在Silverlight UserControls中实现自定义属性的正确方法是什么?
从技术上讲,Silverlight中的每个“页面”都是一个UserControl (它们是从UserControl类派生的)。当我在这里说UserControl时,我指的是一个自定义的UserControl,它将在许多不同的情况下在许多不同的页面中使用(类似于ASP.NET UserControl)。
我希望自定义UserControl支持绑定,而不是依赖于它绑定到的属性的名称,使其始终保持不变。相反,我希望UserControl本身有一个属性,UserControl内部的控件绑定到该属性,UserControl外部的ViewModels也绑定到该属性。(请参考下面的示例)
UserControl中的绑定,MainPage中的绑定,我在MainPage和UserControl之间设置的绑定不起作用。特别是这一行:
<myUserControls:MyCustomUserControl x:Name="MyCustomControl2"
SelectedText="{Binding MainPageSelectedText, Mode=TwoWay}"
Width="200" Height="50" />
输出示例:
MainPage.xaml
<UserControl x:Class="SilverlightCustomUserControl.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:myUserControls="clr-namespace:SilverlightCustomUserControl"
mc:Ignorable="d" d:DesignWidth="640" d:DesignHeight="480"
DataContext="{Binding RelativeSource={RelativeSource Self}}">
<Canvas x:Name="LayoutRoot">
<StackPanel Orientation="Vertical">
<TextBlock Text="UserControl Binding:" Width="200"></TextBlock>
<myUserControls:MyCustomUserControl x:Name="MyCustomControl2" SelectedText="{Binding MainPageSelectedText, Mode=TwoWay}" Width="200" Height="50" />
<TextBlock Text="MainPage Binding:" Width="200"></TextBlock>
<TextBox Text="{Binding MainPageSelectedText, Mode=TwoWay}" Width="200"></TextBox>
<Border BorderBrush="Black" BorderThickness="1">
<TextBlock Text="{Binding MainPageSelectedText}" Width="200" Height="24"></TextBlock>
</Border>
</StackPanel>
</Canvas>
</UserControl>
MainPage.xaml.cs
namespace SilverlightCustomUserControl
{
public partial class MainPage : UserControl, INotifyPropertyChanged
{
//NOTE: would probably be in a ViewModel
public string MainPageSelectedText
{
get { return _MainPageSelectedText; }
set
{
string myValue = value ?? String.Empty;
if (_MainPageSelectedText != myValue)
{
_MainPageSelectedText = value;
OnPropertyChanged("MainPageSelectedText");
}
}
}
private string _MainPageSelectedText;
public MainPage()
{
InitializeComponent();
}
#region INotifyPropertyChanged Members
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(string name)
{
PropertyChangedEventHandler ph = this.PropertyChanged;
if (ph != null)
ph(this, new PropertyChangedEventArgs(name));
}
#endregion
}
}
MyCustomUserControl.xaml
<UserControl
x:Class="SilverlightCustomUserControl.MyCustomUserControl"
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"
DataContext="{Binding RelativeSource={RelativeSource Self}}">
<Grid>
<StackPanel>
<TextBox Text="{Binding SelectedText, Mode=TwoWay}" />
<Border BorderBrush="Black" BorderThickness="1">
<TextBlock Text="{Binding SelectedText}" Height="24"></TextBlock>
</Border>
</StackPanel>
</Grid>
</UserControl>
MyCustomUserControl.xaml.cs
namespace SilverlightCustomUserControl
{
public partial class MyCustomUserControl : UserControl
{
public string SelectedText
{
get { return (string)GetValue(SelectedTextProperty); }
set { SetValue(SelectedTextProperty, value); }
}
public static readonly DependencyProperty SelectedTextProperty =
DependencyProperty.Register("SelectedText", typeof(string), typeof(MyCustomUserControl), new PropertyMetadata("", SelectedText_PropertyChangedCallback));
public MyCustomUserControl()
{
InitializeComponent();
}
private static void SelectedText_PropertyChangedCallback(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
//empty
}
}
}
参考(我是如何走到这一步的):
使用DependencyPropertys:http://geekswithblogs.net/thibbard/archive/2008/04/22/wpf-custom-control-dependency-property-gotcha.aspx
使用DependencyPropertys,将x:Name添加到您的UserControl -使用ElementName添加绑定,在PropertyChangedCallback方法中再次设置自定义属性:Setting Custom Properties in UserControl via DataBinding
不要使用自定义属性,而要依赖底层的数据上下文名称(我不喜欢这个解决方案):wpf trouble using dependency properties in a UserControl
发布于 2009-10-09 07:55:05
我的理解是,您的控件没有从主页面接收到新值的原因是您正在设置控件的DataContext。如果您没有这样做,那么控件的DataContext将从它的父级继承,本例中是主页。
为此,我删除了控件的名称设置,为每个控件添加了x: DataContext,并使用name.SetBinding方法在控件的构造函数中设置了绑定。
我在ctor中进行了绑定,因为我找不到将xaml中声明性绑定的Source属性设置为Self的方法。也就是说,{绑定SelectedText,Mode=TwoWay,Source=Self这里有一些方法}。我确实尝试过使用RelativeSource={RelativeSource Self},但没有任何乐趣。
注意:所有这些都是SL3。
发布于 2014-03-10 12:12:34
您可以在xaml中设置绑定,方法是为用户控件添加一个x:Name
,然后在下面的用户控件中绑定,而不是将数据上下文绑定到自身:
<UserControl
x:Class="SilverlightCustomUserControl.MyCustomUserControl"
x:Name="myUserControl
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">
<Grid>
<StackPanel>
<TextBox Text="{Binding SelectedText, ElementName=myUserContol, Mode=TwoWay}" />
<Border BorderBrush="Black" BorderThickness="1">
<TextBlock Text="{Binding SelectedText,ElementName=myUserControl}" Height="24"></TextBlock>
</Border>
</StackPanel>
</Grid>
</UserControl>
https://stackoverflow.com/questions/1526767
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