According to your description, I guess what you want to ask is how to realize the zoom-in and zoom-out function in Xiaomi camera application. How to change the zoom-in and zoom-out function into a semicircle may be a problem of interface design. The following is the general method to realize the zoom-in and zoom-out function in Xiaomi camera application:

1. Open the Xiaomi camera application.

2. Make sure your phone is in photo mode.

In the lower right corner or the lower left corner of the screen, you will see an icon similar to a magnifying glass. Click the icon.

You can slide two fingers on the screen to enlarge or reduce the picture.

How to change the zoom-in and zoom-out function into a semicircle may require you to modify the Xiaomi camera application or find a third-party camera application to realize it. Please note that modifying system applications may cause system instability or other problems. Be careful if you are not familiar with how to modify the application.

In addition, you can try to search for third-party camera applications in the app store, which may have the semicircle zoom-in and zoom-out function you need. When installing and using third-party applications, please ensure that they come from reliable sources to prevent potential security risks.