Configure the white balance regions on the camera
camera_error_t camera_set_whitebalance_regions(camera_handle_t handle, int numregions, camera_region_t *regions)
When white balance regions are defined, the auto white balance algorithm gives priority to objects in the defined areas of the scene.
Only call this function if the CAMERA_FEATURE_REGIONWHITEBALANCE feature is available. Use the camera_can_feature() function to determine whether this feature is available.
The maximum number of white balance regions that you can configure is returned by the numsupported argument of the camera_get_whitebalance_regions() function.
After setting the regions, you must call the camera_set_whitebalance_mode() function to commit the changes.
The viewfinder must be running before using this function.
CAMERA_EOK when the function successfully completes, otherwise another camera_error_t value that provides the reason that the call failed.