Add a default development token for Mapbox GL styles

The idea here is to have a map working zero conf, without having
to create a token. Useful for developers that want to try Mapbox GL
maps without creating an account.

The token should not be used in production (and will display a warning
telling so). It is subject to change, throttling, etc and also a
violation of the ToS.

Also fixes runtime exception when access token is not set on
mapbox:// style.

Task-number: QTBUG-58599
Change-Id: Ie7205ccbdb3ccaee753b04116aed0f5ba35f8522
Reviewed-by: Paolo Angelelli <paolo.angelelli@qt.io>

1 files changed, 5 insertions, 0 deletions

diff --git a/src/location/doc/src/plugins/mapboxgl.qdoc b/src/location/doc/src/plugins/mapboxgl.qdoc
index b6d56550..98ddd10b 100644
--- a/src/location/doc/src/plugins/mapboxgl.qdoc
+++ b/src/location/doc/src/plugins/mapboxgl.qdoc
@@ -64,6 +64,11 @@ The following table lists optional parameters that can be passed to the Mapbox p
 \row
     \li mapboxgl.access_token
     \li \l{https://www.mapbox.com/help/define-access-token}{Access token} provided by Mapbox.
+    The token can also be specified using the environment variable \c{MAPBOX_ACCESS_TOKEN}, but if also
+    set using a plugin parameter, then this last one will have the precedence over the environment variable.
+    When not set, a development token will be used by default. The development token is subject to the Mapbox
+    \l{https://www.mapbox.com/tos}{Terms of Services} and must not be used in production. This property has
+    no effect on styles hosted outside the Mapbox servers.
 \row
     \li mapboxgl.mapping.additional_style_urls
     \li Additional, comma separated, Mapbox \l{https://www.mapbox.com/help/define-style-url}