENT_SHADER, fragmentShaderCode);

       mProgram = GLES20.glCreateProgram();             // create empty OpenGL ES Program
       GLES20.glAttachShader(mProgram, vertexShader);   // add the vertex shader to program
       GLES20.glAttachShader(mProgram, fragmentShader); // add the fragment shader to program
       GLES20.glLinkProgram(mProgram);                  // creates OpenGL ES program executables
   }

   public void draw(float[] mtx)
   {
       GLES20.glUseProgram(mProgram);

       GLES20.glActiveTexture(GLES20.GL_TEXTURE0);
       GLES20.glBindTexture(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, texture);

       // get handle to vertex shader's vPosition member
       mPositionHandle = GLES20.glGetAttribLocation(mProgram, "vPosition");

       // Enable a handle to the triangle vertices
       GLES20.glEnableVertexAttribArray(mPositionHandle);

       // Prepare the <insert shape here> coordinate data
       GLES20.glVertexAttribPointer(mPositionHandle, COORDS_PER_VERTEX, GLES20.GL_FLOAT, false, vertexStride, vertexBuffer);

       mTextureCoordHandle = GLES20.glGetAttribLocation(mProgram, "inputTextureCoordinate");
       GLES20.glEnableVertexAttribArray(mTextureCoordHandle);

        // textureVerticesBuffer.clear();
        // textureVerticesBuffer.put( transformTextureCoordinates(
        // textureVertices, mtx ));
        // textureVerticesBuffer.position(0);

       GLES20.glVertexAttribPointer(mTextureCoordHandle, COORDS_PER_VERTEX, GLES20.GL_FLOAT, false, vertexStride, textureVerticesBuffer);

       GLES20.glDrawElements(GLES20.GL_TRIANGLES, drawOrder.length, GLES20.GL_UNSIGNED_SHORT, drawListBuffer);

       // Disable vertex array
       GLES20.glDisableVertexAttribArray(mPositionHandle);
       GLES20.glDisableVertexAttribArray(mTextureCoordHandle);
   }

   private  int loadShader(int type, String shaderCode){

       // create a vertex shader type (GLES20.GL_VERTEX_SHADER)
       // or a fragment shader type (GLES20.GL_FRAGMENT_SHADER)
       int shader = GLES20.glCreateShader(type);

       // add the source code to the shader and compile it
       GLES20.glShaderSource(shader, shaderCode);
       GLES20.glCompileShader(shader);

       return shader;
   }
   private float[] transformTextureCoordinates( float[] coords, float[] matrix)
   {
      float[] result = new float[ coords.length ];
      float[] vt = new float[4];

      for ( int i = 0 ; i < coords.length ; i += 2 ) {
          float[] v = { coords[i], coords[i+1], 0 , 1  };
          Matrix.multiplyMV(vt, 0, matrix, 0, v, 0);
          result[i] = vt[0];
          result[i+1] = vt[1];
      }
      return result;
   }
}

步骤三：配置GLSurfaceView：

GLSurfaceView glSurfaceView = new GLSurfaceView(getApplicationContext());
// Setup the surface view for drawing to

glSurfaceView.setEGLContextClientVersion(2);
glSurfaceView.setEGLConfigChooser(8, 8, 8, 8, 16, 0);
glSurfaceView.setRenderer(renderer);
//glSurfaceView.setZOrderOnTop(true);

// Add our WebView to the Android View hierarchy
glSurfaceView.setLayoutParams(new FrameLayout.LayoutParams(FrameLayout.LayoutParams.MATCH_PARENT, FrameLayout.LayoutParams.MATCH_PARENT));

             效果如图所示，上面是猎豹清理大师的widget，下面是GLSurfaceView的Texture，原生的Widget和OpenGL中渲染的一模一样。并且点击widget进行清理时也能达到实时渲染的Veiw动画清理效果，源码链接：https://github.com/MrHuangXin/RenderViewToOpenGL/tree/master