如果以编程方式创建控件，则Windows Media Player视频为黑色

Question

我正在尝试以编程方式创建Windows Media Player控件，以便捕获任何初始化错误。以前，当我简单地将控件放在窗体上时，一切都运行正常。但是现在我正在尝试以编程方式播放内容，视频不会出现在控件中。我只看到了黑色视频，但我听到了音频。

有什么想法吗？

    public TrimVideoControl()
    {
        InitializeComponent();

        // Try creating WMP control
        // We do this here so we can gracefully catch errors if the control doesn't load
        try
        {

            wmPlayer = new AxWMPLib.AxWindowsMediaPlayer();
            ((System.ComponentModel.ISupportInitialize)(wmPlayer)).BeginInit();
            //SuspendLayout();
            wmPlayer.CreateControl();
            wmPlayer.Name = "wmPlayer";
            wmPlayer.Ctlenabled = true;
            System.ComponentModel.ComponentResourceManager resources = new System.ComponentModel.ComponentResourceManager(typeof(TrimVideoControl));
            wmPlayer.OcxState = ((System.Windows.Forms.AxHost.State)(resources.GetObject("wmPlayer.OcxState")));
            wmPlayer.Location = new Point(12, 13);
            wmPlayer.Size = new Size(636, 358);
            wmPlayer.enableContextMenu = true;
            wmPlayer.stretchToFit = true;
            wmPlayer.uiMode = "none";
            wmPlayer.settings.autoStart = false;
            wmPlayer.ErrorEvent += wmPlayer_ErrorEvent;
            wmPlayer.MediaChange += wmPlayer_MediaChange;
            wmPlayer.MediaError += wmPlayer_MediaError;
            wmPlayer.OpenStateChange += wmPlayer_OpenStateChange;
            wmPlayer.PlayStateChange += wmPlayer_PlayStateChange;
            wmPlayer.Warning += wmPlayer_Warning;
            this.Controls.Add(wmPlayer);
            ((System.ComponentModel.ISupportInitialize)(wmPlayer)).EndInit();

            //this.ResumeLayout(false);
            //this.PerformLayout(); 
            //wmPlayer.Show();
            //wmPlayer.BringToFront();
        }
        catch (Exception ex)
        {
            Logger.Error("Error creating WMP control: " + ex);
        }


    }

Answer 1

创建MediaPalyer运行时的确切问题是我们不能对MediaPlayer的状态进行任何更改(任何设置，如url/uimode等)。在组件完全初始化之前。VS-designer将组件的状态序列化为AxHost.State对象，并且不影响任何其他设置。在运行时，您可以使用以下方法：

void AddMediaPlayer(string url) {
    try {
        var wmPlayer = new AxWMPLib.AxWindowsMediaPlayer();

        ((System.ComponentModel.ISupportInitialize)(wmPlayer)).BeginInit();
        wmPlayer.Name = "wmPlayer";
        wmPlayer.Enabled = true;
        wmPlayer.Dock = System.Windows.Forms.DockStyle.Fill;
        this.Controls.Add(wmPlayer);
        ((System.ComponentModel.ISupportInitialize)(wmPlayer)).EndInit();

        // After initialization you can customize the Media Player
        wmPlayer.uiMode = "none";
        wmPlayer.URL = url;
    }
    catch { }
}