[qt] Implement FBO handling

Needed for rendering 3D extrusions properly.

platform/qt/app/mapwindow.cpp

@@ -442,6 +442,9 @@ void MapWindow::initializeGL()
 void MapWindow::paintGL()
 {
     m_frameDraws++;
-    m_map->resize(size(), size() * pixelRatio());
+    m_map->resize(size());
+#if QT_VERSION >= 0x050400
+    m_map->setFramebufferObject(defaultFramebufferObject(), size() * pixelRatio());
+#endif
     m_map->render();
 }

platform/qt/include/qmapboxgl.hpp

@@ -191,8 +191,7 @@ public:
     void scaleBy(double scale, const QPointF &center = QPointF());
     void rotateBy(const QPointF &first, const QPointF &second);
 
-    void resize(const QSize &size, const QSize &framebufferSize);
-    void setFramebufferObject(quint32 fbo);
+    void resize(const QSize &size);
 
     double metersPerPixelAtLatitude(double latitude, double zoom) const;
     QMapbox::ProjectedMeters projectedMetersForCoordinate(const QMapbox::Coordinate &) const;
@@ -227,9 +226,10 @@ public:
     void setFilter(const QString &layer, const QVariant &filter);
 
     // When rendering on a different thread,
-    // should be called on this thread
+    // should be called on the render thread.
     void createRenderer();
     void destroyRenderer();
+    void setFramebufferObject(quint32 fbo, const QSize &size);
 
 public slots:
     void render();

platform/qt/src/qmapboxgl.cpp

@@ -1047,36 +1047,19 @@ void QMapboxGL::rotateBy(const QPointF &first, const QPointF &second)
 }
 
 /*!
-    Resize the map to \a size and scale to fit at \a framebufferSize. For
-    high DPI screens, the size will be smaller than the \a framebufferSize.
-
-    This fallowing example will double the pixel density of the map for
-    a given \c size:
-
-    \code
-        map->resize(size / 2, size);
-    \endcode
+    Resize the map to \a size_ and scale to fit at the framebuffer. For
+    high DPI screens, the size will be smaller than the framebuffer.
 */
-void QMapboxGL::resize(const QSize& size_, const QSize& framebufferSize)
+void QMapboxGL::resize(const QSize& size_)
 {
     auto size = sanitizedSize(size_);
 
     if (d_ptr->mapObj->getSize() == size)
         return;
 
-    d_ptr->mapRenderer->updateFramebufferSize(sanitizedSize(framebufferSize));
     d_ptr->mapObj->setSize(size);
 }
 
-/*!
-    If Mapbox GL needs to rebind the default \a fbo, it will use the
-    ID supplied here.
-*/
-void QMapboxGL::setFramebufferObject(quint32)
-{
-    // FIXME: No-op, implicit.
-}
-
 /*!
     Adds an \a icon to the annotation icon pool. This can be later used by the annotation
     functions to shown any drawing on the map by referencing its \a name.
@@ -1512,6 +1495,20 @@ void QMapboxGL::render()
     d_ptr->mapRenderer->render();
 }
 
+/*!
+    If Mapbox GL needs to rebind the default \a fbo, it will use the
+    ID supplied here. \a size is the size of the framebuffer, which
+    on high DPI screens is usually bigger than the map size.
+*/
+void QMapboxGL::setFramebufferObject(quint32 fbo, const QSize& size)
+{
+    if (!d_ptr->mapRenderer) {
+        createRenderer();
+    }
+
+    d_ptr->mapRenderer->updateFramebuffer(fbo, sanitizedSize(size));
+}
+
 /*!
     Informs the map that the network connection has been established, causing
     all network requests that previously timed out to be retried immediately.

platform/qt/src/qmapboxgl_map_renderer.cpp

@@ -25,10 +25,9 @@ void QMapboxGLMapRenderer::updateParameters(std::shared_ptr<mbgl::UpdateParamete
     m_updateParameters = std::move(newParameters);
 }
 
-void QMapboxGLMapRenderer::updateFramebufferSize(const mbgl::Size &size)
+void QMapboxGLMapRenderer::updateFramebuffer(quint32 fbo, const mbgl::Size &size)
 {
-    std::lock_guard<std::mutex> lock(m_updateMutex);
-    m_backend.setFramebufferSize(size);
+    m_backend.updateFramebuffer(fbo, size);
 }
 
 void QMapboxGLMapRenderer::render()

platform/qt/src/qmapboxgl_map_renderer.hpp

@@ -9,6 +9,8 @@
 #include <mbgl/storage/default_file_source.hpp>
 #include <mbgl/util/shared_thread_pool.hpp>
 
+#include <QtGlobal>
+
 #include <memory>
 #include <mutex>
 #include <queue>
@@ -31,11 +33,11 @@ public:
     void schedule(std::weak_ptr<mbgl::Mailbox> scheduled) final;
 
     void render();
+    void updateFramebuffer(quint32 fbo, const mbgl::Size &size);
     void setObserver(std::shared_ptr<mbgl::RendererObserver>);
 
     // Thread-safe, called by the Frontend
     void updateParameters(std::shared_ptr<mbgl::UpdateParameters>);
-    void updateFramebufferSize(const mbgl::Size &size);
 
 private:
     Q_DISABLE_COPY(QMapboxGLMapRenderer)

platform/qt/src/qmapboxgl_renderer_backend.cpp

@@ -11,7 +11,15 @@
 void QMapboxGLRendererBackend::updateAssumedState()
 {
     assumeFramebufferBinding(ImplicitFramebufferBinding);
-    assumeViewport(0, 0, { 800, 600 });
+    assumeViewport(0, 0, m_size);
+}
+
+void QMapboxGLRendererBackend::bind()
+{
+    assert(mbgl::BackendScope::exists());
+
+    setFramebufferBinding(m_fbo);
+    setViewport(0, 0, m_size);
 }
 
 mbgl::Size QMapboxGLRendererBackend::getFramebufferSize() const
@@ -19,8 +27,9 @@ mbgl::Size QMapboxGLRendererBackend::getFramebufferSize() const
     return m_size;
 }
 
-void QMapboxGLRendererBackend::setFramebufferSize(const mbgl::Size &size)
+void QMapboxGLRendererBackend::updateFramebuffer(quint32 fbo, const mbgl::Size &size)
 {
+    m_fbo = fbo;
     m_size = size;
 }
 

platform/qt/src/qmapboxgl_renderer_backend.hpp

@@ -14,10 +14,10 @@ public:
 
     // mbgl::RendererBackend implementation
     void updateAssumedState() final;
-    void bind() final {}
+    void bind() final;
     mbgl::Size getFramebufferSize() const final;
 
-    void setFramebufferSize(const mbgl::Size &);
+    void updateFramebuffer(quint32 fbo, const mbgl::Size &);
 
 protected:
     mbgl::gl::ProcAddress getExtensionFunctionPointer(const char*) final;
@@ -27,6 +27,7 @@ protected:
     void deactivate() final {}
 
 private:
+    quint32 m_fbo = 0;
     mbgl::Size m_size = { 0, 0 };
 
     Q_DISABLE_COPY(QMapboxGLRendererBackend)

platform/qt/test/qmapboxgl.test.cpp

@@ -15,8 +15,8 @@ QMapboxGLTest::QMapboxGLTest() : size(512, 512), fbo((assert(widget.context()->i
             this, SLOT(onMapChanged(QMapboxGL::MapChange)));
     connect(&map, SIGNAL(needsRendering()),
             this, SLOT(onNeedsRendering()));
-    map.resize(fbo.size(), fbo.size());
-    map.setFramebufferObject(fbo.handle());
+    map.resize(fbo.size());
+    map.setFramebufferObject(fbo.handle(), fbo.size());
     map.setCoordinateZoom(QMapbox::Coordinate(60.170448, 24.942046), 14);
 }