WPF绑定无法找到与引用绑定的源
本文关键字:绑定 引用 WPF | 更新日期: 2023-09-27 18:17:31
我一直遵循这个答案来暴露我的user-control的一些属性。
问题是绑定没有找到源,我不知道如何正确地做。
XAML:<UserControl x:Class="Project.UI.Views.ucFilterDataGrid"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:local="clr-namespace:Project.UI.Views"
xmlns:watermark="clr-namespace:Project.UI.Watermark"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="300">
<StackPanel>
<StackPanel.Resources>
<Style TargetType="{x:Type TextBox}">
<Setter Property="Margin" Value="0,0,00,30"/>
</Style>
</StackPanel.Resources>
<AdornerDecorator>
<TextBox Name="SearchTextBox">
<watermark:WatermarkService.Watermark>
<TextBlock Name="waterMarkText"
Text="{Binding Path=WatermarkContent,
RelativeSource={RelativeSource FindAncestor,
AncestorType=local:ucFilterDataGrid}}"
HorizontalAlignment="Center" >
</TextBlock>
</watermark:WatermarkService.Watermark>
</TextBox>
</AdornerDecorator>
<DataGrid Name="Results">
</DataGrid>
</StackPanel>
CS: namespace Project.UI.Views
{
/// <summary>
/// Interaction logic for ucFilterDataGrid.xaml
/// </summary>
public partial class ucFilterDataGrid : UserControl
{
public ucFilterDataGrid()
{
InitializeComponent();
}
public string WatermarkContent
{
get { return GetValue(WatermarkContentProperty).ToString(); }
set { SetValue(WatermarkContentProperty, value); }
}
public static readonly DependencyProperty WatermarkContentProperty = DependencyProperty.Register("WatermarkContent", typeof(string), typeof(ucFilterDataGrid), new FrameworkPropertyMetadata(string.Empty));
}
}
窗口:
<Grid>
<local:ucFilterDataGrid Margin="301,34,31,287" WatermarkContent="MyTest"/>
</Grid>
结果将是一个空白的TextBlock。如果我只是从我的水印UserControl中删除它,并把它放在与DataGrid相同的水平上,它将工作。
这里的问题是您的TextBlock
被设置为附加属性的值,这里是:
<watermark:WatermarkService.Watermark>
<TextBlock ...>
</TextBlock>
</watermark:WatermarkService.Watermark>
watermark:WatermarkService.Watermark
是一个附加属性。它的值只是内存中的一个对象,与可视树无关。所以你不能使用绑定RelativeSource
或ElementName
。你需要一些代理来连接断开。Source
将用于绑定,您应该尝试的代码如下:
<TextBox Name="SearchTextBox">
<TextBox.Resources>
<DiscreteObjectKeyFrame x:Key="proxy"
Value="{Binding Path=WatermarkContent,
RelativeSource={RelativeSource FindAncestor,
AncestorType=local:ucFilterDataGrid}}"/>
</TextBox.Resources>
<watermark:WatermarkService.Watermark>
<TextBlock Name="waterMarkText"
Text="{Binding Value, Source={StaticResource proxy}}"
HorizontalAlignment="Center" >
</TextBlock>
</watermark:WatermarkService.Watermark>
</TextBox>
前几天我做过类似的东西,如果我没记错的话。您必须从INotifyPropertyChanged
接口派生,并在更新WatermarkContent时告诉组件属性已经更改。否则,xaml (view)将不知道你何时更改了Text,并且绑定也不会更新。
这是你可以尝试的
using System.ComponentModel;
public partial class ucFilterDataGrid : UserControl, INotifyPropertyChanged
{
public static readonly DependencyProperty WatermarkContentProperty = DependencyProperty.Register("WatermarkContent", typeof(string), typeof(ucFilterDataGrid), new FrameworkPropertyMetadata(string.Empty));
public event PropertyChangedEventHandler PropertyChanged;
public ucFilterDataGrid()
{
InitializeComponent();
}
public string WatermarkContent
{
get { GetValue(WatermarkContentProperty).ToString(); }
set {
SetValue(WatermarkContentProperty, value);
RaisePropertyChanged();
}
}
protected virtual void RaisePropertyChanged([CallerMemberName] string propertyName = null)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}
我已经添加了INotifyPropertyChanged,并在每次WatermarkContent被更改时引发事件。
希望有帮助!