I want to implement a custom camera. There is a rectangular frame in the middle of the camera preview interface, and the other parts are translucent. Then I want to get the picture in the rectangular frame. Can anyone give me some advice? Similar to the effect below. 
高洛峰2017-05-16 13:29:07
Recommended for reference
zxing
Its QR code scanning interface has an effect similar to what you need