c# - 右键单击菜单项时如何显示上下文菜单

Question

我正在将 MFC 应用程序移植到 .NET WinForms。在 MFC 应用程序中，您可以右键单击菜单或上下文菜单项，我们会显示另一个包含诊断和配置项的上下文菜单。我正在尝试将此功能移植到 .NET，但遇到了问题。

我已经能够捕获右键单击，禁用底层菜单的单击并在正确位置弹出上下文菜单，但是一旦失去焦点，原始菜单就会消失。

在 MFC 中，我们通过使用 TPM_RECURSE 标志调用 TrackPopupMenuEx 来显示新的上下文菜单。

ContextMenu 和 .NET 中较新的 ContextMenuStrip 类只有一个 Show 方法。有谁知道如何在 .NET 中执行此操作？

编辑

我已经尝试通过 p/invoke 使用 TrackPopupMenuEx，但这限制了您使用 ContextMenu 而不是 ContextMenuStrip，这在我们的应用程序中看起来不合适。它也仍然无法正常工作。它不适用于新的 MenuStrip 和 ContextMenuStrip。

我还尝试了子类化 ToolStripMenuItem 以查看是否可以向其添加上下文菜单。这适用于 MenuStrip，但 ContextMenuStrip 仍然允许右键单击事件作为点击传递。

Answer 1

编辑，由于评论:

在:

protected override void OnClick(EventArgs e)
{
    if (SecondaryContextMenu == null || MouseButtons != MouseButtons.Right)
    {
        base.OnClick(e);
    }
}

这部分

 MouseButtons != MouseButtons.Right

应该并且确实会编译，因为它是对 Control.MouseButtons 的调用。由于Form继承了Control类，直接调用MouseButtons属性即可。

希望对您有所帮助:

public partial class Form1 : Form
{
    class CustomToolStripMenuItem : ToolStripMenuItem
    {
        private ContextMenuStrip secondaryContextMenu;

        public ContextMenuStrip SecondaryContextMenu
        {
            get
            {
                return secondaryContextMenu;
            }
            set
            {
                secondaryContextMenu = value;
            }
        }

        public CustomToolStripMenuItem(string text)
            : base(text)
        { }

        protected override void Dispose(bool disposing)
        {
            if (disposing)
            {
                if (secondaryContextMenu != null)
                {
                    secondaryContextMenu.Dispose();
                    secondaryContextMenu = null;
                }
            }

            base.Dispose(disposing);
        }

        protected override void OnClick(EventArgs e)
        {
            if (SecondaryContextMenu == null || MouseButtons != MouseButtons.Right)
            {
                base.OnClick(e);
            }
        }
    }

    class CustomContextMenuStrip : ContextMenuStrip
    {
        private bool secondaryContextMenuActive = false;
        private ContextMenuStrip lastShownSecondaryContextMenu = null;

        protected override void Dispose(bool disposing)
        {
            if (disposing)
            {
                if (lastShownSecondaryContextMenu != null)
                {
                    lastShownSecondaryContextMenu.Close();
                    lastShownSecondaryContextMenu = null;
                }
            }
            base.Dispose(disposing);
        }

        protected override void OnControlAdded(ControlEventArgs e)
        {
            e.Control.MouseClick += new MouseEventHandler(Control_MouseClick);
            base.OnControlAdded(e);
        }

        protected override void OnControlRemoved(ControlEventArgs e)
        {
            e.Control.MouseClick -= new MouseEventHandler(Control_MouseClick);
            base.OnControlRemoved(e);
        }

        private void Control_MouseClick(object sender, MouseEventArgs e)
        {
            ShowSecondaryContextMenu(e);
        }

        protected override void OnMouseClick(MouseEventArgs e)
        {
            ShowSecondaryContextMenu(e);
            base.OnMouseClick(e);
        }

        private bool ShowSecondaryContextMenu(MouseEventArgs e)
        {
            CustomToolStripMenuItem ctsm = this.GetItemAt(e.Location) as CustomToolStripMenuItem;

            if (ctsm == null || ctsm.SecondaryContextMenu == null || e.Button != MouseButtons.Right)
            {
                return false;
            }

            lastShownSecondaryContextMenu = ctsm.SecondaryContextMenu;
            secondaryContextMenuActive = true;
            ctsm.SecondaryContextMenu.Closed += new ToolStripDropDownClosedEventHandler(SecondaryContextMenu_Closed);
            ctsm.SecondaryContextMenu.Show(Cursor.Position);
            return true;
        }

        void SecondaryContextMenu_Closed(object sender, ToolStripDropDownClosedEventArgs e)
        {
            ((ContextMenuStrip)sender).Closed -= new ToolStripDropDownClosedEventHandler(SecondaryContextMenu_Closed);
            lastShownSecondaryContextMenu = null;
            secondaryContextMenuActive = false;
            Focus();
        }

        protected override void OnClosing(ToolStripDropDownClosingEventArgs e)
        {
            if (secondaryContextMenuActive)
            {
                e.Cancel = true;
            }

            base.OnClosing(e);
        }
    }

    public Form1()
    {
        InitializeComponent();


        CustomToolStripMenuItem itemPrimary1 = new CustomToolStripMenuItem("item primary 1");
        itemPrimary1.SecondaryContextMenu = new ContextMenuStrip();
        itemPrimary1.SecondaryContextMenu.Items.AddRange(new ToolStripMenuItem[] { 
            new ToolStripMenuItem("item primary 1.1"),
            new ToolStripMenuItem("item primary 1.2"),
        });

        CustomToolStripMenuItem itemPrimary2 = new CustomToolStripMenuItem("item primary 2");
        itemPrimary2.DropDownItems.Add("item primary 2, sub 1");
        itemPrimary2.DropDownItems.Add("item primary 2, sub 2");
        itemPrimary2.SecondaryContextMenu = new ContextMenuStrip();
        itemPrimary2.SecondaryContextMenu.Items.AddRange(new ToolStripMenuItem[] { 
            new ToolStripMenuItem("item primary 2.1"),
            new ToolStripMenuItem("item primary 2.2"),
        });

        CustomContextMenuStrip primaryContextMenu = new CustomContextMenuStrip();
        primaryContextMenu.Items.AddRange(new ToolStripItem[]{
            itemPrimary1,
            itemPrimary2
        });

        this.ContextMenuStrip = primaryContextMenu;
    }
}