从线程以外的线程访问的 C# WPF 线程

本文关键字：线程 WPF 访问 | 更新日期: 2023-09-27 18:37:28

我正在尝试创建一个 WPF 应用程序，该应用程序在播放时每秒拍摄视频并截取一次屏幕截图。

法典

    public Form2(string url)
    {
        InitializeComponent();
        axWindowsMediaPlayer1.URL = url;
        new Thread(delegate(){
            CheckFrame();
        }).Start();
    }
    private void CheckFrame()
    {        
        for (int i = 0; i < 100; i++)
        {
            Bitmap screenshot = new Bitmap(axWindowsMediaPlayer1.Bounds.Width, axWindowsMediaPlayer1.Bounds.Height);
            Graphics g = Graphics.FromImage(screenshot);
            g.CopyFromScreen(axWindowsMediaPlayer1.PointToScreen(
                        new System.Drawing.Point()).X,
                    axWindowsMediaPlayer1.PointToScreen(
                        new System.Drawing.Point()).Y, 0, 0, axWindowsMediaPlayer1.Bounds.Size);
            pictureBox1.BackgroundImage = screenshot;
            System.Threading.Thread.Sleep(1000);
        }
    }

使用媒体播放器本身的 x y 值时，出现错误

Additional information: Cross-thread operation not valid: Control 'axWindowsMediaPlayer1' 
accessed from a thread other than the thread it was created on.

当使用 0 作为 X/Y 值时，从形式的角度来看只有 0px 和 0px，它运行良好

从线程以外的线程访问的 C# WPF 线程

在这种情况下，

您可以使用计时器：

Timer tm = new Timer();
public Form2(string url)
{
    InitializeComponent();
    axWindowsMediaPlayer1.URL = url;
    tm.Interval = 1000;
    tm.Tick += tm_Tick;
    tm.Start();
}
int i = -1;
void tm_Tick(object sender, EventArgs e)
{
    if (++i < 100)
    {
        Bitmap screenshot = new Bitmap(axWindowsMediaPlayer1.Bounds.Width, axWindowsMediaPlayer1.Bounds.Height);
        Graphics g = Graphics.FromImage(screenshot);
        g.CopyFromScreen(axWindowsMediaPlayer1.PointToScreen(
                    new System.Drawing.Point()).X,
                axWindowsMediaPlayer1.PointToScreen(
                    new System.Drawing.Point()).Y, 0, 0, axWindowsMediaPlayer1.Bounds.Size);
        pictureBox1.BackgroundImage = screenshot;
    }
    else
    {
        i = -1;
        tm.Stop();
    }
}