Platform: fix iOS display orientation events in Sdl2Application.

src/Magnum/Platform/Sdl2Application.cpp

@@ -321,10 +321,18 @@ void Sdl2Application::mainLoop() {
         switch(event.type) {
             case SDL_WINDOWEVENT:
                 switch(event.window.event) {
-                    case SDL_WINDOWEVENT_RESIZED:
+                    case SDL_WINDOWEVENT_RESIZED: {
+                        #ifndef CORRADE_TARGET_IOS
                         viewportEvent({event.window.data1, event.window.data2});
+                        #else
+                        /* On iOS the window event is in points and not pixels,
+                           but we need pixels to call glViewport() properly */
+                        Vector2i drawableSize;
+                        SDL_GL_GetDrawableSize(_window, &drawableSize.x(), &drawableSize.y());
+                        viewportEvent(drawableSize);
+                        #endif
                         _flags |= Flag::Redraw;
-                        break;
+                    } break;
                     case SDL_WINDOWEVENT_EXPOSED:
                         _flags |= Flag::Redraw;
                         break;

src/Magnum/Platform/Sdl2Application.h

@@ -576,7 +576,12 @@ class Sdl2Application::Configuration {
          * @see @ref WindowFlags, @ref setWindowFlags()
          */
         enum class WindowFlag: Uint32 {
-            Resizable = SDL_WINDOW_RESIZABLE,       /**< Resizable window */
+            /**
+             * Resizable window. On iOS this allows the application to respond
+             * to display orientation changes.
+             */
+            Resizable = SDL_WINDOW_RESIZABLE,
+
             Fullscreen = SDL_WINDOW_FULLSCREEN,     /**< Fullscreen window */
 
             /** No window decoration. On iOS this hides the menu bar. */