如何基于索引更改ItemScontrol中的数据模板

Question

我正在尝试为多项式函数创建动态UI。由于我不知道该顺序，所以我想动态创建它。

我将系数列表设置为项目控制的项目，并计划根据索引更改数据模板。

模板应像这样工作

if (index > 1)
{
  (coefficient text box) + *x ^ (index) + //Polynomial2
}
 else if (index == 1)
 {
  (coefficient text box) + *x +  //Polynomial 1
 }
 else if (index == 0)
{
  (coefficient text box)  //Polynomial
}

最后，我应该看到类似此样本输出的东西

 <DataTemplate x:Key="PolynomialEquationTemplate" >
        <StackPanel Orientation="Horizontal">
            <Label Content="y=" Width="50"></Label>
            <ItemsControl ItemsSource="{Binding DataContext.CoeffList, RelativeSource={RelativeSource Mode=FindAncestor,  AncestorType={x:Type Window}}}" AlternationCount="100" >
                <ItemsControl.ItemTemplate>
                    <DataTemplate>
                        <ContentControl Content={Binding .}>
                            <ContentControl.Style>
                                <Style TargetType="ContentControl">
                                    <Style.Triggers>
                                        <DataTrigger Binding="{Binding Path=(ItemsControl.AlternationIndex), 
                RelativeSource={RelativeSource TemplatedParent} }" Value="1">
                                            <Setter Property="ContentTemplate"
                                    Value="{StaticResource Polynomial1}" />
                                        </DataTrigger>
                                        <DataTrigger Binding="{Binding Path=(ItemsControl.AlternationIndex), 
                RelativeSource={RelativeSource TemplatedParent}}" Value="0">
                                            <Setter Property="ContentTemplate"
                                    Value="{StaticResource Polynomial0}" />
                                        </DataTrigger>
                                        <DataTrigger Binding="{Binding Path=(ItemsControl.AlternationIndex), 
                RelativeSource={RelativeSource TemplatedParent}, Converter={StaticResource BooleanToVisibility}}" Value="True">
                                            <Setter Property="ContentTemplate"
                                    Value="{StaticResource Polynomial2}" />
                                        </DataTrigger>
                                    </Style.Triggers>
                                </Style>
                            </ContentControl.Style>
                        </ContentControl>
                    </DataTemplate>
                </ItemsControl.ItemTemplate>
            </ItemsControl>
        </StackPanel>
    </DataTemplate>

    <DataTemplate x:Key="Polynomial2" >
        <StackPanel Orientation="Horizontal">
            <TextBox Text="{Binding ., RelativeSource={RelativeSource Mode=FindAncestor,  AncestorType={x:Type ItemsControl}}}"></TextBox>
            <Label Content=")*x^"></Label>
            <Label Content="{Binding Path=(ItemsControl.AlternationIndex), 
                RelativeSource={RelativeSource Mode=FindAncestor,  AncestorType={x:Type ItemsControl}}}"></Label>
            <Label Content="+"></Label>
        </StackPanel>
    </DataTemplate>
    <DataTemplate x:Key="Polynomial0" >
        <StackPanel Orientation="Horizontal">
            <TextBox Text="{Binding .,  RelativeSource={RelativeSource Mode=FindAncestor,  AncestorType={x:Type ItemsControl}}}"></TextBox>
          </StackPanel>
    </DataTemplate>
    <DataTemplate x:Key="Polynomial1" >
        <StackPanel Orientation="Horizontal">
            <TextBox Text="{Binding ., RelativeSource={RelativeSource Mode=FindAncestor,  AncestorType={x:Type ItemsControl}}}"></TextBox>
            <Label Content=")*x"></Label>
            <Label Content="+"></Label>
        </StackPanel>
    </DataTemplate>

系数是双重列表(系数值(。

我认为我对绑定有问题，我得到了" system.windows.markup.xamlparseexception;无法将类型的对象施放为'mseternal.internal.nemedobject'type'system.windows.datatemplate的对象。错误

Answer 1

您可以在itemContainerStyle中使用普通触发器和默认的ContentTemplate：

<ItemsControl AlternationCount="100" ItemsSource="{Binding ...}">
    <ItemsControl.ItemContainerStyle>
        <Style TargetType="ContentPresenter">
            <!-- default for any index >= 2 -->
            <Setter Property="ContentTemplate"
                    Value="{StaticResource Polynomial2}"/>
            <Style.Triggers>
                <Trigger Property="ItemsControl.AlternationIndex" Value="0">
                    <Setter Property="ContentTemplate"
                            Value="{StaticResource Polynomial0}"/>
                </Trigger>
                <Trigger Property="ItemsControl.AlternationIndex" Value="1">
                    <Setter Property="ContentTemplate"
                            Value="{StaticResource Polynomial1}"/>
                </Trigger>
            </Style.Triggers>
        </Style>
    </ItemsControl.ItemContainerStyle>
</ItemsControl>