根据项目的数量，列表框的滚动查看器是可见的

Question

我有一个 ListBox，其中定义了 DataTemplate。 ListBox 的 ItemSource (ListBoxItem) 通过 ViewModel 提供。

我希望在项目数超过 5 时显示 ListBox 的滚动查看器。如果有人能帮助我，我将很高兴。

这是我的部分代码：

<ListBox  VerticalAlignment="Stretch" Grid.Column="0"   
                    ItemsSource="{Binding Path=Parts, Mode=OneWay}" SelectedIndex="{Binding CurrentPartIndex}"                       
                    Height="115" BorderThickness="1" BorderBrush="{DynamicResource {x:Static SystemColors.WindowTextBrush}}">                   
    <ListBox.ItemTemplate>
        <DataTemplate>
            <StackPanel Orientation="Horizontal" >
                <Label Grid.Column="0" Content="{Binding CurrentLabel, Mode=OneWay}" MinWidth="150" Width="auto" VerticalAlignment="Stretch"/>
                <Label Grid.Column="1" Content="{Binding ItemNumber, Mode=OneWay}" MinWidth="50" VerticalAlignment="Stretch"/>
                <Label Grid.Column="2" Content="{Binding Cut, Mode=OneWay}" MinWidth="50" VerticalAlignment="Stretch"/>
                <Label Grid.Column="3" Content="{Binding Material, Mode=OneWay}" MinWidth="100" VerticalAlignment="Stretch"/>                           
            </StackPanel>
        </DataTemplate>
    </ListBox.ItemTemplate>
</ListBox>

Answer 1

使用值转换器，以便 ListBox 中的项目数控制 ScrollViewer 的可见性。

转换器：

public class CountToVisibility : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        if ((int)value > 5)
            return ScrollBarVisibility.Visible;
        else
            return ScrollBarVisibility.Hidden;
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}

xaml:

<Window.Resources>
    <local:CountToVisibility x:Key="ctv"/>
</Window.Resources>

...

<ListBox  VerticalAlignment="Stretch" Grid.Column="0"   
                ItemsSource="{Binding Path=Parts, Mode=OneWay}" SelectedIndex="{Binding CurrentPartIndex}"                       
                Height="115" BorderThickness="1" BorderBrush="{DynamicResource {x:Static SystemColors.WindowTextBrush}}"
ScrollViewer.HorizontalScrollBarVisibility="{Binding Path=Parts.Count,Converter={StaticResource ctv}}">                   
<ListBox.ItemTemplate>
    <DataTemplate>
        <StackPanel Orientation="Horizontal" >
            <Label Grid.Column="0" Content="{Binding CurrentLabel, Mode=OneWay}" MinWidth="150" Width="auto" VerticalAlignment="Stretch"/>
            <Label Grid.Column="1" Content="{Binding ItemNumber, Mode=OneWay}" MinWidth="50" VerticalAlignment="Stretch"/>
            <Label Grid.Column="2" Content="{Binding Cut, Mode=OneWay}" MinWidth="50" VerticalAlignment="Stretch"/>
            <Label Grid.Column="3" Content="{Binding Material, Mode=OneWay}" MinWidth="100" VerticalAlignment="Stretch"/>                           
        </StackPanel>
    </DataTemplate>
</ListBox.ItemTemplate>

根据项目的数量，列表框的滚动查看器是可见的

Scrollviewer of a ListBox is Visible according to the count of Items

c#

wpf

xaml

listbox

mvvm