Platform: added ScreenedApplication::globalBeforeDrawEvent().

doc/changelog.dox

@@ -404,6 +404,7 @@ See also:
     default to 32-bit RGBA color buffer instead of 24-bit RGB, to avoid the
     framebuffer degrading to 16-bit colors on some platforms (see
     [mosra/magnum-integration#59](https://github.com/mosra/magnum-integration/issues/59))
+-   Added @ref Platform::BasicScreenedApplication::globalBeforeDrawEvent()
 
 @subsubsection changelog-latest-changes-trade Trade library
 

src/Magnum/Platform/ScreenedApplication.h

@@ -293,13 +293,23 @@ template<class Application> class BasicScreenedApplication:
          */
         virtual void globalViewportEvent(typename Application::ViewportEvent& size);
 
+        /**
+         * @brief Before draw event
+         * @m_since_latest
+         *
+         * Called *before* all screens' @ref BasicScreen::drawEvent() "drawEvent()".
+         * Unlike @ref globalDrawEvent() doesn't need to be implemented.
+         */
+        virtual void globalBeforeDrawEvent();
+
         /**
          * @brief Draw event
          *
          * Called *after* all screens' @ref BasicScreen::drawEvent() "drawEvent()".
          * You should call at least @ref Sdl2Application::swapBuffers() "swapBuffers()".
          * If you want to draw immediately again, call also
-         * @ref Sdl2Application::redraw() "redraw()".
+         * @ref Sdl2Application::redraw() "redraw()". See also
+         * @ref globalBeforeDrawEvent().
          */
         virtual void globalDrawEvent() = 0;
 
@@ -308,9 +318,9 @@ template<class Application> class BasicScreenedApplication:
         friend Containers::LinkedListItem<BasicScreen<Application>, BasicScreenedApplication<Application>>;
         friend BasicScreen<Application>;
         #endif
-        /* The user is supposed to override only globalViewportEvent() and
+        /* The user is supposed to override only globalViewportEvent(),
-           globalDrawEvent(), these implementations are dispatching the events
+           globalDrawEvent() and possibly globalBeforeDrawEvent(), these
-           to attached screens. */
+           implementations are dispatching the events to attached screens. */
         void viewportEvent(typename Application::ViewportEvent& event) override final;
         void drawEvent() override final;
         void mousePressEvent(typename Application::MouseEvent& event) override final;

src/Magnum/Platform/ScreenedApplication.hpp

@@ -212,7 +212,12 @@ template<class Application> void BasicScreenedApplication<Application>::viewport
     for(BasicScreen<Application>& s: *this) s.viewportEvent(event);
 }
 
+template<class Application> void BasicScreenedApplication<Application>::globalBeforeDrawEvent() {}
+
 template<class Application> void BasicScreenedApplication<Application>::drawEvent() {
+    /* Call the "before" global event before all other */
+    globalBeforeDrawEvent();
+
     /* Back-to-front rendering */
     for(BasicScreen<Application>* s = screens().last(); s; s = s->nextNearerScreen())
         if(s->propagatedEvents() & Implementation::PropagatedScreenEvent::Draw) s->drawEvent();