使用TextureView setTransform(Matrix)方法，解决Camera显示变形问题

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使用SurfaceView和TextureView进行Camera开发的时候不可避免的会遇到一个问题：Camera 显示图像变形，图像被拉伸或者手机旋转一定角度(小于90度)图像变形。

总结有三种方法可以解决这个问题：

1. 自定义layout,将SurfaceView 和 TextureView addView到此layout,然后通过onLayou, onMeasue，控制SurfaceView及TextureView大小。

2. 使用SurfaceView和TextureView自带的setLayoutParams(params) 属性设置控件大小。

3. 通过TextureView 的setTransform(matrix)方法，控制Camera显示范围 (SurfaceView没有 setTransform 属性)

下面是TextureView使用 setTransform(matrix)方法控制Camera显示范围的代码

public class MainActivity extends Activity implements SurfaceTextureListener,

OnLayoutChangeListener {
private TextureView textureView;
Matrix matrix;
Camera camera;
int mWidth = 0;
int mHeight = 0;
int mDisplayWidth = 0;
int mDisplayHeight = 0;
int mPreviewWidth = 640;
int mPreviewHeight = 480;
int orientation = 0;


@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
textureView = (TextureView) findViewById(R.id.texture);
textureView.addOnLayoutChangeListener(this);
textureView.setSurfaceTextureListener(this);
camera = Camera.open();
}


@Override
public void onLayoutChange(View v, int left, int top, int right,
int bottom, int oldLeft, int oldTop, int oldRight, int oldBottom) {
// TODO Auto-generated method stub
mWidth = right - left;
mHeight = bottom - top;
}


@Override
public void onSurfaceTextureAvailable(SurfaceTexture surface, int width,
int height) {
// TODO Auto-generated method stub
RectF previewRect = new RectF(0, 0, mWidth, mHeight);
double aspect = (double) mPreviewWidth / mPreviewHeight;

        if (getResources().getConfiguration().orientation
                == Configuration.ORIENTATION_PORTRAIT) {
        aspect = 1 / aspect;
        }

if(mWidth < (mHeight * aspect)) {
mDisplayWidth = mWidth;
mDisplayHeight = (int) (mHeight * aspect + .5);
} else {  
mDisplayWidth = (int) (mWidth / aspect + .5);
mDisplayHeight = mHeight;
}

RectF surfaceDimensions = new RectF(0,0,mDisplayWidth,mDisplayHeight);
Matrix matrix = new Matrix();
matrix.setRectToRect(previewRect, surfaceDimensions, Matrix.ScaleToFit.FILL);
textureView.setTransform(matrix);
Camera.Parameters param = camera.getParameters();
int displayRotation = 0;

        WindowManager windowManager = (WindowManager) MainActivity.this
                .getSystemService(Context.WINDOW_SERVICE);
int rotation = windowManager.getDefaultDisplay().getRotation();


        switch (rotation) {
            case Surface.ROTATION_0:
            displayRotation =  0;
            break;
            case Surface.ROTATION_90:
            displayRotation =  90;
            break;
            case Surface.ROTATION_180:
            displayRotation =  180;
            break;
            case Surface.ROTATION_270:
            displayRotation =  270;
            break;
        }       

Camera.CameraInfo info = new Camera.CameraInfo();
Camera.getCameraInfo(0, info);

if(info.facing == Camera.CameraInfo.CAMERA_FACING_BACK){
orientation = (info.orientation - displayRotation + 360)% 360;
} else { 
orientation = (info.orientation + displayRotation)% 360;
orientation = (360 - orientation) % 360;
}

param.setPreviewSize(mPreviewWidth, mPreviewHeight);
camera.setParameters(param);
camera.setDisplayOrientation(orientation);
try {
camera.setPreviewTexture(surface);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
camera.startPreview();
}


@Override
public boolean onSurfaceTextureDestroyed(SurfaceTexture surface) {
// TODO Auto-generated method stub
camera.stopPreview();
camera.release();
camera = null;
return true;
}


@Override
public void onSurfaceTextureSizeChanged(SurfaceTexture arg0, int width,
int height) {
// TODO Auto-generated method stub
}


@Override
public void onSurfaceTextureUpdated(SurfaceTexture arg0) {
// TODO Auto-generated method stub
}
}