Rendering a Xaml Gauge Control (and other WPF Controls) in ASP.NET MVC

By Anoop Madhusudanan

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In my last post, I introduced XamlAsyncController, a POC implementation that shows how to render Xaml controls from ASP.NET MVC.

To recap, these are the two steps you need to do to render Xaml or a WPF control as an image from your ASP.NET MVC Controller

  1. Inherit your Controller from XamlAsyncController, and add an Async action for serving the image 
  2. Add your Xaml file to the path /Visualizations/{Controller}/{Action}.xaml

Also, now there is one more way of rendering a WPF control from your MVC controller. You can create a WPF control from your controller and pass it as a parameter of StartRendering method, in your Async method.image

The Gauge control XAML I’ve used in this example is the Xaml guage control developed by Evelyn from Codeproject – Credits to Evelyn.

Have a look at the Controller that renders the Button image and the Gauge image, in the shown html page.

    public class VisualsController : XamlAsyncController
    {

        public void GuageAsync()
        {           
            ViewData["Score"]=200d;
            ViewData["Title"] = "Hello";
            StartRendering();
        }

        public ActionResult GuageCompleted()
        {
            return XamlView();
        }

        public void ButtonAsync()
        {
            StartRendering(()=>new Button() { Content="Hello",Height=30, Width=100 });
        }

        public ActionResult ButtonCompleted()
        {
            return XamlView();
        }
     }

And now you can do following to render those images

     
   <h2>Xaml in ASP.NET MVC Demos</h2>
    <h3>Simple Button</h3>
     <image src="/Visuals/Button" />
    <h3>Gauge</h3>
     <image src="/Visuals/Guage" />

As you can see, the Visuals controller returns the image, based on the action name. In the case of ButtonAsync action, you can see that we are creating the WPF Button object directly in the action, and passing it as a parameter of StartRendering method, to render the button as an image.

In case of the GuageAsync action, you may see that we are just calling StartRendering after filling some data in the ViewData. If that is the case, as I explained in my previous post, by convention, we expect the Xaml view in the path Visualizations\Visual\Guage.xaml . Here is our Guage.xaml View, and you can see the we have the ‘Score’ property of our UserControl bound to the ViewData we passed in the GuageAsync action.

<UserControl x:Class="MvcXamlController.Demo.Visualizations.Dashboard.Guage"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:controls="clr-namespace:MvcXamlController.Controls;assembly=MvcXamlController.Controls"
        Width="300" Height="300"     
        mc:Ignorable="d">
    <Grid>
        <controls:CircularGaugeControl x:Name="myGauge1" 
                                        Radius="150" 
                                        ScaleRadius="110" 
                                        ScaleStartAngle="120" 
                                        ScaleSweepAngle="300"
                                        PointerLength="85" 
                                        PointerCapRadius="35" 
                                        MinValue="0" 
                                        MaxValue="1000" 
                                        MajorDivisionsCount="10" 
                                        MinorDivisionsCount="5" 
                                        CurrentValue="{Binding Score}"
                                        ResetPointerOnStartUp="True" 
                                        ImageSize="40,50"
                                        RangeIndicatorThickness="8"
                                        RangeIndicatorRadius="120"
                                        RangeIndicatorLightRadius="10"
                                        RangeIndicatorLightOffset="80"
                                        ScaleLabelRadius="90"
                                        ScaleLabelSize="40,20"
                                        ScaleLabelFontSize="10"
                                        ScaleLabelForeground="LightGray"
                                        MajorTickSize="10,3"
                                        MinorTickSize="3,1"
                                        MajorTickColor="LightGray"
                                        MinorTickColor="LightGray"
                                        ImageOffset="-50"
                                        GaugeBackgroundColor="Black"
                                        PointerThickness ="16"
                                        OptimalRangeStartValue="300"
                                        OptimalRangeEndValue="700" 
                                        DialTextOffset="40" 
                                        DialText="{Binding Title}"
                                        DialTextColor="Black"
                                        >

        </controls:CircularGaugeControl>
    </Grid>
</UserControl>
	

Have a look at the source code here.

There are some limitations as of now. You may note that if the WPF control supports animation (like the Chart controls), you won’t be able to render them properly. How ever, if you create your own UserControls, you can easily make them work

Also, Keep in touch :) follow me in twitter or subscribe to this blog. Interested in more ASP.NET MVC? Read my articles about creating a custom view engine for ASP.NET MVC or using Duck Typed View Models in ASP.NET MVC

Happy coding..

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