WPF – how to bind ScaleTransform to Slider, percentage style!

Whilst working on an image view I needed the ability to bind the value of a Slider to a ScaleTransform as a percentage value and at the same time display the value of the slider in a label. So for a zoom range from 1% to 250% you would usually set the Minimum and Maximum property of your Slider to 0.01 and 2.5 respectively, by then you wouldn’t be able to display the zoom value as a percentage, e.g. Zoom 148%.

So to get around this limitation, in the end I used the range 1 to 250 for the Slider and added another ScaleTransform with ScaleX and ScaleY set to 0.01, like this:

<StackPanel x:Name="LayoutRoot" Background="Gray">
    <StackPanel Orientation="Horizontal">
        <TextBlock Margin="5,5,10,5">Zoom</TextBlock>
        <TextBlock Margin="5,5,0,5" Text="{Binding Path=Value, ElementName=sldZoom, Mode=OneWay}"/>
        <TextBlock Margin="0,5">%</TextBlock>
    </StackPanel>

    <Slider x:Name="sldZoom" Orientation="Horizontal" Minimum="1" Maximum="250" Value="100"/>

    <Image Source="bingonet.png" RenderTransformOrigin="0, 0">
        <Image.RenderTransform>
            <TransformGroup>
                <ScaleTransform ScaleX="0.01" ScaleY="0.01"/>
                <ScaleTransform>
                    <ScaleTransform.ScaleX>
                        <Binding ElementName="sldZoom" Path="Value" Mode="OneWay"/>
                    </ScaleTransform.ScaleX>
                    <ScaleTransform.ScaleY>
                        <Binding ElementName="sldZoom" Path="Value" Mode="OneWay"/>
                    </ScaleTransform.ScaleY>
                </ScaleTransform>
            </TransformGroup>
        </Image.RenderTransform>
    </Image>
</StackPanel>
Liked this article? Support me on Patreon and get direct help from me via a private Slack channel or 1-2-1 mentoring.
Subscribe to my newsletter


Hi, I’m Yan. I’m an AWS Serverless Hero and the author of Production-Ready Serverless.

I specialise in rapidly transitioning teams to serverless and building production-ready services on AWS.

Are you struggling with serverless or need guidance on best practices? Do you want someone to review your architecture and help you avoid costly mistakes down the line? Whatever the case, I’m here to help.

Hire me.


Check out my new course, Complete Guide to AWS Step Functions. In this course, we’ll cover everything you need to know to use AWS Step Functions service effectively. Including basic concepts, HTTP and event triggers, activities, callbacks, nested workflows, design patterns and best practices.

Get Your Copy