Question

I need to enable zooming on the Silverlight charts I use – at the moment this is Silverlight Toolkit. As far as I’ve understood the SL Toolkit charts don’t support zooming, however I’m looking into implementing this functionality. So far I haven’t managed to get far: applying ScaleTransforms to the Series elements doesn’t work as expected.

Can anyone provide me with example code on implementing zooming in Silverlight Toolkit?

Answer 1

I’ve previously looked into implementing zooming on the Silverlight Toolkit charts, however failed because of (probably) the following reasons:

• Silverlight Toolkit charts don’t seem to have been designed to be able to extend for zooming. There are no hooks that you could easily attack some zooming logic to, if you want to create zooming on them, you have to go much deeer.
• The simplest way of implementing zooming is using ScaleTransform and RenderTransform to elements. In case of Silverlight Toolkit you want to apply this to the series. However just calculating the correct ScaleTransform and OffsetTransform are difficult enough
• When scaling, you don’t want everything to scale. If you zoom in 4x on a line series with points on it, you don’t want the line to be 4x thicker and the points to be 4x larger. This means that even if you did implement applying the ScaleTransforms and RenderTransforms correctly, all you would get is a magnifying glass, which is still far from ideal.

After a few hours I gave up on adding this kind of support to the SL toolkit charts and instead looked for other components that support zooming and have a decent API to deal with it. These are the components I’ve found (though I’m sure there’s more):

• Visiblox Charts free version: it has a nice API and implenting zooming takes only a few lines of XAML according to this blog post (also see a post on a comparison with SL toolkit charts). Full disclosure: I have been heavily involved in development of this library.
• Infragistics xamWebChart also claim to have support for zoom in the premium version of their charts
• Telerik RadCharts also seem to allow zooming based on this example – though it’s not clear to me whether you’d have to implement this functionality yourself.

Summing it up, I think the easiest way for you to go it with a component that already has zooming implemented – from my experience it would take a lot of investment to add proper zooming + panning to Silverlight Toolkit charts.