Use the device's flash unit on Android NDK (C)

Page Summary

Enabling the device's flash unit during an AR session can improve visibility.
Not all camera configurations support enabling a flash unit, so check for flash support first.
Enable the flash unit by configuring the AR session with AR_FLASH_MODE_TORCH .
Disable the flash unit by configuring the AR session with AR_FLASH_MODE_OFF .

Enabling the device's flash unit during an AR session can help improve visibility.

Check that the current camera configuration supports flash

Not all camera configurations support enabling a flash unit. Before enabling the flash or offering users the option to enable the flash, ensure that the flash unit is available for the active camera configuration:

 // Get the camera ID from the current session. 
 ArCameraConfig 
 * 
  
 ar_camera_config 
  
 = 
  
 NULL 
 ; 
 ArCameraConfig_create 
 ( 
 ar_session 
 , 
  
& ar_camera_config 
 ); 
 ArSession_getCameraConfig 
 ( 
 ar_session 
 , 
  
 ar_camera_config 
 ); 
 char 
 * 
  
 camera_id 
  
 = 
  
 NULL 
 ; 
 ArCameraConfig_getCameraId 
 ( 
 ar_session 
 , 
  
 ar_camera_config 
 , 
  
& camera_id 
 ); 
 ArCameraConfig_destroy 
 ( 
 ar_camera_config 
 ); 
 // Get the camera characteristics. 
 ACameraManager 
 * 
  
 camera_manager 
  
 = 
  
 ACameraManager_create 
 (); 
 CHECK 
 ( 
 camera_manager 
  
 != 
  
 NULL 
 ); 
 ACameraMetadata 
 * 
  
 characteristics 
  
 = 
  
 NULL 
 ; 
 camera_status_t 
  
 status 
  
 = 
  
 ACameraManager_getCameraCharacteristics 
 ( 
 camera_manager 
 , 
  
 camera_id 
 , 
  
& characteristics 
 ); 
 ArString_release 
 ( 
 camera_id 
 ); 
 CHECK 
 ( 
 status 
  
 == 
  
 ACAMERA_OK 
 ); 
 CHECK 
 ( 
 characteristics 
  
 != 
  
 NULL 
 ); 
 // Check if flash is supported. 
 ACameraMetadata_const_entry 
  
 entry 
 ; 
 status 
  
 = 
  
 ACameraMetadata_getConstEntry 
 ( 
 characteristics 
 , 
  
 ACAMERA_FLASH_INFO_AVAILABLE 
 , 
  
& entry 
 ); 
 CHECK 
 ( 
 status 
  
 == 
  
 ACAMERA_OK 
 ); 
 uint32_t 
  
 is_flash_supported 
  
 = 
  
 false 
 ; 
 if 
  
 ( 
 entry 
 . 
 count 
  
 == 
  
 1 
 && 
 entry 
 . 
 data 
 . 
 u8 
 [ 
 0 
 ] 
  
 == 
  
 ACAMERA_FLASH_INFO_AVAILABLE_TRUE 
 ) 
  
 { 
  
 is_flash_supported 
  
 = 
  
 true 
 ; 
 } 
 ACameraManager_delete 
 ( 
 camera_manager 
 );

Enable the flash unit

Enable the flash unit by configuring the AR session with AR_FLASH_MODE_TORCH :

 ArConfig 
 * 
  
 ar_config 
  
 = 
  
 NULL 
 ; 
 ArConfig_create 
 ( 
 ar_session 
 , 
  
& ar_config 
 ); 
 ArSession_getConfig 
 ( 
 ar_session 
 , 
  
 ar_config 
 ); 
 if 
  
 ( 
 is_flash_supported 
 ) 
  
 { 
  
 ArConfig_setFlashMode 
 ( 
 ar_session 
 , 
  
 ar_config 
 , 
  
 AR_FLASH_MODE_TORCH 
 ); 
 } 
 CHECK 
 ( 
 ArSession_configure 
 ( 
 ar_session 
 , 
  
 ar_config 
 ) 
  
 == 
  
 AR_SUCCESS 
 ); 
 ArConfig_destroy 
 ( 
 ar_config 
 );

Disable the flash unit

Disable the flash unit by configuring the AR session with AR_FLASH_MODE_OFF :

 ArConfig 
 * 
  
 ar_config 
  
 = 
  
 NULL 
 ; 
 ArConfig_create 
 ( 
 ar_session 
 , 
  
& ar_config 
 ); 
 ArSession_getConfig 
 ( 
 ar_session 
 , 
  
 ar_config 
 ); 
 if 
  
 ( 
 is_flash_supported 
 ) 
  
 { 
  
 ArConfig_setFlashMode 
 ( 
 ar_session 
 , 
  
 ar_config 
 , 
  
 AR_FLASH_MODE_OFF 
 ); 
 } 
 CHECK 
 ( 
 ArSession_configure 
 ( 
 ar_session 
 , 
  
 ar_config 
 ) 
  
 == 
  
 AR_SUCCESS 
 ); 
 ArConfig_destroy 
 ( 
 ar_config 
 );