如何自定义Windows窗体的系统菜单？
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我想将旧的About菜单项添加到我的应用程序中。我想将它添加到应用程序的“系统菜单”（当我们点击左上角的应用程序图标时弹出的那个）。那么，我怎么能在.NET中做到这一点？
答案
Windows可以很容易地获取表单系统菜单副本的句柄，以便使用GetSystemMenu function进行自定义。困难的部分是你自己对你返回的菜单进行适当的修改，使用AppendMenu，InsertMenu和DeleteMenu等函数就像你直接针对Win32 API编程一样。
但是，如果您只想添加一个简单的菜单项，那真的不是那么困难。例如，您只需要使用AppendMenu函数，因为您只想在菜单末尾添加一两个项目。做更高级的事情（比如在菜单中间插入项目，在菜单项上显示位图，显示选中的菜单项，设置默认菜单项等）需要更多的工作。但是一旦你知道它是如何完成的，你就可以疯狂了。 documentation on menu-related functions告诉所有人。
以下是表单的完整代码，该表单在其系统菜单（也称为窗口菜单）的底部添加了分隔线和“关于”项：
using System;
using System.Windows.Forms;
using System.Runtime.InteropServices;
public class CustomForm : Form
{
// P/Invoke constants
private const int WM_SYSCOMMAND = 0x112;
private const int MF_STRING = 0x0;
private const int MF_SEPARATOR = 0x800;
// P/Invoke declarations
[DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
private static extern IntPtr GetSystemMenu(IntPtr hWnd, bool bRevert);
[DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
private static extern bool AppendMenu(IntPtr hMenu, int uFlags, int uIDNewItem, string lpNewItem);
[DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
private static extern bool InsertMenu(IntPtr hMenu, int uPosition, int uFlags, int uIDNewItem, string lpNewItem);
// ID for the About item on the system menu
private int SYSMENU_ABOUT_ID = 0x1;
public CustomForm()
{
}
protected override void OnHandleCreated(EventArgs e)
{
base.OnHandleCreated(e);
// Get a handle to a copy of this form's system (window) menu
IntPtr hSysMenu = GetSystemMenu(this.Handle, false);
// Add a separator
AppendMenu(hSysMenu, MF_SEPARATOR, 0, string.Empty);
// Add the About menu item
AppendMenu(hSysMenu, MF_STRING, SYSMENU_ABOUT_ID, "&About…");
}
protected override void WndProc(ref Message m)
{
base.WndProc(ref m);
// Test if the About item was selected from the system menu
if ((m.Msg == WM_SYSCOMMAND) && ((int)m.WParam == SYSMENU_ABOUT_ID))
{
MessageBox.Show("Custom About Dialog");
}
}
}
这就是成品的样子：
另一答案
我已经将Cody Gray的解决方案更进一步，并从中获得了可重复使用的课程。它是我的应用程序日志提交工具的一部分，应该在系统菜单中隐藏其关于信息。
https://github.com/ygoe/FieldLog/blob/master/LogSubmit/Unclassified/UI/SystemMenu.cs
它可以像这样轻松使用：
class MainForm : Form
{
private SystemMenu systemMenu;
public MainForm()
{
InitializeComponent();
// Create instance and connect it with the Form
systemMenu = new SystemMenu(this);
// Define commands and handler methods
// (Deferred until HandleCreated if it's too early)
// IDs are counted internally, separator is optional
systemMenu.AddCommand("&About…", OnSysMenuAbout, true);
}
protected override void WndProc(ref Message msg)
{
base.WndProc(ref msg);
// Let it know all messages so it can handle WM_SYSCOMMAND
// (This method is inlined)
systemMenu.HandleMessage(ref msg);
}
// Handle menu command click
private void OnSysMenuAbout()
{
MessageBox.Show("My about message");
}
}
另一答案
对于你需要的pinvoke数量，增值量相当小。但这是可能的。使用GetSystemMenu（）来检索系统菜单句柄。然后InsertMenuItem添加一个条目。您必须在重写OnHandleCreated（）时执行此操作，以便在重新创建窗口时重新创建菜单。
覆盖WndProc（）以识别用户单击它时生成的WM_SYSCOMMAND消息。访问pinvoke.net，获取您需要的pinvoke声明。
另一答案
我知道这个答案很老但我真的很喜欢LonelyPixel的答案。但是，它需要一些工作才能正确使用WPF。下面是我写的WPF版本，所以你不必:)。
/// <summary>
/// Extends the system menu of a window with additional commands.
/// Adapted from:
/// https://github.com/dg9ngf/FieldLog/blob/master/LogSubmit/Unclassified/UI/SystemMenu.cs
/// </summary>
public class SystemMenuExtension
{
#region Native methods
private const int WM_SYSCOMMAND = 0x112;
private const int MF_STRING = 0x0;
private const int MF_SEPARATOR = 0x800;
[DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
private static extern IntPtr GetSystemMenu(IntPtr hWnd, bool bRevert);
[DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
private static extern bool AppendMenu(IntPtr hMenu, int uFlags, int uIDNewItem, string lpNewItem);
#endregion Native methods
#region Private data
private Window window;
private IntPtr hSysMenu;
private int lastId = 0;
private List<Action> actions = new List<Action>();
private List<CommandInfo> pendingCommands;
#endregion Private data
#region Constructors
/// <summary>
/// Initialises a new instance of the <see cref="SystemMenu"/> class for the specified
/// <see cref="Form"/>.
/// </summary>
/// <param name="window">The window for which the system menu is expanded.</param>
public SystemMenuExtension(Window window)
{
this.window = window;
if(this.window.IsLoaded)
{
WindowLoaded(null, null);
}
else
{
this.window.Loaded += WindowLoaded;
}
}
#endregion Constructors
#region Public methods
/// <summary>
/// Adds a command to the system menu.
/// </summary>
/// <param name="text">The displayed command text.</param>
/// <param name="action">The action that is executed when the user clicks on the command.</param>
/// <param name="separatorBeforeCommand">Indicates whether a separator is inserted before the command.</param>
public void AddCommand(string text, Action action, bool separatorBeforeCommand)
{
int id = ++this.lastId;
if (!this.window.IsLoaded)
{
// The window is not yet created, queue the command for later addition
if (this.pendingCommands == null)
{
this.pendingCommands = new List<CommandInfo>();
}
this.pendingCommands.Add(new CommandInfo
{
Id = id,
Text = text,
Action = action,
Separator = separatorBeforeCommand
});
}
else
{
// The form is created, add the command now
if (separatorBeforeCommand)
{
AppendMenu(this.hSysMenu, MF_SEPARATOR, 0, "");
}
AppendMenu(this.hSysMenu, MF_STRING, id, text);
}
this.actions.Add(action);
}
#endregion Public methods
#region Private methods
private void WindowLoaded(object sender, RoutedEventArgs e)
{
var interop = new WindowInteropHelper(this.window);
HwndSource source = PresentationSource.FromVisual(this.window) as HwndSource;
source.AddHook(WndProc);
this.hSysMenu = GetSystemMenu(interop.EnsureHandle(), false);
// Add all queued commands now
if (this.pendingCommands != null)
{
foreach (CommandInfo command in this.pendingCommands)
{
if (command.Separator)
{
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