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鏈接依賴項屬性xaml wpf

[英]chaining dependency properties xaml wpf

 原文  2014-08-30 02:02:07  9   1    c#/ wpf/ xaml

問題描述

我有一個用戶控件，希望通過其父xaml（在本例中為wpf頁面）進行訪問。 我的用戶控件具有label屬性，我希望通過將其綁定到傳遞到頁面xaml的datacontext中來設置頁面xaml。

在下面的示例中，當前來自xaml頁面的數據綁定似乎正常工作。 我可以通過頁面xaml設置用戶控件標簽的內容，只要我不嘗試將其綁定到頁面數據上下文，當我嘗試這樣做時，標簽始終顯示為空白。

Ive遵循了該網站上建議的其他一些相關示例，但是到目前為止，我還沒有指出我要去哪里。 任何建議將不勝感激。

UserControl XAML 

<UserControl x:Class="Pipeline_General.Custom_Controls.AttributeStack"
         xmlns:pm="clr-namespace:Pipeline_General"
         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" 
         mc:Ignorable="d"
         DataContext = "{Binding RelativeSource={RelativeSource Self}}"
         d:DesignHeight="30" d:DesignWidth="300">
<Grid>
    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="2*" />
        <ColumnDefinition Width="3*" />
    </Grid.ColumnDefinitions>
    <Label Foreground="{x:Static pm:myBrushes.pink}" Content="{Binding Path=Attr}"  Grid.Column="0" HorizontalAlignment="Right" FontFamily="Calibri" FontSize="14" Margin="5,0,5,0"/>
    <Label x:Name="ValLabel" Foreground="{x:Static pm:myBrushes.blue}" Grid.Column="1" HorizontalAlignment="Left" FontFamily="Calibri" FontSize="14" Margin="5,0,5,0"/>
</Grid>

后面的用戶控制代碼 

public partial class AttributeStack : UserControl
{


    public static readonly DependencyProperty AttrProperty = DependencyProperty.Register
        (
             "Attr",
             typeof(string),
             typeof(AttributeStack),
             new PropertyMetadata(string.Empty)
        );

    public static readonly DependencyProperty ValProperty = DependencyProperty.Register
            (
                 "Val",
                 typeof(string),
                 typeof(AttributeStack),
                 new PropertyMetadata(string.Empty)
            );

    public static readonly DependencyProperty ValTextProperty = DependencyProperty.Register
        (
                "ValText",
                typeof(string),
                typeof(AttributeStack),
                new PropertyMetadata(string.Empty)
        );

    public string Val
    {
        get { return (string)GetValue(ValProperty); }
        set { SetValue(ValProperty, value); }
    }

    public string ValText
    {
        get { return (string)GetValue(ValTextProperty); }
        set { SetValue(ValTextProperty, value); }
    }


    public string Attr
    {
        get { return (string)GetValue(AttrProperty); }
        set { SetValue(AttrProperty, value); }
    }


    public AttributeStack()
    {
        InitializeComponent();

        Binding valBinding = new Binding("Val")
        {
            Source = Val,
            Mode = BindingMode.OneWay
        };

        Binding textBinding = new Binding("Content")
        {
            Source = this.ValLabel.Content,
            Mode = BindingMode.OneWay
        };

        ValLabel.SetBinding(Label.ContentProperty, valBinding);
        this.SetBinding(AttributeStack.ValTextProperty, textBinding);
    }
}

頁面XAML 

<Page x:Class="Pipeline_General.SceneView" x:Name="page"
  xmlns:pm="clr-namespace:Pipeline_General"
  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" 
  mc:Ignorable="d" 
  xmlns:cc="clr-namespace:Pipeline_General.Custom_Controls"
  d:DesignHeight="800" d:DesignWidth="600"
  DataContext = "{Binding RelativeSource={RelativeSource Self}}"
  Title="SceneView">
<Grid>
    <ScrollViewer>
        <Grid>
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="*" />
                <ColumnDefinition Width="*" />
            </Grid.ColumnDefinitions>
            <StackPanel Grid.Column="0">
                <Expander IsExpanded="True" Margin="5">
                    <Expander.Header>
                        <Grid x:Name="Grid" HorizontalAlignment="Stretch" Width="NaN">
                            <Border x:Name="Border" Background="Transparent" HorizontalAlignment="Stretch" BorderBrush="{x:Static pm:myBrushes.blue}" BorderThickness="0,0,0,1"
                        Width="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type Expander}}, Path=ActualWidth}">
                                <TextBlock x:Name="HeaderText" FontSize ="18" FontFamily="Calibri" Foreground="{x:Static pm:myBrushes.blue}" Text="General Info: " />
                            </Border>
                        </Grid>
                    </Expander.Header>
                    <StackPanel>
                        <Separator Foreground="Transparent" Height="0" Margin="5"/>
                        <cc:AttributeStack Attr="Title:" Val="{Binding Path=DataContext.Title, RelativeSource={RelativeSource Mode=FindAncestor,AncestorType=Page}}"/>
                        <Separator Foreground="Transparent" Height="0" Margin="5"/>
                        <cc:AttributeStack Attr="Episode:" Val="{Binding Path=DataContext.episode.Key, RelativeSource={RelativeSource Mode=FindAncestor,AncestorType=Page}}"/>
                        <cc:AttributeStack Attr="Sequence:" Val="{Binding Path=DataContext.sequence.Key, RelativeSource={RelativeSource Mode=FindAncestor,AncestorType=Page}}"/>
                        <cc:AttributeStack Attr="Scene:" Val="{Binding Path=Title, RelativeSource={RelativeSource Mode=FindAncestor,AncestorType=Page}}"/>
                        <Separator Foreground="Transparent" Height="0" Margin="5"/>
                        <cc:AttributeStack Attr="Assigned:" Val="{Binding Path=Title, RelativeSource={RelativeSource Mode=FindAncestor,AncestorType=Page}}"/>
                        <cc:AttributeStack Attr="Status:" Val="{Binding Path=Title, RelativeSource={RelativeSource Mode=FindAncestor,AncestorType=Page}}"/>
                        <Separator Foreground="Transparent" Height="0" Margin="5"/>
                        <cc:AttributeStack Attr="Last Saved (Time):" Val="{Binding Path=Title, RelativeSource={RelativeSource Mode=FindAncestor,AncestorType=Page}}"/>
                        <cc:AttributeStack Attr="Last Saved (User):" Val="{Binding Path=Title, RelativeSource={RelativeSource Mode=FindAncestor,AncestorType=Page}}"/>
                        <Separator Foreground="Transparent" Height="0" Margin="5"/>
                        <cc:AttributeStack Attr="Due:" Val="{Binding Path=Title, RelativeSource={RelativeSource Mode=FindAncestor,AncestorType=Page}}"/>
                    </StackPanel>
                </Expander>
            </StackPanel>

            <StackPanel Grid.Column="1">
                <cc:Playblast_Viewer  x:Name="PlayblastView"/>
                <cc:FeedbackCtrl Header="Feedback:"/>
                <cc:FeedbackCtrl Header="NoticeBoard:"/>
            </StackPanel>

        </Grid>
    </ScrollViewer>
</Grid>

綁定到DataContext.Title字段的標簽似乎正在運行，並且設置attr字段似乎正在正常運行/也如預期。 因此，只有Val字段無法工作。

已更新，以包括后面的頁面代碼。 盡管這里幾乎沒有任何事情發生。 

public partial class SceneView : Page
{
    public Scene scene { get; set; }
    public SceneView(Scene s)
    {
        InitializeComponent();
        scene = s;
        this.DataContext = scene;
    }
}

我了解DP中的即時消息非常新穎，因此極有可能以完全不同的方式更好地完成即時消息。 在這種情況下，場景對象具有Im使用頁面和用戶控件公開的多個字段。 我已經用代碼編寫了整個應用程序，而沒有任何xaml，但是現在我正試圖自學xaml，並使下一個版本的原型更加流暢，並將所需的編碼減少80％。

我嘗試將場景對象（即頁面對象的數據上下文）發送給用戶控件。 page.DataContext.episode.Key是后面代碼中的合法字段。 通過上面的xaml，我正在尋找要發送到Val字段的值，該字段隨后將更新ValText（usercontrol中的標簽）Content屬性。

1 個解決方案

解決方案1
 0 已采納  2014-08-30 09:27:45

我已經弄清楚了這個問題。大多數是因為我在xaml仍然是個新手。

我意識到，如果未使用get / set訪問器聲明字段，則datacontext不會訪問字段。 我在后面的頁面代碼中更改了場景聲明，以使其成為一個依賴對象，而不是使用綁定屬性更改事件來設置用戶控件標簽內容，而不是鏈接綁定。 

public partial class AttributeStack : UserControl
{
    #region Val (DependencyProperty)
    public string Val
    {
        get { return (string)GetValue(ValProperty); }
        set { SetValue(ValProperty, value); }
    }
    public static readonly DependencyProperty ValProperty =
        DependencyProperty.Register("Val", typeof(string), typeof(AttributeStack),
          new PropertyMetadata { PropertyChangedCallback = ValChanged });
    private static void ValChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        AttributeStack aStack = d as AttributeStack;
        if (aStack != null && e.NewValue != null)
        {
            aStack.ValLabel.Content = e.NewValue.ToString();
        }
    }
    #endregion

    public static readonly DependencyProperty AttrProperty = DependencyProperty.Register
        (
             "Attr",
             typeof(string),
             typeof(AttributeStack),
             new PropertyMetadata(string.Empty)
        );

    public string Attr
    {
        get { return (string)GetValue(AttrProperty); }
        set { SetValue(AttrProperty, value); }
    }

    public AttributeStack()
    {
        InitializeComponent();
    }
}

} 

public partial class SceneView : Page
{
    public static readonly DependencyProperty sceneProperty = DependencyProperty.Register
        (
             "scene",
             typeof(Scene),
             typeof(SceneView)
        );

    public Scene scene
    {
        get { return (Scene)GetValue(sceneProperty); }
        set { SetValue(sceneProperty, value); }
    }
    public SceneView(Scene s)
    {
        InitializeComponent();
        scene = s;

        this.DataContext = scene;
    }
}

<Page x:Class="Pipeline_General.SceneView" x:Name="page"
  xmlns:pm="clr-namespace:Pipeline_General"
  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" 
  mc:Ignorable="d" 
  xmlns:cc="clr-namespace:Pipeline_General.Custom_Controls"
  d:DesignHeight="800" d:DesignWidth="600"
  DataContext = "{Binding RelativeSource={RelativeSource Self}}"
  Title="SceneView">
<Grid>
    <ScrollViewer>
        <Grid>
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="*" />
                <ColumnDefinition Width="*" />
            </Grid.ColumnDefinitions>
            <StackPanel Grid.Column="0">
                <Expander IsExpanded="True" Margin="5">
                    <Expander.Header>
                        <Grid x:Name="Grid" HorizontalAlignment="Stretch" Width="NaN">
                            <Border x:Name="Border" Background="Transparent" HorizontalAlignment="Stretch" BorderBrush="{x:Static pm:myBrushes.blue}" BorderThickness="0,0,0,1"
                        Width="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type Expander}}, Path=ActualWidth}">
                                <TextBlock x:Name="HeaderText" FontSize ="18" FontFamily="Calibri" Foreground="{x:Static pm:myBrushes.blue}" Text="General Info: " />
                            </Border>
                        </Grid>
                    </Expander.Header>
                    <StackPanel>
                        <Separator Foreground="Transparent" Height="0" Margin="5"/>
                        <cc:AttributeStack Attr="Title:" Val="{Binding Path=scene.Title, RelativeSource={RelativeSource Mode=FindAncestor,AncestorType=Page}}"/>
                        <Separator Foreground="Transparent" Height="0" Margin="5"/>
                        <cc:AttributeStack Attr="Episode:" Val="{Binding Path=scene.episode.Key, RelativeSource={RelativeSource Mode=FindAncestor,AncestorType=Page}}"/>
                        <cc:AttributeStack Attr="Sequence:" Val="{Binding Path=scene.sequence.Key, RelativeSource={RelativeSource Mode=FindAncestor,AncestorType=Page}}"/>
                        <cc:AttributeStack Attr="Scene:" Val="{Binding Path=scene.Key, RelativeSource={RelativeSource Mode=FindAncestor,AncestorType=Page}}"/>
                        <Separator Foreground="Transparent" Height="0" Margin="5"/>
                        <cc:AttributeStack Attr="Assigned:" Val="{}"/>

                        <cc:AttributeStack Attr="Status:" Val="{Binding Path=Title, RelativeSource={RelativeSource Mode=FindAncestor,AncestorType=Page}}"/>
                        <Separator Foreground="Transparent" Height="0" Margin="5"/>
                        <cc:AttributeStack Attr="Last Saved (Time):" Val="{Binding Path=Title, RelativeSource={RelativeSource Mode=FindAncestor,AncestorType=Page}}"/>
                        <cc:AttributeStack Attr="Last Saved (User):" Val="{Binding Path=Title, RelativeSource={RelativeSource Mode=FindAncestor,AncestorType=Page}}"/>
                        <Separator Foreground="Transparent" Height="0" Margin="5"/>
                        <cc:AttributeStack Attr="Due:" Val="{Binding Path=Title, RelativeSource={RelativeSource Mode=FindAncestor,AncestorType=Page}}"/>
                    </StackPanel>
                </Expander>
            </StackPanel>

            <StackPanel Grid.Column="1">
                <cc:Playblast_Viewer  x:Name="PlayblastView"/>
                <cc:FeedbackCtrl Header="Feedback"/>
                <cc:FeedbackCtrl Header="NoticeBoard"/>
            </StackPanel>

        </Grid>
    </ScrollViewer>
</Grid>

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