隧道事件和上下文菜单

Question

我有以下 WPF 控件，其行为应该像 GoogleMaps 那样（左双击缩放，右双击取消缩放）：

<Grid>
    <ScrollViewer x:Name="scrollViewer">
        <Canvas x:Name="myCanvas"/>
    </ScrollViewer>
</Grid>

和一些代码：

void OnScrollViewerPreviewMouseDoubleClick(object sender, MouseButtonEventArgs e)
{
    //this.myCanvas.ContextMenu = null;
    if (e.OriginalSource is Canvas)
    {
        // zoom on left doubleClick
        if (e.ChangedButton == MouseButton.Left)
        {
            ZoomOnMouseOnce();
        } // UNzoom on right doubleClick
        else if (e.ChangedButton == MouseButton.Right)
        {
            UnzoomOnMouseOnce();
        }
        e.Handled = true;
    }
}

问题是当 myCanvas 有 ContextMenu 时，UnZoom 方法不起作用，因为 ScrollViewer 上不再捕获 DoubleClick 事件...

设置 this.myCanvas.ContextMenu = null; 解决了问题，但是有没有办法绕过这个问题？...

Answer 1

更新
上传了演示效果的小示例项目。
http://www.mediafire.com/?du2jr18khx8ooy9

我为此尝试了很多不同的方法我发现的最接近的事情是将 ContextMenu 的 Horizo​​ntalOffset 偏移 1。这允许在上下文菜单打开时右键双击。当 ContextMenu 未打开时它仍然不起作用，因为 ScrollViewer 仅收到第一次单击。

您可以通过使用第一次鼠标右键单击的计时代码来解决此问题，如果在线程耗尽之前再次单击鼠标右键，则可以使用 SendInput 模拟另一次鼠标右键单击。虽然它可能不是那么漂亮，但我完成了工作。

<Canvas ...>
    <Canvas.ContextMenu>
        <ContextMenu Placement="RelativePoint" HorizontalOffset="1">
            <MenuItem Header="MenuItem 1"/>
        </ContextMenu>
    </Canvas.ContextMenu>

代码隐藏

private bool m_waitingForRightMouseDoubleClick = false;
private void scrollViewer_PreviewMouseRightButtonDown(object sender, MouseButtonEventArgs e)
{
    if (e.ChangedButton == MouseButton.Right)
    {
        if (m_waitingForRightMouseDoubleClick == false)
        {
            m_waitingForRightMouseDoubleClick = true;
            Thread thread = new Thread(new System.Threading.ThreadStart(delegate()
                {
                    Thread.Sleep(System.Windows.Forms.SystemInformation.DoubleClickTime);
                    this.Dispatcher.Invoke(System.Windows.Threading.DispatcherPriority.Background,
                        new Action(delegate()
                            {
                                m_waitingForRightMouseDoubleClick = false;
                            }
                            ));
                }));
            thread.Start();
        }
        else
        {
            MouseSimulator.ClickRightMouseButton();
        }
    }
}

MouseSimulator.cs

public class MouseSimulator
{
    [DllImport("user32.dll", SetLastError = true)]
    static extern uint SendInput(uint nInputs, ref INPUT pInputs, int cbSize);

    [StructLayout(LayoutKind.Sequential)]
    struct INPUT
    {
        public SendInputEventType type;
        public MouseKeybdhardwareInputUnion mkhi;
    }
    [StructLayout(LayoutKind.Explicit)]
    struct MouseKeybdhardwareInputUnion
    {
        [FieldOffset(0)]
        public MouseInputData mi;

        [FieldOffset(0)]
        public KEYBDINPUT ki;

        [FieldOffset(0)]
        public HARDWAREINPUT hi;
    }
    [StructLayout(LayoutKind.Sequential)]
    struct KEYBDINPUT
    {
        public ushort wVk;
        public ushort wScan;
        public uint dwFlags;
        public uint time;
        public IntPtr dwExtraInfo;
    }
    [StructLayout(LayoutKind.Sequential)]
    struct HARDWAREINPUT
    {
        public int uMsg;
        public short wParamL;
        public short wParamH;
    }
    struct MouseInputData
    {
        public int dx;
        public int dy;
        public uint mouseData;
        public MouseEventFlags dwFlags;
        public uint time;
        public IntPtr dwExtraInfo;
    }
    [Flags]
    enum MouseEventFlags : uint
    {
        MOUSEEVENTF_MOVE = 0x0001,
        MOUSEEVENTF_LEFTDOWN = 0x0002,
        MOUSEEVENTF_LEFTUP = 0x0004,
        MOUSEEVENTF_RIGHTDOWN = 0x0008,
        MOUSEEVENTF_RIGHTUP = 0x0010,
        MOUSEEVENTF_MIDDLEDOWN = 0x0020,
        MOUSEEVENTF_MIDDLEUP = 0x0040,
        MOUSEEVENTF_XDOWN = 0x0080,
        MOUSEEVENTF_XUP = 0x0100,
        MOUSEEVENTF_WHEEL = 0x0800,
        MOUSEEVENTF_VIRTUALDESK = 0x4000,
        MOUSEEVENTF_ABSOLUTE = 0x8000
    }
    enum SendInputEventType : int
    {
        InputMouse,
        InputKeyboard,
        InputHardware
    }

    public static void ClickRightMouseButton()
    {
        INPUT mouseDownInput = new INPUT();
        mouseDownInput.type = SendInputEventType.InputMouse;
        mouseDownInput.mkhi.mi.dwFlags = MouseEventFlags.MOUSEEVENTF_RIGHTDOWN;
        SendInput(1, ref mouseDownInput, Marshal.SizeOf(new INPUT()));

        INPUT mouseUpInput = new INPUT();
        mouseUpInput.type = SendInputEventType.InputMouse;
        mouseUpInput.mkhi.mi.dwFlags = MouseEventFlags.MOUSEEVENTF_RIGHTUP;
        SendInput(1, ref mouseUpInput, Marshal.SizeOf(new INPUT()));
    }
}