Support 2d trackpad and mighty mouse scrolling on OS X.

webkit/glue/webinputevent_mac.mm

 /*
  * Copyright (C) 2004, 2006, 2007 Apple Inc. All rights reserved.
  * Copyright (C) 2006-2009 Google Inc.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 117 matching lines @@
   // Set coordinates by translating event coordinates from screen to client.
   NSPoint location = [NSEvent mouseLocation];  // global coordinates
   global_x = location.x;
   global_y = location.y;
   NSPoint windowLocal = [event locationInWindow];
   location = [view convertPoint:windowLocal fromView:nil];
   x = location.x;
   y = [view frame].size.height - location.y;  // flip y
 
   // Convert wheel delta amount to a number of pixels to scroll.
+  // Cocoa sets deltaX instead of deltaY if shift is pressed when scrolling
+  // with a scroll wheel, no need to do that ourselves.
   static const float kScrollbarPixelsPerTick = 40.0f;
-  float wheel_delta = [event deltaY];
-  const float delta_lines = wheel_delta * kScrollbarPixelsPerTick;
 
-  // Set scroll amount based on above calculations.
-  if ([event modifierFlags] & NSShiftKeyMask) {
-    delta_x = delta_lines;
-    delta_y = 0;
-    wheel_ticks_x = wheel_delta;
-    wheel_ticks_y = 0;
-  } else {
-    delta_x = 0;
-    delta_y = delta_lines;
-    wheel_ticks_x = 0;
-    wheel_ticks_y = wheel_delta;
-  }
+  wheel_ticks_x = [event deltaX];
+  delta_x = wheel_ticks_x * kScrollbarPixelsPerTick;
+
+  wheel_ticks_y = [event deltaY];
+  delta_y = wheel_ticks_y * kScrollbarPixelsPerTick;
+
   scroll_by_page = false;
 }
 
 // WebKeyboardEvent -----------------------------------------------------------
 
 // ----------------------------------------------------------------------
 // Begin Apple code, copied from KeyEventMac.mm
 //
 // We can share some of this code if we factored it out of KeyEventMac, but
 // the main problem is that it relies on the NSString ctor on String for
@@ skipping 843 matching lines @@
       [unmodified_str length] < kTextLengthCap) {
     [text_str getCharacters:&text[0]];
     [unmodified_str getCharacters:&unmodified_text[0]];
   } else {
     LOG(ERROR) << "Event had text too long; dropped";
   }
   [identifier_str getCString:&key_identifier[0]
                    maxLength:kIdentifierLengthCap
                     encoding:NSASCIIStringEncoding];
 }