MultiValueConverter未能绑定到ViewModel
HelloAll:我正在尝试创建一个用户控件，它需要一个MultiValueConverter来缩放我的应用程序中的画布：
它需要
- Canvas.ActualWidth
- 工程单位X Min
- X-最大英单位
。
public class MultiValueScaleTransform : IMultiValueConverter
{
public object Convert(object[] values, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
double numerator = (double)values[0];
double denominator = (double)values[2] - (double)values[1];
return numerator / denominator;
}
public object[] ConvertBack(object value, Type[] targetTypes, object parameter, System.Globalization.CultureInfo culture)
{
throw new NotImplementedException();
}
}当我输入它的数字时，它似乎工作得很好，但是当我将XAML绑定到查看模型问题时，就会出现这样的情况：
下面是错误消息：
错误7不能在“绑定”类型的“路径”属性上设置“绑定”。“绑定”只能设置在DependencyProperty的DependencyObject上。C：\User\mwardell\Documents\Visual 2013\Projects\HalliburtonCallout (12)\HalliburtonCallouts\HalliburtonCallouts\View\UserControls\WellViewUserCtrl.xaml 31 38 HalliburtonCallouts
<UserControl x:Class="HalliburtonCallouts.View.UserControls.WellViewUserCtrl"
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:Converters="clr-namespace:HalliburtonCallouts.ViewModel.Converters"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="300"
x:Name="uc">
<UserControl.Resources>
<Converters:ColorToImageBrush x:Key="ColorToBrush"/>
<Converters:ColorToBitmapBrush x:Key="ColorToImg"/>
<Converters:ColorToBG x:Key="ColorToBG"/>
<Converters:ColorToFG x:Key="ColorToFG"/>
<Converters:MultiValueScaleTransform x:Key="ScaleTransform"/>
<SolidColorBrush x:Key="BlueBg" Color="#FFA9DCF1"/>
</UserControl.Resources>
<Border Background="Red">
<StackPanel>
<!-- I used these to make sure the bindings of the user control are working-->
<TextBlock Text="OverallStartDepth"></TextBlock>
<TextBlock Text="{Binding OverallStartDepth}"></TextBlock>
<TextBlock Text="OverallEndDepth"></TextBlock>
<TextBlock Text="{Binding OverallEndDepth}"></TextBlock>
<Canvas x:Name="WellCanvas"
HorizontalAlignment="Stretch"
VerticalAlignment="Stretch"
DataContext="{Binding Mode=OneWay, RelativeSource={RelativeSource PreviousData}}" >
<Canvas.RenderTransform>
<ScaleTransform >
<ScaleTransform.ScaleX >
<MultiBinding Converter="{StaticResource ScaleTransform}">
<Binding Path="ActualWidth"/>
<Binding Path="{Binding OverallStartDepth, FallbackValue=0.0}"/>
<Binding Path="{Binding OverallEndDepth,FallbackValue=100.0}"/>
</MultiBinding>
</ScaleTransform.ScaleX>
</ScaleTransform>
</Canvas.RenderTransform>
</Canvas>
</StackPanel>
</Border>
</UserControl>我已经确定OverallEndDepth和OverallStartDepth是Bindable的。请参阅StackPanel前四项左右。Bindability不证明它们是Dep对象的Dep属性吗？
回答 2
Stack Overflow用户
发布于 2016-03-21 08:06:37
您不能也不会绑定MultiBinding中绑定的MultiBinding属性。相反，你只是把他们放进去
<TextBlock Text="{Binding OverallStartDepth}">这相当于
<TextBlock Text="{Binding Path=OverallStartDepth}">并且还可以
<TextBlock>
<TextBlock.Text>
<Binding Path="OverallStartDepth"/>
</TextBlock.Text>
</TextBlock>所以MultiBinding应该是这样写的：
<Canvas ... >
<Canvas.RenderTransform>
<MultiBinding Converter="{StaticResource ScaleTransform}">
<Binding Path="ActualWidth" RelativeSource="{RelativeSource AncestorType=Canvas}"/>
<Binding Path="OverallStartDepth" FallbackValue="0.0"/>
<Binding Path="OverallEndDepth" FallbackValue="100.0"/>
</MultiBinding>
</Canvas.RenderTransform>
</Canvas>也要确保你移除
DataContext="{Binding Mode=OneWay, RelativeSource={RelativeSource PreviousData}}"从画布上
Stack Overflow用户
发布于 2016-03-21 04:27:47
正如错误所述，您不能使用{Binding}，而是可以按其名称获取元素，并从其text属性中获取值。
<TextBlock Text="OverallStartDepth"></TextBlock>
<TextBlock Name="OverallStartDepthTextBlock" Text="{Binding OverallStartDepth}"></TextBlock>
<TextBlock Text="OverallEndDepth"></TextBlock>
<TextBlock Name="OverallEndDepthTextBlock" Text="{Binding OverallEndDepth}"></TextBlock>
<MultiBinding Converter="{StaticResource ScaleTransform}">
<Binding Path="ActualWidth"/>
<Binding ElementName="OverallStartDepthTextBlock" Path="Text"/>
<Binding ElementName="OverallEndDepthTextBlock" Path="Text"/>
</MultiBinding>注意:可以绑定OverallEndDepth的值可以绑定到任何控件的依赖属性。
例如，TextBlock.Text是一个依赖属性- SourceCode
/// <summary> /// DependencyProperty for <see cref="Text" /> property. /// </summary> [CommonDependencyProperty] public static readonly DependencyProperty TextProperty = DependencyProperty.Register( "Text", typeof(string), typeof(TextBlock), new FrameworkPropertyMetadata( string.Empty, FrameworkPropertyMetadataOptions.AffectsMeasure | FrameworkPropertyMetadataOptions.AffectsRender, new PropertyChangedCallback(OnTextChanged), new CoerceValueCallback(CoerceText))); /// <summary> /// The Text property defines the content (text) to be displayed. /// </summary> [Localizability(LocalizationCategory.Text)] public string Text { get { return (string) GetValue(TextProperty); } set { SetValue(TextProperty, value); } }
但是，Binding.Path是一个普通属性，不能绑定，因此您将得到上面的错误- SourceCode。
//源路径(用于CLR绑定)。公共PropertyPath路径{ get {返回_ppath；} set { CheckSealed()；_ppath =值；_attachedPropertiesInPath = -1；if (_ppath != null & _ppath.StartsWithStaticProperty) { if (_sourceInUse == SourceProperties.None _sourceInUse == SourceProperties.StaticSource ==SourceProperties.StaticSource) // (用于compat - Dev11 738992) { SourceReference = StaticSourceRef；}否则抛出新的InvalidOperationException(SR.Get(SRID.BindingConflict，SourceProperties.StaticSource，_sourceInUse));> }
https://stackoverflow.com/questions/36122965
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