Create Map Axes in an App

This example shows how to include map axes in apps created using App Designer. The example also shows how to include app components that control the map projection and the visibility of plotted data.

To view an app created using the steps in this example, see App That Contains Map Axes.

Create New App

Open App Designer and click 2-Panel App with Auto-Reflow.

appdesigner

Create App Components

Add components to the left panel that control the map projection and the visibility of plotted data.

In the top-right corner of the center pane, select Design View to interactively add app components.

Create a component that controls the map projection.

Add a radio button group to the left panel.
Change the title of the group to Map Projection.
Change the text of the radio buttons to Equal Earth, Winkel Tripel, and Mercator.

Create a component that controls the visibility of plotted coastlines, rivers, and cities.

Add a panel to the left panel.
Change the title of the new panel to Data.
Add three check boxes to the Data panel.
Change the text of the check boxes to Coastlines, Rivers, and Cities.
Check each check box. For each check box, in the right pane, select Value.

Set Up Map

Add the map to the right panel.

In the top-right corner of the center pane, select Code View to add the map axes object, load and plot the data, and specify the map projections.

Create a map axes object.

Add a private property that stores the map axes object. Storing objects in properties enables you to access the objects throughout your app code. In the Editor tab, click Property and then Private Property. Then, change the property name in the properties block to RightMapAxes.
Write code that creates a map when you start the app. In the Editor tab, click Callback. Set App to the application and Callback to StartupFcn. Add code to create a map axes in the right panel and store the map axes in the RightMapAxes property. Disable panning and zooming by updating the interaction options of the map axes. (since R2024a) Then, provide geographic context by displaying world land areas in the map axes.
```
function startupFcn(app)
    % Create map axes
    app.RightMapAxes = mapaxes(app.RightPanel,NextPlot="add",Color="#A6A6A6");

    % Disable panning and zooming
    app.RightMapAxes.InteractionOptions.PanSupported = "off";
    app.RightMapAxes.InteractionOptions.ZoomSupported = "off";

    % Display land areas
    land = readgeotable("landareas.shp");
    geoplot(app.RightMapAxes,land,FaceColor="#d9d9d9",FaceAlpha=1,EdgeColor="none", ...
        HandleVisibility="off",PickableParts="none")
end
```

Plot the coastlines, rivers, and cities data.

Add private properties that store the plot objects. In the Editor tab, select Property and then Private Property. Then, change the property name in the properties block to CoastlinesPlot. Repeat this process to add RiversPlot and CitiesPlot properties.

Write code that plots data when you start the app. Within the StartupFcn callback, add code to plot the coastlines, rivers, and cities data in the map axes. Store the plots in the CoastlinesPlot, RiversPlot, and CitiesPlot properties, respectively.

function startupFcn(app)
    % Create map axes
    % ...

    % Disable panning and zooming
    % ...

    % Display land areas
    % ...

    % Display coastlines, rivers, and cities
    rivers = readgeotable("worldrivers.shp");
    cities = readgeotable("worldcities.shp");
    app.CoastlinesPlot = geoplot(app.RightMapAxes,land,EdgeColor="k",FaceColor="none");
    app.RiversPlot = geoplot(app.RightMapAxes,rivers,Color="#0072BD");
    app.CitiesPlot = geoplot(app.RightMapAxes,cities,MarkerEdgeColor="#A2142F");
end

Specify the map projections using projected coordinate reference system (CRS) objects. Create the objects by using the projcrs function.

Add private properties that store the projected CRS objects. In the Editor tab, select Property and then Private Property. Then, change the property name in the properties block to EqualEarthProjectedCRS. Repeat this process to add WinkelTripelProjectedCRS and MercatorProjectedCRS properties.

Write code that creates the projected CRS objects when you start the app. In the StartupFcn callback, add code to create projcrs objects that use the Equal Earth, Winkel Tripel, and Mercator projections. Store the objects in the EqualEarthProjectedCRS, WinkelTripelProjectedCRS, and MercatorProjectedCRS properties, respectively.

function startupFcn(app)
    % Create map axes
    % ...

    % Disable panning and zooming
    % ...

    % Display land areas
    % ...

    % Display coastlines, rivers, and cities
    % ...

    % Create projected CRSs
    app.EqualEarthProjectedCRS = projcrs(8857);
    app.WinkelTripelProjectedCRS = projcrs(54042,Authority="ESRI");
    app.MercatorProjectedCRS = projcrs(54004,Authority="ESRI");
end

Program Component Behavior

Use Code View to program the behaviors of the radio button group and the check boxes.

Write code that changes the projected CRS when you change the radio button selection. In the Editor tab, click Callback. Then, set Component to MapProjectionButtonGroup and Callback to SelectionChangedFcn. Add code that changes the projected CRS of the map axes depending on the selected radio button.

function MapProjectionButtonGroupSelectionChanged(app, event)
    % Change projected CRS of map axes based on selected map projection
    selectedButton = app.MapProjectionButtonGroup.SelectedObject;
    if selectedButton == app.EqualEarthButton % equal earth
        app.RightMapAxes.ProjectedCRS = app.EqualEarthProjectedCRS;
    elseif selectedButton == app.WinkelTripelButton % winkel tripel
        app.RightMapAxes.ProjectedCRS = app.WinkelTripelProjectedCRS;
    elseif selectedButton == app.MercatorButton % mercator
        app.RightMapAxes.ProjectedCRS = app.MercatorProjectedCRS;
    end
end

Write code that toggles that visibility of the plots when you check or uncheck the check boxes. In the Editor tab, click Callback. Then, set Component to CoastlinesCheckBox and Callback to ValueChangedFcn. Add code that changes the visibility of the coastlines plot depending on the value of the check box.
```
function CoastlinesCheckBoxValueChanged(app, event)
    % Change visibility of coastlines plot based on check box
    value = app.CoastlinesCheckBox.Value;
    app.CoastlinesPlot.Visible = value;
end
```
Repeat this step to add ValueChangedFcn callbacks to the rivers check box, RiversCheckBox, and cities check box, CitiesCheckBox.

Run the App

To save and run the app, in the Editor tab, click Run. Change the map projection by clicking the radio buttons. Toggle the visibility of the coastlines, rivers, and cities by clicking the check boxes.

Example: App That Contains Map Axes

Open App

This app plots world coastlines, rivers, and cities into a map axes. Radio buttons enable you to change the map projection. Check boxes enable you to toggle the visibility of the plotted data.