initCameras method

void initCameras([ CameraDescription? cameraDescription ])

Implementation

void initCameras([CameraDescription? cameraDescription]) {
  final _c = _controllerNotifier.value;
  setState(() {
    _maxAvailableZoom = 1;
    _minAvailableZoom = 1;
    _currentZoom = 1;
    _baseZoom = 1;
    _controllerNotifier.value = null;
    _exposureModeDisplayTimer?.cancel();
    _exposurePointDisplayTimer?.cancel();
    _lastExposurePoint.value = null;
    if (_currentExposureOffset.value != 0) {
      _currentExposureOffset.value = 0;
    }
  });
  // controller has already unbind from widgets.
  SchedulerBinding.instance?.addPostFrameCallback((_) async {
    // Dispose at last to avoid disposed usage with assertions.
    await _c?.dispose();
    // When the [cameraDescription] is null, which means this is the first
    // time initializing cameras, so available cameras should be fetched.
    if (cameraDescription == null) {
      cameras = await availableCameras();
    }
    // After cameras fetched, judge again with the list is empty or not to
    // ensure there is at least an available camera for use.
    if (cameraDescription == null && (cameras.isEmpty)) {
      throw CameraException(
        'No CameraDescription found.',
        'No cameras are available in the controller.',
      );
    }

    // Initialize the controller with the given resolution preset.
    _controllerNotifier.value = CameraController(
      cameraDescription ?? cameras[0],
      widget.resolutionPreset,
      enableAudio: enableAudio,
      imageFormatGroup: widget.imageFormatGroup,
    )..addListener(() {
        if (controller.value.hasError) {
          throw CameraException(
            'CameraController exception',
            controller.value.errorDescription,
          );
        }
      });

    try {
      await controller.initialize();
      await Future.wait<void>(<Future<dynamic>>[
        (() async => _maxAvailableExposureOffset =
            await controller.getMaxExposureOffset())(),
        (() async => _minAvailableExposureOffset =
            await controller.getMinExposureOffset())(),
        (() async =>
            _maxAvailableZoom = await controller.getMaxZoomLevel())(),
        (() async =>
            _minAvailableZoom = await controller.getMinZoomLevel())(),
      ]);
    } catch (_) {
      rethrow;
    } finally {
      safeSetState(() {});
    }
  });
}