Use the defaultStyles constant on Android apps

[tmpsantos]

The MacOS and Linux app are now using the defaultStyles as the list of styles we can select from. The iOS and Android apps should use the same list.

defaultStyles was added at #1443

/cc @incanus

[jfirebaugh]

default_styles.hpp should be a header in include/mbgl/platform so it can be included via #include <mbgl/platform/default_styles.hpp>. There shouldn't be relative includes like this in the test/sample apps.

[kkaefer]

There shouldn't be relative includes like this in the test/sample apps.

Why not? My reason for not moving it into the include/mbgl/platform is that it's technically not part of the library.

[jfirebaugh]

I think it should be considered part of the library. If a third-party wanted to build an app with style-switching functionality, they should #include <mbgl/platform/default_styles.hpp> and then use it.

[kkaefer]

The bundled styles aren't technically part of the library either; they're just there because we package them with the apps.

[incanus]

They are part of the library on iOS — we package a MapboxGL.bundle with the static library and headers which contains resources like the compass image and Mapbox logo as well as the included styles. It's a first-class part of the library. Currently we recommend users query for the included styles with an API call, which we hook up by iterating the filesystem directly. This should be a first-class API internal to mbgl that bindings like iOS can query.

[ljbade]

Hmm good idea @incanus.

[incanus]

Punting off of b2 since the bundled styles haven't changed since b1 and nothing under the hood has moved here that makes this any more urgent.

[ljbade]

@1ec5 is looking to implement this in #2746 (comment) for iOS.

On Android I decided to just have a class that provides static constants in the Styles class.

[tobrun]

On Android we have:

/**
 * <p>
 * Style provides URLs to several professional styles designed by Mapbox.
 * </p>
 * These styles are all ready to go in your app. To load one, pass it into {@link MapView#setStyleUrl(String)}
 *
 * @see MapView#setStyleUrl(String)
 */
public class Style {

    /**
     * Indicates the parameter accepts one of the values from {@link Style}.
     */
    @StringDef({MAPBOX_STREETS, EMERALD, LIGHT, DARK, SATELLITE, SATELLITE_STREETS})
    @Retention(RetentionPolicy.SOURCE)
    public @interface StyleUrl {
    }

    // IMPORTANT: If you change any of these you also need to edit them in strings.xml

    /**
     * Mapbox Streets: A complete basemap, perfect for incorporating your own data.
     */
    public static final String MAPBOX_STREETS = "mapbox://styles/mapbox/streets-v8";
    /**
     * Emerald: A versatile style, with emphasis on road networks and public transit.
     */
    public static final String EMERALD = "mapbox://styles/mapbox/emerald-v8";
    /**
     * Light: Subtle light backdrop for data visualizations.
     */
    public static final String LIGHT = "mapbox://styles/mapbox/light-v8";
    /**
     * Dark: Subtle dark backdrop for data visualizations.
     */
    public static final String DARK = "mapbox://styles/mapbox/dark-v8";
    /**
     * Satellite: A beautiful global satellite and aerial imagery layer.
     */
    public static final String SATELLITE = "mapbox://styles/mapbox/satellite-v8";

    /**
     * Satellite Streets: Global satellite and aerial imagery with unobtrusive labels.
     */
    public static final String SATELLITE_STREETS = "mapbox://styles/mapbox/satellite-hybrid-v8";

}

Since @friedbunny removed iOS label, I think this is resolved for both platforms!

[friedbunny]

Yup, iOS happened in #2746.

[tobrun]

It seems the current way is not as requested in this issue.

We should fetch:

• https://github.com/mapbox/mapbox-gl-native/blob/master/include/mbgl/util/default_styles.hpp#L23

and match those urls on the Style class shown above.

-> if we change default_styles.hpp -> our app urls should change automatically.

[1ec5]

On the iOS side, we're relying on a compile-time assertion that the number of default styles hasn't changed since we last updated the iOS-specific list. We also have a unit test to the same effect.

[tobrun]

I was also thinking about handling this at compile time (integrating this as a task in gradle) but instead of asserting, I was thinking about generating the java file.
\cc @bleege @zugaldia

[jfirebaugh]

Obsolete.