未调用Surfaceview surfaceCreated（）函数

Question

我创建了一个Surfaceview来显示我的相机预览。我正在使用onMeasure（）函数在运行时设置表面视图宽度和高度。

如果我从我的onMeasure（）函数中评论“setLayoutParams（lp）”，那么我的表面视图就会被创建并显示相机预览。但它不合适，因为表面宽度和高度不合适能够保持相机预览的宽高比。由于预览看起来有点拉长。为了避免拉伸我正在计算纵横比并且基于纵横比我设置了surfaceview的宽度和高度。这样它就可以显示正确的相机预览。

第一次调用surfaceCreated函数。由于我已经实现了相机切换功能，因此当我切换相机时，会调用surfaceCreated函数，之后它可以正常工作。

您能否告诉我“setLayoutParams（lp）”如何影响Surfaceview的创建？

注意： - 我正在将相机预览对象添加到FrameLayout。这是我片段布局的一部分。

以下是我的CameraPreview课程。

public class CameraPreview extends SurfaceView implements SurfaceHolder.Callback {
String TAG = getClass().getSimpleName();
private SurfaceHolder mHolder;
private Camera        mCamera;
Double  aspectRatio;
Context context;


public CameraPreview(Context context) {
    super(context);
    Log.d(TAG, " CameraPreview constructor");
    this.context = context;
    // Install a SurfaceHolder.Callback so we get notified when the
    // underlying surface is created and destroyed.
    mHolder = getHolder();
    mHolder.addCallback(this);
    // deprecated setting, but required on Android versions prior to 3.0
    mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
    setBackgroundDrawable(getResources().getDrawable(R.drawable.face_capture_layout_border));
}

/**
 * Extract supported preview and flash modes from the camera.
 *
 * @param camera
 */
public void setCamera(Camera camera) {
    mCamera = camera;
    Camera.Parameters params = mCamera.getParameters();
    Camera.Size pictureSize = getLargestPictureSize(params);
    params.setPictureSize(pictureSize.width, pictureSize.height);
    aspectRatio = new Double((float) pictureSize.width / pictureSize.height);
    mCamera.setParameters(params);
    requestLayout();
}

private Camera.Size getLargestPictureSize(Camera.Parameters params) {
    Camera.Size bestSize = null;
    List<Camera.Size> sizeList = params.getSupportedPictureSizes();
    bestSize = sizeList.get(0);
    for (int i = 1; i < sizeList.size(); i++) {
        if ((sizeList.get(i).width * sizeList.get(i).height) >
                (bestSize.width * bestSize.height)) {
            bestSize = sizeList.get(i);
        }
    }
    return bestSize;
}

@Override
public void surfaceCreated(SurfaceHolder holder) {
    Log.d(TAG, " Surface created");
    Surface surface = getHolder().getSurface();
    Log.d(TAG, "Surface is in created valid =>" + surface.isValid());
}

@Override
public void surfaceDestroyed(SurfaceHolder holder) {
    // empty. Take care of releasing the Camera preview in your activity.
    Log.d(TAG, " Surface destroyed");
    // Surface will be destroyed when we return, so stop the preview.
}

void startCameraPreview() {
    // If your preview can change or rotate, take care of those events here.
    // Make sure to stop the preview before resizing or reformatting it.

    if (mHolder.getSurface() == null) {
        // preview surface does not exist
        return;
    }

    // stop preview before making changes
    try {
        mCamera.stopPreview();
    }
    catch (Exception e) {
        // ignore: tried to stop a non-existent preview
    }

    // set preview size and make any resize, rotate or
    // reformatting changes here

    // start preview with new settings
    try {
        mCamera.setPreviewDisplay(mHolder);
        mCamera.startPreview();
    }
    catch (Exception e) {
        Log.d(TAG, "Error starting camera preview: " + e.getMessage());
    }
}

@Override
public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
    Log.d(TAG, " Surface changed");
    startCameraPreview();
}

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    Log.d(TAG, "On measure");
    //Parent frame size
    View parent = (View) getParent();
    int width = parent.getWidth();
    int height = parent.getHeight();
    int surfaceViewWidth = (int) (height / aspectRatio);
    int surfaceViewHeight = (int) (height);
    FrameLayout.LayoutParams lp = new FrameLayout.LayoutParams(surfaceViewWidth, surfaceViewHeight);
    lp.gravity = Gravity.CENTER;
    setLayoutParams(lp);
   super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}

}