Android Camera开发:使用GLSurfaceView预览Camera 基础拍照

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*终于找到了一个可用的链接,,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

 package org.yanzi.camera.preview;

 import javax.microedition.khronos.egl.EGLConfig;
import javax.microedition.khronos.opengles.GL10; import org.yanzi.camera.CameraInterface; import android.content.Context;
import android.graphics.SurfaceTexture;
import android.opengl.GLES11Ext;
import android.opengl.GLES20;
import android.opengl.GLSurfaceView;
import android.opengl.GLSurfaceView.Renderer;
import android.util.AttributeSet;
import android.util.Log; public class CameraGLSurfaceView extends GLSurfaceView implements Renderer, SurfaceTexture.OnFrameAvailableListener {
private static final String TAG = "yanzi";
Context mContext;
SurfaceTexture mSurface;
int mTextureID = -1;
DirectDrawer mDirectDrawer;
public CameraGLSurfaceView(Context context, AttributeSet attrs) {
super(context, attrs);
// TODO Auto-generated constructor stub
mContext = context;
setEGLContextClientVersion(2);
setRenderer(this);
setRenderMode(RENDERMODE_WHEN_DIRTY);
}
@Override
public void onSurfaceCreated(GL10 gl, EGLConfig config) {
// TODO Auto-generated method stub
Log.i(TAG, "onSurfaceCreated...");
mTextureID = createTextureID();
mSurface = new SurfaceTexture(mTextureID);
mSurface.setOnFrameAvailableListener(this);
mDirectDrawer = new DirectDrawer(mTextureID);
CameraInterface.getInstance().doOpenCamera(null); }
@Override
public void onSurfaceChanged(GL10 gl, int width, int height) {
// TODO Auto-generated method stub
Log.i(TAG, "onSurfaceChanged...");
GLES20.glViewport(0, 0, width, height);
if(!CameraInterface.getInstance().isPreviewing()){
CameraInterface.getInstance().doStartPreview(mSurface, 1.33f);
} }
@Override
public void onDrawFrame(GL10 gl) {
// TODO Auto-generated method stub
Log.i(TAG, "onDrawFrame...");
GLES20.glClearColor(1.0f, 1.0f, 1.0f, 1.0f);
GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT | GLES20.GL_DEPTH_BUFFER_BIT);
mSurface.updateTexImage();
float[] mtx = new float[16];
mSurface.getTransformMatrix(mtx);
mDirectDrawer.draw(mtx);
} @Override
public void onPause() {
// TODO Auto-generated method stub
super.onPause();
CameraInterface.getInstance().doStopCamera();
}
private int createTextureID()
{
int[] texture = new int[1]; GLES20.glGenTextures(1, texture, 0);
GLES20.glBindTexture(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, texture[0]);
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); return texture[0];
}
public SurfaceTexture _getSurfaceTexture(){
return mSurface;
}
@Override
public void onFrameAvailable(SurfaceTexture surfaceTexture) {
// TODO Auto-generated method stub
Log.i(TAG, "onFrameAvailable...");
this.requestRender();
} }

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 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

 package org.yanzi.camera.preview;

 import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;
import java.nio.ShortBuffer; import android.opengl.GLES11Ext;
import android.opengl.GLES20;
import android.opengl.Matrix; 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\n"+
"precision mediump float;" +
"varying vec2 textureCoordinate;\n" +
"uniform samplerExternalOES s_texture;\n" +
"void main() {" +
" gl_FragColor = texture2D( s_texture, textureCoordinate );\n" +
"}"; 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, 1.0f,
-1.0f, -1.0f,
1.0f, -1.0f,
1.0f, 1.0f,
}; static float textureVertices[] = {
0.0f, 1.0f,
1.0f, 1.0f,
1.0f, 0.0f,
0.0f, 0.0f,
}; 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;
}
}

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:

       @Override
protected void onResume() {
// TODO Auto-generated method stub
super.onResume();
glSurfaceView.bringToFront();
} @Override
protected void onPause() {
// TODO Auto-generated method stub
super.onPause();
glSurfaceView.onPause();
}

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

    <FrameLayout

        android:layout_width="wrap_content"
android:layout_height="wrap_content" >
<org.yanzi.camera.preview.CameraGLSurfaceView
android:id="@+id/camera_textureview"
android:layout_width="0dip"
android:layout_height="0dip" />
</FrameLayout>

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:

Android Camera开发:使用GLSurfaceView预览Camera 基础拍照

下图为使用了变换矩阵,划片扭曲的还真说不上来咋扭曲的,但足以说明OpenGL ES在渲染效果上的强大,就是设置了个矩阵,不用一帧帧处理,就能得到不一样显示效果。

Android Camera开发:使用GLSurfaceView预览Camera 基础拍照

-----------------------------本文系原创,转载请注明作者yanzi1225627

版本号:PlayCamera_V3.0.0[2014-6-22].zip

CSDN下载链接:http://download.csdn.net/detail/yanzi1225627/7547263

百度云盘:

附个OpenGL ES简明教程:http://www.apkbus.com/android-20427-1-1.html

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