[qt] add ResourceTransform API

platform/qt/include/qmapboxgl.hpp

@@ -10,6 +10,8 @@
 #include <QString>
 #include <QStringList>
 
+#include <functional>
+
 class QMapboxGLPrivate;
 
 // This header follows the Qt coding style: https://wiki.qt.io/Qt_Coding_Style
@@ -59,6 +61,9 @@ public:
     QString apiBaseUrl() const;
     void setApiBaseUrl(const QString &);
 
+    std::function<std::string(const std::string &&)> resourceTransform() const;
+    void setResourceTransform(std::function<std::string(const std::string &&)> &);
+
 private:
     GLContextMode m_contextMode;
     ConstrainMode m_constrainMode;
@@ -69,6 +74,7 @@ private:
     QString m_assetPath;
     QString m_accessToken;
     QString m_apiBaseUrl;
+    std::function<std::string(const std::string &&)> m_resourceTransform;
 };
 
 struct Q_DECL_EXPORT QMapboxGLCameraOptions {

platform/qt/src/qmapboxgl.cpp

@@ -29,6 +29,7 @@
 #include <mbgl/util/run_loop.hpp>
 #include <mbgl/util/shared_thread_pool.hpp>
 #include <mbgl/util/traits.hpp>
+#include <mbgl/actor/scheduler.hpp>
 
 #if QT_VERSION >= 0x050000
 #include <QGuiApplication>
@@ -361,6 +362,27 @@ void QMapboxGLSettings::setApiBaseUrl(const QString& url)
     m_apiBaseUrl = url;
 }
 
+/*!
+    Returns resource transformation callback used to transform requested URLs.
+*/
+std::function<std::string(const std::string &&)> QMapboxGLSettings::resourceTransform() const
+{
+    return m_resourceTransform;
+}
+
+/*!
+    Sets the resource transformation callback.
+
+    When given, resource transformation callback will be used to transform the
+    requested resource URLs before they are requested from internet. This can be
+    used add or remove custom parameters, or reroute certain requests to other
+    servers or endpoints.
+*/
+void QMapboxGLSettings::setResourceTransform(std::function<std::string(const std::string &&)> &transform)
+{
+    m_resourceTransform = transform;
+}
+
 /*!
     \class QMapboxGL
     \brief The QMapboxGL class is a Qt wrapper for the Mapbox GL Native engine.
@@ -1499,6 +1521,18 @@ QMapboxGLPrivate::QMapboxGLPrivate(QMapboxGL *q, const QMapboxGLSettings &settin
         settings.cacheDatabaseMaximumSize()))
     , threadPool(mbgl::sharedThreadPool())
 {
+    // Setup resource transform if needed
+    if (settings.resourceTransform()) {
+      m_resourceTransform =
+        std::make_unique< mbgl::Actor<mbgl::ResourceTransform> >( *mbgl::Scheduler::GetCurrent(),
+                                                                  [callback = settings.resourceTransform()]
+                                                                  (mbgl::Resource::Kind , const std::string&& url_)  -> std::string {
+                                                                    return callback(std::move(url_));
+                                                                  }
+                                                                  );
+      fileSourceObj->setResourceTransform(m_resourceTransform->self());
+    }
+
     // Setup and connect the renderer frontend
     frontend = std::make_unique<QMapboxGLRendererFrontend>(
             std::make_unique<mbgl::Renderer>(*this, pixelRatio, *fileSourceObj, *threadPool,

platform/qt/src/qmapboxgl_p.hpp

@@ -3,15 +3,19 @@
 #include "qmapboxgl.hpp"
 #include "qmapboxgl_renderer_frontend_p.hpp"
 
+#include <mbgl/actor/actor.hpp>
 #include <mbgl/map/map.hpp>
 #include <mbgl/renderer/renderer_backend.hpp>
 #include <mbgl/util/default_thread_pool.hpp>
 #include <mbgl/storage/default_file_source.hpp>
 #include <mbgl/util/geo.hpp>
+#include <mbgl/storage/resource_transform.hpp>
 
 #include <QObject>
 #include <QSize>
 
+#include <memory>
+
 class QMapboxGLPrivate : public QObject, public mbgl::RendererBackend, public mbgl::MapObserver
 {
     Q_OBJECT
@@ -68,4 +72,7 @@ signals:
     void needsRendering();
     void mapChanged(QMapboxGL::MapChange);
     void copyrightsChanged(const QString &copyrightsHtml);
+
+private:
+    std::unique_ptr< mbgl::Actor<mbgl::ResourceTransform> > m_resourceTransform;
 };