如何让WPF中不同自定义控件的Label与Value列尺寸统一？

当前自定义控件LabelTexUserControl的Label和Value列无法跨控件对齐，核心原因是每个UserControl内部的Grid单独设置了IsSharedSizeScope="True"，导致SharedSizeGroup仅在当前控件内部生效，无法与其他控件共享尺寸。

解决方案 #

1. 移除自定义控件内部Grid的IsSharedSizeScope属性，让父容器的SharedSizeScope全局生效
2. 确保所有控件的列使用相同的SharedSizeGroup名称
3. 保持父容器（MainWindow的Grid）的IsSharedSizeScope="True"

修改后的LabelTexUserControl XAML #

<UserControl x:Class="LabelDoubleTextBox.LabelTexUserControl"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             xmlns:local="clr-namespace:LabelDoubleTextBox"
             mc:Ignorable="d" 
             d:DesignHeight="450" d:DesignWidth="800">
    <!-- 移除内部Grid的IsSharedSizeScope="True" -->
    <Grid>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="Auto" SharedSizeGroup="LabelColumn"/>
            <ColumnDefinition Width="Auto" SharedSizeGroup="ValueColumn"/>
        </Grid.ColumnDefinitions>
        <Label Grid.Column="0" Content="{Binding Label,RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type local:LabelTexUserControl}}}"  Margin="5"/>
        <Label Grid.Column="1" Content="{Binding Value,RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type local:LabelTexUserControl}}}" Margin="5" />
    </Grid>
</UserControl>

LabelTexUserControl后台代码（无需修改） #

public partial class LabelTexUserControl : UserControl
{
    public LabelTexUserControl()
    {
        InitializeComponent();
    }

    public static readonly DependencyProperty LabelProperty = DependencyProperty.Register(
        nameof(Label), typeof(string), typeof(LabelTexUserControl), new PropertyMetadata(default(string)));

    public string Label
    {
        get { return (string)GetValue(LabelProperty); }
        set { SetValue(LabelProperty, value); }
    }

    public static readonly DependencyProperty ValueProperty = DependencyProperty.Register(
        nameof(Value), typeof(string), typeof(LabelTexUserControl), new PropertyMetadata(default(string)));

    public string Value
    {
        get { return (string)GetValue(ValueProperty); }
        set { SetValue(ValueProperty, value); }
    }
}

MainWindow XAML（无需修改，已正确配置） #

<Window.DataContext>
    <local:MainWindowVM/>
</Window.DataContext>
<Grid IsSharedSizeScope="True">
    <Grid.RowDefinitions>
        <RowDefinition Height="Auto"/>
        <RowDefinition Height="Auto"/>
    </Grid.RowDefinitions>
    <local:LabelTexUserControl Grid.Row="0" Label="My Label" Value="{Binding VMValue}"/>
    <local:LabelTexUserControl Grid.Row="1" Label="Warning...... but I am just super loooong... lalala" Value="{Binding Terrify}"/>
</Grid>

MainWindowVM代码（无需修改） #

public class MainWindowVM
{
    public string VMValue => "This is a value";
    public string Terrify => "Dont be terrify";
}

原理说明 #

IsSharedSizeScope的作用范围是当前容器及其直接/间接子元素。之前在每个UserControl内部的Grid开启该属性，导致每个控件的SharedSizeGroup仅在自身内部生效。将IsSharedSizeScope移到父容器（MainWindow的Grid）后，所有子控件的SharedSizeGroup会在整个父容器范围内共享尺寸：Label列会自动调整为所有Label中的最大宽度，Value列同理，实现全局对齐效果。

内容的提问来源于stack exchange，提问作者Graviton