Android SurfaceTexture和GLSurfaceView做Camera预览

GLSurfaceView是 OpenGL中的一个类，也是可以预览Camera的，而且在预览Camera上有其独到之处。独到之处在哪？当使用Surfaceview无能为力、痛不欲生时就只有使用GLSurfaceView了，它能够真正做到让Camera的数据和显示分离，所以搞明白了这个，像Camera只开预览不显示这都是小菜，妥妥的。Android4.0的自带Camera源码是用SurfaceView预览的，但到了4.2就换成了GLSurfaceView来预览。如今到了4.4又用了自家的TextureView，所以从中可以窥探出新增TextureView的用意。

虽说Android4.2的Camera源码是用GLSurfaceView预览的，但是进行了大量的封装又封装的，由于是OpenGL小白，真是看的不知所云。俺滴要求不高，只想弄个可拍照的摸清GLSurfaceView在预览Camera上的使用流程。经过一番百度一无所获，后来翻出去Google一大圈也没发现可用的。倒是很多人都在用GLSurfaceView和Surfaceview同时预览Camera，Surfaceview用来预览数据，在上面又铺了一层GLSurfaceView绘制一些信息。无奈自己摸索，整出来的是能拍照也能得到数据，但是界面上不是一块白板就是一块黑板啥都不显示。后来在stackoverflow终于找到了一个可用的链接，哈哈，苍天啊，终于柳暗花明了！参考此链接，自己又改改摸索了一天才彻底搞定。之所以费这么多时间是不明白OpenGL ES2.0的绘制基本流程，跟简单的OpenGL的绘制还是稍有区别。下面上源码:

一、CameraGLSurfaceView.java 此类继承GLSurfaceView，并实现了两个接口

**[java]** [view plain](http://blog.csdn.net/yanzi1225627/article/details/33339965#)[copy](http://blog.csdn.net/yanzi1225627/article/details/33339965#)[print](http://blog.csdn.net/yanzi1225627/article/details/33339965#)[?](http://blog.csdn.net/yanzi1225627/article/details/33339965#)[![在CODE上查看代码片](https://code.csdn.net/assets/CODE_ico.png)](https://code.csdn.net/snippets/402612)[![派生到我的代码片](https://code.csdn.net/assets/ico_fork.svg)](https://code.csdn.net/snippets/402612/fork)

  <div>
  </div>
  
  <div>
    <embed id="ZeroClipboardMovie_1" src="http://static.blog.csdn.net/scripts/ZeroClipboard/ZeroClipboard.swf" type="application/x-shockwave-flash" width="24" height="13" align="middle" name="ZeroClipboardMovie_1">
    </embed>
  </div>
</div>

- <span style=<span class="string">&#8220;font-family:Comic Sans MS;font-size:18px;&#8221;</span>><span class="keyword">package</span> org.yanzi.camera.preview;

- 
- <span class="keyword">import</span> javax.microedition.khronos.egl.EGLConfig;

- <span class="keyword">import</span> javax.microedition.khronos.opengles.GL10;

- 
- <span class="keyword">import</span> org.yanzi.camera.CameraInterface;

- 
- <span class="keyword">import</span> android.content.Context;

- <span class="keyword">import</span> android.graphics.SurfaceTexture;

- <span class="keyword">import</span> android.opengl.GLES11Ext;

- <span class="keyword">import</span> android.opengl.GLES20;

- <span class="keyword">import</span> android.opengl.GLSurfaceView;

- <span class="keyword">import</span> android.opengl.GLSurfaceView.Renderer;

- <span class="keyword">import</span> android.util.AttributeSet;

- <span class="keyword">import</span> android.util.Log;

- 
- <span class="keyword">public</span> <span class="keyword">class</span> CameraGLSurfaceView <span class="keyword">extends</span> GLSurfaceView <span class="keyword">implements</span> Renderer, SurfaceTexture.OnFrameAvailableListener {

- <span class="keyword">private</span> <span class="keyword">static</span> <span class="keyword">final</span> String TAG = <span class="string">&#8220;yanzi&#8221;</span>;

- Context mContext;

- SurfaceTexture mSurface;

- <span class="keyword">int</span> mTextureID = &#8211;<span class="number">1</span>;

- DirectDrawer mDirectDrawer;

- <span class="keyword">public</span> CameraGLSurfaceView(Context context, AttributeSet attrs) {

- <span class="keyword">super</span>(context, attrs);

- <span class="comment">// TODO Auto-generated constructor stub</span>

- mContext = context;

- setEGLContextClientVersion(<span class="number">2</span>);

- setRenderer(<span class="keyword">this</span>);

- setRenderMode(RENDERMODE_WHEN_DIRTY);

- }

- <span class="annotation">@Override</span>

- <span class="keyword">public</span> <span class="keyword">void</span> onSurfaceCreated(GL10 gl, EGLConfig config) {

- <span class="comment">// TODO Auto-generated method stub</span>

- Log.i(TAG, <span class="string">&#8220;onSurfaceCreated&#8230;&#8221;</span>);

- mTextureID = createTextureID();

- mSurface = <span class="keyword">new</span> SurfaceTexture(mTextureID);

- mSurface.setOnFrameAvailableListener(<span class="keyword">this</span>);

- mDirectDrawer = <span class="keyword">new</span> DirectDrawer(mTextureID);

- CameraInterface.getInstance().doOpenCamera(<span class="keyword">null</span>);

- 
- }

- <span class="annotation">@Override</span>

- <span class="keyword">public</span> <span class="keyword">void</span> onSurfaceChanged(GL10 gl, <span class="keyword">int</span> width, <span class="keyword">int</span> height) {

- <span class="comment">// TODO Auto-generated method stub</span>

- Log.i(TAG, <span class="string">&#8220;onSurfaceChanged&#8230;&#8221;</span>);

- GLES20.glViewport(<span class="number"></span>, <span class="number"></span>, width, height);

- <span class="keyword">if</span>(!CameraInterface.getInstance().isPreviewing()){

- CameraInterface.getInstance().doStartPreview(mSurface, <span class="number">1</span>.33f);

- }

- 
- 
- }

- <span class="annotation">@Override</span>

- <span class="keyword">public</span> <span class="keyword">void</span> onDrawFrame(GL10 gl) {

- <span class="comment">// TODO Auto-generated method stub</span>

- Log.i(TAG, <span class="string">&#8220;onDrawFrame&#8230;&#8221;</span>);

- GLES20.glClearColor(<span class="number">1</span>.0f, <span class="number">1</span>.0f, <span class="number">1</span>.0f, <span class="number">1</span>.0f);

- GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT | GLES20.GL_DEPTH_BUFFER_BIT);

- mSurface.updateTexImage();

- <span class="keyword">float</span>[] mtx = <span class="keyword">new</span> <span class="keyword">float</span>[<span class="number">16</span>];

- mSurface.getTransformMatrix(mtx);

- mDirectDrawer.draw(mtx);

- }

- 
- <span class="annotation">@Override</span>

- <span class="keyword">public</span> <span class="keyword">void</span> onPause() {

- <span class="comment">// TODO Auto-generated method stub</span>

- <span class="keyword">super</span>.onPause();

- CameraInterface.getInstance().doStopCamera();

- }

- <span class="keyword">private</span> <span class="keyword">int</span> createTextureID()

- {

- <span class="keyword">int</span>[] texture = <span class="keyword">new</span> <span class="keyword">int</span>[<span class="number">1</span>];

- 
- GLES20.glGenTextures(<span class="number">1</span>, texture, <span class="number"></span>);

- GLES20.glBindTexture(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, texture[<span class="number"></span>]);

- GLES20.glTexParameterf(GLES11Ext.GL_TEXTURE_EXTERNAL_OES,

- GL10.GL_TEXTURE_MIN_FILTER,GL10.GL_LINEAR);

- GLES20.glTexParameterf(GLES11Ext.GL_TEXTURE_EXTERNAL_OES,

- GL10.GL_TEXTURE_MAG_FILTER, GL10.GL_LINEAR);

- GLES20.glTexParameteri(GLES11Ext.GL_TEXTURE_EXTERNAL_OES,

- GL10.GL_TEXTURE_WRAP_S, GL10.GL_CLAMP_TO_EDGE);

- GLES20.glTexParameteri(GLES11Ext.GL_TEXTURE_EXTERNAL_OES,

- GL10.GL_TEXTURE_WRAP_T, GL10.GL_CLAMP_TO_EDGE);

- 
- <span class="keyword">return</span> texture[<span class="number"></span>];

- }

- <span class="keyword">public</span> SurfaceTexture _getSurfaceTexture(){

- <span class="keyword">return</span> mSurface;

- }

- <span class="annotation">@Override</span>

- <span class="keyword">public</span> <span class="keyword">void</span> onFrameAvailable(SurfaceTexture surfaceTexture) {

- <span class="comment">// TODO Auto-generated method stub</span>

- Log.i(TAG, <span class="string">&#8220;onFrameAvailable&#8230;&#8221;</span>);

- <span class="keyword">this</span>.requestRender();

- }

- 
- }

- </span>

关于这个类进行简单说明:

1、 Renderer这个接口里有三个回调: onSurfaceCreated() onSurfaceChanged() onDrawFrame(), 在onSurfaceCreated里设置了GLSurfaceView的版本: setEGLContextClientVersion(2); 如果没这个设置是啥都画不出来了，因为Android支持OpenGL ES1.1和2.0及最新的3.0，而且版本间差别很大。不告诉他版本他不知道用哪个版本的api渲染。在设置setRenderer(this);后，再设置它的模式为RENDERMODE_WHEN_DIRTY。这个也很关键，看api：

When renderMode is RENDERMODE_CONTINUOUSLY, the renderer is called repeatedly to re-render the scene. When renderMode is RENDERMODE_WHEN_DIRTY, the renderer only rendered when the surface is created, or when [requestRender](http://blog.csdn.net/huiguixian/article/details/36900865) is called. Defaults to RENDERMODE_CONTINUOUSLY.

Using RENDERMODE_WHEN_DIRTY can improve battery life and overall system performance by allowing the GPU and CPU to idle when the view does not need to be updated.

大意是 RENDERMODE_CONTINUOUSLY模式就会一直Render，如果设置成RENDERMODE_WHEN_DIRTY，就是当有数据时才 rendered或者主动调用了GLSurfaceView的requestRender.默认是连续模式，很显然Camera适合脏模式，一秒30帧，当有数据来时再渲染。

2、正因是RENDERMODE_WHEN_DIRTY所以就要告诉GLSurfaceView什么时候Render，也就是啥时候进到 onDrawFrame()这个函数里。SurfaceTexture.OnFrameAvailableListener这个接口就干了这么一件事，当有数据上来后会进到

public void onFrameAvailable(SurfaceTexture surfaceTexture) {
// TODO Auto-generated method stub
Log.i(TAG, “onFrameAvailable…”);
this.requestRender();
}

这里，然后执行requestRender()。

3、网上有一些OpenGL ES的示例是在Activity里实现了SurfaceTexture.OnFrameAvailableListener此接口，其实这个无所谓。无论是被谁实现，关键看在回调里干了什么事。

4、与TextureView里对比可知，TextureView预览时因为实现了SurfaceTextureListener会自动创建SurfaceTexture。但在GLSurfaceView里则要手动创建同时绑定一个纹理ID。

5、本文在onSurfaceCreated()里打开Camera，在onSurfaceChanged()里开启预览，默认1.33的比例。原因是相比前两种预览，此处SurfaceTexture创建需要一定时间。如果想要开预览时由Activity发起，则要GLSurfaceView利用 Handler将创建的SurfaceTexture传递给Activity。

二、DirectDrawer.java 此类非常关键，负责将SurfaceTexture内容绘制到屏幕上

  <div>
  </div>
  
  <div>
    <embed id="ZeroClipboardMovie_2" src="http://static.blog.csdn.net/scripts/ZeroClipboard/ZeroClipboard.swf" type="application/x-shockwave-flash" width="24" height="13" align="middle" name="ZeroClipboardMovie_2">
    </embed>
  </div>
</div>

- <span style=<span class="string">&#8220;font-family:Comic Sans MS;font-size:18px;&#8221;</span>><span class="keyword">package</span> org.yanzi.camera.preview;

- 
- <span class="keyword">import</span> java.nio.ByteBuffer;

- <span class="keyword">import</span> java.nio.ByteOrder;

- <span class="keyword">import</span> java.nio.FloatBuffer;

- <span class="keyword">import</span> java.nio.ShortBuffer;

- 
- <span class="keyword">import</span> android.opengl.GLES11Ext;

- <span class="keyword">import</span> android.opengl.GLES20;

- <span class="keyword">import</span> android.opengl.Matrix;

- 
- <span class="keyword">public</span> <span class="keyword">class</span> DirectDrawer {

- <span class="keyword">private</span> <span class="keyword">final</span> String vertexShaderCode =

- <span class="string">&#8220;attribute vec4 vPosition;&#8221;</span> +

- <span class="string">&#8220;attribute vec2 inputTextureCoordinate;&#8221;</span> +

- <span class="string">&#8220;varying vec2 textureCoordinate;&#8221;</span> +

- <span class="string">&#8220;void main()&#8221;</span> +

- <span class="string">&#8220;{&#8220;</span>+

- <span class="string">&#8220;gl_Position = vPosition;&#8221;</span>+

- <span class="string">&#8220;textureCoordinate = inputTextureCoordinate;&#8221;</span> +

- <span class="string">&#8220;}&#8221;</span>;

- 
- <span class="keyword">private</span> <span class="keyword">final</span> String fragmentShaderCode =

- <span class="string">&#8220;#extension GL_OES_EGL_image_external : require\n&#8221;</span>+

- <span class="string">&#8220;precision mediump float;&#8221;</span> +

- <span class="string">&#8220;varying vec2 textureCoordinate;\n&#8221;</span> +

- <span class="string">&#8220;uniform samplerExternalOES s_texture;\n&#8221;</span> +

- <span class="string">&#8220;void main() {&#8220;</span> +

- <span class="string">&#8221;  gl_FragColor = texture2D( s_texture, textureCoordinate );\n&#8221;</span> +

- <span class="string">&#8220;}&#8221;</span>;

- 
- <span class="keyword">private</span> FloatBuffer vertexBuffer, textureVerticesBuffer;

- <span class="keyword">private</span> ShortBuffer drawListBuffer;

- <span class="keyword">private</span> <span class="keyword">final</span> <span class="keyword">int</span> mProgram;

- <span class="keyword">private</span> <span class="keyword">int</span> mPositionHandle;

- <span class="keyword">private</span> <span class="keyword">int</span> mTextureCoordHandle;

- 
- <span class="keyword">private</span> <span class="keyword">short</span> drawOrder[] = { <span class="number"></span>, <span class="number">1</span>, <span class="number">2</span>, <span class="number"></span>, <span class="number">2</span>, <span class="number">3</span> }; <span class="comment">// order to draw vertices</span>

- 
- <span class="comment">// number of coordinates per vertex in this array</span>

- <span class="keyword">private</span> <span class="keyword">static</span> <span class="keyword">final</span> <span class="keyword">int</span> COORDS_PER_VERTEX = <span class="number">2</span>;

- 
- <span class="keyword">private</span> <span class="keyword">final</span> <span class="keyword">int</span> vertexStride = COORDS_PER_VERTEX * <span class="number">4</span>; <span class="comment">// 4 bytes per vertex</span>

- 
- <span class="keyword">static</span> <span class="keyword">float</span> squareCoords[] = {

- &#8211;<span class="number">1</span>.0f,  <span class="number">1</span>.0f,

- &#8211;<span class="number">1</span>.0f, &#8211;<span class="number">1</span>.0f,

- <span class="number">1</span>.0f, &#8211;<span class="number">1</span>.0f,

- <span class="number">1</span>.0f,  <span class="number">1</span>.0f,

- };

- 
- <span class="keyword">static</span> <span class="keyword">float</span> textureVertices[] = {

- <span class="number"></span>.0f, <span class="number">1</span>.0f,

- <span class="number">1</span>.0f, <span class="number">1</span>.0f,

- <span class="number">1</span>.0f, <span class="number"></span>.0f,

- <span class="number"></span>.0f, <span class="number"></span>.0f,

- };

- 
- <span class="keyword">private</span> <span class="keyword">int</span> texture;

- 
- <span class="keyword">public</span> DirectDrawer(<span class="keyword">int</span> texture)

- {

- <span class="keyword">this</span>.texture = texture;

- <span class="comment">// initialize vertex byte buffer for shape coordinates</span>

- ByteBuffer bb = ByteBuffer.allocateDirect(squareCoords.length * <span class="number">4</span>);

- bb.order(ByteOrder.nativeOrder());

- vertexBuffer = bb.asFloatBuffer();

- vertexBuffer.put(squareCoords);

- vertexBuffer.position(<span class="number"></span>);

- 
- <span class="comment">// initialize byte buffer for the draw list</span>

- ByteBuffer dlb = ByteBuffer.allocateDirect(drawOrder.length * <span class="number">2</span>);

- dlb.order(ByteOrder.nativeOrder());

- drawListBuffer = dlb.asShortBuffer();

- drawListBuffer.put(drawOrder);

- drawListBuffer.position(<span class="number"></span>);

- 
- ByteBuffer bb2 = ByteBuffer.allocateDirect(textureVertices.length * <span class="number">4</span>);

- bb2.order(ByteOrder.nativeOrder());

- textureVerticesBuffer = bb2.asFloatBuffer();

- textureVerticesBuffer.put(textureVertices);

- textureVerticesBuffer.position(<span class="number"></span>);

- 
- <span class="keyword">int</span> vertexShader    = loadShader(GLES20.GL_VERTEX_SHADER, vertexShaderCode);

- <span class="keyword">int</span> fragmentShader  = loadShader(GLES20.GL_FRAGMENT_SHADER, fragmentShaderCode);

- 
- mProgram = GLES20.glCreateProgram();             <span class="comment">// create empty OpenGL ES Program</span>

- GLES20.glAttachShader(mProgram, vertexShader);   <span class="comment">// add the vertex shader to program</span>

- GLES20.glAttachShader(mProgram, fragmentShader); <span class="comment">// add the fragment shader to program</span>

- GLES20.glLinkProgram(mProgram);                  <span class="comment">// creates OpenGL ES program executables</span>

- }

- 
- <span class="keyword">public</span> <span class="keyword">void</span> draw(<span class="keyword">float</span>[] mtx)

- {

- GLES20.glUseProgram(mProgram);

- 
- GLES20.glActiveTexture(GLES20.GL_TEXTURE0);

- GLES20.glBindTexture(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, texture);

- 
- <span class="comment">// get handle to vertex shader&#8217;s vPosition member</span>

- mPositionHandle = GLES20.glGetAttribLocation(mProgram, <span class="string">&#8220;vPosition&#8221;</span>);

- 
- <span class="comment">// Enable a handle to the triangle vertices</span>

- GLES20.glEnableVertexAttribArray(mPositionHandle);

- 
- <span class="comment">// Prepare the <insert shape here> coordinate data</span>

- GLES20.glVertexAttribPointer(mPositionHandle, COORDS_PER_VERTEX, GLES20.GL_FLOAT, <span class="keyword">false</span>, vertexStride, vertexBuffer);

- 
- mTextureCoordHandle = GLES20.glGetAttribLocation(mProgram, <span class="string">&#8220;inputTextureCoordinate&#8221;</span>);

- GLES20.glEnableVertexAttribArray(mTextureCoordHandle);

- 
- <span class="comment">//        textureVerticesBuffer.clear();</span>

- <span class="comment">//        textureVerticesBuffer.put( transformTextureCoordinates( textureVertices, mtx ));</span>

- <span class="comment">//        textureVerticesBuffer.position(0);</span>

- GLES20.glVertexAttribPointer(mTextureCoordHandle, COORDS_PER_VERTEX, GLES20.GL_FLOAT, <span class="keyword">false</span>, vertexStride, textureVerticesBuffer);

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

- 
- <span class="comment">// Disable vertex array</span>

- GLES20.glDisableVertexAttribArray(mPositionHandle);

- GLES20.glDisableVertexAttribArray(mTextureCoordHandle);

- }

- 
- <span class="keyword">private</span>  <span class="keyword">int</span> loadShader(<span class="keyword">int</span> type, String shaderCode){

- 
- <span class="comment">// create a vertex shader type (GLES20.GL_VERTEX_SHADER)</span>

- <span class="comment">// or a fragment shader type (GLES20.GL_FRAGMENT_SHADER)</span>

- <span class="keyword">int</span> shader = GLES20.glCreateShader(type);

- 
- <span class="comment">// add the source code to the shader and compile it</span>

- GLES20.glShaderSource(shader, shaderCode);

- GLES20.glCompileShader(shader);

- 
- <span class="keyword">return</span> shader;

- }

- <span class="keyword">private</span> <span class="keyword">float</span>[] transformTextureCoordinates( <span class="keyword">float</span>[] coords, <span class="keyword">float</span>[] matrix)

- {

- <span class="keyword">float</span>[] result = <span class="keyword">new</span> <span class="keyword">float</span>[ coords.length ];

- <span class="keyword">float</span>[] vt = <span class="keyword">new</span> <span class="keyword">float</span>[<span class="number">4</span>];

- 
- <span class="keyword">for</span> ( <span class="keyword">int</span> i = <span class="number"></span> ; i < coords.length ; i += <span class="number">2</span> ) {

- <span class="keyword">float</span>[] v = { coords[i], coords[i+<span class="number">1</span>], <span class="number"></span> , <span class="number">1</span>  };

- Matrix.multiplyMV(vt, <span class="number"></span>, matrix, <span class="number"></span>, v, <span class="number"></span>);

- result[i] = vt[<span class="number"></span>];

- result[i+<span class="number">1</span>] = vt[<span class="number">1</span>];

- }

- <span class="keyword">return</span> result;

- }

- }

- </span>

三、有了上面两个类就完成95%的工作，可以将GLSurfaceView看成是有生命周期的。在onPause里进行关闭Camera，在Activity里复写两个方法:

  <div>
  </div>
  
  <div>
    <embed id="ZeroClipboardMovie_3" src="http://static.blog.csdn.net/scripts/ZeroClipboard/ZeroClipboard.swf" type="application/x-shockwave-flash" width="24" height="13" align="middle" name="ZeroClipboardMovie_3">
    </embed>
  </div>
</div>

- <span style=<span class="string">&#8220;font-family:Comic Sans MS;font-size:18px;&#8221;</span>>    <span class="annotation">@Override</span>

- <span class="keyword">protected</span> <span class="keyword">void</span> onResume() {

- <span class="comment">// TODO Auto-generated method stub</span>

- <span class="keyword">super</span>.onResume();

- glSurfaceView.bringToFront();

- }

- 
- <span class="annotation">@Override</span>

- <span class="keyword">protected</span> <span class="keyword">void</span> onPause() {

- <span class="comment">// TODO Auto-generated method stub</span>

- <span class="keyword">super</span>.onPause();

- glSurfaceView.onPause();

- }</span>

这个glSurfaceView.bringToFront();其实不写也中。在布局里写入自定义的GLSurfaceView就ok了:

**[html]** [view plain](http://blog.csdn.net/yanzi1225627/article/details/33339965#)[copy](http://blog.csdn.net/yanzi1225627/article/details/33339965#)[print](http://blog.csdn.net/yanzi1225627/article/details/33339965#)[?](http://blog.csdn.net/yanzi1225627/article/details/33339965#)[![在CODE上查看代码片](https://code.csdn.net/assets/CODE_ico.png)](https://code.csdn.net/snippets/402612)[![派生到我的代码片](https://code.csdn.net/assets/ico_fork.svg)](https://code.csdn.net/snippets/402612/fork)

  <div>
  </div>
  
  <div>
    <embed id="ZeroClipboardMovie_4" src="http://static.blog.csdn.net/scripts/ZeroClipboard/ZeroClipboard.swf" type="application/x-shockwave-flash" width="24" height="13" align="middle" name="ZeroClipboardMovie_4">
    </embed>
  </div>
</div>

- <span class="tag"><</span><span class="tag-name">span</span> <span class="attribute">style</span>=<span class="attribute-value">&#8220;font-family:Comic Sans MS;font-size:18px;&#8221;</span><span class="tag">></span>    <span class="tag"><</span><span class="tag-name">FrameLayout</span>

- <span class="attribute">android:layout_width</span>=<span class="attribute-value">&#8220;wrap_content&#8221;</span>

- <span class="attribute">android:layout_height</span>=<span class="attribute-value">&#8220;wrap_content&#8221;</span> <span class="tag">></span>

- <span class="tag"><</span><span class="tag-name">org.yanzi.camera.preview.CameraGLSurfaceView</span>

- <span class="attribute">android:id</span>=<span class="attribute-value">&#8220;@+id/camera_textureview&#8221;</span>

- <span class="attribute">android:layout_width</span>=<span class="attribute-value">&#8220;0dip&#8221;</span>

- <span class="attribute">android:layout_height</span>=<span class="attribute-value">&#8220;0dip&#8221;</span> <span class="tag">/></span>

- <span class="tag"></</span><span class="tag-name">FrameLayout</span><span class="tag">></span><span class="tag"></</span><span class="tag-name">span</span><span class="tag">></span>

CameraActivity里只负责UI部分，CameraGLSurfaceView负责开Camera、预览，并调用DirectDrawer里的draw()进行绘制。其他代码就不上了。

注意事项:

1、**在onDrawFrame()里，如果不调用mDirectDrawer.draw(mtx);是啥都显示不出来的！！！**这是GLSurfaceView的特别之处。为啥呢？因为GLSurfaceView不是Android亲生的，而Surfaceview和TextureView是。所以得自己按照OpenGL ES的流程画。

2、究竟 mDirectDrawer.draw(mtx)里在哪获取的Buffer目前杂家还么看太明白，貌似么有请求buffer，而是根据 GLSurfaceView里创建的SurfaceTexture之前，生成的有个纹理ID。这个纹理ID一方面跟SurfaceTexture是绑定在一起的，另一方面跟DirectDrawer绑定，而SurfaceTexture作渲染载体。

3、参考链接里有,有人为了解决问题，给出了下面三段代码:

@Override
public void onDrawFrame(GL10 gl)
{
    float[] mtx = new float[16];
    mSurface.updateTexImage();
    mSurface.getTransformMatrix(mtx);    

    mDirectVideo.draw(mtx);
}

 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;
 }

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

我已经把代码都融入到了此demo，只不过在draw()方法里么有使用。原因是使用之后，得到的预览画面反而是变形的，而不用的话是ok的。上面的代码是得到SurfaceTexture的变换矩阵：mSurface.getTransformMatrix

然后将此矩阵传递给draw()，在draw的时候对textureVerticesBuffer作一个变化，然后再画。

下图是未加这个矩阵变换效果时: