C# Windows窗体从嵌入式Windows Media Player捕获图像

Question

我有一个用C#编写的windows窗体应用程序，它使用嵌入式Windows Media Player (AxInterop.WMPLib.dll和WMPLib.dll)来播放一些视频文件。现在，我需要添加一个选项，以捕获点击按钮上的视频图像。如果我将windowless选项设置为true，我可以捕获视频图像，但当我将windowless选项设置为true时，我在某些计算机上看不到视频图像。如果没有windowless选项，我只能在下面的代码中看到黑屏：

        System.Drawing.Image ret = null;
        try{
            Bitmap bitmap = new Bitmap(wmPlayer.Width-26, wmPlayer.Height-66);
            {
                Graphics g = Graphics.FromImage(bitmap);
                {
                    Graphics gg = wmPlayer.CreateGraphics();
                    {
                        this.BringToFront();

                           g.CopyFromScreen(
                            wmPlayer.PointToScreen(
                                new System.Drawing.Point()).X+13,
                            wmPlayer.PointToScreen(
                                new System.Drawing.Point()).Y,
                            0, 0,
                            new System.Drawing.Size(
                                wmPlayer.Width-26,
                                wmPlayer.Height-66)  
                            );
                    }
                }
                using (MemoryStream ms = new MemoryStream()){
                        bitmap.Save(ms, System.Drawing.Imaging.ImageFormat.Png);
                        ret = System.Drawing.Image.FromStream(ms);
                        ret.Save(@"C:\\WMP_capture.png");
                        pictureBox1.Image=ret;
                }
            }
            bitmap.Dispose();

        }catch (Exception){ }

在C#中没有windowless选项的情况下，如何从嵌入式Windows Media Player中播放的视频中捕获帧(快照)？

或者是否有任何其它用于C# windows窗体的视频播放器可以容易地实现并且支持捕获功能。

Answer 1

希望这段代码能为您工作

if (!string.IsNullOrEmpty(axWindowsMediaPlayer1.URL)){
axWindowsMediaPlayer1.Ctlcontrols.pause();

System.Drawing.Image ret = null;
try
{
    // take picture BEFORE saveFileDialog pops up!!
    Bitmap bitmap = new Bitmap(axWindowsMediaPlayer1.Width, axWindowsMediaPlayer1.Height);
    {
        Graphics g = Graphics.FromImage(bitmap);
        {
            Graphics gg = axWindowsMediaPlayer1.CreateGraphics();
            {
                //timerTakePicFromVideo.Start();
                this.BringToFront();
                g.CopyFromScreen(
                    axWindowsMediaPlayer1.PointToScreen(
                        new System.Drawing.Point()).X,
                    axWindowsMediaPlayer1.PointToScreen(
                        new System.Drawing.Point()).Y,
                    0, 0,
                    new System.Drawing.Size(
                        axWindowsMediaPlayer1.Width,
                        axWindowsMediaPlayer1.Height)
                    );
            }
        }
        // afterwards save bitmap file if user wants to
        if (saveFileDialog1.ShowDialog() == DialogResult.OK)
        {
            using (MemoryStream ms = new MemoryStream())
            {
                bitmap.Save(ms, System.Drawing.Imaging.ImageFormat.Png);
                ret = System.Drawing.Image.FromStream(ms);
                ret.Save(saveFileDialog1.FileName);
            }
        }
    }
}
catch (Exception ex)
{
    Debug.WriteLine(ex.Message);
}

}

另一个演示：http://www.codeproject.com/Articles/34663/DirectShow-Examples-for-Using-SampleGrabber-for-Gr