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aepot
Asked:2023-06-10 00:24:27 +0000 UTC2023-06-10 00:24:27 +0000 UTC

如何在 Windows 窗体和 WPF 中将 MessageBox 居中？

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要使弹出对话框居中于父窗口的中心，您可以实现自己的对话框并使用它代替MessageBox. 但有时这是多余的，您需要以一种简单而熟悉的方式使用它，而且如果您有一个旧项目，您可以改进它的行为而无需花费大量时间进行修改。

MessageBox默认弹出在屏幕中央，但是如何让它在窗口中央呢？

c#

1 个回答

  1. Best Answer

    没有现成的方法，Windows不支持这样的技巧。但是你可以自己实现。

    我有一个已经实施了很长时间的解决方案，我称之为MessageBoxEx，我决定分享它。

    WPF 的 Requires类MessageBoxEx需要安装 NuGet 包System.Drawing.Common。Winforms 默认包含此包，因此无需安装。

    using System.Drawing;

    以下是完成的课程：

    Windows 窗体

    public static class MessageBoxEx
{
    private static Form _owner;
    private static readonly HookProc _hookProc = new HookProc(MessageBoxHookProc);
    private static IntPtr _hHook = IntPtr.Zero;

    public static DialogResult Show(Form owner, string text)
    {
        Initialize(owner);
        return MessageBox.Show(owner, text);
    }

    public static DialogResult Show(Form owner, string text, string caption)
    {
        Initialize(owner);
        return MessageBox.Show(owner, text, caption);
    }

    public static DialogResult Show(Form owner, string text, string caption, MessageBoxButtons buttons)
    {
        Initialize(owner);
        return MessageBox.Show(owner, text, caption, buttons);
    }

    public static DialogResult Show(Form owner, string text, string caption, MessageBoxButtons buttons, MessageBoxIcon icon)
    {
        Initialize(owner);
        return MessageBox.Show(owner, text, caption, buttons, icon);
    }

    public static DialogResult Show(Form owner, string text, string caption, MessageBoxButtons buttons, MessageBoxIcon icon, MessageBoxDefaultButton defButton)
    {
        Initialize(owner);
        return MessageBox.Show(owner, text, caption, buttons, icon, defButton);
    }

    public static DialogResult Show(Form owner, string text, string caption, MessageBoxButtons buttons, MessageBoxIcon icon, MessageBoxDefaultButton defButton, MessageBoxOptions options)
    {
        Initialize(owner);
        return MessageBox.Show(owner, text, caption, buttons, icon, defButton, options);
    }

    private delegate IntPtr HookProc(int nCode, IntPtr wParam, IntPtr lParam);

    private const int WH_CALLWNDPROCRET = 12;

    private enum CbtHookAction : int
    {
        HCBT_MOVESIZE = 0,
        HCBT_MINMAX = 1,
        HCBT_QS = 2,
        HCBT_CREATEWND = 3,
        HCBT_DESTROYWND = 4,
        HCBT_ACTIVATE = 5,
        HCBT_CLICKSKIPPED = 6,
        HCBT_KEYSKIPPED = 7,
        HCBT_SYSCOMMAND = 8,
        HCBT_SETFOCUS = 9
    }

    [DllImport("user32.dll")]
    private static extern bool GetWindowRect(IntPtr hWnd, ref Rectangle lpRect);

    [DllImport("user32.dll")]
    private static extern int MoveWindow(IntPtr hWnd, int X, int Y, int nWidth, int nHeight, bool bRepaint);

    [DllImport("user32.dll")]
    private static extern IntPtr SetWindowsHookEx(int idHook, HookProc lpfn, IntPtr hInstance, int threadId);

    [DllImport("user32.dll")]
    private static extern int UnhookWindowsHookEx(IntPtr idHook);

    [DllImport("user32.dll")]
    private static extern IntPtr CallNextHookEx(IntPtr idHook, int nCode, IntPtr wParam, IntPtr lParam);

    [DllImport("kernel32.dll")]
    private static extern int GetCurrentThreadId();

    [StructLayout(LayoutKind.Sequential)]
    private struct CWPRETSTRUCT
    {
        public IntPtr lResult;
        public IntPtr lParam;
        public IntPtr wParam;
        public CbtHookAction message;
        public IntPtr hwnd;
    };

    private static void Initialize(Form owner)
    {
        _owner = owner;
        if (owner is Form form && form.WindowState == FormWindowState.Normal)
        {
            if (_hHook != IntPtr.Zero)
            {
                throw new NotSupportedException("Multiple calls are not supported");
            }

            _hHook = SetWindowsHookEx(WH_CALLWNDPROCRET, _hookProc, IntPtr.Zero, GetCurrentThreadId());
        }
    }

    private static IntPtr MessageBoxHookProc(int nCode, IntPtr wParam, IntPtr lParam)
    {
        if (nCode < 0)
        {
            return CallNextHookEx(_hHook, nCode, wParam, lParam);
        }

        CWPRETSTRUCT msg = Marshal.PtrToStructure<CWPRETSTRUCT>(lParam);
        IntPtr hook = _hHook;

        if (msg.message == CbtHookAction.HCBT_ACTIVATE)
        {
            try
            {
                CenterWindow(msg.hwnd);
            }
            finally
            {
                UnhookWindowsHookEx(_hHook);
                _hHook = IntPtr.Zero;
            }
        }

        return CallNextHookEx(hook, nCode, wParam, lParam);
    }

    private static void CenterWindow(IntPtr hChildWnd)
    {
        if (_owner is Form form)
        {
            Rectangle recChild = new Rectangle(0, 0, 0, 0);
            _ = GetWindowRect(hChildWnd, ref recChild);

            int width = recChild.Width - recChild.X;
            int height = recChild.Height - recChild.Y;

            int x = form.Left + ((form.Width - width) / 2);
            int y = form.Top + ((form.Height - height) / 2);

            _ = MoveWindow(hChildWnd, x, y, width, height, false);
        }
    }
}

    WPF

    public static class MessageBoxEx
{
    private static Window _owner;
    private static readonly HookProc _hookProc = new HookProc(MessageBoxHookProc);
    private static IntPtr _hHook = IntPtr.Zero;

    public static MessageBoxResult Show(Window owner, string text)
    {
        Initialize(owner);
        return MessageBox.Show(owner, text);
    }

    public static MessageBoxResult Show(Window owner, string text, string caption)
    {
        Initialize(owner);
        return MessageBox.Show(owner, text, caption);
    }

    public static MessageBoxResult Show(Window owner, string text, string caption, MessageBoxButton buttons)
    {
        Initialize(owner);
        return MessageBox.Show(owner, text, caption, buttons);
    }

    public static MessageBoxResult Show(Window owner, string text, string caption, MessageBoxButton buttons, MessageBoxImage icon)
    {
        Initialize(owner);
        return MessageBox.Show(owner, text, caption, buttons, icon);
    }

    public static MessageBoxResult Show(Window owner, string text, string caption, MessageBoxButton buttons, MessageBoxImage icon, MessageBoxResult defButton)
    {
        Initialize(owner);
        return MessageBox.Show(owner, text, caption, buttons, icon, defButton);
    }

    public static MessageBoxResult Show(Window owner, string text, string caption, MessageBoxButton buttons, MessageBoxImage icon, MessageBoxResult defButton, MessageBoxOptions options)
    {
        Initialize(owner);
        return MessageBox.Show(owner, text, caption, buttons, icon, defButton, options);
    }

    private delegate IntPtr HookProc(int nCode, IntPtr wParam, IntPtr lParam);

    private const int WH_CALLWNDPROCRET = 12;

    private enum CbtHookAction : int
    {
        HCBT_MOVESIZE = 0,
        HCBT_MINMAX = 1,
        HCBT_QS = 2,
        HCBT_CREATEWND = 3,
        HCBT_DESTROYWND = 4,
        HCBT_ACTIVATE = 5,
        HCBT_CLICKSKIPPED = 6,
        HCBT_KEYSKIPPED = 7,
        HCBT_SYSCOMMAND = 8,
        HCBT_SETFOCUS = 9
    }

    [DllImport("user32.dll")]
    private static extern bool GetWindowRect(IntPtr hWnd, ref Rectangle lpRect);

    [DllImport("user32.dll")]
    private static extern int MoveWindow(IntPtr hWnd, int X, int Y, int nWidth, int nHeight, bool bRepaint);

    [DllImport("user32.dll")]
    private static extern IntPtr SetWindowsHookEx(int idHook, HookProc lpfn, IntPtr hInstance, int threadId);

    [DllImport("user32.dll")]
    private static extern int UnhookWindowsHookEx(IntPtr idHook);

    [DllImport("user32.dll")]
    private static extern IntPtr CallNextHookEx(IntPtr idHook, int nCode, IntPtr wParam, IntPtr lParam);

    [DllImport("kernel32.dll")]
    private static extern int GetCurrentThreadId();

    [StructLayout(LayoutKind.Sequential)]
    private struct CWPRETSTRUCT
    {
        public IntPtr lResult;
        public IntPtr lParam;
        public IntPtr wParam;
        public CbtHookAction message;
        public IntPtr hwnd;
    };

    private static void Initialize(Window owner)
    {
        _owner = owner;
        if (owner is Window window && window.WindowState == WindowState.Normal)
        {
            if (_hHook != IntPtr.Zero)
            {
                throw new NotSupportedException("Multiple calls are not supported");
            }

            _hHook = SetWindowsHookEx(WH_CALLWNDPROCRET, _hookProc, IntPtr.Zero, GetCurrentThreadId());
        }
    }

    private static IntPtr MessageBoxHookProc(int nCode, IntPtr wParam, IntPtr lParam)
    {
        if (nCode < 0)
        {
            return CallNextHookEx(_hHook, nCode, wParam, lParam);
        }

        CWPRETSTRUCT msg = Marshal.PtrToStructure<CWPRETSTRUCT>(lParam);
        IntPtr hook = _hHook;

        if (msg.message == CbtHookAction.HCBT_ACTIVATE)
        {
            try
            {
                CenterWindow(msg.hwnd);
            }
            finally
            {
                UnhookWindowsHookEx(_hHook);
                _hHook = IntPtr.Zero;
            }
        }

        return CallNextHookEx(hook, nCode, wParam, lParam);
    }

    private static void CenterWindow(IntPtr hChildWnd)
    {
        if (_owner is Window window)
        {
            Rectangle recChild = new Rectangle(0, 0, 0, 0);
            _ = GetWindowRect(hChildWnd, ref recChild);

            int width = recChild.Width - recChild.X;
            int height = recChild.Height - recChild.Y;

            PresentationSource source = PresentationSource.FromVisual(window);
            double scaleX = source.CompositionTarget.TransformToDevice.M11;
            double scaleY = source.CompositionTarget.TransformToDevice.M22;

            int x = (int)((window.Left + (window.Width - width / scaleX) / 2) * scaleX);
            int y = (int)((window.Top + (window.Height - height / scaleY) / 2) * scaleY);

            _ = MoveWindow(hChildWnd, x, y, width, height, false);
        }
    }
}

    如您所见，这两个类几乎相同，但适用于所需的 UI 引擎。

    用法

    就像通常的一样MessageBox，只有第一个参数是传递相对于它应该居中的窗口（或窗体）。

    Winforms 和 WPF 的用法是一样的：

    MessageBoxEx.Show(this, "Hello World");

    this它在哪里Form用于 Winforms 或WindowWPF。

    • 0

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