如何在属性更改时更改控件的外观?

可能最好的方法是为实现的值编写一个包装类 INotifyPropertyChanged 并显示读/写 Value 类型属性 object ValueHasChanged 财产。然后,您可以很容易地在 价值

if (!value.Equals(_Value))
{
   _Value = value;
   ValueHasChanged=true;
   OnPropertyChanged("Value");
}

而不是你的视图模型类公开 string DateTime 属性,它应该暴露 ValueWrapper

private string SomeStringField;

private ValueWrapper _SomeStringProperty;

public ValueWrapper SomeStringProperty
{
   get 
   { 
      return (_SomeStringProperty == null) 
         ? _SomeStringProperty = new ValueWrapper(SomeStringField) 
         : _SomeStringProperty; 
   }
}

然后您可以构建一个样式,如:

<Style x:Key="ShowChangedValue">
   <Setter Property="Background" Value="White"/>
   <Style.Triggers>
      <DataTrigger Binding="{Binding ValueHasChanged}" Value="True">
         <Setter Property="Background" Value="AliceBlue"/>
      </DataTrigger>
    </Style.Triggers>
</Style>

使用方式如下:

<TextBox DataContext="{Binding SomeStringProperty}" 
         Text="{Binding Value, Mode=TwoWay}"
         Style="{StaticResource ShowChangedValue}"/>

这其中有一些恼人的事情,比如要在主视图模型类中更改属性的值,现在必须使用 SomeStringProperty.Value = "foo" SomeStringProperty = "foo"

创建 ValueTracker 类,该类将提供以下3个附加的依赖项属性

-这将是应跟踪的控件的属性

默认值 -这是一个被认为是默认值的值,否则就会触发样式触发器。

-这将指示如果当前值与默认值匹配,则此属性将在触发器测试中使用。

这是一个快速的测试,它不是完美的,但我相信一点点软性将使事情进展顺利,当然,有更多WPF经验的人可以改进这个想法。

using System;
using System.Windows;
using System.ComponentModel;

namespace WpfApplication1
{
  public static class ValueTracker
  {
    // Attached dependency property for DefaultValue 
    public static object GetDefaultValue(DependencyObject obj)
    {
      return (object)obj.GetValue(DefaultValueProperty);
    }

    public static void SetDefaultValue(DependencyObject obj, object value)
    {
      obj.SetValue(DefaultValueProperty, value);
    }

    public static readonly DependencyProperty DefaultValueProperty =
        DependencyProperty.RegisterAttached("DefaultValue", 
        typeof(object), typeof(ValueTracker), new UIPropertyMetadata(0));

    // Attached dependency property for IsDefaultValue 
    public static bool GetIsDefaultValue(DependencyObject obj)
    {      
      return (bool)obj.GetValue(IsDefaultValueProperty);
    }

    private static void SetIsDefaultValue(DependencyObject obj, bool value)
    {
      obj.SetValue(IsDefaultValueProperty, value);
    }

    public static readonly DependencyProperty IsDefaultValueProperty =
        DependencyProperty.RegisterAttached("IsDefaultValue", 
        typeof(bool), typeof(ValueTracker), new UIPropertyMetadata(false));

    // Attached dependency property for TrackedProperty 
    public static DependencyProperty GetTrackProperty(DependencyObject obj)
    {
      return (DependencyProperty)obj.GetValue(TrackPropertyProperty);
    }

    public static void SetTrackProperty(DependencyObject obj, DependencyProperty value)
    {      
      obj.SetValue(TrackPropertyProperty, value);
    }

    public static readonly DependencyProperty TrackPropertyProperty =
        DependencyProperty.RegisterAttached("TrackProperty", 
        typeof(DependencyProperty), typeof(ValueTracker), 
        new UIPropertyMetadata(TrackPropertyChanged));


    public static void TrackPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {   
      DependencyProperty oldProperty = e.OldValue as DependencyProperty;
      if (oldProperty != null)
      {
        DependencyPropertyDescriptor dpd = 
          DependencyPropertyDescriptor.FromProperty(oldProperty, typeof(UIElement));

        if (dpd != null)
        {
          dpd.RemoveValueChanged(d, TrackedPropertyValueChanged);
        }
      }

      DependencyProperty newProperty = e.NewValue as DependencyProperty;
      if (newProperty != null)
      {        
        DependencyPropertyDescriptor dpd = 
          DependencyPropertyDescriptor.FromProperty(newProperty, typeof(UIElement));

        if (dpd != null)
        {
          dpd.AddValueChanged(d, TrackedPropertyValueChanged);
        }        
      }
    }

    private static void TrackedPropertyValueChanged(object sender, EventArgs e)
    {
      DependencyObject o = sender as DependencyObject;
      if (o != null)
      {         
        object defaultValue = Convert.ChangeType(GetDefaultValue(o), GetTrackProperty(o).PropertyType);
        SetIsDefaultValue(o, Object.Equals(o.GetValue(GetTrackProperty(o)), defaultValue));        
      }
    }
  }
}

以上可按如下方式使用。

2-对于要跟踪的每个控件,附加样式并设置ValueTracker.DefaultValue并设置应使用ValueTracker.TrackProperty.

<Window x:Class="WpfApplication1.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:r="clr-namespace:WpfApplication1"
        mc:Ignorable="d" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
        xmlns:local="clr-namespace:WpfApplication1"
        Title="MainWindow"         
        d:DesignHeight="221" d:DesignWidth="287"
        Width="250" Height="250">
  <StackPanel Loaded="StackPanel_Loaded" >
    <StackPanel.Resources>
      <Style TargetType="{x:Type Control}" x:Key="trackChanges">
        <Style.Triggers>
          <Trigger Property="local:ValueTracker.IsDefaultValue" Value="false">
            <Setter Property="FontWeight" Value="Bold" />
          </Trigger>
        </Style.Triggers>
      </Style>
    </StackPanel.Resources>

    <TextBox Name="textbox1" Width="100" Height="23" 
             local:ValueTracker.DefaultValue="Help" 
             local:ValueTracker.TrackProperty="TextBox.Text" 
             Style="{StaticResource ResourceKey=trackChanges}" />

    <ComboBox Name="combobox1" 
              SelectedIndex="2" 
              local:ValueTracker.DefaultValue="2" 
              local:ValueTracker.TrackProperty="ComboBox.SelectedIndex" 
              Style="{StaticResource ResourceKey=trackChanges}">
      <ComboBox.Items>
        <ComboBoxItem>Item 1</ComboBoxItem>
        <ComboBoxItem>Item 2</ComboBoxItem>
        <ComboBoxItem>Item 3</ComboBoxItem>
        <ComboBoxItem>Item 4</ComboBoxItem>
      </ComboBox.Items>
    </ComboBox>
  </StackPanel>
</Window>

我会重新编写关于INotifyPropertyChanged的设计模式的阅读

dispatcher on msdn

假设你想打印新的电路板你应该这样做

  printDelgate paintControlDelgate = () => paintControl();
  m_CurrentDispatcher.Invoke(paintControlDelgate);

<ControlTemplate x:Key="StarTemplate" TargetType="{x:Type Button}">
    <Grid>
        <ed:RegularPolygon Visibility="Collapsed" Name="star1" Fill="{Binding Path=ButtonColor}" 
                               InnerRadius="0.47211" Margin="20.5,16,15.5,8" PointCount="5"  Stroke="Black"
                               StrokeThickness="2"  Height="40" Width="40"/>
        <ed:RegularPolygon Name="star2" Fill="Black" Visibility="Visible"  InnerRadius="0.47211" Margin="20.5,16,15.5,8"
                               PointCount="5"  Stroke="Black" StrokeThickness="6"  Height="40" Width="40"/>
    </Grid>

    <ControlTemplate.Triggers>

        <Trigger Property="IsPressed"  Value="True">
            <Setter TargetName="star1" Property="Visibility" Value="Visible"/>
            <Setter TargetName="star2" Property="Visibility" Value="Collapsed"/>
        </Trigger>

所以当按钮被按下时,它的内容可见性就会改变。