[Qt] Make it possible to add a layer before another layer

2 files changed, 9 insertions, 7 deletions

diff --git a/platform/qt/include/qmapboxgl.hpp b/platform/qt/include/qmapboxgl.hpp
index 00c5735a93..478c15a51e 100644
--- a/platform/qt/include/qmapboxgl.hpp
+++ b/platform/qt/include/qmapboxgl.hpp
@@ -219,8 +219,8 @@ public:
         QMapbox::CustomLayerRenderFunction,
         QMapbox::CustomLayerDeinitializeFunction,
         void* context,
-        char* before = NULL);
-    void addLayer(const QVariantMap &params);
+        const QString& before = QString());
+    void addLayer(const QVariantMap &params, const QString& before = QString());
     bool layerExists(const QString &id);
     void removeLayer(const QString &id);
 
diff --git a/platform/qt/src/qmapboxgl.cpp b/platform/qt/src/qmapboxgl.cpp
index e1b8889603..80b64f05df 100644
--- a/platform/qt/src/qmapboxgl.cpp
+++ b/platform/qt/src/qmapboxgl.cpp
@@ -1334,7 +1334,7 @@ void QMapboxGL::addCustomLayer(const QString &id,
         QMapbox::CustomLayerRenderFunction renderFn,
         QMapbox::CustomLayerDeinitializeFunction deinitFn,
         void *context,
-        char *before)
+        const QString& before)
 {
     d_ptr->mapObj->addLayer(std::make_unique<mbgl::style::CustomLayer>(
             id.toStdString(),
@@ -1344,13 +1344,14 @@ void QMapboxGL::addCustomLayer(const QString &id,
             (mbgl::style::CustomLayerRenderFunction)renderFn,
             reinterpret_cast<mbgl::style::CustomLayerDeinitializeFunction>(deinitFn),
             context),
-            before ? mbgl::optional<std::string>(before) : mbgl::optional<std::string>());
+            before.isEmpty() ? mbgl::optional<std::string>() : mbgl::optional<std::string>(before.toStdString()));
 }
 
 /*!
     Adds a style layer to the map as specified by the \l
     {https://www.mapbox.com/mapbox-gl-style-spec/#root-layers}{Mapbox style specification} with
-    \a params.
+    \a params. The layer will be added under the layer specified by \a before, if specified.
+    Otherwise it will be added as the topmost layer.
 
     This example shows how to add a layer that will be used to show a route line on the map. Note
     that nothing will be drawn until we set paint properties using setPaintProperty().
@@ -1366,7 +1367,7 @@ void QMapboxGL::addCustomLayer(const QString &id,
 
     /note The source must exist prior to adding a layer.
 */
-void QMapboxGL::addLayer(const QVariantMap &params)
+void QMapboxGL::addLayer(const QVariantMap &params, const QString& before)
 {
     using namespace mbgl::style;
     using namespace mbgl::style::conversion;
@@ -1378,7 +1379,8 @@ void QMapboxGL::addLayer(const QVariantMap &params)
         return;
     }
 
-    d_ptr->mapObj->addLayer(std::move(*layer));
+    d_ptr->mapObj->addLayer(std::move(*layer),
+        before.isEmpty() ? mbgl::optional<std::string>() : mbgl::optional<std::string>(before.toStdString()));
 }
 
 /*!