C# DirectShow预览摄像头并截图

using DirectShowLib;using System.Runtime.InteropServices;using System.Runtime.InteropServices.ComTypes;using System.Drawing.Imaging;

namespace Test{public partial class FormDirect : Form, ISampleGrabberCB{

private int _previewWidth = 640;private int _previewHeight = 480;private int _previewStride = 0;private int _previewFPS = 30;private volatile bool isGrab = false;

IVideoWindow videoWindow = null;IMediaControl mediaControl = null;IFilterGraph2 graphBuilder = null;ICaptureGraphBuilder2 captureGraphBuilder = null;

DsROTEntry rot = null;

public FormDirect(){InitializeComponent();}

private void button2_Click(object sender, EventArgs e){//截图isGrab = true;

}

private void button3_Click(object sender, EventArgs e){string button_text = button3.Text;if (button_text.Equals("Start Webcam")){button3.Text = "Stop Webcam";StartCamera();}else{button3.Text = "Start Webcam";StopCamera();}}

private void StartCamera(){

DsDevice[] devices = DsDevice.GetDevicesOfCat(FilterCategory.VideoInputDevice);if (devices.Length == 0){MessageBox.Show("No USB webcam connected");button3.Text = "Start Webcam";return;}else{

CaptureVideo(devices[0]);}}

private void StopCamera(){button3.Text = "Start Webcam";CloseInterfaces();}

public void CaptureVideo(DsDevice device){pictureBox1.Image = null;int hr = 0;IBaseFilter sourceFilter = null;ISampleGrabber sampleGrabber = null;

try{// Get DirectShow interfaces GetInterfaces();

// Attach the filter graph to the capture graph hr = this.captureGraphBuilder.SetFiltergraph(this.graphBuilder);DsError.ThrowExceptionForHR(hr);

// Use the system device enumerator and class enumerator to find// a video capture/preview device, such as a desktop USB video camera.

sourceFilter = SelectCaptureDevice(device);// Add Capture filter to graph.

hr = this.graphBuilder.AddFilter(sourceFilter, "Video Capture");DsError.ThrowExceptionForHR(hr);

// Initialize SampleGrabber.

sampleGrabber = new SampleGrabber() as ISampleGrabber;// Configure SampleGrabber. Add preview callback.

ConfigureSampleGrabber(sampleGrabber);// Add SampleGrabber to graph.

hr = this.graphBuilder.AddFilter(sampleGrabber as IBaseFilter, "Frame Callback");DsError.ThrowExceptionForHR(hr);

// Configure preview settings.

SetConfigParams(this.captureGraphBuilder, sourceFilter, _previewFPS, _previewWidth, _previewHeight);

// Render the preview hr = this.captureGraphBuilder.RenderStream(PinCategory.Preview, MediaType.Video, sourceFilter, (sampleGrabber as IBaseFilter),null);

DsError.ThrowExceptionForHR(hr);

SaveSizeInfo(sampleGrabber);

// Set video window style and position SetupVideoWindow();

// Add our graph to the running object table, which will allow// the GraphEdit application to "spy" on our graph rot = new DsROTEntry(this.graphBuilder);

// Start previewing video data hr = this.mediaControl.Run();DsError.ThrowExceptionForHR(hr);}catch{MessageBox.Show("An unrecoverable error has occurred.");}finally{if (sourceFilter != null){Marshal.ReleaseComObject(sourceFilter);sourceFilter = null;}

if (sampleGrabber != null){Marshal.ReleaseComObject(sampleGrabber);sampleGrabber = null;}}}

public void CaptureVideo(){pictureBox1.Image = null;int hr = 0;IBaseFilter sourceFilter = null;ISampleGrabber sampleGrabber = null;

try{// Get DirectShow interfaces GetInterfaces();

// Attach the filter graph to the capture graph hr = this.captureGraphBuilder.SetFiltergraph(this.graphBuilder);DsError.ThrowExceptionForHR(hr);

// Use the system device enumerator and class enumerator to find// a video capture/preview device, such as a desktop USB video camera.

sourceFilter = FindCaptureDevice();// Add Capture filter to graph.

hr = this.graphBuilder.AddFilter(sourceFilter, "Video Capture");DsError.ThrowExceptionForHR(hr);

// Initialize SampleGrabber.

sampleGrabber = new SampleGrabber() as ISampleGrabber;// Configure SampleGrabber. Add preview callback.

ConfigureSampleGrabber(sampleGrabber);

// Add SampleGrabber to graph.

hr = this.graphBuilder.AddFilter(sampleGrabber as IBaseFilter, "Frame Callback");DsError.ThrowExceptionForHR(hr);

// Configure preview settings.

SetConfigParams(this.captureGraphBuilder, sourceFilter, _previewFPS, _previewWidth, _previewHeight);

// Render the preview hr = this.captureGraphBuilder.RenderStream(PinCategory.Preview, MediaType.Video, sourceFilter, (sampleGrabber as IBaseFilter),null);DsError.ThrowExceptionForHR(hr);

SaveSizeInfo(sampleGrabber);

// Set video window style and position SetupVideoWindow();

// Add our graph to the running object table, which will allow// the GraphEdit application to "spy" on our graph rot = new DsROTEntry(this.graphBuilder);

// Start previewing video data hr = this.mediaControl.Run();DsError.ThrowExceptionForHR(hr);}catch{MessageBox.Show("An unrecoverable error has occurred.");}finally{if (sourceFilter != null){Marshal.ReleaseComObject(sourceFilter);sourceFilter = null;}

if (sampleGrabber != null){Marshal.ReleaseComObject(sampleGrabber);sampleGrabber = null;}}}

public IBaseFilter SelectCaptureDevice(DsDevice device){object source = null;Guid iid = typeof(IBaseFilter).GUID;device.Mon.BindToObject(null, null, ref iid, out source);return (IBaseFilter)source;}

public IBaseFilter FindCaptureDevice(){int hr = 0;#if USING_NET11 UCOMIEnumMoniker classEnum = null;UCOMIMoniker[] moniker = new UCOMIMoniker[1];#else IEnumMoniker classEnum = null;IMoniker[] moniker = new IMoniker[1];#endif object source = null;

// Create the system device enumerator ICreateDevEnum devEnum = (ICreateDevEnum)new CreateDevEnum();

// Create an enumerator for the video capture devices hr = devEnum.CreateClassEnumerator(FilterCategory.VideoInputDevice, out classEnum, 0);DsError.ThrowExceptionForHR(hr);

// The device enumerator is no more needed Marshal.ReleaseComObject(devEnum);

// If there are no enumerators for the requested type, then// CreateClassEnumerator will succeed, but classEnum will be NULL.

if (classEnum == null){throw new ApplicationException("No video capture device was detected.\r\n\r\n" +"This sample requires a video capture device, such as a USB WebCam,\r\n" +"to be installed and working properly. The sample will now close.");}

// Use the first video capture device on the device list.

// Note that if the Next() call succeeds but there are no monikers,// it will return 1 (S_FALSE) (which is not a failure). Therefore, we// check that the return code is 0 (S_OK).

#if USING_NET11 int i;if (classEnum.Next (moniker.Length, moniker, IntPtr.Zero) == 0)#else if (classEnum.Next(moniker.Length, moniker, IntPtr.Zero) == 0)#endif{// Bind Moniker to a filter object Guid iid = typeof(IBaseFilter).GUID;moniker[0].BindToObject(null, null, ref iid, out source);}else{throw new ApplicationException("Unable to access video capture device!");}

// Release COM objects Marshal.ReleaseComObject(moniker[0]);Marshal.ReleaseComObject(classEnum);

// An exception is thrown if cast fail return (IBaseFilter)source;}

public void GetInterfaces(){int hr = 0;

// An exception is thrown if cast fail this.graphBuilder = (IFilterGraph2)new FilterGraph();this.captureGraphBuilder = (ICaptureGraphBuilder2)new CaptureGraphBuilder2();this.mediaControl = (IMediaControl)this.graphBuilder;this.videoWindow = (IVideoWindow)this.graphBuilder;

DsError.ThrowExceptionForHR(hr);}

public void CloseInterfaces(){if (mediaControl != null){int hr = mediaControl.StopWhenReady();DsError.ThrowExceptionForHR(hr);}

if (videoWindow != null){videoWindow.put_Visible(OABool.False);videoWindow.put_Owner(IntPtr.Zero);}

// Remove filter graph from the running object table.

if (rot != null){rot.Dispose();rot = null;}

// Release DirectShow interfaces.

Marshal.ReleaseComObject(this.mediaControl); this.mediaControl = null;Marshal.ReleaseComObject(this.videoWindow); this.videoWindow = null;Marshal.ReleaseComObject(this.graphBuilder); this.graphBuilder = null;Marshal.ReleaseComObject(this.captureGraphBuilder); this.captureGraphBuilder = null;}

public void SetupVideoWindow(){int hr = 0;

// Set the video window to be a child of the PictureBox hr = this.videoWindow.put_Owner(pictureBox1.Handle);DsError.ThrowExceptionForHR(hr);

hr = this.videoWindow.put_WindowStyle(WindowStyle.Child);DsError.ThrowExceptionForHR(hr);

// Make the video window visible, now that it is properly positioned hr = this.videoWindow.put_Visible(OABool.True);DsError.ThrowExceptionForHR(hr);

// Set the video position Rectangle rc = pictureBox1.ClientRectangle;hr = videoWindow.SetWindowPosition(0, 0, _previewWidth, _previewHeight);DsError.ThrowExceptionForHR(hr);}

private void SetConfigParams(ICaptureGraphBuilder2 capGraph, IBaseFilter capFilter, int iFrameRate, int iWidth, int iHeight){int hr;object config;AMMediaType mediaType;// Find the stream config interface hr = capGraph.FindInterface(PinCategory.Capture, MediaType.Video, capFilter, typeof(IAMStreamConfig).GUID, out config);

IAMStreamConfig videoStreamConfig = config as IAMStreamConfig;if (videoStreamConfig == null){throw new Exception("Failed to get IAMStreamConfig");}

// Get the existing format block hr = videoStreamConfig.GetFormat(out mediaType);DsError.ThrowExceptionForHR(hr);

// copy out the videoinfoheader VideoInfoHeader videoInfoHeader = new VideoInfoHeader();Marshal.PtrToStructure(mediaType.formatPtr, videoInfoHeader);

// if overriding the framerate, set the frame rate if (iFrameRate > 0){videoInfoHeader.AvgTimePerFrame = 10000000 / iFrameRate;}

// if overriding the width, set the width if (iWidth > 0){videoInfoHeader.BmiHeader.Width = iWidth;}

// if overriding the Height, set the Height if (iHeight > 0){videoInfoHeader.BmiHeader.Height = iHeight;}

// Copy the media structure back Marshal.StructureToPtr(videoInfoHeader, mediaType.formatPtr, false);

// Set the new format hr = videoStreamConfig.SetFormat(mediaType);DsError.ThrowExceptionForHR(hr);

DsUtils.FreeAMMediaType(mediaType);mediaType = null;}

private void SaveSizeInfo(ISampleGrabber sampleGrabber){int hr;

// Get the media type from the SampleGrabber AMMediaType media = new AMMediaType();hr = sampleGrabber.GetConnectedMediaType(media);DsError.ThrowExceptionForHR(hr);

if ((media.formatType != FormatType.VideoInfo) || (media.formatPtr == IntPtr.Zero)){throw new NotSupportedException("Unknown Grabber Media Format");}

// Grab the size info VideoInfoHeader videoInfoHeader = (VideoInfoHeader)Marshal.PtrToStructure(media.formatPtr, typeof(VideoInfoHeader));_previewStride = _previewWidth * (videoInfoHeader.BmiHeader.BitCount / 8);

DsUtils.FreeAMMediaType(media);media = null;}

private void ConfigureSampleGrabber(ISampleGrabber sampleGrabber){AMMediaType media;int hr;

// Set the media type to Video/RBG24 media = new AMMediaType();media.majorType = MediaType.Video;media.subType = MediaSubType.RGB24;media.formatType = FormatType.VideoInfo;

hr = sampleGrabber.SetMediaType(media);DsError.ThrowExceptionForHR(hr);

DsUtils.FreeAMMediaType(media);media = null;

hr = sampleGrabber.SetCallback(this, 1);DsError.ThrowExceptionForHR(hr);}

public int BufferCB(double SampleTime, IntPtr pBuffer, int BufferLen){

if (isGrab){Bitmap v = new Bitmap(_previewWidth, _previewHeight, _previewStride,PixelFormat.Format24bppRgb, pBuffer);//v.RotateFlip(RotateFlipType.Rotate180FlipX);v.RotateFlip(RotateFlipType.Rotate90FlipX);

this.BeginInvoke((MethodInvoker)delegate{pictureBox2.BackgroundImage = v;

isGrab = false;});}return 0;}