在WPF中限制"自动"和"1*"的行高

Question

我有一个WPF应用程序,其布局由顶层的3行组成Grid.

我希望中间行占用它所需的空间(它需要的最大空间是有限的,但取决于窗口的宽度).底行应占用剩余空间.棘手的部分是顶行.它的大小可以根据按钮切换大部分内容的可见性而变化.我希望它最多使用50%的高度但不超过它真正需要的高度.以下XAML描述了我想要完成的任务:

    <Grid.RowDefinitions>
        <!-- neither "1*" nor "Auto" fully meets my needs -->
        <RowDefinition Height="Min(1*,Auto)"></RowDefinition>

        <RowDefinition Height="Auto"></RowDefinition>

        <RowDefinition Height="1*"></RowDefinition>
    </Grid.RowDefinitions>

行是:

1. WrapPanel
2. WrapPanel
3. TextBox

如果这很重要

Answer 1

如果我的理解对不对,你很可能Auto再绑定MaxHeight属性到Height的Grid.也许是这样的:

MaxHeightConverter.cs:

public class MaxHeightConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        if (value == null)
            throw new ArgumentException("MaxHeightConverter expects a height value", "values");

        return ((double)value / 2);
    }

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

MyWindow.xaml:

...
xmlns:converters="clr-namespace:MyApp.Namespace"
...
<Window.Resources>
    <converters:MaxHeightConverter x:Key="MaxHeightValue" />
</Window.Resources>

<Grid x:Name="root">
    <Grid.RowDefinitions>
        <RowDefinition Height="Auto"></RowDefinition>
        <RowDefinition Height="Auto"></RowDefinition>
        <RowDefinition Height="1*"></RowDefinition>
    </Grid.RowDefinitions>

    <WrapPanel >
        <WrapPanel.MaxHeight>
            <Binding Converter="{StaticResource MaxHeightValue}" ElementName="root" Path="ActualHeight" />
        </WrapPanel.MaxHeight>
    </WrapPanel>
</Grid>
...

希望这可以帮助.

Answer 2

另一种只使用XAML可以实现此目的的方法是绑定到您想要的高度的隐藏对象:

<Grid>
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="1*" />
            <RowDefinition Height="1*" />
        </Grid.RowDefinitions>
        <Border Background="White" Visibility="Hidden" x:Name="HalfHeightRow" x:FieldModifier="private" />
    </Grid>
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto" />
            <RowDefinition Height="Auto" />
            <RowDefinition Height="*" />
        </Grid.RowDefinitions>

        <Border Height="1000" Background="Red" MaxHeight="{Binding ActualHeight, ElementName=HalfHeightRow}" />
        <Border Grid.Row="1" Height="100" Background="Green" />
        <Border Grid.Row="2" Background="Blue" />
    </Grid>