Get map coordinates

Overview

You will learn: how to display the latitude and longitude, scale, and zoom level of the map in a custom widget.

The out-of-the-box Map widget in ArcGIS Experience Builder contains an instance of a View from the ArcGIS API for JavaScript. The View provides a way to interact with the map and to retrieve information about the map location. Using properties and event handlers on the View you can find the current spatial reference information, latitude and longitude, scale, and zoom level for the map or any screen point location. Once you have this information you can display it in a custom widget, use it to find other locations on the earth, or use it to set the initial extent of your Map when your Experience starts.

In this tutorial, you will access the map widget and display the latitude and longitude of the mouse cursor over the map in your custom widget.

Prerequisites

Steps

Get the starter widget

1. Download the Starter Widget template here.

   More info

   If you have already completed the create a starter widget tutorial, you can start with that. Duplicate the widget folder within /client/your-extensions/widgets.

2. In the ArcGIS Experience Builder folder, extract the zip into the following path: /client/your-extensions/widgets.

Change the widget name

1. In the terminal where the npm start is running in the client folder, stop the script by pressing ctrl + c.

2. In your file browser, go to the folder where Experience Builder was extracted.

3. In the Experience Builder folder, expand the following path: /client/your-extensions/widgets.

4. In the widgets folder, rename the starter-widget folder to get-map-coordinates.

5. In the newly-renamed get-map-coordinates folder, open the manifest.json file in the code editor.

6. In the code editor, modify the name property to get-map-coordinates.

   More info

   It is important that the `name` property of the `manifest.json` matches the name of the folder for your widget. You can also update the other metadata in the `manifest.json` file at this time, like the description of the widget, the author, etc.
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    {
      // *** UPDATE ***
      // "name": "starter-widget",
      "name": "get-map-coordinates",
      "type": "widget",
      "version": "1.11.0",

7. After the version property in manifest.json, add a jimu-arcgis dependency. Declaring this allows the usage of ArcGIS API for JavaScript modules within the widget.

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   {
      "name": "get-map-coordinates",
      "type": "widget",
      "version": "1.11.0",
      // *** ADD ***
      "dependency": ["jimu-arcgis"],

Implement the settings panel

A settings panel can be implemented to allow Experience authors to customize the widget. The settings panel appears in the right-hand sidebar when a widget is selected in ArcGIS Experience Builder. To create the panel, create a React component.

1. In the widget root folder, create a config.json file that contains an empty object.

   More info

   At a later time, widget configuration parameters can be added to this object to store widget setting values.

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   {}

2. In the src folder, create another folder called setting.

3. In the setting folder, create a setting.tsx file.

4. Open the setting/setting.tsx file and include the following import statements.

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   import { React } from 'jimu-core'
   import { AllWidgetSettingProps } from 'jimu-for-builder'

5. Add code to implement the component.

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   const Setting = (props: AllWidgetSettingProps<any>) => {
     return (
       <div className="widget-setting-demo">This is your starter widget setting area!</div>
     )
   }
   
   export default Setting

6. In the terminal, stop (ctrl + c) (if applicable) and start the npm start script in the client folder.

Enable selecting a map view data source

In ArcGIS Experience Builder, there can be more than one Map Widget on the page at a time. Because of this, a custom widget must have a section of its Settings Panel that allows the author to choose which map widget to use.

1. In the setting/setting.tsx file, include the MapWidgetSelector module from the jimu library.

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   import { MapWidgetSelector } from 'jimu-ui/advanced/setting-components'

2. Within the component, define the onMapWidgetSelected function.

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   // *** ADD ***
   const onMapWidgetSelected = (useMapWidgetIds: string[]) => {
     props.onSettingChange({
       id: props.id,
       useMapWidgetIds: useMapWidgetIds
     })
   }
   
   return (
     <div className="widget-setting-demo">This is your starter widget setting area!</div>
   )

3. In the return() statement, add a tag representing the MapWidgetSelector.

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   return (
     <div className="widget-setting-demo">
       <MapWidgetSelector
         useMapWidgetIds={props.useMapWidgetIds}
         onSelect={onMapWidgetSelected}
       />
     </div>
   )

Access the map

In the previous step, the settings panel was enhanced to allow the Map widget to be selected. The map object can be accessed using the JimuMapViewComponent.

1. In the widget.tsx file, add the JimuMapViewComponent and JimuMapView types from the jimu-arcgis library, and destructure the React variable to get access to the getState import.

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   import { React, AllWidgetProps } from 'jimu-core'
   /** ADD: **/
   import { JimuMapViewComponent, JimuMapView } from 'jimu-arcgis'
   const { useState } = React

2. To display the latitude and longitude property of the mouse, the mouse pointer state must be tracked. Within the component, set up the state using useState().

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    const { useState } = React
   
    const Widget = (props: AllWidgetProps<any>) => {
      // *** ADD ***//
      const [latitude, setLatitude] = useState<string>('')
      const [longitude, setLongitude] = useState<string>('')
   
      return (

3. In the return section, add the JimuMapViewComponent to the JSX markup.

   More info

   The first two lines of the added code ({props.useMapWidgetIds &&...) are how to use conditionals in JSX. This is basically saying "only add the JimuMapViewComponent if the Experience author has chosen a valid map widget in the settings panel."

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    return (
      <div className="widget-starter jimu-widget">
        {
          props.useMapWidgetIds &&
          props.useMapWidgetIds.length === 1 && (
            <JimuMapViewComponent
              useMapWidgetId={props.useMapWidgetIds?.[0]}
              onActiveViewChange={activeViewChangeHandler}
            />
          )
        }
      </div>
    )

4. At the top of widget.tsx, import the Point class, which will be used in the next step.

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   import Point from 'esri/geometry/Point'

5. Define the activeViewChangeHandler function, just below the setState commands. This function will be called once - when the map is ready. In this function, set up a listener to update the latitude and longitude state every time the pointer-move event is triggered.

   More info

   Create a Point object using the incoming mouse x and y position and then convert the coordinates to map coordinates using the view.toMap() function. Set the state of the latitude and longitude to display the coordinate values.

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    /** ADD: **/
    const activeViewChangeHandler = (jmv: JimuMapView) => {
     if (jmv) {
       // When the pointer moves, take the pointer location and create a Point
       // Geometry out of it (`view.toMap(...)`), then update the state.
       jmv.view.on('pointer-move', evt => {
         const point: Point = jmv.view.toMap({
           x: evt.x,
           y: evt.y
         })
         setLatitude(point.latitude.toFixed(3))
         setLongitude(point.longitude.toFixed(3))
       })
     }
   }

Display the latitude and longitude coordinates

Now that the latitude and longitude is stored in the component's state, you can easily display the values in the the JSX that is returned from the function component.

1. In the return() statement (right after the JimuMapViewComponent placed earlier), add JSX to display the latitude and longitude.

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   return (
     <div className="widget-starter jimu-widget">
       {
         props.useMapWidgetIds &&
         props.useMapWidgetIds.length === 1 && (
           <JimuMapViewComponent
             useMapWidgetId={props.useMapWidgetIds?.[0]}
             onActiveViewChange={activeViewChangeHandler}
           />
         )
       }
       {/* *** ADD: *** */}
       <p>Lat/Lon: {latitude} {longitude}</p>
     </div>
   )

Test the widget

Once the code changes have been made, you can test your widget by running ArcGIS Experience Builder and viewing your experience.

1. In a web browser, go to Experience Builder. e.g. https://localhost:3001

   More info

   If Experience Builder did not open a tab for you, browse to https://localhost:3001. If you get a "Invalid SSL Certificate" issue, click "Proceed Anyway".

2. In Experience Builder, click Create New to create a new experience page.

3. Click the Create button on the Blank scrolling template.

4. The Insert widget panel is opened for you. From there, drag a Map widget and your new Get Map Coordinates widget onto the experience.

   More info

   The widget may show an invalid icon right now. That's ok - you have not created one yet!

5. In the widget settings panel, choose Map from the map selection dropdown.

6. In the Experience Builder toolbar, click Save then Preview and the experience will open in a new browser tab with your custom widget and a map. Mouse over the map to see the latitude and longitude of the cursor location.

Congratulations, you're done!

In the Experience Builder preview, hover over the map to see the latitude and longitude values dynamically change in the custom widget. Compare your widget with our completed widget, and see the top of this page for an example for how the Experience should look.