SendKeys.Send（“ {ENTER}”）命令在方法中不起作用，但在事件方法中起作用

Question

我已经找到问题My previous question的解决方案，并且可以使用：

SendKeys.Send("{ENTER}");以自动单击对话框上的“确定”按钮

我现在的问题是，SendKeys.Send("{ENTER}");将在事件方法即Start_click中起作用，而在方法Start_Vid();中将不起作用

我得到了错误：

  

'SendKeys无法在此应用程序内运行，因为该应用程序未处理Windows消息。更改应用程序以处理消息，或使用SendKeys.SendWait方法'

我不知道为什么它不起作用以及错误消息是什么意思？

代码如下：

using System;
using System.Threading;
using System.Windows.Input;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using AForge.Video;
using AForge.Video.DirectShow;
using Accord.Video.FFMPEG;
using AForge.Video.VFW;

namespace WindowsFormsApp1
{
    public partial class Form1 : Form
    {
        private FilterInfoCollection VideoCaptureDevices;
        private VideoCaptureDevice FinalVideo = null;
        private VideoCaptureDeviceForm captureDevice;
        private Bitmap video;
        private VideoFileWriter FileWriter = new VideoFileWriter();
        private SaveFileDialog saveAvi;

        public Form1()
        {
            InitializeComponent();
            Console.WriteLine(date1);
            Console.WriteLine(date2);
            Console.WriteLine(date3);
            Console.WriteLine(date3);

            Start_Vid();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            VideoCaptureDevices = new FilterInfoCollection(FilterCategory.VideoInputDevice);
            captureDevice = new VideoCaptureDeviceForm();

        }

        void FinalVideo_NewFrame(object sender, NewFrameEventArgs eventArgs)
        {
            if (Stop.Text == "Stop Record")
            {
                video = (Bitmap)eventArgs.Frame.Clone();
                pictureBox1.Image = (Bitmap)eventArgs.Frame.Clone();
                //AVIwriter.Quality = 0;
                FileWriter.WriteVideoFrame(video);
                //AVIwriter.AddFrame(video);
            }
            else
            {
                video = (Bitmap)eventArgs.Frame.Clone();
                pictureBox1.Image = (Bitmap)eventArgs.Frame.Clone();
            }
        }

        private void Stop_Vid()
        {
            if (Stop.Text == "Stop Record")
            {
                Stop.Text = "Stop";
                if (FinalVideo == null)
                { return; }
                if (FinalVideo.IsRunning)
                {
                    //this.FinalVideo.Stop();
                    FileWriter.Close();
                    //this.AVIwriter.Close();
                    pictureBox1.Image = null;
                }
            }
            else
            {
                this.FinalVideo.Stop();
                FileWriter.Close();
                //this.AVIwriter.Close();
                pictureBox1.Image = null;
            }
        }
        private void butstop_Click(object sender, EventArgs e)
        {
            if (Stop.Text == "Stop Record")
            {
                Stop.Text = "Stop";
                if (FinalVideo == null)
                { return; }
                if (FinalVideo.IsRunning)
                {
                    //this.FinalVideo.Stop();
                    FileWriter.Close();
                    //this.AVIwriter.Close();
                    pictureBox1.Image = null;
                }
            }
            else
            {
                this.FinalVideo.Stop();
                FileWriter.Close();
                //this.AVIwriter.Close();
                pictureBox1.Image = null;
            }
        }

        private void button3_Click(object sender, EventArgs e)
        {
            pictureBox1.Image.Save("IMG" + DateTime.Now.ToString("hhmmss") + ".jpg");
        }

        private void Form1_FormClosing(object sender, FormClosingEventArgs e)
        {
            if (FinalVideo == null)
            { return; }
            if (FinalVideo.IsRunning)
            {
                this.FinalVideo.Stop();
                FileWriter.Close();
                //this.AVIwriter.Close();
            }
        }

        private void Save_Click(object sender, EventArgs e)
        {
            saveAvi = new SaveFileDialog();
            saveAvi.Filter = "Avi Files (*.avi)|*.avi";
            saveAvi.FileName = "New Vid1";

            if (saveAvi.ShowDialog() == System.Windows.Forms.DialogResult.OK)
            {
                int h = captureDevice.VideoDevice.VideoResolution.FrameSize.Height;
                int w = captureDevice.VideoDevice.VideoResolution.FrameSize.Width;
                FileWriter.Open(saveAvi.FileName, w, h, 25, VideoCodec.Default, 5000000);
                FileWriter.WriteVideoFrame(video);


                //AVIwriter.Open(saveAvi.FileName, w, h);
                Stop.Text = "Stop Record";
                //FinalVideo = captureDevice.VideoDevice;
                //FinalVideo.NewFrame += new NewFrameEventHandler(FinalVideo_NewFrame);
                //FinalVideo.Start();
            }


        }

        //##############################################//
        //        Method not working        //
        //##############################################//

        private void Start_Vid()
        {
            SendKeys.Send("{ENTER}");
            if (captureDevice.ShowDialog(this) == DialogResult.OK)
            {

                VideoCaptureDevice videoSource = captureDevice.VideoDevice;
                FinalVideo = captureDevice.VideoDevice;
                FinalVideo.NewFrame += new NewFrameEventHandler(FinalVideo_NewFrame);
                FinalVideo.Start();
            }
        }

        //##############################################//
        //        Method working            //
        //##############################################//

        private void Start_Click(object sender, EventArgs e)
        {
            SendKeys.Send("{ENTER}");
            if (captureDevice.ShowDialog(this) == DialogResult.OK)
            {
                VideoCaptureDevice videoSource = captureDevice.VideoDevice;
                FinalVideo = captureDevice.VideoDevice;
                FinalVideo.NewFrame += new NewFrameEventHandler(FinalVideo_NewFrame);
                FinalVideo.Start();
            }
        }
        private void Close_Click(object sender, EventArgs e)
        {
            this.Close();
        }
    }
}

Answer 1

尝试使用SendKeys.SendWait方法。
如果不起作用，请尝试使用安德鲁（Andrew）的this AutoHotKey包装器。

通过使用这些代码行可以解决问题。

var ahk = AutoHotkeyEngine.Instance;
ahk.ExecRaw("Send {Enter}");