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Question

想象一下我可以动态更改主题的wpf应用程序。我这样做是通过在Application-resource级别交换ResourceDictionaries。主题资源为TextBox等定义了隐式样式。

现在我在我的应用程序中有一个部分，其中文本框应该具有此特定样式“NonDefaultTextBoxStyle”而不是应用程序范围的隐式文本。

我很乐意这样做（使用DynamicResource，因为主题可以在运行时更改）：

<StackPanel>
    <StackPanel.Resources>
        <Style TargetType="TextBox" BasedOn="{DynamicResource NonDefaultTextBoxStyle}"/>
    </StackPanel.Resources>
    <TextBox .../>
    <TextBox .../>
    <TextBox .../>
</StackPanel>

而不是必须这样做：

<StackPanel>
    <TextBox Style="{DynamicResource NonDefaultTextBoxStyle}" .../>
    <TextBox Style="{DynamicResource NonDefaultTextBoxStyle}" .../>
    <TextBox Style="{DynamicResource NonDefaultTextBoxStyle}" .../>
</StackPanel>

现在为了简化这一点，我想到了在StackPanel上设置一个可继承的附加属性，它将在每个后代文本框上设置一个指定的样式。

这是个好主意吗？有更简单的方法吗？我错过了什么吗？

这很大程度上归结为：什么是样式中的BasedOn =“{DynamicResource ...}”的替代方案？

Answer 1

我有完全相同的问题但是对于ItemsContainerStyle ...所以我做了很多你所说的并写了一个AttachedProperty，它将允许为BasedOn提供动态资源。

DynamicResource for Style BasedOn

以下是针对您的情况修改的解决方案：

public class DynamicStyle
{
    public static Style GetBaseStyle(DependencyObject obj)
    {
        return (Style)obj.GetValue(BaseStyleProperty);
    }

    public static void SetBaseStyle(DependencyObject obj, Style value)
    {
        obj.SetValue(BaseStyleProperty, value);
    }

    // Using a DependencyProperty as the backing store for BaseStyle.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty BaseStyleProperty =
        DependencyProperty.RegisterAttached("BaseStyle", typeof(Style), typeof(DynamicStyle), new UIPropertyMetadata(DynamicStyle.StylesChanged));

    public static Style GetDerivedStyle(DependencyObject obj)
    {
        return (Style)obj.GetValue(DerivedStyleProperty);
    }

    public static void SetDerivedStyle(DependencyObject obj, Style value)
    {
        obj.SetValue(DerivedStyleProperty, value);
    }

    // Using a DependencyProperty as the backing store for DerivedStyle.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty DerivedStyleProperty =
        DependencyProperty.RegisterAttached("DerivedStyle", typeof(Style), typeof(DynamicStyle), new UIPropertyMetadata(DynamicStyle.StylesChanged));

    private static void StylesChanged(DependencyObject target, DependencyPropertyChangedEventArgs e)
    {
        if (!typeof(FrameworkElement).IsAssignableFrom(target.GetType()))
            throw new InvalidCastException("Target must be FrameworkElement");

        var Element = (FrameworkElement)target;

        var Styles = new List<Style>();

        var BaseStyle = GetBaseStyle(target);

        if (BaseStyle != null)
            Styles.Add(BaseStyle);

        var DerivedStyle = GetDerivedStyle(target);

        if (DerivedStyle != null)
            Styles.Add(DerivedStyle);

        Element.Style = MergeStyles(Styles);
    }

    private static Style MergeStyles(ICollection<Style> Styles)
    {
        var NewStyle = new Style();

        foreach (var Style in Styles)
        {
            foreach (var Setter in Style.Setters)
                NewStyle.Setters.Add(Setter);

            foreach (var Trigger in Style.Triggers)
                NewStyle.Triggers.Add(Trigger);
        }

        return NewStyle;
    }
}

这是一个使用它的例子：

<!-- xmlns:ap points to the namespace where DynamicStyle class lives -->
<Button ap:DynamicStyle.BaseStyle="{DynamicResource {x:Type Button}}">
    <ap:DynamicStyle.DerivedStyle>
        <Style TargetType="Button">
            <Style.Triggers>
                <MultiDataTrigger>
                    <MultiDataTrigger.Conditions>
                        <Condition Binding="{Binding Path=FirstButtonWarning}" Value="True"/>
                        <Condition Binding="{Binding RelativeSource={RelativeSource Self}, Path=IsEnabled}" Value="True"/>
                    </MultiDataTrigger.Conditions>
                    <MultiDataTrigger.Setters>
                        <Setter Property="Background" Value="{DynamicResource WarningBackground}"/>
                        <Setter Property="Foreground" Value="{DynamicResource WarningForeground}"/>
                    </MultiDataTrigger.Setters>
                </MultiDataTrigger>
            </Style.Triggers>
        </Style>
    </ap:DynamicStyle.DerivedStyle>
    <TextBlock Text="Button that changes background and foreground when warning is active"/>
</Button>

Answer 2

真的需要成为DynamicResource吗？所以也许this会帮助你

如果不是这里是StaticResource的简单示例

App.xaml

<Application.Resources>
        <Style x:Key="myResource" TargetType="Button">
            <Setter Property="Background" Value="Black"/>
            <Setter Property="Foreground" Value="White"/>
        </Style>         
    </Application.Resources>

<强> MainWindow.xaml

<StackPanel>
    <StackPanel.Resources>
        <Style TargetType="Button" BasedOn="{StaticResource myResource}"/>
    </StackPanel.Resources>
    <Button Content="blubb" Height="23" Width="75" />
</StackPanel>

如果两者都无济于事，您可以提供添加资源的方式

修改

好的，现在应该回答你的问题

App.xaml

<Application.Resources>

    <SolidColorBrush  x:Key="background"  Color="Red" />
    <SolidColorBrush  x:Key="foreground"  Color="Blue" />

    <Style x:Key="NonDefaultTextBoxStyle" >
        <Setter Property="TextBox.Background" Value="{DynamicResource background}"/>
        <Setter Property="TextBox.Foreground" Value="{DynamicResource foreground}"/>
    </Style>

</Application.Resources>

<强> MainWindow.xaml

<StackPanel>
    <Button Content="Button" Height="23" Width="75" Click="Button_Click" />

    <StackPanel>
        <StackPanel.Resources>
            <Style   TargetType="{x:Type TextBox}" BasedOn="{StaticResource NonDefaultTextBoxStyle}">
            </Style>
        </StackPanel.Resources>
        <TextBox Text="bliii" Height="23" Width="75" />
        <TextBox Text="blaaa" Height="23" Width="75" />
        <TextBox Text="blubb" Height="23" Width="75" />
    </StackPanel>

</StackPanel>

<强> MainWindow.cs

private void Button_Click(object sender, RoutedEventArgs e)
        {
            this.Resources["background"] = Brushes.Black;
            this.Resources["foreground"] = Brushes.Yellow;
        }

设置本地隐式样式，不同于主题样式/替代为BasedOn DynamicResource

2 个答案:

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