c#在winfrom里面怎么设置按键录制视频全屏

要在 C# WinForms 应用程序中录制全屏视频，可以使用 Windows API 中的 GDI+ 和 DirectShow 库。下面是一个简单的示例代码，演示如何使用 GDI+ 和 DirectShow 来录制全屏视频：

using System;
using System.Drawing;
using System.Runtime.InteropServices;
using System.Windows.Forms;
using DirectShowLib;

namespace ScreenRecorder
{
    public partial class MainForm : Form
    {
        private IFilterGraph2 filterGraph;
        private ISampleGrabber sampleGrabber;
        private IMediaControl mediaControl;
        private IBaseFilter grabberFilter;
        private int stride;

        public MainForm()
        {
            InitializeComponent();
            stride = 4 * ((Screen.PrimaryScreen.Bounds.Width * 32 + 31) / 32);
        }

        private void button_start_Click(object sender, EventArgs e)
        {
            // 创建 FilterGraph 对象
            filterGraph = (IFilterGraph2)new FilterGraph();

            // 创建 SampleGrabber 对象
            sampleGrabber = (ISampleGrabber)new SampleGrabber();

            // 设置 SampleGrabber 参数
            AMMediaType mediaType = new AMMediaType();
            mediaType.majorType = MediaType.Video;
            mediaType.subType = MediaSubType.RGB32;
            mediaType.formatType = FormatType.VideoInfo;
            sampleGrabber.SetMediaType(mediaType);
            sampleGrabber.SetBufferSamples(true);

            // 添加 SampleGrabber 到 FilterGraph 中
            grabberFilter = (IBaseFilter)sampleGrabber;
            filterGraph.AddFilter(grabberFilter, "Grabber");

            // 枚举视频输入设备，选择第一个全屏设备
            DsDevice[] devices = DsDevice.GetDevicesOfCat(FilterCategory.VideoInputDevice);
            for (int i = 0; i < devices.Length; i++)
            {
                if (devices[i].Name.ToLower().Contains("screen capture"))
                {
                    // 创建 VideoCapture 对象，并将其添加到 FilterGraph 中
                    IBaseFilter videoCapture = (IBaseFilter)new VideoCapture();
                    filterGraph.AddFilter(videoCapture, "Video Capture");

                    // 连接 VideoCapture 和 SampleGrabber
                    IPin captureOut = DsFindPin.ByDirection(videoCapture, PinDirection.Output, 0);
                    IPin grabberIn = DsFindPin.ByDirection(grabberFilter, PinDirection.Input, 0);
                    filterGraph.Connect(captureOut, grabberIn);

                    // 设置采集视频的大小和位置
                    VideoInfoHeader videoInfo = new VideoInfoHeader();
                    videoInfo.BmiHeader.Width = Screen.PrimaryScreen.Bounds.Width;
                    videoInfo.BmiHeader.Height = Screen.PrimaryScreen.Bounds.Height;
                    videoInfo.BmiHeader.BitCount = 32;
                    videoInfo.BmiHeader.Compression = 0;
                    videoInfo.BmiHeader.ImageSize = videoInfo.BmiHeader.Width * videoInfo.BmiHeader.Height * videoInfo.BmiHeader.BitCount / 8;
                    videoInfo.BmiHeader.Planes = 1;
                    videoInfo.AvgTimePerFrame = 333333;
                    sampleGrabber.SetMediaType(mediaType);
                    sampleGrabber.GetConnectedMediaType(mediaType);
                    Marshal.PtrToStructure(mediaType.formatPtr, videoInfo);
                    videoInfo.SrcRect.Right = videoInfo.SrcRect.Left + Screen.PrimaryScreen.Bounds.Width;
                    videoInfo.SrcRect.Bottom = videoInfo.SrcRect.Top + Screen.PrimaryScreen.Bounds.Height;
                    videoInfo.TargetRect.Right = videoInfo.TargetRect.Left + Screen.PrimaryScreen.Bounds.Width;
                    videoInfo.TargetRect.Bottom = videoInfo.TargetRect.Top + Screen.PrimaryScreen.Bounds.Height;
                    sampleGrabber.SetMediaType(mediaType);
                    sampleGrabber.SetOneShot(false);
                    sampleGrabber.SetBufferSamples(true);
                    sampleGrabber.SetCallback(new SampleGrabberCallback(this));
                    sampleGrabber.SetMediaType(mediaType);
                    sampleGrabber.GetConnectedMediaType(mediaType);
                    Marshal.StructureToPtr(videoInfo, mediaType.formatPtr, false);
                    sampleGrabber.SetMediaType(mediaType);

                    // 创建 MediaControl 对象，并开始录制
                    mediaControl = (IMediaControl)filterGraph;
                    mediaControl.Run();

                    break;
                }
            }
        }

        private void button_stop_Click(object sender, EventArgs e)
        {
            // 停止录制
            if (mediaControl != null)
                mediaControl.Stop();

            // 释放资源
            if (mediaControl != null) Marshal.ReleaseComObject(mediaControl);
            if (grabberFilter != null) Marshal.ReleaseComObject(grabberFilter);
            if (sampleGrabber != null) Marshal.ReleaseComObject(sampleGrabber);
            if (filterGraph != null) Marshal.ReleaseComObject(filterGraph);
        }

        private class SampleGrabberCallback : ISampleGrabberCB
        {
            private MainForm parent;
            private Bitmap bitmap;

            public SampleGrabberCallback(MainForm parent)
            {
                this.parent = parent;
            }

            public int SampleCB(double sampleTime, IMediaSample sample)
            {
                return 0;
            }

            public int BufferCB(double sampleTime, IntPtr buffer, int bufferLength)
            {
                // 将采集到的视频数据转换为位图
                if (bitmap == null)
                    bitmap = new Bitmap(Screen.PrimaryScreen.Bounds.Width, Screen.PrimaryScreen.Bounds.Height, parent.stride, System.Drawing.Imaging.PixelFormat.Format32bppRgb, buffer);
                else
                    bitmap = new Bitmap(bitmap.Width, bitmap.Height, parent.stride, System.Drawing.Imaging.PixelFormat.Format32bppRgb, buffer);

                // 在窗口中显示录制的视频
                parent.pictureBox.Image = bitmap;

                return 0;
            }
        }
    }
}

在上面的示例代码中，我们创建了一个 MainForm 窗口，并在窗口中添加了两个按钮和一个 PictureBox 控件。单击“开始”按钮时，程序会枚举视频输入设备，并选择第一个全屏设备。然后，程序会创建 FilterGraph 对象，并将 VideoCapture 和 SampleGrabber 添加到其中。最后，程序会创建 MediaControl 对象，并开始录制视频。单击“停止”按钮时，程序会停止录制，并释放所有资源。

需要注意的是，上面的代码只是一个简单的示例，可能存在一些问题。例如，程序可能无法正确识别视频输入设备，或者无法正确处理某些视频格式。如果您想要实现更高级的功能，可以参考 MSDN 上的相关文档，或者使用开源的视频录制库（如 FFmpeg）。