How does OPPO mobile phone take pictures with gestures?

OPPO mobile phone takes pictures with gestures:

When you need to take a long-distance selfie or group photo with the front camera, you can complete the photo by gesture. You don't need to touch the phone buttons, just make a gesture in front of the camera, and you can let the phone take your picture.

Open "Gesture Photo" from the camera settings to complete the settings, so that the camera can automatically capture instructions to shoot. When using this function for the first time, a designated gesture will appear on the screen to guide, just open one hand and aim at the camera, 3? After a few seconds, the camera will automatically shoot.

Note: The operation path refers to ColorOS? 6 system.