在运行时更改MergedDictionaries

Question

我目前正在开发一个WPF应用程序，它允许用户在运行时更改其主题(无需任何重启)。我现在使用的是这里的代码：

http://svetoslavsavov.blogspot.de/2009/07/switching-wpf-interface-themes-at.html

我用一条Try语句修改了它：

private static void ApplyTheme(FrameworkElement targetElement, Uri dictionaryUri)
    {
        if (targetElement == null) return;

        try
        {
            ResourceDictionary themeDictionary = null;
            if (dictionaryUri != null)
            {
                themeDictionary = new ResourceDictionary();
                themeDictionary.Source = dictionaryUri;

                targetElement.Resources.MergedDictionaries.Insert(0, themeDictionary);
            }

            List<ResourceDictionary> existingDictionaries =
                (from dictionary in targetElement.Resources.MergedDictionaries.OfType<ResourceDictionary>()
                 select dictionary).ToList();

            foreach (ResourceDictionary thDictionary in existingDictionaries)
            {
                if (themeDictionary == thDictionary) continue;
                try
                {
                    targetElement.Resources.MergedDictionaries.Remove(thDictionary);
                }
                catch { }
            }
        }
        finally { }
    }

但是，如果我在应用程序中设置了ScrollBars的样式，它就不会真正起作用。第一次，它总是把相同的ComboBox变成一个矩形，你不能再使用它了：

http://goo.gl/eNC2m0

第二次抛出异常：

Unable to cast object of type 'MS.Internal.NamedObject' to type 'System.Windows.FrameworkTemplate'.

如果我删除Try语句，它在第一次就已经抛出了异常。

ScrollBar样式如下所示：

<!-- Colors -->
<Color x:Key="Accent">#FFFEB809</Color>
<SolidColorBrush x:Key="AccentBrush" Color="{StaticResource Accent}"/>
<Color x:Key="AccentConsole">#22FEB809</Color>
<SolidColorBrush x:Key="AccentConsoleBrush" Color="{StaticResource AccentConsole}"/>
<Color x:Key="AccentLight">#FFFFDB82</Color>
<SolidColorBrush x:Key="AccentLightBrush" Color="{StaticResource AccentLight}"/>
<Color x:Key="AccentLightConsole">#22FFDB82</Color>
<SolidColorBrush x:Key="AccentLightConsoleBrush" Color="{StaticResource AccentLightConsole}"/>
<Color x:Key="AccentText">#FFFFFFFF</Color>
<SolidColorBrush x:Key="AccentTextBrush" Color="{StaticResource AccentText}"/>
<Color x:Key="Border">#FFCCCCCC</Color>
<SolidColorBrush x:Key="BorderBrush" Color="{StaticResource Border}"/>
<Color x:Key="CaptionBar">#FFFCFCFC</Color>
<SolidColorBrush x:Key="CaptionBarBrush" Color="{StaticResource CaptionBar}"/>
<Color x:Key="ConsoleBackground">#FF222222</Color>
<SolidColorBrush x:Key="ConsoleBackgroundBrush" Color="{StaticResource ConsoleBackground}"/>
<Color x:Key="ControlBackground">White</Color>
<SolidColorBrush x:Key="ControlBackgroundBrush" Color="{StaticResource ControlBackground}"/>
<Color x:Key="NavigationHeader">#88000000</Color>
<SolidColorBrush x:Key="NavigationHeaderBrush" Color="{StaticResource NavigationHeader}"/>
<Color x:Key="Window">#FFFAFAFA</Color>
<SolidColorBrush x:Key="WindowBrush" Color="{StaticResource Window}"/>

<Style x:Key="{x:Type ScrollBar}" TargetType="{x:Type ScrollBar}">
    <Setter Property="SnapsToDevicePixels" Value="True"/>
    <Setter Property="OverridesDefaultStyle" Value="True"/>
    <Setter Property="Margin" Value="2"/>
    <Style.Triggers>
        <Trigger Property="Orientation" Value="Horizontal">
            <Setter Property="Template" Value="{StaticResource HorizontalScrollBar}"/>
            <Setter Property="Height" Value="24"/>
        </Trigger>
        <Trigger Property="Orientation" Value="Vertical">
            <Setter Property="Template" Value="{StaticResource VerticalScrollBar}"/>
            <Setter Property="Width" Value="24"/>
        </Trigger>
    </Style.Triggers>
</Style>
<ControlTemplate x:Key="HorizontalScrollBar" TargetType="{x:Type ScrollBar}">
    <Grid>
        <Border Background="#22000000" CornerRadius="4">
            <Track Name="PART_Track">
                <Track.DecreaseRepeatButton>
                    <RepeatButton Style="{StaticResource ScrollBarPageButton}" Command="ScrollBar.PageLeftCommand"/>
                </Track.DecreaseRepeatButton>
                <Track.Thumb>
                    <!-- The problem occurs here -->
                    <Thumb Style="{StaticResource HorizontalScrollBarThumb}"/>
                </Track.Thumb>
                <Track.IncreaseRepeatButton>
                    <RepeatButton Style="{StaticResource ScrollBarPageButton}" Command="ScrollBar.PageRightCommand"/>
                </Track.IncreaseRepeatButton>
            </Track>
        </Border>
    </Grid>
</ControlTemplate>
<ControlTemplate x:Key="VerticalScrollBar" TargetType="{x:Type ScrollBar}">
    <Grid>
        <Border Background="#22000000" CornerRadius="4">
            <Track Name="PART_Track" IsDirectionReversed="True">
                <Track.DecreaseRepeatButton>
                    <RepeatButton Style="{StaticResource ScrollBarPageButton}" Command="ScrollBar.PageUpCommand"/>
                </Track.DecreaseRepeatButton>
                <Track.Thumb>
                    <!-- The problem occurs here -->
                    <Thumb Style="{StaticResource VerticalScrollBarThumb}"/>
                </Track.Thumb>
                <Track.IncreaseRepeatButton>
                    <RepeatButton Style="{StaticResource ScrollBarPageButton}" Command="ScrollBar.PageDownCommand"/>
                </Track.IncreaseRepeatButton>
            </Track>
        </Border>
    </Grid>
</ControlTemplate>
<Style x:Key="HorizontalScrollBarThumb" TargetType="{x:Type Thumb}">
    <Setter Property="SnapsToDevicePixels" Value="True"/>
    <Setter Property="Foreground" Value="#FF585858"/>
    <Setter Property="FontFamily" Value="Segoe UI Semibold"/>
    <Setter Property="FontSize" Value="14"/>
    <Setter Property="Padding" Value="8"/>
    <Setter Property="Focusable" Value="False"/>
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type Thumb}">
                <Grid>
                    <Grid.ColumnDefinitions>
                        <ColumnDefinition Width="24"/>
                        <ColumnDefinition Width="*"/>
                        <ColumnDefinition Width="24"/>
                    </Grid.ColumnDefinitions>
                    <RepeatButton Style="{StaticResource LeftScrollBarLineButton}" Command="ScrollBar.LineLeftCommand"/>
                    <Border Name="Base" Background="{StaticResource ControlBackgroundBrush}" BorderBrush="{StaticResource BorderBrush}" BorderThickness="0,1,0,1" Grid.Column="1">
                        <TextBlock Text="" FontFamily="Segoe UI Symbol" Foreground="#FF585858" HorizontalAlignment="Center" VerticalAlignment="Center"/>
                    </Border>
                    <RepeatButton Style="{StaticResource RightScrollBarLineButton}" Command="ScrollBar.LineRightCommand" Grid.Column="2"/>
                </Grid>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>
<Style x:Key="VerticalScrollBarThumb" TargetType="{x:Type Thumb}">
    <Setter Property="SnapsToDevicePixels" Value="True"/>
    <Setter Property="Foreground" Value="#FF585858"/>
    <Setter Property="FontFamily" Value="Segoe UI Semibold"/>
    <Setter Property="FontSize" Value="14"/>
    <Setter Property="Padding" Value="8"/>
    <Setter Property="Focusable" Value="False"/>
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type Thumb}">
                <Grid>
                    <Grid.RowDefinitions>
                        <RowDefinition Height="24"/>
                        <RowDefinition Height="*"/>
                        <RowDefinition Height="24"/>
                    </Grid.RowDefinitions>
                    <RepeatButton Style="{StaticResource TopScrollBarLineButton}" Command="ScrollBar.LineUpCommand"/>
                    <Border Name="Base" Background="{StaticResource ControlBackgroundBrush}" BorderBrush="{StaticResource BorderBrush}" BorderThickness="1,0,1,0" Grid.Row="1">
                        <TextBlock Text="" FontFamily="Segoe UI Symbol" Foreground="#FF585858" HorizontalAlignment="Center" VerticalAlignment="Center"/>
                    </Border>
                    <RepeatButton Style="{StaticResource BottomScrollBarLineButton}" Command="ScrollBar.LineDownCommand" Grid.Row="2"/>
                </Grid>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>
<Style x:Key="LeftScrollBarLineButton" TargetType="{x:Type RepeatButton}">
    <Setter Property="SnapsToDevicePixels" Value="True"/>
    <Setter Property="Foreground" Value="#FF585858"/>
    <Setter Property="FontFamily" Value="Segoe UI Symbol"/>
    <Setter Property="FontSize" Value="14"/>
    <Setter Property="Padding" Value="8"/>
    <Setter Property="Focusable" Value="False"/>
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type RepeatButton}">
                <Border Name="Base" Background="{StaticResource ControlBackgroundBrush}" BorderBrush="{StaticResource BorderBrush}" CornerRadius="4,0,0,4" BorderThickness="1,1,0,1">
                    <TextBlock Text="" Foreground="{TemplateBinding Foreground}" FontFamily="{TemplateBinding FontFamily}" FontSize="{TemplateBinding FontSize}" HorizontalAlignment="Center" VerticalAlignment="Center"/>
                </Border>
                <ControlTemplate.Triggers>
                    <Trigger Property="IsMouseOver" Value="True">
                        <Setter TargetName="Base" Property="Background">
                            <Setter.Value>
                                <LinearGradientBrush StartPoint="0.5,0" EndPoint="0.5,1">
                                    <LinearGradientBrush.RelativeTransform>
                                        <RotateTransform Angle="-90"/>
                                    </LinearGradientBrush.RelativeTransform>
                                    <GradientStop Color="{StaticResource AccentLight}" Offset="0"/>
                                    <GradientStop Color="{StaticResource ControlBackground}" Offset="1"/>
                                </LinearGradientBrush>
                            </Setter.Value>
                        </Setter>
                    </Trigger>
                </ControlTemplate.Triggers>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>
<Style x:Key="RightScrollBarLineButton" TargetType="{x:Type RepeatButton}">
    <Setter Property="SnapsToDevicePixels" Value="True"/>
    <Setter Property="Foreground" Value="#FF585858"/>
    <Setter Property="FontFamily" Value="Segoe UI Symbol"/>
    <Setter Property="FontSize" Value="14"/>
    <Setter Property="Padding" Value="8"/>
    <Setter Property="Focusable" Value="False"/>
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type RepeatButton}">
                <Border Name="Base" Background="{StaticResource ControlBackgroundBrush}" BorderBrush="{StaticResource BorderBrush}" CornerRadius="0,4,4,0" BorderThickness="0,1,1,1">
                    <TextBlock Text="" Foreground="{TemplateBinding Foreground}" FontFamily="{TemplateBinding FontFamily}" FontSize="{TemplateBinding FontSize}" HorizontalAlignment="Center" VerticalAlignment="Center"/>
                </Border>
                <ControlTemplate.Triggers>
                    <Trigger Property="IsMouseOver" Value="True">
                        <Setter TargetName="Base" Property="Background">
                            <Setter.Value>
                                <LinearGradientBrush StartPoint="0.5,0" EndPoint="0.5,1">
                                    <LinearGradientBrush.RelativeTransform>
                                        <RotateTransform Angle="90"/>
                                    </LinearGradientBrush.RelativeTransform>
                                    <GradientStop Color="{StaticResource AccentLight}" Offset="0"/>
                                    <GradientStop Color="{StaticResource ControlBackground}" Offset="1"/>
                                </LinearGradientBrush>
                            </Setter.Value>
                        </Setter>
                    </Trigger>
                </ControlTemplate.Triggers>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>
<Style x:Key="TopScrollBarLineButton" TargetType="{x:Type RepeatButton}">
    <Setter Property="SnapsToDevicePixels" Value="True"/>
    <Setter Property="Foreground" Value="#FF585858"/>
    <Setter Property="FontFamily" Value="Segoe UI Symbol"/>
    <Setter Property="FontSize" Value="14"/>
    <Setter Property="Padding" Value="8"/>
    <Setter Property="Focusable" Value="False"/>
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type RepeatButton}">
                <Border Name="Base" Background="{StaticResource ControlBackgroundBrush}" BorderBrush="{StaticResource BorderBrush}" CornerRadius="4,4,0,0" BorderThickness="1,1,1,0">
                    <TextBlock Text="" Foreground="{TemplateBinding Foreground}" FontFamily="{TemplateBinding FontFamily}" FontSize="{TemplateBinding FontSize}" HorizontalAlignment="Center" VerticalAlignment="Center"/>
                </Border>
                <ControlTemplate.Triggers>
                    <Trigger Property="IsMouseOver" Value="True">
                        <Setter TargetName="Base" Property="Background">
                            <Setter.Value>
                                <LinearGradientBrush StartPoint="0.5,0" EndPoint="0.5,1">
                                    <GradientStop Color="{StaticResource AccentLight}" Offset="0"/>
                                    <GradientStop Color="{StaticResource ControlBackground}" Offset="1"/>
                                </LinearGradientBrush>
                            </Setter.Value>
                        </Setter>
                    </Trigger>
                </ControlTemplate.Triggers>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>
<Style x:Key="BottomScrollBarLineButton" TargetType="{x:Type RepeatButton}">
    <Setter Property="SnapsToDevicePixels" Value="True"/>
    <Setter Property="Foreground" Value="#FF585858"/>
    <Setter Property="FontFamily" Value="Segoe UI Symbol"/>
    <Setter Property="FontSize" Value="14"/>
    <Setter Property="Padding" Value="8"/>
    <Setter Property="Focusable" Value="False"/>
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type RepeatButton}">
                <Border Name="Base" Background="{StaticResource ControlBackgroundBrush}" BorderBrush="{StaticResource BorderBrush}" CornerRadius="0,0,4,4" BorderThickness="1,0,1,1">
                    <TextBlock Text="" Foreground="{TemplateBinding Foreground}" FontFamily="{TemplateBinding FontFamily}" FontSize="{TemplateBinding FontSize}" HorizontalAlignment="Center" VerticalAlignment="Center"/>
                </Border>
                <ControlTemplate.Triggers>
                    <Trigger Property="IsMouseOver" Value="True">
                        <Setter TargetName="Base" Property="Background">
                            <Setter.Value>
                                <LinearGradientBrush StartPoint="0.5,0" EndPoint="0.5,1">
                                    <GradientStop Color="{StaticResource AccentLight}" Offset="1"/>
                                    <GradientStop Color="{StaticResource ControlBackground}" Offset="0"/>
                                </LinearGradientBrush>
                            </Setter.Value>
                        </Setter>
                    </Trigger>
                </ControlTemplate.Triggers>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>
<Style x:Key="ScrollBarPageButton" TargetType="{x:Type RepeatButton}">
    <Setter Property="SnapsToDevicePixels" Value="True"/>
    <Setter Property="Foreground" Value="#FF585858"/>
    <Setter Property="FontFamily" Value="Segoe UI Semibold"/>
    <Setter Property="FontSize" Value="14"/>
    <Setter Property="Padding" Value="8"/>
    <Setter Property="Focusable" Value="False"/>
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type RepeatButton}">
                <Border/>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

但是当我用<Thumb/>替换<Thumb Style="{StaticResource HorizontalScrollBarThumb}"/>和<Thumb Style="{StaticResource VerticalScrollBarThumb}"/>时，它就能工作了。

我只是在拇指样式中找不到任何可能导致这个问题的东西。

谢谢你的帮助。

Answer 1

这是因为模板的顺序。只需更改模板的顺序，如下图所示。在XAML中引用StaticResources之前，应该先对其进行解析。

​

​

此外，上面粘贴的XAML代码还缺少一些笔刷资源，如AccentLight、ControlBackgroundBrush。我不知道在您的应用程序中定义的这些资源是否具有正确的层次结构。也检查一下这个。