macosx: invert scrolling direction if the devices inverts its event

aka if you scroll to the right, you want the movie to skip to the right, etc.

NEWS

 Changes between 1.1.10 and 1.1.11-git:
 ----------------------------------
 
+Mac OS X Interface:
+ * Fixed scrolling direction if the input device's signal is inverted
+
 Translations:
  * Update of Slovak, Lithunanian
 

modules/gui/macosx/controls.m

@@ -559,19 +559,41 @@
 - (void)scrollWheel:(NSEvent *)theEvent
 {
     intf_thread_t * p_intf = VLCIntf;
+    BOOL b_invertedEventFromDevice = NO;
+    if ([theEvent respondsToSelector:@selector(isDirectionInvertedFromDevice)] )
+    {
+        if ([theEvent isDirectionInvertedFromDevice] )
+            b_invertedEventFromDevice = YES;
+    }
+
     float f_yabsvalue = [theEvent deltaY] > 0.0f ? [theEvent deltaY] : -[theEvent deltaY];
     float f_xabsvalue = [theEvent deltaX] > 0.0f ? [theEvent deltaX] : -[theEvent deltaX];
     int i, i_yvlckey, i_xvlckey;
 
-    if ([theEvent deltaY] < 0.0f)
-        i_yvlckey = KEY_MOUSEWHEELDOWN;
-    else
-        i_yvlckey = KEY_MOUSEWHEELUP;
+    if (b_invertedEventFromDevice )
+    {
+        if ([theEvent deltaY] > 0.0f)
+            i_yvlckey = KEY_MOUSEWHEELDOWN;
+        else
+            i_yvlckey = KEY_MOUSEWHEELUP;
 
-    if ([theEvent deltaX] < 0.0f)
-        i_xvlckey = KEY_MOUSEWHEELRIGHT;
+        if ([theEvent deltaX] > 0.0f)
+            i_xvlckey = KEY_MOUSEWHEELRIGHT;
+        else
+            i_xvlckey = KEY_MOUSEWHEELLEFT;
+    }
     else
-        i_xvlckey = KEY_MOUSEWHEELLEFT;
+    {
+        if ([theEvent deltaY] < 0.0f)
+            i_yvlckey = KEY_MOUSEWHEELDOWN;
+        else
+            i_yvlckey = KEY_MOUSEWHEELUP;
+
+        if ([theEvent deltaX] < 0.0f)
+            i_xvlckey = KEY_MOUSEWHEELRIGHT;
+        else
+            i_xvlckey = KEY_MOUSEWHEELLEFT;
+    }
 
     /* Send multiple key event, depending on the intensity of the event */
     for (i = 0; i < (int)(f_yabsvalue/4.+1.) && f_yabsvalue > 0.05 ; i++)