C# Camera.SetPreviewCallback方法代码示例

			public void SurfaceCreated (ISurfaceHolder holder)
			{
				try {
					camera = Camera.Open ();
					camera.SetPreviewDisplay (holder);
					camera.SetPreviewCallback (this);

				} catch (Exception e) {
					ShutdownCamera ();

					// TODO: log or otherwise handle this exception

					throw;
				}
			}

        public void OnSurfaceTextureAvailable(Android.Graphics.SurfaceTexture surface, int width, int height)
        {
            _camera = Camera.Open ();
            ConfigureCamera ();

            Preview preview = new Preview ();
            preview.OnFrame += OnPreviewFrame;
            _camera.SetPreviewCallback (preview);

            _textureView.LayoutParameters = new FrameLayout.LayoutParams (width, height);

            try {
                _camera.SetPreviewTexture (surface);
                _camera.StartPreview ();

            } catch (Exception e) {
                Console.WriteLine (e.Message);
            }
        }

		public void OnPreviewFrame (byte[] data, Camera camera)
		{
			var parameters = camera.GetParameters ();
			var size = parameters.PreviewSize;

			var barcode = new Image (size.Width, size.Height, "Y800");
			barcode.SetData (data);

			var result = scanner.ScanImage (barcode);

			if (result == 0)
				return;
			

			camera.SetPreviewCallback (null);
			camera.StopPreview ();

			var scannerResult = GetScannerResult ();

			ScanComplete?.Invoke (this, new ScanCompleteEventArgs (scannerResult));
		}

		public void SurfaceCreated (ISurfaceHolder holder)
		{
			try {
				Console.WriteLine("Surface created");

				camera = Android.Hardware.Camera.Open ();
				camera.SetPreviewDisplay (holder);
				camera.SetPreviewCallback (this);

				Console.WriteLine("Surface Created end");

			} catch (Exception) {
				ShutdownCamera ();
				Console.WriteLine("Exception, shutdown camera");

				// TODO: log or otherwise handle this exception

				//throw;
			}
		}

		public void SurfaceCreated (ISurfaceHolder holder)
		{
			try 
			{
#if __ANDROID_9__

				var numCameras = Android.Hardware.Camera.NumberOfCameras;
				var camInfo = new Android.Hardware.Camera.CameraInfo();
				var found = false;

				for (int i = 0; i < numCameras; i++)
				{
					Android.Hardware.Camera.GetCameraInfo(i, camInfo);
					if (camInfo.Facing == CameraFacing.Back)
					{
						camera = Android.Hardware.Camera.Open(i);
						found = true;
						break;
					}
				}

				if (!found)
				{
					Android.Util.Log.Debug("ZXing.Net.Mobile", "Finding rear camera failed, opening camera 0...");
					camera = Android.Hardware.Camera.Open(0);
				}
#else
				camera = Android.Hardware.Camera.Open();
#endif
				if (camera == null)
					Android.Util.Log.Debug("ZXing.Net.Mobile", "Camera is null :(");


				//camera = Android.Hardware.Camera.Open ();
				camera.SetPreviewDisplay (holder);
				camera.SetPreviewCallback (this);

			} catch (Exception ex) {
				ShutdownCamera ();

				// TODO: log or otherwise handle this exception
				Console.WriteLine("Setup Error: " + ex);
				//throw;
			}
		}

        /// <summary>
        /// Create the camera and try to set auto focus with flash
        /// </summary>
        /// <param name="holder"></param>
		public void CreateCamera(ISurfaceHolder holder) {
			try
			{
				_camera = Camera.Open();
				Camera.Parameters p = _camera.GetParameters();
				p.PictureFormat = Android.Graphics.ImageFormatType.Jpeg;
				p.JpegQuality = 100;
				hasAutoFocus = (p.SupportedFocusModes.Contains(Camera.Parameters.FocusModeAuto));
				if (hasAutoFocus)
				{
					p.FocusMode = Camera.Parameters.FocusModeAuto;
					focusReady = true;
				}
				else if (p.SupportedFocusModes.Contains(Camera.Parameters.FocusModeContinuousPicture))
				{
					p.FocusMode = Camera.Parameters.FocusModeContinuousPicture;
				}
				if (p.SupportedFlashModes.Contains(Camera.Parameters.FlashModeOn))
				{
					p.FlashMode = Camera.Parameters.FlashModeOn;
				}
				_camera.SetParameters(p);
				_camera.SetDisplayOrientation(90);
				_camera.SetPreviewCallback(this);
				_camera.Lock();
				_camera.SetPreviewDisplay(holder);
				_camera.StartPreview();
				if (hasAutoFocus)
				{
					Toast.MakeText(this, "Press screen to focus", ToastLength.Long).Show();
				}
			}
			catch (Exception e)
			{
			}
		}