Silverlight XAML绑定ElementName [英] Silverlight XAML Binding ElementName
本文介绍了Silverlight XAML绑定ElementName的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我有以下XAML:
<sdk:Label Content="{Binding RefreshTextToggle, Converter={StaticResource enumToText}, ConverterParameter=ItemsOfInterest,FallbackValue='Please select items of interest to you'}"
Style="{StaticResource StandardLabel}"
Height="{Binding ElementName=ItemsOfInterest,Path=Height}"/>
<ListBox Name="ItemsOfInterest"
ItemsSource="{Binding Path=ItemsOfInterest}"
Margin="5"
MinHeight="25"
Width="250"
HorizontalAlignment="Left">
ItemsOfInterest的高度是动态的，取决于其中有多少个元素.
The height of the ItemsOfInterest is dynamic pending on how many elements are in it.
任何人都知道我在进行高度限制时做错了什么吗?它甚至与ItemsOfInterst的大小都不一样.
Anyone see what I am doing wrong with the height binding? It isn't even close to the same size as the ItemsOfInterst.
推荐答案
You should bind to ActualHeight, which specifies the height it was arranged at. The Height property allows you to set a fixed height, but doesn't tell you exactly how tall it is when arranged.
实际上，这是一个 Silverlight的已知错误.
您必须像这样使用SizeChanged事件:
You would have to use the SizeChanged event like so:
<UserControl x:Class="SilverlightApplication3.MainPage"
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:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d" d:DesignHeight="300" d:DesignWidth="400">
<Grid x:Name="LayoutRoot" Background="White">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*" />
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition Height="*" />
</Grid.RowDefinitions>
<Button Content="Add Item" Click="Button_Click" />
<ListBox x:Name="listBox1" Grid.Column="0" Grid.Row="1" VerticalAlignment="Top" SizeChanged="listBox1_SizeChanged" />
<ListBox x:Name="listBox2" Grid.Column="1" Grid.Row="1" VerticalAlignment="Top" />
</Grid>
</UserControl>
带有以下代码:
using System.Windows;
using System.Windows.Controls;
namespace SilverlightApplication3 {
public partial class MainPage : UserControl {
public MainPage() {
InitializeComponent();
}
private int counter;
private void Button_Click(object sender, RoutedEventArgs e) {
this.counter++;
this.listBox1.Items.Add(counter.ToString());
}
private void listBox1_SizeChanged(object sender, SizeChangedEventArgs e) {
this.listBox2.Height = this.listBox1.ActualHeight;
}
}
}
您可能还可以将其包装成一个不错的附加行为.
这是这样的行为:
You could probably wrap this up into a nice attached behavior also.
Here is such a behavior:
<UserControl x:Class="SilverlightApplication3.MainPage"
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:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:local="clr-namespace:SilverlightApplication3"
mc:Ignorable="d" d:DesignHeight="300" d:DesignWidth="400">
<Grid x:Name="LayoutRoot" Background="White">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*" />
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition Height="*" />
</Grid.RowDefinitions>
<Button Content="Add Item" Click="Button_Click" />
<ListBox x:Name="listBox1" Grid.Column="0" Grid.Row="1" VerticalAlignment="Top" />
<ListBox x:Name="listBox2" Grid.Column="1" Grid.Row="1" VerticalAlignment="Top" local:SizeSynchronizationBehavior.HeightElement="{Binding ElementName=listBox1}" />
</Grid>
</UserControl>
带有以下代码:
using System;
using System.Windows;
using System.Windows.Controls;
namespace SilverlightApplication3 {
public partial class MainPage : UserControl {
public MainPage() {
InitializeComponent();
}
private int counter;
private void Button_Click(object sender, RoutedEventArgs e) {
this.counter++;
this.listBox1.Items.Add(counter.ToString());
}
}
public static class SizeSynchronizationBehavior {
#region Dependency Properties
///////////////////////////////////////////////////////////////////////////////////
// HeightElement
///////////////////////////////////////////////////////////////////////////////////
/// <summary>
/// Identifies the <c>HeightElement</c> attached dependency property. This field is read-only.
/// </summary>
/// <value>The identifier for the <c>HeightElement</c> attached dependency property.</value>
public static readonly DependencyProperty HeightElementProperty = DependencyProperty.RegisterAttached("HeightElement",
typeof(FrameworkElement), typeof(SizeSynchronizationBehavior), new PropertyMetadata(null, OnHeightElementPropertyValueChanged));
/// <summary>
/// Gets the value of the <see cref="HeightElementProperty"/> attached property for the specified <see cref="FrameworkElement"/>.
/// </summary>
/// <param name="obj">The object to which the attached property is retrieved.</param>
/// <returns>
/// The value of the <see cref="HeightElementProperty"/> attached property for the the specified <see cref="FrameworkElement"/>.
/// </returns>
public static FrameworkElement GetHeightElement(FrameworkElement obj) {
if (obj == null) throw new ArgumentNullException("obj");
return (FrameworkElement)obj.GetValue(HeightElementProperty);
}
/// <summary>
/// Sets the value of the <see cref="HeightElementProperty"/> attached property to the specified <see cref="FrameworkElement"/>.
/// </summary>
/// <param name="obj">The object to which the attached property is written.</param>
/// <param name="value">
/// The new value of the <see cref="HeightElementProperty"/> attached property to the specified <see cref="FrameworkElement"/>.
/// </param>
public static void SetHeightElement(FrameworkElement obj, FrameworkElement value) {
if (obj == null) throw new ArgumentNullException("obj");
obj.SetValue(HeightElementProperty, value);
}
/// <summary>
/// Called when <see cref="HeightElementProperty"/> is changed.
/// </summary>
/// <param name="d">The dependency object that was changed.</param>
/// <param name="e">The <see cref="DependencyPropertyChangedEventArgs"/> instance containing the event data.</param>
private static void OnHeightElementPropertyValueChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) {
FrameworkElement element = d as FrameworkElement;
if (element == null)
return;
SizeChangedEventHandler heightSizeChangedEventHandler = GetSizeChangedEventHandler(element);
if (heightSizeChangedEventHandler == null) {
heightSizeChangedEventHandler = (sender, eventArgs) => {
FrameworkElement he = GetHeightElement(element);
if (he != null)
element.Height = he.ActualHeight;
};
SetSizeChangedEventHandler(element, heightSizeChangedEventHandler);
}
FrameworkElement heightElement = e.OldValue as FrameworkElement;
if (heightElement != null)
heightElement.SizeChanged += heightSizeChangedEventHandler;
heightElement = e.NewValue as FrameworkElement;
if (heightElement != null)
heightElement.SizeChanged += heightSizeChangedEventHandler;
}
///////////////////////////////////////////////////////////////////////////////////
// SizeChangedEventHandler
///////////////////////////////////////////////////////////////////////////////////
/// <summary>
/// Identifies the <c>SizeChangedEventHandler</c> attached dependency property. This field is read-only.
/// </summary>
/// <value>The identifier for the <c>SizeChangedEventHandler</c> attached dependency property.</value>
private static readonly DependencyProperty SizeChangedEventHandlerProperty = DependencyProperty.RegisterAttached("SizeChangedEventHandler",
typeof(SizeChangedEventHandler), typeof(SizeSynchronizationBehavior), new PropertyMetadata(null));
/// <summary>
/// Gets the value of the <see cref="SizeChangedEventHandlerProperty"/> attached property for the specified <see cref="FrameworkElement"/>.
/// </summary>
/// <param name="obj">The object to which the attached property is retrieved.</param>
/// <returns>
/// The value of the <see cref="SizeChangedEventHandlerProperty"/> attached property for the the specified <see cref="FrameworkElement"/>.
/// </returns>
private static SizeChangedEventHandler GetSizeChangedEventHandler(FrameworkElement obj) {
if (obj == null) throw new ArgumentNullException("obj");
return (SizeChangedEventHandler)obj.GetValue(SizeChangedEventHandlerProperty);
}
/// <summary>
/// Sets the value of the <see cref="SizeChangedEventHandlerProperty"/> attached property to the specified <see cref="FrameworkElement"/>.
/// </summary>
/// <param name="obj">The object to which the attached property is written.</param>
/// <param name="value">
/// The new value of the <see cref="SizeChangedEventHandlerProperty"/> attached property to the specified <see cref="FrameworkElement"/>.
/// </param>
private static void SetSizeChangedEventHandler(FrameworkElement obj, SizeChangedEventHandler value) {
if (obj == null) throw new ArgumentNullException("obj");
obj.SetValue(SizeChangedEventHandlerProperty, value);
}
#endregion // Dependency Properties
}
}
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