String format using MultiBinding?

Question

I'm trying to display a string in XAML using Label control. Following is my XAML code :

<Label Height="28" HorizontalAlignment="Left" Margin="233,68,0,0" Name="label13" VerticalAlignment="Top">
    <Label.Content>
        <MultiBinding StringFormat="{}{0} x {1}">
              <Binding Path="Width" />
              <Binding Path="Height" />
        </MultiBinding>
    </Label.Content>

Width and Height are two properties of my class Movie. I want the label to display : "Width x Height" ex. 800 x 640 However the label control remains empty. Any help is appreciated. I WANT TO DO THIS WITHOUT USING A CONVERTER.

---

I have modified my xaml by using a TextBlock instead of Label. But still it wont populate display the output.

<TextBlock Height="28" HorizontalAlignment="Left" Margin="233,68,0,0" Name="label13" VerticalAlignment="Top">
                <TextBlock.Text>
                    <MultiBinding StringFormat="{}{0} x {1}">
                        <Binding Path="Width" />
                        <Binding Path="Height" />
                    </MultiBinding>
                </TextBlock.Text>
            </TextBlock>

Apocrine

Did you look at this? https://mcmap.net/q/428650/-binding-stringformat – Decosta

have you implement the INotificationChanged interface for your class movie? is your Binding correct? (look at the vs output window) – Brig

Answer 1

you are trying to bind a string to an object. But StringFormat requires its target to be a string type.

try putting a TextBlock in your label content and bind your data to it

<StackPanel>
  <Slider x:Name="sl1" Minimum="10" Maximum="100"/>
  <Slider x:Name="sl2" Minimum="10" Maximum="100"/>
  <Label x:Name="label13" Background="Yellow" Foreground="Black">
    <Label.Content>
        <TextBlock>
          <TextBlock.Text>
            <MultiBinding StringFormat="{}{0} x {1} Test">
              <Binding ElementName="sl1" Path="Value" />
              <Binding ElementName="sl2" Path="Value" />
            </MultiBinding>
          </TextBlock.Text>
        </TextBlock>
    </Label.Content>
  </Label>
</StackPanel>

EDIT your class Movie must implement the INotificationPropertyChanged interface and your two properties must raise the property changed event with their proprty names!

hope this helps

Brig

can you elaborate why it works when TextBlock is inside Label and doesn't work otherwise? – Discomposure

@Discomposure because the target of the binding is a different type. TextBlock.Text is a string, but Label.Content is an object. The StringFormat property only kicks in for string-typed targets. – Mettah