Getting Started with the Radial Gauge

This tutorial explains how to set up a basic Telerik UI for ASP.NET Core Radial Gauge and highlights the major steps in the configuration of the component.

You will initialize a Radial Gauge and configure its Scale, which is responsible for the visualization of the gauge. Then, you will handle the basic JavaScript keydown event to acknowledge when the user presses the Up or Down arrow keys and update the value of the Radial Gauge Pointer using its client-side reference. Finally, you can run the sample code in Telerik REPL and continue exploring the components.

Prerequisites

To successfully complete the tutorial, you need a project that is already configured to use the Telerik UI for ASP.NET Core components:

• You can use the Telerik REPL playground and skip installing the components on your system and configuring a project.

• You can prepare a Visual Studio project by following either of these guides:

  • Creating a new pre-configured project for the Telerik UI for ASP.NET Core components from a project template.

  • Manually configuring an existing project as described in the First Steps on Windows or First Steps on Mac articles.

1. Prepare the CSHTML File

The first step is to add the required directives at the top of the .cshtml document:

• To use the Telerik UI for ASP.NET Core HtmlHelpers:

  @using Kendo.Mvc.UI
  

• To use the Telerik UI for ASP.NET Core TagHelpers:

  @addTagHelper *, Kendo.Mvc
  

Optionally, you can structure the document by adding the desired HTML elements like headings, divs, and paragraphs. In this tutorial, you will also apply some styles to the gauge and its container.

    <style>
        #gauge-container {
            width: 386px;
            height: 386px;
            text-align: center;
            margin: 20px auto 30px auto;
        }

        #gauge {
            width: 350px;
            height: 300px;
            margin: 0 auto;
        }
    </style>
    <div id="example">

        <div id="gauge-container">
            <p>Modify the Temperature with the Up and Down Arrows of the Keyboard</p>
            <!-- Component Configuration -->
        </div>
    </div>

2. Initialize the Radial Gauge

Use the Radial Gauge HtmlHelper or TagHelper to add the component to a page:

• The Name() configuration method is mandatory as its value is used for the id and the name attributes of the Radial Gauge element.
• Utilize the .Pointer() method to set an initial value for the Radial Gauge.

    @using Kendo.Mvc.UI

    @(Html.Kendo().RadialGauge()
        .Name("gauge")
        .Pointer(pointer => pointer.Value(65))
    )

    @using Kendo.Mvc.UI
    @addTagHelper *, Kendo.Mvc

    <kendo-radialgauge name="gauge" >
        <radialgauge-pointers>
            <pointer value="65">
            </pointer>
        </radialgauge-pointers>
    </kendo-radialgauge>

3. Configure the Radial Gauge

Configure the Scale configuration method of the Radial Gauge. It exposes the RadialGaugeSettingsBuilder which allows you to then set up the Min, Max, MajorTicks, MinorTicks, Labels and Reverse properties.

    @using Kendo.Mvc.UI

    @(Html.Kendo().RadialGauge()
        .Name("gauge")
        .Pointer(pointer => pointer.Value(65))
        .Scale(x =>
           x.Min(0)
            .Max(140)
            .MajorTicks(M=>M.Visible(true))
            .MinorTicks(m => m.Visible(true))
            .Labels(l => l.Visible(true))
        )
    )

    @using Kendo.Mvc.UI
    @addTagHelper *, Kendo.Mvc

    <kendo-radialgauge name="gauge">
        <radialgauge-pointers>
            <pointer value="65">
            </pointer>
        </radialgauge-pointers>
        <scale min="0" max="140">
                <radialgauge-scale-major-ticks visible="true"/>
                <radialgauge-scale-minor-ticks visible="true"/>
                <radialgauge-scale-labels position="GaugeRadialScaleLabelsPosition.Inside"/>
         </scale>
    </kendo-radialgauge>

4. (Optional) Reference Existing Radial Gauge Instances

You can reference the Radial Gauge instances that you have created and build on top of their existing configuration:

1. Use the id attribute of the component instance to establish a reference.

       $(document).ready( function (e) {
           var radialgaugeReference = $("#gauge").data("kendoRadialGauge"); // radialgaugeReference is a reference to the existing Radial Gauge instance of the helper.
       });
   

2. Use the Radial Gauge client-side API to control the behavior of the component. In this example, you will use the value method to change the value of the Radial Gauge when the user presses the ArrowUp or ArrowDown keyboard buttons.

       $("body").on("keydown",function(e){
           if(e.key=="ArrowUp"){
               updateValue(1);
           }else if(e.key=="ArrowDown"){
               updateValue(-1);
           }
       })   
   
       function updateValue(number) {
           var gauge = $("#gauge").data("kendoRadialGauge");
           gauge.value(gauge.value()+number);
       }
   

Explore this Tutorial in REPL

You can continue experimenting with the code sample above by running it in the Telerik REPL server playground:

• Sample code with the Radial Gauge HtmlHelper
• Sample code with the Radial Gauge TagHelper

Next Steps

• Explore the Scale Options of the Radial Gauge

See Also

• Using the API of the Radial Gauge for ASP.NET Core (Demo)
• Client-Side API of the Radial Gauge
• Server-Side API of the Radial Gauge
• Knowledge Base Section