c#-当DataGrid嵌套在分组的DataGrid中时,相对列宽不起作用

2022-09-30 12:04:03

假设我有一个具有6个属性的对象：

public class MyClass
{
    public string Attribute1 { get; set; }
    public string Attribute2 { get; set; }
    public string Attribute3 { get; set; }
    public string Attribute4 { get; set; }
    public string Attribute5 { get; set; }
    public string Attribute6 { get; set; }
}

我在DataGrid中显示这些对象的集合：

<Grid>
    <DataGrid x:Name="myGrid" Margin="5, 5, 5, 5" AutoGenerateColumns="False" CanUserAddRows="False" IsReadOnly="True">
        <DataGrid.GroupStyle>
            <GroupStyle ContainerStyle="{StaticResource GroupHeaderStyle}">
                <GroupStyle.Panel>
                    <ItemsPanelTemplate>
                        <DataGridRowsPresenter/>
                    </ItemsPanelTemplate>
                </GroupStyle.Panel>
            </GroupStyle>
        </DataGrid.GroupStyle>
        <DataGrid.Columns>
            <DataGridTextColumn Header="Attribute1" Binding="{Binding Attribute1}" Width="5*"/>
            <DataGridTextColumn Header="Attribute2" Binding="{Binding Attribute2}" Width="5*"/>
            <DataGridTextColumn Header="Attribute3" Binding="{Binding Attribute3}" Width="10*"/>
        </DataGrid.Columns>
    </DataGrid>
</Grid>

我这样填充网格,按“ Attribute1”分组…

    public MainWindow()
    {
        InitializeComponent();

        ObservableCollection<MyClass> data = new ObservableCollection<MyClass>();
        data.Add(new MyClass { Attribute1 = "Red", Attribute4 = "Circle", Attribute5 = "Large", Attribute6 = "Transparent" });
        data.Add(new MyClass { Attribute1 = "Red", Attribute4 = "Square", Attribute5 = "Medium", Attribute6 = "Opaque" });
        data.Add(new MyClass { Attribute1 = "Red", Attribute4 = "Triangle", Attribute5 = "Large", Attribute6 = "Opaque" });
        data.Add(new MyClass { Attribute1 = "Yellow", Attribute4 = "Square", Attribute5 = "Large", Attribute6 = "Transparent" });
        data.Add(new MyClass { Attribute1 = "Blue", Attribute4 = "Triangle", Attribute5 = "Small", Attribute6 = "Transparent" });
        data.Add(new MyClass { Attribute1 = "Blue", Attribute4 = "Sphere", Attribute5 = "Small", Attribute6 = "Opaque" });


        ListCollectionView lcv = new ListCollectionView(data);
        lcv.GroupDescriptions.Add(new PropertyGroupDescription("Attribute1"));
        myGrid.ItemsSource = lcv;

    }

我设置GroupItems的样式以在扩展器中显示嵌套的DataGrid：

<Window.Resources>
    <Style x:Key="GroupHeaderStyle" TargetType="{x:Type GroupItem}">
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type GroupItem}">
                    <Expander x:Name="exp" IsExpanded="True" Foreground="Black">
                        <Expander.Header>
                                <TextBlock Foreground="Black" Text="{Binding Name}"/>
                        </Expander.Header>
                        <DockPanel>
                            <DataGrid ItemsSource="{Binding Items}" x:Name="subGrid" AutoGenerateColumns="False" IsReadOnly="True" CanUserAddRows="False">
                                <DataGrid.Columns>
                                    <DataGridTextColumn Header="Attribute 4" Binding="{Binding Attribute4}" Width="Auto"/>
                                    <DataGridTextColumn Header="Attribute 5" Binding="{Binding Attribute5}" Width="Auto"/>
                                    <DataGridTextColumn Header="Attribute 6" Binding="{Binding Attribute6}" Width="Auto"/>
                                </DataGrid.Columns>
                            </DataGrid>
                        </DockPanel>
                    </Expander>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
</Window.Resources>

将我嵌套的DataGrid列的宽度设置为“自动” …,效果很好：

问题是当我尝试使用相对宽度时…

<DataGrid ItemsSource="{Binding Items}" x:Name="subGrid" AutoGenerateColumns="False" IsReadOnly="True" CanUserAddRows="False">
    <DataGrid.Columns>
        <DataGridTextColumn Header="Attribute 4" Binding="{Binding Attribute4}" Width="1*"/>
        <DataGridTextColumn Header="Attribute 5" Binding="{Binding Attribute5}" Width="1*"/>
        <DataGridTextColumn Header="Attribute 6" Binding="{Binding Attribute6}" Width="2*"/>
    </DataGrid.Columns>
</DataGrid>

现在看起来像这样…

列不仅非常瘦,而且不能像往常一样使用鼠标来调整它们的大小.

这个问题确实让我感到困惑.我已经搜索过SO,并尝试了一些与运气相关的问题.

如何设置嵌套DataGrid上的列以使用相对宽度？

解决方法:

我认为问题在于WPF不知道DockPanel的宽度如何,因此您会得到那些瘦小的列.

一种解决方案是将DockPanel(或DataGrid)的宽度设置为固定宽度,例如500像素.

另一个解决方案是将DataGrid的宽度绑定到DockPanel的ActualWidth.这可以工作,但是DataGrid只会增大大小,而当窗口变小时不会缩小.

<DataGrid ItemsSource="{Binding Items}" 
          x:Name="subGrid" 
          AutoGenerateColumns="False" 
          IsReadOnly="True" 
          CanUserAddRows="False" 
          Width="{Binding 
                  RelativeSource={RelativeSource AncestorType=DockPanel}, Path=ActualWidth}">

另一个解决方案是将DockPanel的宽度绑定到Expander的ActualWidth.问题是它不能正常工作… Expander变大,因为DockPanel变大,我们陷入了循环.我们真正想要的是扩展器的ActualWidth减去足以不使扩展器增加其宽度的值.我尝试了一下,“ ActualWidth-3”似乎有效(但是idk为什么3 …).如果添加填充或边距,则可能需要更改这3个.为了使它成为一个绑定,我们需要一个IValueConverter.

public class ActualWidthConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        if (value is double)
            return (double)value - 3;
        return value;
    }
    public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}

您需要将转换器添加为资源(应用程序或窗口或其他)：

<Window ....
    xmlns:app="clr-namespace:WpfApplication25">
<Window.Resources>
    <app:ActualWidthConverter x:Key="ActualWidthConverter" />
</Window.Resources>

而且,当然,您需要将绑定应用于DockPanel的Width：

<DockPanel Width="{Binding RelativeSource={RelativeSource AncestorType=Expander}, Path=ActualWidth, Converter={StaticResource ActualWidthConverter}}">

这不是一个完美的解决方案,但也许会有所帮助？此方法的替代版本可以使用MultiBinding.传递扩展器的ActualWidth和DockPanel的Margin：ActualWidth-Margin.Left-Margin.Right-3(我仍然想知道为什么3？在其他人的计算机上也将是3).

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