Question

我有一个WPF应用程序，主窗口的装饰是自定义的，通过WindowStyle =“None”。我绘制自己的标题栏和最小/最大/关闭按钮。不幸的是，Windows在调整窗口大小时不会强制执行MinWidth和MinHeight属性，从而允许窗口一直调整到3x3（appx - 刚好足以显示窗口增长的句柄）。

我已经不得不拦截窗口事件（sp.0x0024）来修复由WindowStyle = none引起的最大化错误（它将在Windows任务栏上最大化）。我并不害怕拦截更多事件来实现我的需要。

有没有人知道如何让我的窗口不在我的MinWidth和MinHeight属性下调整大小，如果可能的话？谢谢！

Answer 1

我能够通过将handled（WindowProc()的最后一个参数）设置为false来解决此问题，在0x0024的情况下（OP提到他已经挂钩修复了最大化），然后在Window XAML中设置MinHeight和MinWidth。这使得此窗口消息的处理可以转换为默认的WPF机制。

这样，Window上的Min *属性管理最小大小，自定义GetMinMaxInfo代码管理最大大小。

Answer 2

你确实需要处理一条Windows消息，但这并不复杂。

你必须处理WM_WINDOWPOSCHANGING消息，在WPF中这样做需要一些样板代码，你可以在下面看到实际逻辑只有两行代码。

internal enum WM
{
   WINDOWPOSCHANGING = 0x0046,
}

[StructLayout(LayoutKind.Sequential)]
internal struct WINDOWPOS
{
   public IntPtr hwnd;
   public IntPtr hwndInsertAfter;
   public int x;
   public int y;
   public int cx;
   public int cy;
   public int flags;
}

private void Window_SourceInitialized(object sender, EventArgs ea)
{
   HwndSource hwndSource = (HwndSource)HwndSource.FromVisual((Window)sender);
   hwndSource.AddHook(DragHook);
}

private static IntPtr DragHook(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handeled)
{
   switch ((WM)msg)
   {
      case WM.WINDOWPOSCHANGING:
      {
          WINDOWPOS pos = (WINDOWPOS)Marshal.PtrToStructure(lParam, typeof(WINDOWPOS));
          if ((pos.flags & (int)SWP.NOMOVE) != 0)
          {
              return IntPtr.Zero;
          }

          Window wnd = (Window)HwndSource.FromHwnd(hwnd).RootVisual;
          if (wnd == null)
          {
             return IntPtr.Zero;
          }

          bool changedPos = false;

          // ***********************
          // Here you check the values inside the pos structure
          // if you want to override them just change the pos
          // structure and set changedPos to true
          // ***********************

          // this is a simplified version that doesn't work in high-dpi settings
          // pos.cx and pos.cy are in "device pixels" and MinWidth and MinHeight 
          // are in "WPF pixels" (WPF pixels are always 1/96 of an inch - if your
          // system is configured correctly).
          if(pos.cx < MinWidth) { pos.cx = MinWidth; changedPos = true; }
          if(pos.cy < MinHeight) { pos.cy = MinHeight; changedPos = true; }


          // ***********************
          // end of "logic"
          // ***********************

          if (!changedPos)
          {
             return IntPtr.Zero;
          }

          Marshal.StructureToPtr(pos, lParam, true);
          handeled = true;
       }
       break;
   }

   return IntPtr.Zero;
}

Answer 3

以下代码适用于任何DPI设置。

case 0x0046: //Window position message to be handled to restrict the min and max height of the window on 120% screen
                    {
                        WINDOWPOS pos = (WINDOWPOS)Marshal.PtrToStructure(lParam, typeof(WINDOWPOS));
                        if ((pos.flags & (int)SWP.NOMOVE) != 0)
                        {
                            return IntPtr.Zero;
                        }

                        System.Windows.Window wnd = (System.Windows.Window)HwndSource.FromHwnd(hwnd).RootVisual;
                        if (wnd == null)
                        {
                            return IntPtr.Zero;
                        }

                        bool changedPos = false;

                        //Convert the original to original size based on DPI setting. Need for 120% screen
                        PresentationSource MainWindowPresentationSource = PresentationSource.FromVisual(wnd);
                        Matrix m = MainWindowPresentationSource.CompositionTarget.TransformToDevice;
                        if (pos.cx < (wnd.MinWidth * m.M11)) { pos.cx = (int)(wnd.MinWidth * m.M11); changedPos = true; }
                        if (pos.cy < (wnd.MinHeight * m.M22)) { pos.cy = (int)(wnd.MinHeight * m.M22); changedPos = true; }

                        if (!changedPos)
                        {
                            return IntPtr.Zero;
                        }

                        Marshal.StructureToPtr(pos, lParam, true);
                        handled = true;
                    }
                    break;

Answer 4

我目前无法验证这一点，因为我在Mac笔记本电脑上，但我相信我之前通过处理SizeChanged事件然后检测MinWidth / Height是否被违反来完成此操作，如果是，只需将宽度/高度属性设置回最小值。

Answer 5

解决方案正在运行，但有一个错误。当我尝试通过拖动顶部或左边框来调整窗口大小时窗口正在移动。它发生在changePos为真时。这是没有这个bug的代码：

private static WindowPos _prevPos = new WindowPos();
/// <summary>
/// You do need to handle a windows message to do it, but it's not complicated. 
/// You have to handle the WM_WINDOWPOSCHANGING message, doing that in WPF requires
///  a bit of boilerplate code, you can see below the actual logic is just two lines of code.
/// </summary>
/// <param name="hwnd"></param>
/// <param name="lParam"></param>
private static bool OnWmWindowPosChanging(IntPtr hwnd, IntPtr lParam)
{
    // ReSharper disable once InconsistentNaming
    const int SwpNoMove = 0x0002;
    WindowPos pos = (WindowPos) Marshal.PtrToStructure(lParam, typeof (WindowPos));
    if ((pos.flags & SwpNoMove) != 0) return false;

    Window wnd = (Window) HwndSource.FromHwnd(hwnd)?.RootVisual;
    if (wnd == null) return false;

    bool changePos = false;

    if (pos.cx < wnd.MinWidth)
    {
        pos.cx = (int)wnd.MinWidth;
        // here is we keep pos x
        if (_prevPos.hwnd != IntPtr.Zero)
            pos.x = _prevPos.x;
        changePos = true;
    }

    if (pos.cy < wnd.MinHeight)
    {
        pos.cy = (int)wnd.MinHeight;
        // here is we keep pos y
        if (_prevPos.hwnd != IntPtr.Zero)
            pos.y = _prevPos.y;
        changePos = true;
    }

    // Debug.WriteLine($"x = {pos.x}, y = {pos.y}; w = {pos.cx}, h = {pos.cy}");

    if (!changePos) return false;
    // Keep prev pos for bounded window
    _prevPos = pos;
    Marshal.StructureToPtr(pos, lParam, true);

    return true;
}

如何强制MinWidth＆amp;在WindowFtyle =“None”的WPF窗口中的MinHeight？

5 个答案: