add in support for passing down the "natural" (or flipped) scrolling direction in the MouseWheelEvent event

include/SDL_events.h

@@ -260,6 +260,7 @@ typedef struct SDL_MouseWheelEvent
     Uint32 which;       /**< The mouse instance id, or SDL_TOUCH_MOUSEID */
     Sint32 x;           /**< The amount scrolled horizontally, positive to the right and negative to the left */
     Sint32 y;           /**< The amount scrolled vertically, positive away from the user and negative toward the user */
+    Uint32 direction;   /**< Set to one of the SDL_MOUSEWHEEL_* defines. When FLIPPED the values in X and Y will be opposite. Multiply by -1 to change them back */
 } SDL_MouseWheelEvent;
 
 /**

include/SDL_mouse.h

@@ -60,6 +60,15 @@ typedef enum
     SDL_NUM_SYSTEM_CURSORS
 } SDL_SystemCursor;
 
+/**
+ * \brief Scroll direction types for the Scroll event
+ */
+typedef enum
+{
+    SDL_MOUSEWHEEL_NORMAL,    /**< The scroll direction is normal */
+    SDL_MOUSEWHEEL_FLIPPED    /**< The scroll direction is flipped / natural */
+} SDL_MouseWheelDirection;
+
 /* Function prototypes */
 
 /**

src/core/linux/SDL_evdev.c

@@ -681,10 +681,10 @@ SDL_EVDEV_Poll(void)
                         SDL_SendMouseMotion(mouse->focus, mouse->mouseID, SDL_TRUE, 0, events[i].value);
                         break;
                     case REL_WHEEL:
-                        SDL_SendMouseWheel(mouse->focus, mouse->mouseID, 0, events[i].value);
+                        SDL_SendMouseWheel(mouse->focus, mouse->mouseID, 0, events[i].value, SDL_MOUSEWHEEL_NORMAL);
                         break;
                     case REL_HWHEEL:
-                        SDL_SendMouseWheel(mouse->focus, mouse->mouseID, events[i].value, 0);
+                        SDL_SendMouseWheel(mouse->focus, mouse->mouseID, events[i].value, 0, SDL_MOUSEWHEEL_NORMAL);
                         break;
                     default:
                         break;

src/events/SDL_mouse.c

@@ -397,7 +397,7 @@ SDL_SendMouseButton(SDL_Window * window, SDL_MouseID mouseID, Uint8 state, Uint8
 }
 
 int
-SDL_SendMouseWheel(SDL_Window * window, SDL_MouseID mouseID, int x, int y)
+SDL_SendMouseWheel(SDL_Window * window, SDL_MouseID mouseID, int x, int y, SDL_MouseWheelDirection direction)
 {
     SDL_Mouse *mouse = SDL_GetMouse();
     int posted;
@@ -419,6 +419,7 @@ SDL_SendMouseWheel(SDL_Window * window, SDL_MouseID mouseID, int x, int y)
         event.wheel.which = mouseID;
         event.wheel.x = x;
         event.wheel.y = y;
+        event.wheel.direction = (Uint32)direction;
         posted = (SDL_PushEvent(&event) > 0);
     }
     return posted;

src/events/SDL_mouse_c.h

@@ -120,7 +120,7 @@ extern int SDL_SendMouseMotion(SDL_Window * window, SDL_MouseID mouseID, int rel
 extern int SDL_SendMouseButton(SDL_Window * window, SDL_MouseID mouseID, Uint8 state, Uint8 button);
 
 /* Send a mouse wheel event */
-extern int SDL_SendMouseWheel(SDL_Window * window, SDL_MouseID mouseID, int x, int y);
+extern int SDL_SendMouseWheel(SDL_Window * window, SDL_MouseID mouseID, int x, int y, SDL_MouseWheelDirection direction);
 
 /* Shutdown the mouse subsystem */
 extern void SDL_MouseQuit(void);

src/main/haiku/SDL_BApp.h

@@ -254,7 +254,7 @@ private:
             return;
         }
         win = GetSDLWindow(winID);
-        SDL_SendMouseWheel(win, 0, xTicks, yTicks);
+        SDL_SendMouseWheel(win, 0, xTicks, yTicks, SDL_MOUSEWHEEL_NORMAL);
     }
 
     void _HandleKey(BMessage *msg) {

src/video/cocoa/SDL_cocoamouse.m

@@ -399,6 +399,13 @@ Cocoa_HandleMouseWheel(SDL_Window *window, NSEvent *event)
 
     float x = -[event deltaX];
     float y = [event deltaY];
+    SDL_MouseWheelDirection direction = SDL_MOUSEWHEEL_NORMAL;
+
+    if ([event respondsToSelector:@selector(isDirectionInvertedFromDevice)]) {
+        if ([event isDirectionInvertedFromDevice] == YES) {
+            direction = SDL_MOUSEWHEEL_FLIPPED;
+        }
+    }
 
     if (x > 0) {
         x += 0.9f;
@@ -410,7 +417,7 @@ Cocoa_HandleMouseWheel(SDL_Window *window, NSEvent *event)
     } else if (y < 0) {
         y -= 0.9f;
     }
-    SDL_SendMouseWheel(window, mouse->mouseID, (int)x, (int)y);
+    SDL_SendMouseWheel(window, mouse->mouseID, (int)x, (int)y, direction);
 }
 
 void

src/video/mir/SDL_mirevents.c

@@ -137,7 +137,7 @@ HandleTouchMotion(int device_id, int source_id, float x, float y, float pressure
 static void
 HandleMouseScroll(SDL_Window* sdl_window, int hscroll, int vscroll)
 {
-    SDL_SendMouseWheel(sdl_window, 0, hscroll, vscroll);
+    SDL_SendMouseWheel(sdl_window, 0, hscroll, vscroll, SDL_MOUSEWHEEL_NORMAL);
 }
 
 static void

src/video/nacl/SDL_naclevents.c

@@ -357,7 +357,7 @@ void NACL_PumpEvents(_THIS) {
                     case PP_INPUTEVENT_TYPE_WHEEL:
                         /* FIXME: GetTicks provides high resolution scroll events */
                         fp = driverdata->ppb_wheel_input_event->GetDelta(event);
-                        SDL_SendMouseWheel(mouse->focus, mouse->mouseID, (int) fp.x, (int) fp.y);
+                        SDL_SendMouseWheel(mouse->focus, mouse->mouseID, (int) fp.x, (int) fp.y, SDL_MOUSEWHEEL_NORMAL);
                         break;
                         
                     case PP_INPUTEVENT_TYPE_MOUSEENTER:

src/video/wayland/SDL_waylandevents.c

@@ -184,7 +184,7 @@ pointer_handle_axis(void *data, struct wl_pointer *pointer,
                 return;
         }
 
-        SDL_SendMouseWheel(window->sdlwindow, 0, x, y);
+        SDL_SendMouseWheel(window->sdlwindow, 0, x, y, SDL_MOUSEWHEEL_NORMAL);
     }
 }
 

src/video/windows/SDL_windowsevents.c

@@ -498,12 +498,12 @@ WIN_WindowProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
             s_AccumulatedMotion += GET_WHEEL_DELTA_WPARAM(wParam);
             if (s_AccumulatedMotion > 0) {
                 while (s_AccumulatedMotion >= WHEEL_DELTA) {
-                    SDL_SendMouseWheel(data->window, 0, 0, 1);
+                    SDL_SendMouseWheel(data->window, 0, 0, 1, SDL_MOUSEWHEEL_NORMAL);
                     s_AccumulatedMotion -= WHEEL_DELTA;
                 }
             } else {
                 while (s_AccumulatedMotion <= -WHEEL_DELTA) {
-                    SDL_SendMouseWheel(data->window, 0, 0, -1);
+                    SDL_SendMouseWheel(data->window, 0, 0, -1, SDL_MOUSEWHEEL_NORMAL);
                     s_AccumulatedMotion += WHEEL_DELTA;
                 }
             }
@@ -517,12 +517,12 @@ WIN_WindowProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
             s_AccumulatedMotion += GET_WHEEL_DELTA_WPARAM(wParam);
             if (s_AccumulatedMotion > 0) {
                 while (s_AccumulatedMotion >= WHEEL_DELTA) {
-                    SDL_SendMouseWheel(data->window, 0, 1, 0);
+                    SDL_SendMouseWheel(data->window, 0, 1, 0, SDL_MOUSEWHEEL_NORMAL);
                     s_AccumulatedMotion -= WHEEL_DELTA;
                 }
             } else {
                 while (s_AccumulatedMotion <= -WHEEL_DELTA) {
-                    SDL_SendMouseWheel(data->window, 0, -1, 0);
+                    SDL_SendMouseWheel(data->window, 0, -1, 0, SDL_MOUSEWHEEL_NORMAL);
                     s_AccumulatedMotion += WHEEL_DELTA;
                 }
             }

src/video/winrt/SDL_winrtpointerinput.cpp

@@ -315,7 +315,7 @@ WINRT_ProcessPointerWheelChangedEvent(SDL_Window *window, Windows::UI::Input::Po
 
     // FIXME: This may need to accumulate deltas up to WHEEL_DELTA
     short motion = pointerPoint->Properties->MouseWheelDelta / WHEEL_DELTA;
-    SDL_SendMouseWheel(window, 0, 0, motion);
+    SDL_SendMouseWheel(window, 0, 0, motion, SDL_MOUSEWHEEL_NORMAL);
 }
 
 void

src/video/x11/SDL_x11events.c

@@ -990,7 +990,7 @@ X11_DispatchEvent(_THIS)
     case ButtonPress:{
             int ticks = 0;
             if (X11_IsWheelEvent(display,&xevent,&ticks)) {
-                SDL_SendMouseWheel(data->window, 0, 0, ticks);
+                SDL_SendMouseWheel(data->window, 0, 0, ticks, SDL_MOUSEWHEEL_NORMAL);
             } else {
                 if(xevent.xbutton.button == Button1) {
                     if (ProcessHitTest(_this, data, &xevent)) {