根据索引更改 ListBoxItem 的颜色

Question

我正在尝试根据索引值更改 ListBox 中其中一项的前景（文本）颜色。例如，如果索引为 1，则索引 1 处的项目将具有与所有其他项目不同的文本颜色。索引不是列表选择索引，而是我自己的值。

我在 Google 上四处搜索，发现了一些使用 AlternationIndex 的想法，但我无法让它发挥作用。转换器正在接收 0（零）或 DependencyProperty#Unset 用于 AlternationIndex 绑定。

这是我的代码：

<ListBox x:Name="videoList" SelectionMode="Single" AlternationCount="{Binding Mode=OneWay, Path=Items.Count}" Grid.Column="1" SelectionChanged="videoList_SelectionChanged">
    <ListBox.ItemContainerStyle>
        <Style TargetType="{x:Type ListBoxItem}">
            <Style.Triggers>
                <DataTrigger Value="True">
                    <DataTrigger.Binding>
                        <MultiBinding Mode="OneWay" Converter="{StaticResource EqualityConverter}">
                            <MultiBinding.Bindings>
                                <Binding ElementName="videoWindow" Mode="OneWay" Path="VideoIndex" />
                                <Binding RelativeSource="{RelativeSource AncestorType=ListBoxItem}" Path="(ItemsControl.AlternationIndex)" />
                            </MultiBinding.Bindings>
                        </MultiBinding>
                    </DataTrigger.Binding>
                    <DataTrigger.Setters>
                        <Setter Property="Foreground" Value="Blue" />
                    </DataTrigger.Setters>
                </DataTrigger>
            </Style.Triggers>
        </Style>
    </ListBox.ItemContainerStyle>
</ListBox>

对于我尝试过的 RelativeSource：Self、TemplatedParent 和 AncestorType=ListBoxItem。我还尝试了很多不同的路径值组合。

我无法让它工作。有什么建议吗？

解决方案：在Clemens的帮助下，原来是因为ListBox AlternationCount的绑定不正确。糟糕！

<ListBox x:Name="videoList" 
         SelectionMode="Single" 
         AlternationCount="{Binding RelativeSource={RelativeSource Self}, Mode=OneWay, Path=Items.Count}" 
         Grid.Column="1" 
         SelectionChanged="videoList_SelectionChanged">
    <ListBox.ItemContainerStyle>
        <Style TargetType="{x:Type ListBoxItem}">
            <Style.Triggers>
                <DataTrigger Value="True">
                    <DataTrigger.Binding>
                        <MultiBinding Mode="OneWay" Converter="{StaticResource EqualityConverter}">
                            <MultiBinding.Bindings>
                                <Binding ElementName="videoWindow" Mode="OneWay" Path="VideoIndex" />
                                <Binding RelativeSource="{RelativeSource Self}" Path="(ItemsControl.AlternationIndex)" />
                            </MultiBinding.Bindings>
                        </MultiBinding>
                    </DataTrigger.Binding>
                    <Setter Property="Foreground" Value="Blue" />
                </DataTrigger>
            </Style.Triggers>
        </Style>
    </ListBox.ItemContainerStyle>
</ListBox>

Answer 1

它适用于 RelativeSource Self 和足够大的 AlternationCount，例如int.MaxValue.

<ListBox AlternationCount="2147483647" ...>
    <ListBox.ItemContainerStyle>
        <Style TargetType="{x:Type ListBoxItem}">
            <Style.Triggers>
                <DataTrigger Value="True">
                    <DataTrigger.Binding>
                        <MultiBinding Converter="{StaticResource EqualityConverter}">
                            <MultiBinding.Bindings>
                                <Binding ElementName="videoWindow"
                                         Path="VideoIndex"/>
                                <Binding RelativeSource="{RelativeSource Self}"
                                         Path="(ItemsControl.AlternationIndex)"/>
                            </MultiBinding.Bindings>
                        </MultiBinding>
                    </DataTrigger.Binding>
                    <DataTrigger.Setters>
                        <Setter Property="Foreground" Value="Blue"/>
                    </DataTrigger.Setters>
                </DataTrigger>
            </Style.Triggers>
        </Style>
    </ListBox.ItemContainerStyle>
</ListBox>

根据索引更改 ListBoxItem 的颜色

Changing color of ListBoxItem based on index

wpf

indexing

listbox

listboxitem