WPF Grid行高自适应问题：折叠StackPanel时动态分配高度

你的核心问题在于，原来的RowDefinition用固定的*分配高度，即使对应的StackPanel设为Collapsed，该行依然会占据分配的空间，导致剩余行无法自动均分。下面给你两种可行的实现方案：

方案一：使用值转换器（推荐，扩展性强） #

这种方式通过绑定StackPanel的可见性，动态调整对应RowDefinition的高度：

1. 创建值转换器 #

首先在项目中添加一个实现IValueConverter的类，用来把Visibility转换为对应的GridLength：

using System;
using System.Globalization;
using System.Windows;
using System.Windows.Data;

namespace YourNamespace
{
    public class VisibilityToStarGridLengthConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            if (value is Visibility visibility)
            {
                // 可见时占1份星号空间，折叠时占0高度
                return visibility == Visibility.Visible 
                    ? new GridLength(1, GridUnitType.Star) 
                    : new GridLength(0);
            }
            // 默认返回1*
            return new GridLength(1, GridUnitType.Star);
        }

        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            throw new NotImplementedException("反向转换不需要实现");
        }
    }
}

2. 修改XAML代码 #

在Grid中引用转换器，并绑定每个RowDefinition的Height到对应StackPanel的Visibility：

<Grid>
    <Grid.Resources>
        <!-- 替换成你的项目命名空间 -->
        <local:VisibilityToStarGridLengthConverter x:Key="VisToStarConverter"/>
    </Grid.Resources>
    <Grid.RowDefinitions>
        <RowDefinition Height="{Binding ElementName=panel1, Path=Visibility, Converter={StaticResource VisToStarConverter}}" />
        <RowDefinition Height="{Binding ElementName=panel2, Path=Visibility, Converter={StaticResource VisToStarConverter}}" />
        <RowDefinition Height="{Binding ElementName=panel3, Path=Visibility, Converter={StaticResource VisToStarConverter}}" />
    </Grid.RowDefinitions>
    <StackPanel x:Name="panel1" Grid.Row="0" Visibility="Visible">
        <TextBlock x:Name="txt1" Text="FIRST ROW" />
    </StackPanel>
    <StackPanel x:Name="panel2" Grid.Row="1" Visibility="Visible">
        <TextBlock x:Name="txt2" Text="SECOND ROW" />
    </StackPanel>
    <StackPanel x:Name="panel3" Grid.Row="2" Visibility="Visible">
        <TextBlock x:Name="txt3" Text="THIRD ROW" />
    </StackPanel>
</Grid>

原理：每个行的高度会随对应面板的可见性动态变化——可见时参与星号分配，折叠时占用0高度，Grid会自动将剩余空间均分给所有可见的行，完全符合你的需求。

方案二：纯XAML触发器（无需C#代码） #

如果不想写后台代码，可以用DataTrigger来实现同样的效果：

<Grid>
    <Grid.RowDefinitions>
        <RowDefinition x:Name="row1" Height="*"/>
        <RowDefinition x:Name="row2" Height="*"/>
        <RowDefinition x:Name="row3" Height="*"/>
    </Grid.RowDefinitions>
    <StackPanel x:Name="panel1" Grid.Row="0" Visibility="Visible">
        <TextBlock x:Name="txt1" Text="FIRST ROW" />
    </StackPanel>
    <StackPanel x:Name="panel2" Grid.Row="1" Visibility="Visible">
        <TextBlock x:Name="txt2" Text="SECOND ROW" />
    </StackPanel>
    <StackPanel x:Name="panel3" Grid.Row="2" Visibility="Visible">
        <TextBlock x:Name="txt3" Text="THIRD ROW" />
    </StackPanel>

    <Grid.Triggers>
        <!-- 折叠时将对应行高度设为0 -->
        <DataTrigger Binding="{Binding ElementName=panel1, Path=Visibility}" Value="Collapsed">
            <Setter TargetName="row1" Property="Height" Value="0"/>
        </DataTrigger>
        <DataTrigger Binding="{Binding ElementName=panel2, Path=Visibility}" Value="Collapsed">
            <Setter TargetName="row2" Property="Height" Value="0"/>
        </DataTrigger>
        <DataTrigger Binding="{Binding ElementName=panel3, Path=Visibility}" Value="Collapsed">
            <Setter TargetName="row3" Property="Height" Value="0"/>
        </DataTrigger>
        <!-- 恢复可见时重置为星号分配 -->
        <DataTrigger Binding="{Binding ElementName=panel1, Path=Visibility}" Value="Visible">
            <Setter TargetName="row1" Property="Height" Value="*"/>
        </DataTrigger>
        <DataTrigger Binding="{Binding ElementName=panel2, Path=Visibility}" Value="Visible">
            <Setter TargetName="row2" Property="Height" Value="*"/>
        </DataTrigger>
        <DataTrigger Binding="{Binding ElementName=panel3, Path=Visibility}" Value="Visible">
            <Setter TargetName="row3" Property="Height" Value="*"/>
        </DataTrigger>
    </Grid.Triggers>
</Grid>

原理：通过触发器监听每个StackPanel的可见性变化，动态修改对应行的高度，效果和方案一完全一致，适合简单场景快速实现。

内容的提问来源于stack exchange，提问作者Cleve