Why does my StringFormat not work in WPF [duplicate]

Question

I've seen a few questions like this on SO but none of the answers work for me! Here's my abridged code:

<Grid Margin="10,4,2,3">

    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="*" />
        <ColumnDefinition Width="150" />
    </Grid.ColumnDefinitions>

    <Image Name="myImage" />

    <WrapPanel Orientation="Vertical" Grid.Column="1" >
        <Label x:Name="labelDimensions" Content="Image Dimensions" />
        <Grid>
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="3*" />
                <ColumnDefinition Width="1*" />
                <ColumnDefinition Width="3*" />
            </Grid.ColumnDefinitions>

            <Label Grid.Column="0" 
                   x:Name="imageWidth" 
                   Content="{Binding Path=ActualWidth, 
                             ElementName=myImage, 
                             StringFormat={}{0:1234.5}}" />
            <Label Grid.Column="1" x:Name="label3" Content=" x " />
            <Label Grid.Column="2" 
                   x:Name="imageHeight" 
                   Content="{Binding Path=ActualHeight, 
                             ElementName=myImage, 
                             StringFormat={}{0:1234.5}}" />
        </Grid>
    </WrapPanel>

</Grid>

I am expecting to see, below the 'Image Dimensions' label, something like "641.3 x 480.0" but no matter what I do, it comes out with stuff like "641.30000000 x 480".

I've formats like {0:1234.5} and {0:#,#.#} but nether have any effect. I've also tried ConentStringFormat as one SO answer suggested but that didn't even compile.

Any advice would be hugely appreciated.

Answer 1

Use the ContentStringFormat instead.

StringFormat is only used when binding to a property of type String. The Content property of Label is of type object as you can see here, so StringFormat will not work.

Answer 2

Try giving StringFormat={}{0:F1} :

<Label Grid.Column="0" 
       x:Name="imageWidth" 
       Content="{Binding Path=ActualWidth, 
                 ElementName=myImage, 
                 StringFormat={}{0:F1}" />
<Label Grid.Column="1" x:Name="label3" Content=" x " />
<Label Grid.Column="2" 
        x:Name="imageHeight" 
        Content="{Binding Path=ActualHeight, 
                  ElementName=myImage, 
                  StringFormat={}{0:F1}" />