c# - 防止 ToolStripMenuItems 跳转到第二个屏幕

Question

我有一个主要通过 NotifyIcon 的 ContextMenuStrip 操作的应用程序
ToolStripMenuItems 有多个级别，用户可以通过它们。
问题是，当用户有两个屏幕时，MenuItems 在没有可用空间时跳转到第二个屏幕。像这样:

我怎样才能强制他们保持在同一个屏幕上？我尝试通过网络进行搜索，但找不到合适的答案。

这是我用来测试这个 senario 的一段代码示例:

public partial class Form1 : Form
{

    public Form1()
    {
        InitializeComponent();

        var resources = new ComponentResourceManager(typeof(Form1));
        var notifyIcon1 = new NotifyIcon(components);
        var contextMenuStrip1 = new ContextMenuStrip(components);
        var level1ToolStripMenuItem = new ToolStripMenuItem("level 1 drop down");
        var level2ToolStripMenuItem = new ToolStripMenuItem("level 2 drop down");
        var level3ToolStripMenuItem = new ToolStripMenuItem("level 3 drop down");

        notifyIcon1.ContextMenuStrip = contextMenuStrip1;
        notifyIcon1.Icon = ((Icon)(resources.GetObject("notifyIcon1.Icon")));
        notifyIcon1.Visible = true;

        level2ToolStripMenuItem.DropDownItems.Add(level3ToolStripMenuItem);
        level1ToolStripMenuItem.DropDownItems.Add(level2ToolStripMenuItem);
        contextMenuStrip1.Items.Add(level1ToolStripMenuItem);
    }
}

Answer 1

这并不容易，但您可以在 DropDownOpening 中编写代码查看菜单所在位置(边界)、当前屏幕的事件，然后设置 DropDownDirection的 ToolStripMenuItem :

private void submenu_DropDownOpening(object sender, EventArgs e)
{
    ToolStripMenuItem menuItem = sender as ToolStripMenuItem;
    if (menuItem.HasDropDownItems == false)
    {
        return; // not a drop down item
    }
    // Current bounds of the current monitor
    Rectangle Bounds = menuItem.GetCurrentParent().Bounds;
    Screen CurrentScreen = Screen.FromPoint(Bounds.Location);
    // Look how big our children are:
    int MaxWidth = 0;
    foreach (ToolStripMenuItem subitem in menuItem.DropDownItems)
    {
        MaxWidth = Math.Max(subitem.Width, MaxWidth);
    }
    MaxWidth += 10; // Add a little wiggle room

    int FarRight = Bounds.Right + MaxWidth;
    int CurrentMonitorRight = CurrentScreen.Bounds.Right;

    if (FarRight > CurrentMonitorRight)
    {
        menuItem.DropDownDirection = ToolStripDropDownDirection.Left;
    }
    else
    {
        menuItem.DropDownDirection = ToolStripDropDownDirection.Right;
    }
}

此外，请确保您拥有 DropDownOpening事件连接(你真的需要将它添加到每个菜单项):

level1ToolStripMenuItem += submenu_DropDownOpening;