数据绑定的逻辑错误：属性似乎不会更新 [英] Logical Errors with data binding: a property seems not to update

问题描述

大家好，



我有这个XAML

 <  边框    CornerRadius   =  10   已移除  =  {Binding SelColor，Mode = OneWay}    BorderBrush   = 黑色    BorderThickness   =  1   保证金  =  7 >  
 <  矩形    MinHeight   =  20     MinWidth   =  180   填充  = 透明    /  >  
 <   / Border  >  
 <   Expander    标题  =  ChooseColor   扩展  =  Expander_Expanded   名称  =  Exp   已折叠  =  Exp_Collapsed >  
 <   StackPanel  >  
 <   StackPanel    方向  = 水平   保证金  =  2 >  
 <   TextBlock    文字  =  R   前景  =  {Binding Foreground}  /  >  
 <  滑块   已移除  =  {Dynami cResource RedSliderGrad}   最小  =  0   最大  =  255    MinWidth   =  180   值  =  {Binding SelColor。 Color.R，Mode = TwoWay，UpdateSourceTrigger = PropertyChanged}    ValueChanged   =  Slider_ValueChanged  /  >  
 <   / StackPanel  >  
 <   StackPanel    方向  = 水平   保证金  =  2 >  
 <   TextBlock    文本  =  G   前景  =  {Binding Fore地面}  /  >  
 <   Slider    已删除  =  {DynamicResource GreenSliderGrad}   最小  =  0   最大  =  255    MinWidth   =   180   值 < span class =code-keyword> =  {Binding SelColo r.Color.G，Mode = TwoWay，UpdateSourceTrigger = PropertyChanged}    ValueChanged   =  Slider_ValueChanged  /  >  
 <   / StackPanel  >  
 <   StackPanel    方向  = 水平   保证金  =   2 >  
  <   TextBlock    文本  =  B   前景  =  {Binding Foreground}  /  >  
 <  滑块   已移除  = < span class =code-keyword> {DynamicResource BlueSliderGrad}   最小  =  0   最大  = < span class =code-keyword> 255    MinWidth   =  180   值  =  {Binding SelColor.Color.B，Mode = TwoWay，UpdateSourceTrigger = PropertyChanged}    ValueChanged   =  Slider_ValueChanged  /  >  
 <   / StackPanel  >  
 <   / StackPanel  >  
  <   / Expander  >  
 <   / StackPanel  >  

和这个C＃代码：

  public  SolidColorBrush SelColor 
 {
  get  { return （的SolidColorBrush）的GetValue（SelColorProperty）; } 
  set  
 {
 SetValue（SelColorProperty， value ）; 
  if （PropertyChanged！=  null ）
 PropertyChanged（ this ， new  PropertyChangedEventArgs（  SelColor））; 
} 
} 
 
  //  使用DependencyProperty作为后盾商店为SelColor。这样可以实现动画，样式，装订等......  
  public   static   readonly  DependencyProperty SelColorProperty = 
 DependencyProperty.Register（  SelColor， typeof （SolidColorBrush）， typeof （ColorChooser）， new  PropertyMetadata（ new  SolidColorBrush（Color.FromArgb（ 255 ，  204 ， 204 ， 204 ））） ）; 
 
  public  ColorChooser（）
 {
 InitializeComponent（）; 
  this  .DataContext =  this ; 
} 
 
  private   void  Expander_Expanded（ object  sender，RoutedEventArgs e）
 {
  //   this.Exp.IsExpanded = true;  
  //   this.Height + = this.Exp .ActualHeight;  
} 
 
  private   void  Exp_Collapsed（ object  sender，RoutedEventArgs e）
 {
  //   this.Exp.IsExpanded = true;  
  //   this .Height  -  = this.Exp.ActualHeight;  
  //   this.Exp.IsE xpanded = false;  
} 
 
  public   event  PropertyChangedEventHandler PropertyChanged; 
 
  private   void  Slider_ValueChanged（对象发​​件人，RoutedPropertyChangedEventArgs< double> e）
 {
 
} 

我注意到，随着滑块的变化，甚至SelColor也会发生变化，但是边框的背景并没有反映出这种变化......为什么？



谢谢！



Jymmy097

解决方案

颜色 SolidColorBrush 是 struct ，而不是类，所以你无法以与类相同的方式绑定到它，因为当它被绑定引用时，它会得到<$ c> 的 SelColor.Color 来自 SolidColorBrush ，与 >颜色

Hi everybody,

I have this XAML

<Border CornerRadius="10" removed="{Binding SelColor, Mode=OneWay}" BorderBrush="Black" BorderThickness="1" Margin="7">
            <Rectangle MinHeight="20" MinWidth="180" Fill="Transparent" />
        </Border>
        <Expander Header="ChooseColor" Expanded="Expander_Expanded" Name="Exp" Collapsed="Exp_Collapsed">
            <StackPanel>
                <StackPanel Orientation="Horizontal" Margin="2">
                    <TextBlock Text="R" Foreground="{Binding Foreground}"/>
                    <Slider removed="{DynamicResource RedSliderGrad}" Minimum="0" Maximum="255" MinWidth="180" Value="{Binding SelColor.Color.R, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" ValueChanged="Slider_ValueChanged"/>
                </StackPanel>
                <StackPanel Orientation="Horizontal" Margin="2">
                    <TextBlock Text="G" Foreground="{Binding Foreground}"/>
                    <Slider removed="{DynamicResource GreenSliderGrad}" Minimum="0" Maximum="255" MinWidth="180" Value="{Binding SelColor.Color.G, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" ValueChanged="Slider_ValueChanged"/>
                </StackPanel>
                <StackPanel Orientation="Horizontal" Margin="2">
                    <TextBlock Text="B" Foreground="{Binding Foreground}"/>
                    <Slider removed="{DynamicResource BlueSliderGrad}" Minimum="0" Maximum="255" MinWidth="180" Value="{Binding SelColor.Color.B, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" ValueChanged="Slider_ValueChanged"/>
                </StackPanel>
            </StackPanel>
        </Expander>
    </StackPanel>

and this C# code:

public SolidColorBrush SelColor
        {
            get { return (SolidColorBrush)GetValue(SelColorProperty); }
            set
            {
                SetValue(SelColorProperty, value);
                if (PropertyChanged != null)
                    PropertyChanged(this, new PropertyChangedEventArgs("SelColor"));
            }
        }

        // Using a DependencyProperty as the backing store for SelColor.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty SelColorProperty =
            DependencyProperty.Register("SelColor", typeof(SolidColorBrush), typeof(ColorChooser), new PropertyMetadata(new SolidColorBrush(Color.FromArgb(255, 204, 204, 204))));

        public ColorChooser()
        {
            InitializeComponent();
            this.DataContext = this;
        }

        private void Expander_Expanded(object sender, RoutedEventArgs e)
        {
            //this.Exp.IsExpanded = true;
            //this.Height += this.Exp.ActualHeight;
        }

        private void Exp_Collapsed(object sender, RoutedEventArgs e)
        {
            //this.Exp.IsExpanded = true;
            //this.Height -= this.Exp.ActualHeight;
            //this.Exp.IsExpanded = false;
        }

        public event PropertyChangedEventHandler PropertyChanged;

        private void Slider_ValueChanged(object sender, RoutedPropertyChangedEventArgs<double> e)
        {

        }

I noticed that, as the slider changes, even the SelColor changes, but that changement is not reflected by the background of the border... Why?

Thanks!

Jymmy097

解决方案

The Color of a SolidColorBrush is a struct, not a class, so you can't bind to it the same way as a class, because when it is referenced by the binding, it gets a copy of the SelColor.Color from the SolidColorBrush, not the same actual instance of the Color.

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