绑定不正确更新控件属性MVVM [英] Binding does not update usercontrol property correctly MVVM

问题描述

编辑：老code删除

我将它放在我的MainWindow.xaml

I place it on my MainWindow.xaml

 <SpinTextBlock:SpinTextBlock Text="{Binding Path=DataContext.WelcomeTitle, ElementName=Window,UpdateSourceTrigger=PropertyChanged}" Height="60" Width="40" x:Name="TextBlock"/>

和其绑定到财产MainViewModel.cs

And bind it to a property in MainViewModel.cs

        public string WelcomeTitle
    {
        get
        {
            return _welcomeTitle;
        }

        set
        {
            if (_welcomeTitle == value)
            {
                return;
            }

            _welcomeTitle = value;
            RaisePropertyChanged(WelcomeTitle);
            Dispatcher.CurrentDispatcher.BeginInvoke(
new Action<String>(RaisePropertyChanged),
DispatcherPriority.DataBind, "WelcomeTitle");
        }
    }

一切工作正常，但在我的用户时，在视图模型的值更新不更新该属性的文本。相反，从视图模型的更新是直接放在文本块（在该用户）和故事板和我的用户的所有属性完全不叫。

Everything works fine, except that property Text in my UserControl doesn't update when the value in the ViewModel is updated. Instead the update from the ViewModel is directly placed on the TextBlock (in the UserControl) and the storyboard and all properties on my usercontrol isn't called at all.

任何人都得到了解决呢？

Anyone got a solution to this?

编辑工作的解决方案

用户控件code-后面。不得不听的属性更改开始我的故事板和更新属性。

Usercontrol code-behind. Had to listen for the property change to start my storyboard and update properties.

    public partial class SpinTextBlock : INotifyPropertyChanged 
{
    public static readonly DependencyProperty TextProperty =
        DependencyProperty.Register("Text", typeof(string), typeof(SpinTextBlock), new FrameworkPropertyMetadata(
 string.Empty,
 new PropertyChangedCallback(OnTextPropertyChanged)));

    private static void OnTextPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        SpinTextBlock obj = d as SpinTextBlock;
        obj.OnTextChanged(e.NewValue as string);

    }

    private  void OnTextChanged(string newValue)
    {
        UpdateTextBlocks(newValue);
    }

    public static readonly DependencyProperty TextOldProperty =
      DependencyProperty.Register("TextOld", typeof(string), typeof(SpinTextBlock), new PropertyMetadata(default(string)));

    public string Text
    {
        get
        {
            return (string)GetValue(TextProperty);
        }
        set
        {
            SetValue(TextProperty, value);
        }
    }

    private string TextOld
    {
        get
        {
            return (string)GetValue(TextOldProperty);
        }
        set
        {
            SetValue(TextOldProperty, value);
        }
    }

    public bool AddZeroBeforeTextIfSingleValue { get; set; }

    public SpinTextBlock()
    {
        InitializeComponent();
        AddZeroBeforeTextIfSingleValue = true;
        TextBlockOld.Visibility = Visibility.Collapsed;

    }

    void UpdateTextBlocks(string newValue)
    {
        if (AddZeroBeforeTextIfSingleValue)
        {
            AddZeroToValue(ref newValue);
        }
        TextOld = TextBlockMain.Text;
        StartAnimation();
    }

    void StartAnimation()
    {
        TextBlockOld.Visibility = Visibility.Visible;
        Storyboard sb = this.Resources["StoryboardChangeTexts"] as Storyboard;
        sb.Begin();
    }

    void AddZeroToValue(ref string value)
    {
        if (value != null && value.Length == 1)
        {
            value = "0" + value;
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;

UserControl xaml
<UserControl x:Class="Y.Infrastructure.SpinTextBlock.SpinTextBlock"
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"
         x:Name="userControl"
mc:Ignorable="d"
FontSize="36"
Foreground="Black"
d:DesignHeight="60" d:DesignWidth="40">
<UserControl.Resources>
    <Storyboard x:Key="StoryboardChangeTexts">
        <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Opacity)" Storyboard.TargetName="TextBlockOld">
            <EasingDoubleKeyFrame KeyTime="0" Value="1"/>
            <EasingDoubleKeyFrame KeyTime="0:0:0.4" Value="0"/>
        </DoubleAnimationUsingKeyFrames>
        <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.RenderTransform).(TransformGroup.Children)[3].(TranslateTransform.Y)" Storyboard.TargetName="TextBlockMain">
            <EasingDoubleKeyFrame KeyTime="0" Value="-35"/>
            <EasingDoubleKeyFrame KeyTime="0:0:0.4" Value="0"/>
        </DoubleAnimationUsingKeyFrames>
        <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.RenderTransform).(TransformGroup.Children)[3].(TranslateTransform.Y)" Storyboard.TargetName="TextBlockOld">
            <EasingDoubleKeyFrame KeyTime="0" Value="0"/>
            <EasingDoubleKeyFrame KeyTime="0:0:0.4" Value="35"/>
        </DoubleAnimationUsingKeyFrames>
    </Storyboard>
</UserControl.Resources>

<Grid x:Name="LayoutRoot" Background="Black">
    <TextBlock HorizontalAlignment="Center" x:FieldModifier="private" Foreground="White" FontSize="36" Text="{Binding Text, ElementName=userControl}" x:Name="TextBlockMain" FontWeight="Bold" FontFamily="Segoe UI Semibold">
        <TextBlock.RenderTransform>
            <TransformGroup>
                <ScaleTransform/>
                <SkewTransform/>
                <RotateTransform/>
                <TranslateTransform/>
            </TransformGroup>
        </TextBlock.RenderTransform>
    </TextBlock>
    <TextBlock HorizontalAlignment="Center" x:FieldModifier="private" Foreground="White" FontSize="36" Text="{Binding TextOld, ElementName=userControl}" x:Name="TextBlockOld" FontWeight="Bold" FontFamily="Segoe UI Semibold">
        <TextBlock.RenderTransform>
            <TransformGroup>
                <ScaleTransform/>
                <SkewTransform/>
                <RotateTransform/>
                <TranslateTransform/>
            </TransformGroup>
        </TextBlock.RenderTransform>
    </TextBlock>
</Grid>

推荐答案

呼叫 UpdateTextBlocks（值）你的财产文本的制定者将不会被调用，导致运行会调用的SetValue（TextProperty，值）; 直接

The call UpdateTextBlocks(value) in the setter of your property Text will not be called, cause the runtime will call SetValue(TextProperty, value); directly.

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