如何在WPF Viewbox中保持恒定的FontSize? [英] How do I keep a constant FontSize in WPF Viewbox?

问题描述

我有一个Viewbox，其中有许多TextBlock，它们由ViewBox完美缩放和定位.像这样:

I have a Viewbox with a number of TextBlocks that are scaled and positioned perfectly by the ViewBox. Something like this:

<Viewbox Stretch="Uniform">
    <Canvas Width="100" Height="100">
        <Ellipse Width="100" Height="100" Stroke="Black"/>
        <TextBlock Width="100" TextAlignment="Center" FontSize="12">Top Center</TextBlock>
    </Canvas>
</Viewbox>

如果用户调整Viewbox的大小，则其内容将完美缩放以匹配.但是，无论Viewbox的实际大小如何，我都希望将FontSize保持为12.

If the user resizes the Viewbox its contents are perfectly scaled to match. However I would like to keep the FontSize to 12 regardless of the actual size of the Viewbox.

我该怎么做?我可以在XAML中执行此操作而不附加到Resize事件吗?

How can I do this? Can I do this in XAML without attaching to an Resize event?

推荐答案

ViewBox不允许您保持恒定的字体大小，这不是它的工作原理.您需要将文本放在视图框外才能实现:

ViewBox won't allow you to keep a constant font size, that's just not how it works. You need to put the text outside the view box for that to happen:

<Grid>
    <Viewbox Stretch="Uniform">
        <Canvas Width="100" Height="100">
            <Ellipse Width="100" Height="100" Stroke="Black"/>
        </Canvas>
    </Viewbox>
    <TextBlock TextAlignment="Center" FontSize="12">Top Center</TextBlock>
</Grid>

请注意，我从TextBlock中删除了Width属性，只是让它沿网格的宽度伸展，让文本对齐方式保持居中.

Note that I removed the Width property from the TextBlock, I just let it stretch for the width of the grid, letting the text alignment take care of the centering.

或者，您可以发挥创意并将FontSize属性绑定到ViewBox的ActualWidth并对其进行适当缩放，例如:

Or, you could get creative and bind the FontSize property to the ActualWidth of the ViewBox and having it scaled appropriately, for example:

转换器:

class ViewBoxConstantFontSizeConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        if (!(value is double)) return null;
        double d = (double)value;
        return 100 / d * 12;
    }

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

用法:

<Window.Resources>
    ...
    <local:ViewBoxConstantFontSizeConverter x:Key="conv"/>
</Window.Resources>
...
<Viewbox Name="vb" Stretch="Uniform">
    <Canvas Width="100" Height="100">
        <Ellipse Width="100" Height="100" Stroke="Black"/>
        <TextBlock Width="100" TextAlignment="Center"
                   FontSize="{Binding ElementName=vb, 
                                      Path=ActualWidth, 
                                      Converter={StaticResource conv}}">
            Top Center
        </TextBlock>
    </Canvas>
</Viewbox>

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