我基本上试图在按钮悬停上实现弹出窗口。当用户悬停在按钮上时，我希望弹出窗口显示。如果不是，我只想出现标签。它有点像工具提示，除了我不希望Popup在经过一段时间后消失。我有点使用按钮上的ControlTemplate工作，有两个警告：
Xaml代码：
<Window>
<Window.Resources>
<Style x:Key="LabelStyle" TargetType="Label">
<Setter Property="Margin" Value="0, 0, 0, 5" />
<Setter Property="Width" Value="58" />
<Setter Property="Height" Value="28" />
<Setter Property="Padding" Value="1, 0, 1, 0" />
</Style>
<ControlTemplate x:Key="ButtonControlTemplate" TargetType="Button">
<StackPanel>
<Button Width="48" Height="48" Background="White" Name="ItemButton">
<ContentPresenter Content="{TemplateBinding Property=ContentControl.Content}" />
</Button>
<Label Style="{StaticResource LabelStyle}" VerticalContentAlignment="Top" HorizontalContentAlignment="Center" Name="ItemLabel">
<TextBlock TextWrapping="Wrap" TextAlignment="Center" FontSize="11" LineHeight="13" LineStackingStrategy="BlockLineHeight">
Hello World!
</TextBlock>
</Label>
<Popup Name="ItemPopup" Placement="Bottom" PlacementTarget="{Binding ElementName=ItemButton}">
<TextBlock Background="Red">Hello World!</TextBlock>
</Popup>
</StackPanel>
<ControlTemplate.Triggers>
<Trigger SourceName="ItemButton" Property="IsMouseOver" Value="True">
<Setter TargetName="ItemLabel" Property="Visibility" Value="Hidden" />
<Setter TargetName="ItemPopup" Property="IsOpen" Value="True" />
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Window.Resources>
<StackPanel>
<Button Background="Green" Template="{StaticResource ButtonControlTemplate}">
<Image Source="http://leduc998.files.wordpress.com/2010/10/msft_logo.jpg" />
</Button>
</StackPanel>
</Window>
编辑：修复了闪烁问题。只需要将Popup放置在底部和中心位置。
答案 0 :(得分：2)
我最终必须编写一个转换器，根据弹出窗口和放置目标的高度将其移动。
使用这样的多重绑定将信息传递给我的转换器以获取VerticalOffset：
<MultiBinding Converter="{StaticResource PopupVerticalAligner}">
<Binding RelativeSource="{RelativeSource Self}" Path="PlacementTarget.ActualHeight" />
<Binding RelativeSource="{RelativeSource Self}" Path="ActualHeight" />
</MultiBinding>
答案 1 :(得分：0)
您是否尝试过MouseEnter事件？然后，您可以在DispatcherTimer上打开弹出窗口，然后再次关闭它。
答案 2 :(得分：0)
添加到sohum的answer，这是我如何将我的ListView-Popup底部置于ToggleButton下面。它可以根据listview的宽度正确地进行偏移。我还留下了点滴和碎片，给了togglebutton直观的行为，比如再次单击togglebutton来隐藏弹出窗口。
<ToggleButton x:Name="ParentToggleButton" IsChecked="{Binding ToggleButtonStatus}" IsHitTestVisible="{Binding ElementName=ToggledPopup, Path=IsOpen, Converter={StaticResource BoolToInvertedBoolConverter}}" >
<ToggleButton.Content>...</ToggleButton.Content>
</ToggleButton>
<Popup PlacementTarget="{Binding ElementName=ParentToggleButton}" Placement="Bottom" StaysOpen="False" IsOpen="{Binding ToggleButtonStatus}" x:Name="ToggledPopup">
<Popup.HorizontalOffset>
<MultiBinding Converter="{StaticResource CenterToolTipConverter}">
<Binding RelativeSource="{RelativeSource Self}" Path="PlacementTarget.ActualWidth"/>
<Binding ElementName="INeedYourWidth" Path="ActualWidth"/>
</MultiBinding>
</Popup.HorizontalOffset>
<ListView x:Name="INeedYourWidth" ItemsSource="{Binding ItemsSource}" >
<ListView.ItemTemplate>
<DataTemplate>...</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</Popup>
BoolToInvertedBoolConverter如果为false则返回true，如果为true则返回false（允许弹出窗口在用户尝试取消它时折叠），并且可以在sohum的link中找到CenterToolTipConverter。
答案 3 :(得分：0)
更好的方法是将 PlacementTarget 控件置于Grid内，并使Popup控件成为Grid的同一个孩子，同时保持Placement=Bottom }。这将在PlacementTarget控件下显示您的Popup以底部为中心。没有转换器，没有样式，简单的简单XAML。
答案 4 :(得分：0)
尽管这已经是一个老问题了，但我也有同样的需求-我需要能够将Popup与其放置目标对齐。我对转换器解决方案不满意，我想出了自己的解决方案，使用了附加的依赖项属性，在这里与您以及有同样需求的任何人共享这些属性。
注意：此解决方案不介绍如何在鼠标上显示
Popup悬停。它仅涵盖最棘手的部分-Popup与其放置目标的对齐。有几种方法可以在鼠标悬停时显示Popup，例如使用 Triggers 或 Bindings ，这两种方法在StackOverflow上都有广泛介绍。
此解决方案使用单个静态类，该类公开了一些附加的依赖项属性。使用这些属性，您可以将Popup与其PlacementTarget或其PlacementRectangle水平或垂直对齐。仅当Popup的{{1}}属性的值表示边缘（Placement，Left，Top或Right时，才发生对齐。
Bottom上面的代码创建了一个静态类，该类公开了using System;
using System.Windows;
using System.Windows.Controls.Primitives;
using System.Windows.Media;
namespace MyProjectName.Ui
{
/// <summary>
/// Exposes attached dependency properties that provide
/// additional functionality for <see cref="Popup"/> controls.
/// </summary>
/// <seealso cref="Popup"/>
/// <seealso cref="DependencyProperty"/>
public static class PopupProperties
{
#region Properties
#region IsMonitoringState attached dependency property
/// <summary>
/// Attached <see cref="DependencyProperty"/>. This property
/// registers (<b>true</b>) or unregisters (<b>false</b>) a
/// <see cref="Popup"/> from the popup monitoring mechanism
/// used internally by <see cref="PopupProperties"/> to keep
/// the <see cref="Popup"/> in synchrony with the
/// <see cref="PopupProperties"/>' attached properties. A
/// <see cref="Popup"/> will be automatically unregistered from
/// this mechanism after it is unloaded.
/// </summary>
/// <seealso cref="Popup"/>
private static readonly DependencyProperty IsMonitoringStateProperty
= DependencyProperty.RegisterAttached("IsMonitoringState",
typeof(bool), typeof(PopupProperties),
new FrameworkPropertyMetadata(false,
FrameworkPropertyMetadataOptions.None,
new PropertyChangedCallback(IsMonitoringStatePropertyChanged)));
private static void IsMonitoringStatePropertyChanged(
DependencyObject dObject, DependencyPropertyChangedEventArgs e)
{
Popup popup = (Popup)dObject;
bool value = (bool)e.NewValue;
if (value)
{
// Attach popup.
popup.Opened += Popup_Opened;
popup.Unloaded += Popup_Unloaded;
// Update popup.
UpdateLocation(popup);
}
else
{
// Detach popup.
popup.Opened -= Popup_Opened;
popup.Unloaded -= Popup_Unloaded;
}
}
private static bool GetIsMonitoringState(Popup popup)
{
if (popup is null)
throw new ArgumentNullException(nameof(popup));
return (bool)popup.GetValue(IsMonitoringStateProperty);
}
private static void SetIsMonitoringState(Popup popup, bool isMonitoringState)
{
if (popup is null)
throw new ArgumentNullException(nameof(popup));
popup.SetValue(IsMonitoringStateProperty, isMonitoringState);
}
#endregion
#region HorizontalPlacementAlignment attached dependency property
public static readonly DependencyProperty HorizontalPlacementAlignmentProperty
= DependencyProperty.RegisterAttached("HorizontalPlacementAlignment",
typeof(AlignmentX), typeof(PopupProperties),
new FrameworkPropertyMetadata(AlignmentX.Left,
FrameworkPropertyMetadataOptions.None,
new PropertyChangedCallback(HorizontalPlacementAlignmentPropertyChanged)),
new ValidateValueCallback(HorizontalPlacementAlignmentPropertyValidate));
private static void HorizontalPlacementAlignmentPropertyChanged(
DependencyObject dObject, DependencyPropertyChangedEventArgs e)
{
Popup popup = (Popup)dObject;
SetIsMonitoringState(popup, true);
UpdateLocation(popup);
}
private static bool HorizontalPlacementAlignmentPropertyValidate(object obj)
{
return Enum.IsDefined(typeof(AlignmentX), obj);
}
public static AlignmentX GetHorizontalPlacementAlignment(Popup popup)
{
if (popup is null)
throw new ArgumentNullException(nameof(popup));
return (AlignmentX)popup.GetValue(HorizontalPlacementAlignmentProperty);
}
public static void SetHorizontalPlacementAlignment(Popup popup, AlignmentX alignment)
{
if (popup is null)
throw new ArgumentNullException(nameof(popup));
popup.SetValue(HorizontalPlacementAlignmentProperty, alignment);
}
#endregion
#region VerticalPlacementAlignment attached dependency property
public static readonly DependencyProperty VerticalPlacementAlignmentProperty
= DependencyProperty.RegisterAttached("VerticalPlacementAlignment",
typeof(AlignmentY), typeof(PopupProperties),
new FrameworkPropertyMetadata(AlignmentY.Top,
FrameworkPropertyMetadataOptions.None,
new PropertyChangedCallback(VerticalPlacementAlignmentPropertyChanged)),
new ValidateValueCallback(VerticalPlacementAlignmentPropertyValidate));
private static void VerticalPlacementAlignmentPropertyChanged(
DependencyObject dObject, DependencyPropertyChangedEventArgs e)
{
Popup popup = (Popup)dObject;
SetIsMonitoringState(popup, true);
UpdateLocation(popup);
}
private static bool VerticalPlacementAlignmentPropertyValidate(object obj)
{
return Enum.IsDefined(typeof(AlignmentY), obj);
}
public static AlignmentY GetVerticalPlacementAlignment(Popup popup)
{
if (popup is null)
throw new ArgumentNullException(nameof(popup));
return (AlignmentY)popup.GetValue(VerticalPlacementAlignmentProperty);
}
public static void SetVerticalPlacementAlignment(Popup popup, AlignmentY alignment)
{
if (popup is null)
throw new ArgumentNullException(nameof(popup));
popup.SetValue(VerticalPlacementAlignmentProperty, alignment);
}
#endregion
#region HorizontalOffset attached dependency property
public static readonly DependencyProperty HorizontalOffsetProperty
= DependencyProperty.RegisterAttached("HorizontalOffset",
typeof(double), typeof(PopupProperties),
new FrameworkPropertyMetadata(0d,
FrameworkPropertyMetadataOptions.None,
new PropertyChangedCallback(HorizontalOffsetPropertyChanged)),
new ValidateValueCallback(HorizontalOffsetPropertyValidate));
private static void HorizontalOffsetPropertyChanged(
DependencyObject dObject, DependencyPropertyChangedEventArgs e)
{
Popup popup = (Popup)dObject;
SetIsMonitoringState(popup, true);
UpdateLocation(popup);
}
private static bool HorizontalOffsetPropertyValidate(object obj)
{
double value = (double)obj;
return !double.IsNaN(value) && !double.IsInfinity(value);
}
public static double GetHorizontalOffset(Popup popup)
{
if (popup is null)
throw new ArgumentNullException(nameof(popup));
return (double)popup.GetValue(HorizontalOffsetProperty);
}
public static void SetHorizontalOffset(Popup popup, double offset)
{
if (popup is null)
throw new ArgumentNullException(nameof(offset));
popup.SetValue(HorizontalOffsetProperty, offset);
}
#endregion
#region VerticalOffset attached dependency property
public static readonly DependencyProperty VerticalOffsetProperty
= DependencyProperty.RegisterAttached("VerticalOffset",
typeof(double), typeof(PopupProperties),
new FrameworkPropertyMetadata(0d,
FrameworkPropertyMetadataOptions.None,
new PropertyChangedCallback(VerticalOffsetPropertyChanged)),
new ValidateValueCallback(VerticalOffsetPropertyValidate));
private static void VerticalOffsetPropertyChanged(
DependencyObject dObject, DependencyPropertyChangedEventArgs e)
{
Popup popup = (Popup)dObject;
SetIsMonitoringState(popup, true);
UpdateLocation(popup);
}
private static bool VerticalOffsetPropertyValidate(object obj)
{
double value = (double)obj;
return !double.IsNaN(value) && !double.IsInfinity(value);
}
public static double GetVerticalOffset(Popup popup)
{
if (popup is null)
throw new ArgumentNullException(nameof(popup));
return (double)popup.GetValue(VerticalOffsetProperty);
}
public static void SetVerticalOffset(Popup popup, double offset)
{
if (popup is null)
throw new ArgumentNullException(nameof(offset));
popup.SetValue(VerticalOffsetProperty, offset);
}
#endregion
#endregion Properties
#region Methods
private static void OnMonitorState(Popup popup)
{
if (popup is null)
throw new ArgumentNullException(nameof(popup));
UpdateLocation(popup);
}
private static void UpdateLocation(Popup popup)
{
// Validate parameters.
if (popup is null)
throw new ArgumentNullException(nameof(popup));
// If the popup is not open, we don't need to update its position yet.
if (!popup.IsOpen)
return;
// Setup initial variables.
double offsetX = 0d;
double offsetY = 0d;
PlacementMode placement = popup.Placement;
UIElement placementTarget = popup.PlacementTarget;
Rect placementRect = popup.PlacementRectangle;
// If the popup placement mode is an edge of the placement target,
// determine the alignment offset.
if (placement == PlacementMode.Top || placement == PlacementMode.Bottom
|| placement == PlacementMode.Left || placement == PlacementMode.Right)
{
// Try to get the popup size. If its size is empty, use the size
// of its child, if any child exists.
Size popupSize = GetElementSize(popup);
UIElement child = popup.Child;
if ((popupSize.IsEmpty || popupSize.Width <= 0d || popupSize.Height <= 0d)
&& child != null)
{
popupSize = GetElementSize(child);
}
// Get the placement rectangle size. If it's empty, get the
// placement target's size, if a target is set.
Size targetSize;
if (placementRect.Width > 0d && placementRect.Height > 0d)
targetSize = placementRect.Size;
else if (placementTarget != null)
targetSize = GetElementSize(placementTarget);
else
targetSize = Size.Empty;
// If we have a valid popup size and a valid target size, determine
// the offset needed to align the popup to the target rectangle.
if (!popupSize.IsEmpty && popupSize.Width > 0d && popupSize.Height > 0d
&& !targetSize.IsEmpty && targetSize.Width > 0d && targetSize.Height > 0d)
{
switch (placement)
{
// Horizontal alignment offset.
case PlacementMode.Top:
case PlacementMode.Bottom:
switch (GetHorizontalPlacementAlignment(popup))
{
case AlignmentX.Left:
offsetX = 0d;
break;
case AlignmentX.Center:
offsetX = -(popupSize.Width - targetSize.Width) / 2d;
break;
case AlignmentX.Right:
offsetX = -(popupSize.Width - targetSize.Width);
break;
default:
break;
}
break;
// Vertical alignment offset.
case PlacementMode.Left:
case PlacementMode.Right:
switch (GetVerticalPlacementAlignment(popup))
{
case AlignmentY.Top:
offsetY = 0d;
break;
case AlignmentY.Center:
offsetY = -(popupSize.Height - targetSize.Height) / 2d;
break;
case AlignmentY.Bottom:
offsetY = -(popupSize.Height - targetSize.Height);
break;
default:
break;
}
break;
default:
break;
}
}
}
// Add the developer specified offsets to the offsets we've calculated.
offsetX += GetHorizontalOffset(popup);
offsetY += GetVerticalOffset(popup);
// Apply the final computed offsets to the popup.
popup.SetCurrentValue(Popup.HorizontalOffsetProperty, offsetX);
popup.SetCurrentValue(Popup.VerticalOffsetProperty, offsetY);
}
private static Size GetElementSize(UIElement element)
{
if (element is null)
return new Size(0d, 0d);
else if (element is FrameworkElement frameworkElement)
return new Size(frameworkElement.ActualWidth, frameworkElement.ActualHeight);
else
return element.RenderSize;
}
#endregion Methods
#region Event handlers
private static void Popup_Unloaded(object sender, RoutedEventArgs e)
{
if (sender is Popup popup)
{
// Stop monitoring the popup state, because it was unloaded.
SetIsMonitoringState(popup, false);
}
}
private static void Popup_Opened(object sender, EventArgs e)
{
if (sender is Popup popup)
{
OnMonitorState(popup);
}
}
#endregion Event handlers
}
}
控件的4个附加的依赖项属性。即，它们是Popup，HorizontalPlacementAlignment，VerticalPlacementAlignment和HorizontalOffset。
VerticalOffset和HorizontalPlacementAlignment附加的依赖项属性使您可以相对于弹出窗口的VerticalPlacementAlignment或PlacementTarget对齐弹出窗口。为此，该机制使用PlacementRectangle和Popup.HorizontalOffset属性来定位Popup.VerticalOffset。
由于该机制使用Popup和Popup.HorizontalOffset属性来工作，因此此类提供了自己的Popup.VerticalOffset和HorizontalOffset属性（附加的依赖项属性）。除了对齐方式，您还可以使用它们来调整VerticalOffset的位置。
每次打开Popup时，该机制都会自动更新Popup的位置。但是，当弹出窗口大小更改或其放置目标或放置矩形大小更改时，其位置不会自动更新。尽管如此，只要投入更多的工作，该功能就可以轻松实现。
您可以像下面的示例一样在Popup上使用附加的属性。在此示例中，我们有一个简单的Popup和一个Button。 Popup显示为与Popup的底部对齐，并水平居中于Button的中心。
Button通过将<Button x:Name="MyTargetElement">My Button</Button>
<Popup xmlns:ui="clr-namespace:MyProjectName.Ui"
PlacementTarget="{Binding ElementName=MyTargetElement}"
Placement="Bottom"
ui:PopupProperties.HorizontalPlacementAlignment="Center"
ui:PopupProperties.VerticalOffset="2">
</Popup>
和ui:PopupProperties.HorizontalPlacementAlignment="Center"添加到ui:PopupProperties.VerticalOffset="2"，它将与放置目标的水平中心对齐，并且还具有2个WPF垂直偏移单位。
请注意在Popup上使用xmlns:ui="clr-namespace:MyProjectName.Ui"。此属性仅从项目上的Popup命名空间导入类型，并通过使用XAML属性上的MyProjectName.Ui前缀使它们可用。在示例中，为简单起见，在ui:上设置了此属性，但是通常在使用这些自定义附加依赖项属性的Popup或Window上设置它。
使用附加的依赖项属性来实现此功能的想法是使它在XAML中的使用尽可能简单。对于简单的一次性需求，使用转换器可能更易于实现。但是，在这种情况下，使用附加的依赖项属性可能会提供一种更加动态且易于使用的方法。