前言
Popup显示时会置顶显示。尤其是 Popup设置了StayOpen=true时，会一直置顶显示，问题更明显。
置顶显示问题现象：
解决方案
怎么解决问题？
获取绑定UserControl所在的窗口，窗口层级变化时，通知更新当前Popup的Tostmost属性。
1. 添加附加属性
在属性变更中，监听Loaded/UnLoaded事件，在加载后处理相应的逻辑。
private static readonly DependencyProperty TopmostInCurrentWindowProperty = DependencyProperty.RegisterAttached("TopmostInCurrentWindow",
typeof(bool), typeof(Popup), new FrameworkPropertyMetadata(false, OnTopmostInCurrentWindowChanged));
public static bool GetTopmostInCurrentWindow(DependencyObject obj)
{
return (bool)obj.GetValue(TopmostInCurrentWindowProperty);
}
public static void SetTopmostInCurrentWindow(DependencyObject obj, bool value)
{
obj.SetValue(TopmostInCurrentWindowProperty, value);
}
private static void OnTopmostInCurrentWindowChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
if (d is Popup popup)
{
_popup = popup;
popup.Loaded -= OnPopupLoaded;
popup.Unloaded -= OnPopupUnloaded;
if ((bool)e.NewValue)
{
popup.Loaded += OnPopupLoaded;
popup.Unloaded += OnPopupUnloaded;
}
}
}
2. 添加事件监听
在Popup.Loaded事件中，监听Popup所在窗口的唤醒事件。同时,Unloaded事件中注销所在窗口的事件监听。
在窗口唤醒事件监听逻辑中，设置当前popup选择性的置顶显示
添加Popup的MouseDown事件监听，点击Popup的内容后，Popup置顶显示、窗口层级也发相应的变化。
static void OnPopupLoaded(object sender, RoutedEventArgs e)
{
if (!(sender is Popup popup))
return; popup.Child?.AddHandler(UIElement.PreviewMouseLeftButtonDownEvent, new MouseButtonEventHandler(OnChildPreviewMouseLeftButtonDown), true); _parentWindow = Window.GetWindow(popup);
if (_parentWindow == null)
return; _parentWindow.Activated -= OnParentWindowActivated;
_parentWindow.Deactivated -= OnParentWindowDeactivated;
_parentWindow.Activated += OnParentWindowActivated;
_parentWindow.Deactivated += OnParentWindowDeactivated;
} static void OnPopupUnloaded(object sender, RoutedEventArgs e)
{
if (_parentWindow == null)
return;
_parentWindow.Activated -= OnParentWindowActivated;
_parentWindow.Deactivated -= OnParentWindowDeactivated;
} private static void OnParentWindowActivated(object sender, EventArgs e)
{
SetTopmostState(true);
} private static void OnParentWindowDeactivated(object sender, EventArgs e)
{
//Parent Window Deactivated
if (IsTopmost == false)
{
SetTopmostState(IsTopmost);
}
} static void OnChildPreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
SetTopmostState(true); if (!_parentWindow.IsActive && IsTopmost == false)
{
_parentWindow.Activate();
}
}
3. 选择性置顶显示
记录/设置当前Popup的置顶显示状态
选择性置顶显示-可以显示在最顶层，也可以只显示在当前窗口的上层。
private static bool IsTopmost
{
get => _isTopmost;
set
{
_isTopmost = value;
SetTopmostState(value);
}
} private static void SetTopmostState(bool isTop)
{
if (_appliedTopMost.HasValue && _appliedTopMost == isTop)
{
return;
} if (_popup?.Child == null)
return; var hwndSource = (PresentationSource.FromVisual(_popup.Child)) as HwndSource; if (hwndSource == null)
return;
var hwnd = hwndSource.Handle; RECT rect; if (!GetWindowRect(hwnd, out rect))
return; if (isTop)
{
SetWindowPos(hwnd, HWND_TOPMOST, rect.Left, rect.Top, (int)_popup.Width, (int)_popup.Height, TOPMOST_FLAGS);
}
else
{
// 重新激活Topmost，需要bottom->top->notop
SetWindowPos(hwnd, HWND_BOTTOM, rect.Left, rect.Top, (int)_popup.Width, (int)_popup.Height, TOPMOST_FLAGS);
SetWindowPos(hwnd, HWND_TOP, rect.Left, rect.Top, (int)_popup.Width, (int)_popup.Height, TOPMOST_FLAGS);
SetWindowPos(hwnd, HWND_NOTOPMOST, rect.Left, rect.Top, (int)_popup.Width, (int)_popup.Height, TOPMOST_FLAGS);
} _appliedTopMost = isTop;
}
以下是窗口消息处理、私有字段：
通过user32.dll的GetWindowRect和SetWindowPos函数，处理Popup层级问题
#region 窗口消息
[StructLayout(LayoutKind.Sequential)]
public struct RECT
{
public int Left;
public int Top;
public int Right;
public int Bottom;
}
[DllImport("user32.dll")]
[return: MarshalAs(UnmanagedType.Bool)]
private static extern bool GetWindowRect(IntPtr hWnd, out RECT lpRect);
[DllImport("user32.dll")]
private static extern bool SetWindowPos(IntPtr hWnd, IntPtr hWndInsertAfter, int X, int Y, int cx, int cy, uint uFlags);
static readonly IntPtr HWND_TOPMOST = new IntPtr(-);
static readonly IntPtr HWND_NOTOPMOST = new IntPtr(-);
static readonly IntPtr HWND_TOP = new IntPtr();
static readonly IntPtr HWND_BOTTOM = new IntPtr();
private const UInt32 SWP_NOSIZE = 0x0001;
const UInt32 SWP_NOMOVE = 0x0002;
const UInt32 SWP_NOREDRAW = 0x0008;
const UInt32 SWP_NOACTIVATE = 0x0010;
const UInt32 SWP_NOOWNERZORDER = 0x0200;
const UInt32 SWP_NOSENDCHANGING = 0x0400;
//很重要，窗口切换等需要将popup显示层级重新刷新
const UInt32 TOPMOST_FLAGS =
SWP_NOACTIVATE | SWP_NOOWNERZORDER | SWP_NOSIZE | SWP_NOMOVE | SWP_NOREDRAW | SWP_NOSENDCHANGING;
#endregion
#region private fileds
private static bool? _appliedTopMost;
private static bool _alreadyLoaded;
private static Window _parentWindow;
private static Popup _popup;
private static bool _isTopmost;
#endregion
下载 此Demo
注：也可以通过自定义用户控件Popup实现，逻辑一样：
/// <summary>
/// 解决StayOpen=true时，永远置顶的问题
/// </summary>
public class MyPopup : Popup
{
public static readonly DependencyProperty IsTopmostProperty = DependencyProperty.Register("IsTopmost", typeof(bool), typeof(MyPopup), new FrameworkPropertyMetadata(false, OnIsTopmostChanged)); private bool? _appliedTopMost;
private bool _alreadyLoaded;
private Window _parentWindow; public bool IsTopmost
{
get { return (bool)GetValue(IsTopmostProperty); }
set { SetValue(IsTopmostProperty, value); }
} /// <summary>
/// ctor
/// </summary>
public MyPopup()
{
Loaded += OnPopupLoaded;
Unloaded += OnPopupUnloaded;
} void OnPopupLoaded(object sender, RoutedEventArgs e)
{
if (_alreadyLoaded)
return; _alreadyLoaded = true; if (Child != null)
{
Child.AddHandler(PreviewMouseLeftButtonDownEvent, new MouseButtonEventHandler(OnChildPreviewMouseLeftButtonDown), true);
} _parentWindow = Window.GetWindow(this); if (_parentWindow == null)
return; _parentWindow.Activated += OnParentWindowActivated;
_parentWindow.Deactivated += OnParentWindowDeactivated;
} private void OnPopupUnloaded(object sender, RoutedEventArgs e)
{
if (_parentWindow == null)
return;
_parentWindow.Activated -= OnParentWindowActivated;
_parentWindow.Deactivated -= OnParentWindowDeactivated;
} void OnParentWindowActivated(object sender, EventArgs e)
{
SetTopmostState(true);
} void OnParentWindowDeactivated(object sender, EventArgs e)
{
Debug.WriteLine("Parent Window Deactivated"); if (IsTopmost == false)
{
SetTopmostState(IsTopmost);
}
} void OnChildPreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{ SetTopmostState(true); if (!_parentWindow.IsActive && IsTopmost == false)
{
_parentWindow.Activate();
}
} private static void OnIsTopmostChanged(DependencyObject obj, DependencyPropertyChangedEventArgs e)
{
var thisobj = (MyPopup)obj; thisobj.SetTopmostState(thisobj.IsTopmost);
} protected override void OnOpened(EventArgs e)
{
SetTopmostState(IsTopmost);
base.OnOpened(e);
} private void SetTopmostState(bool isTop)
{
if (_appliedTopMost.HasValue && _appliedTopMost == isTop)
{
return;
} if (Child == null)
return; var hwndSource = (PresentationSource.FromVisual(Child)) as HwndSource; if (hwndSource == null)
return;
var hwnd = hwndSource.Handle; RECT rect; if (!GetWindowRect(hwnd, out rect))
return; if (isTop)
{
SetWindowPos(hwnd, HWND_TOPMOST, rect.Left, rect.Top, (int)Width, (int)Height, TOPMOST_FLAGS);
}
else
{
// 重新激活Topmost，需要bottom->top->notop
SetWindowPos(hwnd, HWND_BOTTOM, rect.Left, rect.Top, (int)Width, (int)Height, TOPMOST_FLAGS);
SetWindowPos(hwnd, HWND_TOP, rect.Left, rect.Top, (int)Width, (int)Height, TOPMOST_FLAGS);
SetWindowPos(hwnd, HWND_NOTOPMOST, rect.Left, rect.Top, (int)Width, (int)Height, TOPMOST_FLAGS);
} _appliedTopMost = isTop;
} [StructLayout(LayoutKind.Sequential)]
public struct RECT {
public int Left;
public int Top;
public int Right;
public int Bottom;
} [DllImport("user32.dll")]
[return: MarshalAs(UnmanagedType.Bool)]
private static extern bool GetWindowRect(IntPtr hWnd, out RECT lpRect); [DllImport("user32.dll")]
private static extern bool SetWindowPos(IntPtr hWnd, IntPtr hWndInsertAfter, int X,
int Y, int cx, int cy, uint uFlags); static readonly IntPtr HWND_TOPMOST = new IntPtr(-);
static readonly IntPtr HWND_NOTOPMOST = new IntPtr(-);
static readonly IntPtr HWND_TOP = new IntPtr();
static readonly IntPtr HWND_BOTTOM = new IntPtr(); private const UInt32 SWP_NOSIZE = 0x0001;
const UInt32 SWP_NOMOVE = 0x0002;
const UInt32 SWP_NOZORDER = 0x0004;
const UInt32 SWP_NOREDRAW = 0x0008;
const UInt32 SWP_NOACTIVATE = 0x0010; const UInt32 SWP_FRAMECHANGED = 0x0020; /* The frame changed: send WM_NCCALCSIZE */
const UInt32 SWP_SHOWWINDOW = 0x0040;
const UInt32 SWP_HIDEWINDOW = 0x0080;
const UInt32 SWP_NOCOPYBITS = 0x0100;
const UInt32 SWP_NOOWNERZORDER = 0x0200; /* Don’t do owner Z ordering */
const UInt32 SWP_NOSENDCHANGING = 0x0400; /* Don’t send WM_WINDOWPOSCHANGING */ //很重要，窗口切换等需要将popup显示层级重新刷新
const UInt32 TOPMOST_FLAGS =
SWP_NOACTIVATE | SWP_NOOWNERZORDER | SWP_NOSIZE | SWP_NOMOVE | SWP_NOREDRAW | SWP_NOSENDCHANGING;
}
解决方案总结
添加如上附加属性或者用户控件Popup后，能解决置顶问题，Popup只会出现在所在窗口上层。
截图如下：
