Question

设置BackgroundProperty会直接破坏IsMouseOver样式触发器。如何直接设置BackgroundProperty并保留触发器以便在此之后工作？

XAML：

<Window x:Class="WpfTriggers.MainWindow"
        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"
        mc:Ignorable="d"
        Title="MainWindow" Height="350" Width="525">
    <Window.Resources>
        <SolidColorBrush x:Key="OriginalBackground" Color="Blue"/>
        <SolidColorBrush x:Key="TemplateBackground" Color="Red"/>
        <Style TargetType="Label" >
            <Style.Setters>
                <Setter Property="Background" Value="{StaticResource OriginalBackground}"/>
                <Setter Property="Foreground" Value="White"/>
            </Style.Setters>
            <Style.Triggers>
                <Trigger Property="IsMouseOver" Value="True">
                    <Setter Property="Background" Value="{StaticResource TemplateBackground}"/>
                </Trigger>
            </Style.Triggers>
        </Style>
    </Window.Resources>
    <Grid>
        <StackPanel>
            <Label Focusable="True" x:Name="label">Hi!</Label>
            <Button Click="Button_Click">Over</Button>
        </StackPanel>
    </Grid>
   </Window>

代码背后：

using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;
namespace WpfTriggers
{
    public partial class MainWindow : Window
    {
        public MainWindow() => InitializeComponent();    
        void Button_Click(object sender, RoutedEventArgs e) => label.SetValue(Control.BackgroundProperty, Brushes.Green);       
    }
}

Answer 1

您无法直接设置样式中使用的属性（结果就是您的样本）。您必须使用Binding。一些添加到您的代码：

    public MainWindow()
    {
        DataContext = this;
        InitializeComponent();
        SetValue(BgBrushProperty, Resources["OriginalBackground"]);
    }

    void Button_Click(object sender, RoutedEventArgs e) => SetValue(BgBrushProperty, Brushes.Green);


    // Using a DependencyProperty as the backing store for BgBrush.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty BgBrushProperty =
        DependencyProperty.Register("BgBrush", typeof(Brush), typeof(MainWindow), new PropertyMetadata());

和XAML ......

 <Style.Setters>
    <Setter Property="Background" Value="{Binding BgBrush}"/>
    <Setter Property="Foreground" Value="White"/>
</Style.Setters>

你也可以像这样使用DynamicResource：

<Style.Setters>
    <Setter Property="Background" Value="{DynamicResource OriginalBackground}"/>
    <Setter Property="Foreground" Value="White"/>
</Style.Setters>

使用此代码：

    public MainWindow() => InitializeComponent();
    void Button_Click(object sender, RoutedEventArgs e) => Resources["OriginalBackground"] = Brushes.Green;

Answer 2

我们通过复制风格解决了问题，暂时用背景设定器克隆替换它并且返回风格。这是作为一种行为生成的，它通过完全自定义的动态绑定模仿数据触发器。

    public static class extensions
{
    /// <summary>
    /// Shallow clone of style.
    /// </summary>
    /// <param name="original">Style to clone.</param>
    /// <returns>Cloned style.</returns>
    public static Style ShallowClone(this Style original)
    {
        var cloned = new Style(original.TargetType, original.BasedOn);
        foreach (var s in original.Setters) cloned.Setters.Add(s);
        foreach (var t in original.Triggers) cloned.Triggers.Add(t);
        cloned.Resources = original.Resources;
        return cloned;
    }
}

    Style old;

    private void Button_MouseEnter_5(object sender, System.Windows.Input.MouseEventArgs e)
    {
        old = labelWithMofidiableStyle.Style;
        Style style = old.ShallowClone();
        style.Setters.Add(new Setter { Property = Control.BackgroundProperty, Value = this.FindResource("DynamicBackground") });
        labelWithMofidiableStyle.Style = style;
    }



    private void Button_MouseLeave_5(object sender, System.Windows.Input.MouseEventArgs e)
    {
        labelWithMofidiableStyle.Style = old;
    }

样式触发器在直接SetValue后停止工作

2 个答案: