android画图-----图像预览

真高不明白 图像预览的例子 竟然放在这里，我觉得放在照相机那里边更好一些，这个例子很简单，就是先要获得图像预览的持有者 SurfaceHolder，然后相机通过它得到一个浏览的窗口。但是最主要 也是为啥把这个例子放在这 就是因为SurfaceHolder必须添加一个监听器实现几个接口：
class Preview extends SurfaceView implements SurfaceHolder.Callback {
SurfaceHolder mHolder;
Camera mCamera;

Preview(Context context) {
super(context);

// Install a SurfaceHolder.Callback so we get notified when the
// underlying surface is created and destroyed.
mHolder = getHolder();
mHolder.addCallback(this);
mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}

public void surfaceCreated(SurfaceHolder holder) {
// The Surface has been created, acquire the camera and tell it where
// to draw.
mCamera = Camera.open();
try {
mCamera.setPreviewDisplay(holder);
} catch (IOException exception) {
mCamera.release();
mCamera = null;
// TODO: add more exception handling logic here
}
}

public void surfaceDestroyed(SurfaceHolder holder) {
// Surface will be destroyed when we return, so stop the preview.
// Because the CameraDevice object is not a shared resource, it's very
// important to release it when the activity is paused.
mCamera.stopPreview();
mCamera.release();
mCamera = null;
}

public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
// Now that the size is known, set up the camera parameters and begin
// the preview.
Camera.Parameters parameters = mCamera.getParameters();
parameters.setPreviewSize(w, h);
mCamera.setParameters(parameters);
mCamera.startPreview();
}

}

public class CameraPreview extends Activity {
private Preview mPreview;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);

// Hide the window title.
requestWindowFeature(Window.FEATURE_NO_TITLE);

// Create our Preview view and set it as the content of our activity.
mPreview = new Preview(this);
setContentView(mPreview);
}

}

这里面用到最多的就是相机的设置了不说了。