设置WPF控件以展开以填充可用空间，仅此而已 [英] Setting a WPF control to expand to fill available space, and no more

问题描述

如何设置WPF控件以填充其父级容器中的可用空间，而不扩展父级容器?

How can I set up a WPF control to fill the available space in its parent's container, but not expand the parent?

以下代码段描述了我正在尝试的布局.我希望Grid能够扩展以容纳Expander，并且我希望ListBox仅填充Grid.我希望当Grid太小而无法显示所有ListBoxItem时，出现ListBox的滚动条.

The following snippet describes the layout I am attempting. I would like the Grid to stretch to accommodate the Expander, and I would like the ListBox only to fill the Grid. I want the ListBox's scroll bar to appear when the Grid is too small to show all the ListBoxItems.

<ScrollViewer>
    <Grid>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="Auto" />
            <ColumnDefinition />
        </Grid.ColumnDefinitions>
        <Grid.RowDefinitions>
            <RowDefinition />
        </Grid.RowDefinitions>
        <ListBox Grid.Row="0" Grid.Column="0" />
        <Expander Grid.Row="0" Grid.Column="1" Header="Expander" />
    </Grid>
</ScrollViewer>

当前发生的情况是Grid拉伸以适合整个ListBox，并且出现外部ScrollViewer的垂直滚动条.我只希望在Expander太大而无法在屏幕上显示时显示外部滚动条.

Currently what happens is that the Grid stretches to fit the entire ListBox, and the outer ScrollViewer's vertical scroll bar appears. I only want the outer scroll bar to appear when the Expander gets too big to fit on screen.

推荐答案

为解决相同的问题，我编写了特殊的容器类:

To solve the same problem I wrote special container class:

class FrugalContainer : Decorator
{
    protected override Size MeasureOverride(Size availableSize)
    {
        return new Size(0, 0);
    }

    protected override Size ArrangeOverride(Size arrangeSize)
    {
        // get it all
        Child.Measure(arrangeSize);
        Child.Arrange(new Rect(arrangeSize));
        return Child.RenderSize;
    }
}

用容器围绕ListBox，ListBox的高度与Expander的高度相同.

Surround your ListBox by the container and the height of ListBox will be the same as of Expander.

<Grid>
    <Grid.ColumnDefinitions>
        <ColumnDefinition />
        <ColumnDefinition />
    </Grid.ColumnDefinitions>
    <Grid.RowDefinitions>
        <RowDefinition />
    </Grid.RowDefinitions>
    <FrugalContainer Grid.Row="0" Grid.Column="0" >
        <ListBox />
    </FrugalContainer>
    <Expander Grid.Row="0" Grid.Column="1" Header="Expander" />
</Grid>

请注意，我从列的定义中删除了Width="Auto"，因为FrugalContainer会尽可能小.因此，您不能将父网格的单元格的宽度或高度设置为自动".

Note that I remove Width="Auto" from column's definition because the FrugalContainer will be as small as it can. So you can't set the width or height of the parent grid's cell to Auto.

如果需要自动调整大小，请重写容器:

If you need autosizing, rewrite the container:

class FrugalHeightContainer : Decorator
{
    protected override Size MeasureOverride(Size availableSize)
    {
        Child.Measure(availableSize);
        return new Size(Child.DesiredSize.Width, 0);
    }

    protected override Size ArrangeOverride(Size arrangeSize)
    {
        Child.Measure(arrangeSize);
        Child.Arrange(new Rect(arrangeSize));
        return Child.RenderSize;
    }
}

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