Split Sdl2Application mainLoopIteration in event, tickEvent and drawEvent parts

src/Magnum/Platform/Sdl2Application.cpp

@@ -847,21 +847,7 @@ void Sdl2Application::exit(const int exitCode) {
     _exitCode = exitCode;
 }
 
-bool Sdl2Application::mainLoopIteration() {
-    /* If exit was requested directly in the constructor, exit immediately
-       without calling anything else */
-    if(_flags & Flag::Exit) return false;
-
-    #ifndef CORRADE_TARGET_EMSCRIPTEN
-    CORRADE_ASSERT(_window, "Platform::Sdl2Application::mainLoopIteration(): no window opened", {});
-    #else
-    CORRADE_ASSERT(_surface, "Platform::Sdl2Application::mainLoopIteration(): no window opened", {});
-    #endif
-
-    #ifndef CORRADE_TARGET_EMSCRIPTEN
-    const UnsignedInt timeBefore = _minimalLoopPeriod ? SDL_GetTicks() : 0;
-    #endif
-
+bool Sdl2Application::mainLoopEventIteration() {
     #ifdef CORRADE_TARGET_EMSCRIPTEN
     /* The resize event is not fired on window resize, so poll for the canvas
        size here. But only if the window was requested to be resizable, to
@@ -993,15 +979,50 @@ bool Sdl2Application::mainLoopIteration() {
             default: if(!(_flags & Flag::NoAnyEvent)) anyEvent(event);
         }
     }
+    return !(_flags & Flag::Exit);
+}
 
-    /* Tick event */
-    if(!(_flags & Flag::NoTickEvent)) tickEvent();
+bool Sdl2Application::mainLoopTickEventIteration() {
+    if(!(_flags & Flag::NoTickEvent)) {
+        tickEvent();
+        return true;
+    }
+    return false;
+}
 
-    /* Draw event */
+bool Sdl2Application::mainLoopDrawEventIteration() {
     if(_flags & Flag::Redraw) {
         _flags &= ~Flag::Redraw;
         drawEvent();
+        return true;
+    }
+    return false;  
+}
+
+bool Sdl2Application::mainLoopIteration() {
+    /* If exit was requested directly in the constructor, exit immediately
+       without calling anything else */
+    if(_flags & Flag::Exit) return false;
+
+    #ifndef CORRADE_TARGET_EMSCRIPTEN
+    CORRADE_ASSERT(_window, "Platform::Sdl2Application::mainLoopIteration(): no window opened", {});
+    #else
+    CORRADE_ASSERT(_surface, "Platform::Sdl2Application::mainLoopIteration(): no window opened", {});
+    #endif
+
+    #ifndef CORRADE_TARGET_EMSCRIPTEN
+    const UnsignedInt timeBefore = _minimalLoopPeriod ? SDL_GetTicks() : 0;
+    #endif
+
+    /* exit was requested in the event loop */
+    if (!mainLoopEventIteration())
+        return false;
+
+    /* call tickEvent() if implemented */
+    mainLoopTickEventIteration();
 
+    /* drawEvent() was called */
+    if (mainLoopDrawEventIteration()) {
         #ifndef CORRADE_TARGET_EMSCRIPTEN
         /* If VSync is not enabled, delay to prevent CPU hogging (if set) */
         if(!(_flags & Flag::VSyncEnabled) && _minimalLoopPeriod) {

src/Magnum/Platform/Sdl2Application.h

@@ -571,13 +571,41 @@ class Sdl2Application {
          * @return @cpp false @ce if @ref exit() was called and the application
          *      should exit, @cpp true @ce otherwise
          *
+         * Calls @ref mainLoopEventIteration(), @ref mainLoopTickEventIteration() and
+         * @ref mainLoopDrawEventIteration() managing the delays between them.
          * Called internally from @ref exec(). If you want to have better
          * control over how the main loop behaves, you can call this function
+         * (or the sub mainLoopIteration functions)
          * yourself from your own `main()` function instead of it being called
          * automatically from @ref exec() / @ref MAGNUM_SDL2APPLICATION_MAIN().
          */
         bool mainLoopIteration();
 
+        /**
+         * @brief Process pending application events
+         * @return @cpp false @ce if @ref exit() was called and the application
+         *      should exit, @cpp true @ce otherwise
+         * 
+         * Called internally from @ref mainLoopIteration().
+         */
+        bool mainLoopEventIteration();
+
+        /**
+         * @brief Calls @ref tickEvent() if implemented
+         * @return @cpp true @ce if @ref tickEvent() was called, @cpp false @ce otherwise
+         * 
+         * Called internally from @ref mainLoopIteration().
+         */
+        bool mainLoopTickEventIteration();
+
+        /**
+         * @brief Calls @ref drawEvent() if @ref Flag::Redraw is set and unset it.
+         * @return @cpp true @ce if @ref drawEvent() was called, @cpp false @ce otherwise
+         * 
+         * Called internally from @ref mainLoopIteration().
+         */
+        bool mainLoopDrawEventIteration();
+
         /**
          * @brief Exit application
          * @param exitCode  The exit code the application should return