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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_tstatus=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_entryentry;status=ACameraMetadata_getConstEntry(characteristics,ACAMERA_FLASH_INFO_AVAILABLE,&entry);CHECK(status==ACAMERA_OK);uint32_tis_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:
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Missing the information I need","missingTheInformationINeed","thumb-down"],["Too complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-07-14 UTC."],[[["\u003cp\u003eUsing the device's flash during an AR session can enhance visibility in low-light environments.\u003c/p\u003e\n"],["\u003cp\u003eBefore enabling the flash, verify if the active camera configuration supports it using provided code snippets to check for flash availability.\u003c/p\u003e\n"],["\u003cp\u003eEnable the flash by configuring the AR session with \u003ccode\u003eAR_FLASH_MODE_TORCH\u003c/code\u003e and disable it using \u003ccode\u003eAR_FLASH_MODE_OFF\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eAlthough attempting to enable flash on unsupported devices won't cause errors, it also won't have any effect on the session.\u003c/p\u003e\n"]]],["To use a flash unit during an AR session, first verify if the current camera configuration supports it. Retrieve the camera's characteristics and check for `ACAMERA_FLASH_INFO_AVAILABLE_TRUE`. If supported, use `ArConfig_setFlashMode` with `AR_FLASH_MODE_TORCH` to enable it and configure the session. To disable, use `AR_FLASH_MODE_OFF` instead. Note that setting the flash mode on an unsupported camera will have no effect.\n"],null,["# Use the device's flash unit on Android NDK (C)\n\n\u003cbr /\u003e\n\nEnabling the device's flash unit during an AR session can help improve\nvisibility.\n\nCheck that the current camera configuration supports flash\n----------------------------------------------------------\n\nNot all camera configurations support enabling a flash unit.\nBefore enabling the flash or offering users the option to enable the flash,\nensure that the flash unit is available for the active camera\nconfiguration: \n\n```c\n// Get the camera ID from the current session.\nArCameraConfig* ar_camera_config = NULL;\nArCameraConfig_create(ar_session, &ar_camera_config);\nArSession_getCameraConfig(ar_session, ar_camera_config);\nchar* camera_id = NULL;\nArCameraConfig_getCameraId(ar_session, ar_camera_config, &camera_id);\nArCameraConfig_destroy(ar_camera_config);\n\n// Get the camera characteristics.\nACameraManager* camera_manager = ACameraManager_create();\nCHECK(camera_manager != NULL);\nACameraMetadata* characteristics = NULL;\ncamera_status_t status = ACameraManager_getCameraCharacteristics(camera_manager, camera_id, &characteristics);\nArString_release(camera_id);\nCHECK(status == ACAMERA_OK);\nCHECK(characteristics != NULL);\n\n// Check if flash is supported.\nACameraMetadata_const_entry entry;\nstatus = ACameraMetadata_getConstEntry(characteristics, ACAMERA_FLASH_INFO_AVAILABLE, &entry);\nCHECK(status == ACAMERA_OK);\nuint32_t is_flash_supported = false;\nif (entry.count == 1 && entry.data.u8[0] == ACAMERA_FLASH_INFO_AVAILABLE_TRUE) {\n is_flash_supported = true;\n}\n\nACameraManager_delete(camera_manager);\n```\n\nEnable the flash unit\n---------------------\n\nEnable the flash unit by configuring the AR session with\n[`AR_FLASH_MODE_TORCH`](/ar/reference/c/group/ar-config#arflashmode): \n\n```c\nArConfig* ar_config = NULL;\nArConfig_create(ar_session, &ar_config);\nArSession_getConfig(ar_session, ar_config);\nif (is_flash_supported) {\n ArConfig_setFlashMode(ar_session, ar_config, AR_FLASH_MODE_TORCH);\n}\nCHECK(ArSession_configure(ar_session, ar_config) == AR_SUCCESS);\nArConfig_destroy(ar_config);\n```\n| **Note:** Configuring [`AR_FLASH_MODE_TORCH`](/ar/reference/c/group/ar-config#arflashmode) with a camera configuration that does not support a flash unit will have no effect.\n\nDisable the flash unit\n----------------------\n\nDisable the flash unit by configuring the AR session with\n[`AR_FLASH_MODE_OFF`](/ar/reference/c/group/ar-config#arflashmode): \n\n```c\nArConfig* ar_config = NULL;\nArConfig_create(ar_session, &ar_config);\nArSession_getConfig(ar_session, ar_config);\nif (is_flash_supported) {\n ArConfig_setFlashMode(ar_session, ar_config, AR_FLASH_MODE_OFF);\n}\nCHECK(ArSession_configure(ar_session, ar_config) == AR_SUCCESS);\nArConfig_destroy(ar_config);\n```"]]
