为什么屏幕保护控制面板没有在窗体死亡时杀死它?

本文关键字：窗体 控制面板 屏幕保护 为什么 | 更新日期: 2023-09-27 18:19:21

使用我在CodeProject上找到的代码，我创建了一个屏幕保护程序。下面的表单是当用户选择我的屏幕保护程序时，我在控制面板中显示的一个小表单。

一切似乎都很好;表单正确地调整大小并在控制面板的正确位置绘制(它是空白的)，随着CP移动等。但是当控制面板关闭(或者用另一个屏幕保护程序的迷你预览取代我的表单)时，我的应用程序并没有死。它只是挂在内存中。

我的表单没有收到表单关闭/关闭消息，或者可见性改变等。我对亲子关系的定义有错吗?

下面是相关代码。所有导入的WinAPI调用都返回预期的值，而GetLastError总是返回零，所以我认为这不是问题…

    private void miniControlPanelForm_Load(object sender, EventArgs e)
    {
        // note that iphWnd is a class variable, passed to us by windows
        // set our window style to WS_CHILD, so that our window is
        // destroyed when parent window is destroyed.
        // get the current window style, but with WS_CHILD set
        IntPtr ip = new IntPtr();
        int index = (int)NativeMethods.WindowLongFlags.GWL_STYLE | 0x40000000;   
        ip = NativeMethods.GetWindowLongPtr(this.Handle, index);
        int error = System.Runtime.InteropServices.Marshal.GetLastWin32Error();
        // set that value as our current Style
        object ohRef = new object();
        HandleRef hRef = new HandleRef(ohRef, this.Handle);
        IntPtr ip2 = new IntPtr();
        int index2 = (int)NativeMethods.WindowLongFlags.GWL_STYLE;
        ip2 = NativeMethods.SetWindowLongPtr(hRef, index2, ip);
        error = System.Runtime.InteropServices.Marshal.GetLastWin32Error();
        // set the passed preview window as the parent of this window
        IntPtr newOldParent = NativeMethods.SetParent(this.Handle, iphWnd);
        error = System.Runtime.InteropServices.Marshal.GetLastWin32Error();
        //set our window's size to the size of our window's new parent
        Rectangle ParentRect = new Rectangle();
        NativeMethods.GetClientRect(iphWnd, ref ParentRect);
        this.Size = ParentRect.Size;
        //set our location at (0, 0)
        this.Location = new Point(0, 0);
    }

我有Application。在各种"窗体正在关闭"事件处理程序中退出，但它们永远不会被调用…

为什么屏幕保护控制面板没有在窗体死亡时杀死它?

如果您正确地使窗体成为控制面板窗口的子窗体，那么所有这些问题都将消失。下面是我现在的做法，它在所有情况下都有效。

在表单中，添加以下内容，这将在创建时强制表单的窗口样式为WS_CHILD:

    /// <summary>
    /// Override CreateParams property so we can add "WS_CHILD" to
    /// the Style each time it is queried during window creation.
    /// </summary>
    protected override CreateParams CreateParams
    {
        get
        {
            // get the base params and modify them
            CreateParams cp = base.CreateParams;
            cp.Style |= NativeMethods.WindowStyles.WS_CHILD;
            return cp;
        }
    }

在接收控制面板的hWnd并创建表单的代码中，使用SetParent使表单成为控制面板的子窗体:

    /// <summary>
    /// Show the form in the little control panel preview window.
    /// </summary>
    /// <param name="hWnd">hwnd passed to us at launch by windows</param>
    static void ShowMiniPreview(IntPtr hWnd)
    {
        if (NativeMethods.IsWindow(hWnd))
        {
            miniControlPanelForm preview = new miniControlPanelForm(hWnd);
            IntPtr newParent = NativeMethods.SetParent(preview.Handle, hWnd);
            // Set the size of the form to the size of the parent window (using the passed hWnd).
            System.Drawing.Rectangle ParentRect = new System.Drawing.Rectangle();
            bool fSuccess = NativeMethods.GetClientRect(hWnd, ref ParentRect);
            // Set our size to new rect and location at (0, 0)
            preview.Size = ParentRect.Size;
            preview.Location = new System.Drawing.Point(0, 0);
            // Show the form
            preview.Show();
            // and run it
            Application.Run(preview);
        }
    }

请注意，"native emethods"是我的类与各种Win32方法和常数声明为pinvoke:

    [DllImport("user32.dll", SetLastError = true)]
    internal static extern IntPtr SetParent(IntPtr hWndChild, IntPtr hWndNewParent);
    public static class WindowStyles
    {
        public static readonly Int32
        WS_CHILD = 0x40000000;
    }
    [DllImport("user32.dll", SetLastError = true)]
    internal static extern bool GetClientRect(IntPtr hWnd, ref Rectangle rect);
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