我发现的唯一方法是结合使用调用 GetKeyState API 函数 (user32.dll) 和 定时器.以下是它在测试应用上的运行情况:

The only way I found was to use a combination of calling the GetKeyState API function (user32.dll) and of a Timer. Here is as it works on the test app:

System.Windows.Forms.Timer keyManagerTimer = new System.Windows.Forms.Timer();
int count = 0;

public Form1()
{
    InitializeComponent();

    this.keyManagerTimer.Tick += (s, e) => ProcessKeys();
    this.keyManagerTimer.Interval = 25;
}

protected override bool ProcessCmdKey(ref Message msg, Keys keyData)
{
    if ((keyData & Keys.Right) != 0)
    {
        keyManagerTimer.Enabled = true;
        return true;
    }
    return base.ProcessCmdKey(ref msg, keyData);
}

private void ProcessKeys()
{
    bool isShiftKeyPressed = IsKeyPressed(Keys.ShiftKey);
    bool isRightKeyPressed = IsKeyPressed(Keys.Right);

    if (isRightKeyPressed && !isShiftKeyPressed)
    {
        count++;
    }
    else if (isRightKeyPressed && isShiftKeyPressed)
    {
        count += 10;
    }
    label.Text = "count = " + count.ToString();
}

public static bool IsKeyPressed(Keys key)
{
    return BitConverter.GetBytes(GetKeyState((int)key))[1] > 0;
}

[DllImport("user32")]
private static extern short GetKeyState(int vKey);

在我的实际代码中，我在拥有视频的 Control 的 Leave 事件上禁用了 Timer.另一种解决方案可能是使用 IMessageFilter(请参阅此处).

In my real code then I disable the Timer on the Leave event of the Control where I have the video. Possibly another solution might have been to use the IMessageFilter (see here).