Handle keyboard in QML

src/magnum_render.h

@@ -45,6 +45,7 @@ public:
         m_count(count) {}
 
   void draw(const Matrix4 &transformation, SceneGraph::Camera3D &camera);
+
   void count(int count);
   void hue(float hue);
   void t(float t);
@@ -62,6 +63,9 @@ public:
   MagnumRenderer();
   ~MagnumRenderer();
 
+  /**
+   * @brief Called when Qt needs to resize/re-create FBO.
+   */
   void reset(Platform::GLContext *ctx,
              GL::Framebuffer fbo,
              Vector2i windowSize,
@@ -72,16 +76,25 @@ public:
   void t(float t);
   void hue(float hue);
   void count(int count);
-  Containers::Optional<ArcBallCamera> camera();
+
+  Containers::Optional<ArcBallCamera>& camera();
+  void lagging(float lagging);
+  float lagging();
 
 private:
+  /**
+   * @brief We need to delay initialization until we have valid OpenGL context.
+   */
   void lazyInitialize();
+  /**
+   * @brief Reset OpenGL state to our desired state.
+   */
   void prepGLState();
 
   bool m_init;
   int m_count;
 
-  Platform::GLContext *m_ctx;
+  Platform::GLContext *m_ctx{nullptr};
   GL::Framebuffer m_FBO{NoCreate};
 
   Scene3D m_scene;