如何在WindowStyle ="None"的WPF窗口中强制MinWidth和MinHeight？

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,如果有可能的话？谢谢!!

Answer 1

我能够通过设置来解决这个问题handled(最后一个参数WindowProc()),以false的情况下为0x0024(其中OP提到他已经钩住修复最大化),然后设置MinHeight,并MinWidth在窗口XAML.这使得此窗口消息的处理可以进入默认的WPF机制.

这样,Window管理最小大小的Min*属性和自定义GetMinMaxInfo代码管理最大大小.

Answer 2

你需要处理一个Windows消息才能做到这一点,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的逻辑只是两行代码.

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;
}