Popup出于这些原因，我个人讨厌 WPF 的内置控件，我的解决方法是使用自定义弹出用户控件
基本上，我会将 Popup 放在一个允许其子级重叠的面板中，例如 aGrid或 a Canvas，并将其放置在它应该位于的任何内容之上。
它包括 DependencyProperties 来指定它的父面板以及它是否打开，并且是普通 VisualTree 的一部分，因此它会随着您的 Window 移动并以与任何常规 UI 元素相同的方式运行。
典型用法如下所示：
<Grid x:Name="ParentPanel">
<ItemsControl ... />
<local:PopupPanel Content="{Binding PopupContent}"
local:PopupPanel.PopupParent="{Binding ElementName=ParentPanel}"
local:PopupPanel.IsPopupVisible="{Binding IsPopupVisible}" />
</Grid>
可以在我的博客上找到 UserControl 的代码以及可下载的使用示例，但我也会在此处发布它的副本。
UserControl 的 XAML 是：
<UserControl x:Class="PopupPanelSample.PopupPanel"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:local="clr-namespace:PopupPanelSample"
FocusManager.IsFocusScope="True"
>
<UserControl.Template>
<ControlTemplate TargetType="{x:Type local:PopupPanel}">
<ControlTemplate.Resources>
<!-- Converter to get Popup Positioning -->
<local:ValueDividedByParameterConverter x:Key="ValueDividedByParameterConverter" />
<!-- Popup Visibility -->
<BooleanToVisibilityConverter x:Key="BooleanToVisibilityConverter" />
<Style x:Key="PopupPanelContentStyle" TargetType="{x:Type Grid}">
<Setter Property="Grid.Visibility" Value="{Binding Path=IsPopupVisible,
RelativeSource={RelativeSource AncestorType={x:Type local:PopupPanel}},
Converter={StaticResource BooleanToVisibilityConverter}}"/>
</Style>
</ControlTemplate.Resources>
<Grid x:Name="PopupPanelContent" Style="{StaticResource PopupPanelContentStyle}">
<Grid.Resources>
<!-- Storyboard to show Content -->
<Storyboard x:Key="ShowEditPanelStoryboard" SpeedRatio="5">
<DoubleAnimation
Storyboard.TargetName="PopupPanelContent"
Storyboard.TargetProperty="RenderTransform.(ScaleTransform.ScaleX)"
From="0.00" To="1.00" Duration="00:00:01"
/>
<DoubleAnimation
Storyboard.TargetName="PopupPanelContent"
Storyboard.TargetProperty="RenderTransform.(ScaleTransform.ScaleY)"
From="0.00" To="1.00" Duration="00:00:01"
/>
</Storyboard>
</Grid.Resources>
<!-- Setting up RenderTransform for Popup Animation -->
<Grid.RenderTransform>
<ScaleTransform
CenterX="{Binding Path=PopupParent.ActualWidth, Converter={StaticResource ValueDividedByParameterConverter}, ConverterParameter=2, RelativeSource={RelativeSource AncestorType={x:Type local:PopupPanel}}}"
CenterY="{Binding Path=PopupParent.ActualHeight, Converter={StaticResource ValueDividedByParameterConverter}, ConverterParameter=2, RelativeSource={RelativeSource AncestorType={x:Type local:PopupPanel}}}"
/>
</Grid.RenderTransform>
<!-- Grayscale background & prevents mouse input -->
<Rectangle
Fill="Gray"
Opacity="{Binding Path=BackgroundOpacity, RelativeSource={RelativeSource AncestorType={x:Type local:PopupPanel}}}"
Height="{Binding RelativeSource={RelativeSource AncestorType={x:Type local:PopupPanel}}, Path=Height}"
Width="{Binding RelativeSource={RelativeSource AncestorType={x:Type local:PopupPanel}}, Path=Width}"
/>
<!-- Popup Content -->
<ContentControl x:Name="PopupContentControl"
KeyboardNavigation.TabNavigation="Cycle"
PreviewKeyDown="PopupPanel_PreviewKeyDown"
PreviewLostKeyboardFocus="PopupPanel_LostFocus"
IsVisibleChanged="PopupPanel_IsVisibleChanged"
HorizontalAlignment="Center" VerticalAlignment="Center"
>
<ContentPresenter Content="{TemplateBinding Content}" />
</ContentControl>
</Grid>
</ControlTemplate>
</UserControl.Template>
</UserControl>
UserControl 背后的代码如下所示：
using System;
using System.ComponentModel;
using System.Globalization;
using System.Linq;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Threading;
namespace PopupPanelSample
{
/// <summary>
/// Panel for handling Popups:
/// - Control with name PART_DefaultFocusControl will have default focus
/// - Can define PopupParent to determine if this popup should be hosted in a parent panel or not
/// - Can define the property EnterKeyCommand to specifify what command to run when the Enter key is pressed
/// - Can define the property EscapeKeyCommand to specify what command to run when the Escape key is pressed
/// - Can define BackgroundOpacity to specify how opaque the background will be. Value is between 0 and 1.
/// </summary>
public partial class PopupPanel : UserControl
{
#region Fields
bool _isLoading = false; // Flag to tell identify when DataContext changes
private UIElement _lastFocusControl; // Last control that had focus when popup visibility changes, but isn't closed
#endregion // Fields
#region Constructors
public PopupPanel()
{
InitializeComponent();
this.DataContextChanged += Popup_DataContextChanged;
// Register a PropertyChanged event on IsPopupVisible
DependencyPropertyDescriptor dpd = DependencyPropertyDescriptor.FromProperty(PopupPanel.IsPopupVisibleProperty, typeof(PopupPanel));
if (dpd != null) dpd.AddValueChanged(this, delegate { IsPopupVisible_Changed(); });
dpd = DependencyPropertyDescriptor.FromProperty(PopupPanel.ContentProperty, typeof(PopupPanel));
if (dpd != null) dpd.AddValueChanged(this, delegate { Content_Changed(); });
}
#endregion // Constructors
#region Events
#region Property Change Events
// When DataContext changes
private void Popup_DataContextChanged(object sender, DependencyPropertyChangedEventArgs e)
{
DisableAnimationWhileLoading();
}
// When Content Property changes
private void Content_Changed()
{
DisableAnimationWhileLoading();
}
// Sets an IsLoading flag so storyboard doesn't run while loading
private void DisableAnimationWhileLoading()
{
_isLoading = true;
this.Dispatcher.BeginInvoke(DispatcherPriority.Render,
new Action(delegate() { _isLoading = false; }));
}
// Run storyboard when IsPopupVisible property changes to true
private void IsPopupVisible_Changed()
{
bool isShown = GetIsPopupVisible(this);
if (isShown && !_isLoading)
{
FrameworkElement panel = FindChild<FrameworkElement>(this, "PopupPanelContent");
if (panel != null)
{
// Run Storyboard
Storyboard animation = (Storyboard)panel.FindResource("ShowEditPanelStoryboard");
animation.Begin();
}
}
// When hiding popup, clear the LastFocusControl
if (!isShown)
{
_lastFocusControl = null;
}
}
#endregion // Change Events
#region Popup Events
// When visibility is changed, set the default focus
void PopupPanel_IsVisibleChanged(object sender, DependencyPropertyChangedEventArgs e)
{
if ((bool)e.NewValue)
{
ContentControl popupControl = FindChild<ContentControl>(this, "PopupContentControl");
this.Dispatcher.BeginInvoke(DispatcherPriority.Render,
new Action(delegate()
{
// Verify object really is visible because sometimes it's not once we switch to Render
if (!GetIsPopupVisible(this))
{
return;
}
if (_lastFocusControl != null && _lastFocusControl.Focusable)
{
_lastFocusControl.Focus();
}
else
{
_lastFocusControl = FindChild<UIElement>(popupControl, "PART_DefaultFocusControl") as UIElement;
// If we can find the part named PART_DefaultFocusControl, set focus to it
if (_lastFocusControl != null && _lastFocusControl.Focusable)
{
_lastFocusControl.Focus();
}
else
{
_lastFocusControl = FindFirstFocusableChild(popupControl);
// If no DefaultFocusControl found, try and set focus to the first focusable element found in popup
if (_lastFocusControl != null)
{
_lastFocusControl.Focus();
}
else
{
// Just give the Popup UserControl focus so it can handle keyboard input
popupControl.Focus();
}
}
}
}
)
);
}
}
// When popup loses focus but isn't hidden, store the last element that had focus so we can put it back later
void PopupPanel_LostFocus(object sender, RoutedEventArgs e)
{
DependencyObject focusScope = FocusManager.GetFocusScope(this);
_lastFocusControl = FocusManager.GetFocusedElement(focusScope) as UIElement;
}
// Keyboard Events
private void PopupPanel_PreviewKeyDown(object sender, KeyEventArgs e)
{
if (e.Key == Key.Escape)
{
PopupPanel popup = FindAncester<PopupPanel>((DependencyObject)sender);
ICommand cmd = GetPopupEscapeKeyCommand(popup);
if (cmd != null && cmd.CanExecute(null))
{
cmd.Execute(null);
e.Handled = true;
}
else
{
// By default the Escape Key closes the popup when pressed
var expression = this.GetBindingExpression(PopupPanel.IsPopupVisibleProperty);
var dataType = expression.DataItem.GetType();
dataType.GetProperties().Single(x => x.Name == expression.ParentBinding.Path.Path)
.SetValue(expression.DataItem, false, null);
}
}
else if (e.Key == Key.Enter)
{
// Don't want to run Enter command if focus is in a TextBox with AcceptsReturn = True
if (!(e.KeyboardDevice.FocusedElement is TextBox &&
(e.KeyboardDevice.FocusedElement as TextBox).AcceptsReturn == true))
{
PopupPanel popup = FindAncester<PopupPanel>((DependencyObject)sender);
ICommand cmd = GetPopupEnterKeyCommand(popup);
if (cmd != null && cmd.CanExecute(null))
{
cmd.Execute(null);
e.Handled = true;
}
}
}
}
#endregion // Popup Events
#endregion // Events
#region Dependency Properties
// Parent for Popup
#region PopupParent
public static readonly DependencyProperty PopupParentProperty =
DependencyProperty.Register("PopupParent", typeof(FrameworkElement),
typeof(PopupPanel), new PropertyMetadata(null, null, CoercePopupParent));
private static object CoercePopupParent(DependencyObject obj, object value)
{
// If PopupParent is null, return the Window object
return (value ?? FindAncester<Window>(obj));
}
public FrameworkElement PopupParent
{
get { return (FrameworkElement)this.GetValue(PopupParentProperty); }
set { this.SetValue(PopupParentProperty, value); }
}
// Providing Get/Set methods makes them show up in the XAML designer
public static FrameworkElement GetPopupParent(DependencyObject obj)
{
return (FrameworkElement)obj.GetValue(PopupParentProperty);
}
public static void SetPopupParent(DependencyObject obj, FrameworkElement value)
{
obj.SetValue(PopupParentProperty, value);
}
#endregion
// Popup Visibility - If popup is shown or not
#region IsPopupVisibleProperty
public static readonly DependencyProperty IsPopupVisibleProperty =
DependencyProperty.Register("IsPopupVisible", typeof(bool),
typeof(PopupPanel), new PropertyMetadata(false, null));
public static bool GetIsPopupVisible(DependencyObject obj)
{
return (bool)obj.GetValue(IsPopupVisibleProperty);
}
public static void SetIsPopupVisible(DependencyObject obj, bool value)
{
obj.SetValue(IsPopupVisibleProperty, value);
}
#endregion // IsPopupVisibleProperty
// Transparency level for the background filler outside the popup
#region BackgroundOpacityProperty
public static readonly DependencyProperty BackgroundOpacityProperty =
DependencyProperty.Register("BackgroundOpacity", typeof(double),
typeof(PopupPanel), new PropertyMetadata(.5, null));
public static double GetBackgroundOpacity(DependencyObject obj)
{
return (double)obj.GetValue(BackgroundOpacityProperty);
}
public static void SetBackgroundOpacity(DependencyObject obj, double value)
{
obj.SetValue(BackgroundOpacityProperty, value);
}
#endregion ShowBackgroundProperty
// Command to execute when Enter key is pressed
#region PopupEnterKeyCommandProperty
public static readonly DependencyProperty PopupEnterKeyCommandProperty =
DependencyProperty.RegisterAttached("PopupEnterKeyCommand", typeof(ICommand),
typeof(PopupPanel), new PropertyMetadata(null, null));
public static ICommand GetPopupEnterKeyCommand(DependencyObject obj)
{
return (ICommand)obj.GetValue(PopupEnterKeyCommandProperty);
}
public static void SetPopupEnterKeyCommand(DependencyObject obj, ICommand value)
{
obj.SetValue(PopupEnterKeyCommandProperty, value);
}
#endregion PopupEnterKeyCommandProperty
// Command to execute when Enter key is pressed
#region PopupEscapeKeyCommandProperty
public static readonly DependencyProperty PopupEscapeKeyCommandProperty =
DependencyProperty.RegisterAttached("PopupEscapeKeyCommand", typeof(ICommand),
typeof(PopupPanel), new PropertyMetadata(null, null));
public static ICommand GetPopupEscapeKeyCommand(DependencyObject obj)
{
return (ICommand)obj.GetValue(PopupEscapeKeyCommandProperty);
}
public static void SetPopupEscapeKeyCommand(DependencyObject obj, ICommand value)
{
obj.SetValue(PopupEscapeKeyCommandProperty, value);
}
#endregion PopupEscapeKeyCommandProperty
#endregion Dependency Properties
#region Visual Tree Helpers
public static UIElement FindFirstFocusableChild(DependencyObject parent)
{
// Confirm parent is valid.
if (parent == null) return null;
UIElement foundChild = null;
int childrenCount = VisualTreeHelper.GetChildrenCount(parent);
for (int i = 0; i < childrenCount; i++)
{
UIElement child = VisualTreeHelper.GetChild(parent, i) as UIElement;
// This is returning me things like ContentControls, so for now filtering to buttons/textboxes only
if (child != null && child.Focusable && child.IsVisible)
{
foundChild = child;
break;
}
// recursively drill down the tree
foundChild = FindFirstFocusableChild(child);
// If the child is found, break so we do not overwrite the found child.
if (foundChild != null) break;
}
return foundChild;
}
public static T FindAncester<T>(DependencyObject current)
where T : DependencyObject
{
// Need this call to avoid returning current object if it is the same type as parent we are looking for
current = VisualTreeHelper.GetParent(current);
while (current != null)
{
if (current is T)
{
return (T)current;
}
current = VisualTreeHelper.GetParent(current);
};
return null;
}
/// <summary>
/// Looks for a child control within a parent by name
/// </summary>
public static T FindChild<T>(DependencyObject parent, string childName)
where T : DependencyObject
{
// Confirm parent and childName are valid.
if (parent == null) return null;
T foundChild = null;
int childrenCount = VisualTreeHelper.GetChildrenCount(parent);
for (int i = 0; i < childrenCount; i++)
{
var child = VisualTreeHelper.GetChild(parent, i);
// If the child is not of the request child type child
T childType = child as T;
if (childType == null)
{
// recursively drill down the tree
foundChild = FindChild<T>(child, childName);
// If the child is found, break so we do not overwrite the found child.
if (foundChild != null) break;
}
else if (!string.IsNullOrEmpty(childName))
{
var frameworkElement = child as FrameworkElement;
// If the child's name is set for search
if (frameworkElement != null && frameworkElement.Name == childName)
{
// if the child's name is of the request name
foundChild = (T)child;
break;
}
else
{
// recursively drill down the tree
foundChild = FindChild<T>(child, childName);
// If the child is found, break so we do not overwrite the found child.
if (foundChild != null) break;
}
}
else
{
// child element found.
foundChild = (T)child;
break;
}
}
return foundChild;
}
#endregion
}
// Converter for Popup positioning
public class ValueDividedByParameterConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
double n, d;
if (double.TryParse(value.ToString(), out n)
&& double.TryParse(parameter.ToString(), out d)
&& d != 0)
{
return n / d;
}
return 0;
} public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
}
}
