Oppo mobile phone locks the screen, how to cancel taking pictures?

Take the OPPO R9 mobile phone as an example, and the logout method is as follows:

First turn on the OPPO R9 mobile phone, then find the "Settings" item on the desktop of the OPPO R9 mobile phone, and click Enter.

2. After entering the setting interface of OPPO R9 mobile phone, find the item "Camera" in the drop-down menu, and then click Enter.

Third, after entering, find the "flash function" and turn it off.

Fourth, this cancels the function that the mobile phone can still take pictures when the screen is locked.