如何在Android中编程创建双曝光效果？

public class DoubleExposureView extends View {
    private Bitmap mBitmap1;
    private Bitmap mBitmap2;
    private Paint mPaint;

    public DoubleExposureView(Context context) {
        super(context);
        init();
    }

    public DoubleExposureView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    private void init() {
        mPaint = new Paint();
        mPaint.setAlpha(128); // 设置透明度，范围0-255
        mBitmap1 = BitmapFactory.decodeResource(getResources(), R.drawable.image1);
        mBitmap2 = BitmapFactory.decodeResource(getResources(), R.drawable.image2);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        // 绘制第一张图片
        canvas.drawBitmap(mBitmap1, 0, 0, null);
        // 绘制第二张图片，应用透明度以实现双曝光效果
        canvas.drawBitmap(mBitmap2, 0, 0, mPaint);
    }
}