Adding momentum/overscroll to views:: ScrollViews

ui/events/cocoa/events_mac.mm

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/events/event_utils.h"
 
 #include <Cocoa/Cocoa.h>
 #include <stdint.h>
 
 #include "base/logging.h"
@@ skipping 25 matching lines @@
     case NSRightMouseUp:
     case NSOtherMouseUp:
       return ET_MOUSE_RELEASED;
     case NSLeftMouseDragged:
     case NSRightMouseDragged:
     case NSOtherMouseDragged:
       return ET_MOUSE_DRAGGED;
     case NSMouseMoved:
       return ET_MOUSE_MOVED;
     case NSScrollWheel:
-      return ET_MOUSEWHEEL;
+      return ET_SCROLL;
     case NSMouseEntered:
       return ET_MOUSE_ENTERED;
     case NSMouseExited:
       return ET_MOUSE_EXITED;
     case NSEventTypeSwipe:
       return ET_SCROLL_FLING_START;
     case NSAppKitDefined:
     case NSSystemDefined:
       return ET_UNKNOWN;
     case NSFlagsChanged:
@@ skipping 89 matching lines @@
     // -scrollingDelta{X|Y} have float return types but they return values that
     // are already rounded to integers.
     // The values are the same as the values returned from calling
     // CGEventGetIntegerValueField(kCGScrollWheelEventPointDeltaAxis{1|2}).
     return gfx::Vector2d([event scrollingDeltaX], [event scrollingDeltaY]);
   } else {
     // Empirically, a value of 0.1 is typical for one mousewheel click. Positive
     // values when scrolling up or to the left. Scrolling quickly results in a
     // higher delta per click, up to about 15.0. (Quartz documentation suggests
     // +/-10).
-    // Multiply by 1000 to vaguely approximate WHEEL_DELTA on Windows (120).
-    const CGFloat kWheelDeltaMultiplier = 1000;
-    return gfx::Vector2d(kWheelDeltaMultiplier * [event deltaX],
-                         kWheelDeltaMultiplier * [event deltaY]);
+    // Use the same multiplier as content::WebMouseWheelEventBuilder.
+    const double kScrollbarPixelsPerCocoaTick = 40.0;
+    return gfx::Vector2d(kScrollbarPixelsPerCocoaTick * [event deltaX],
+                         kScrollbarPixelsPerCocoaTick * [event deltaY]);
   }
 }
 
 base::NativeEvent CopyNativeEvent(const base::NativeEvent& event) {
   return [event copy];
 }
 
 void ReleaseCopiedNativeEvent(const base::NativeEvent& event) {
   [event release];
 }
@@ skipping 21 matching lines @@
                         /* force */ 0.f,
                         /* tilt_x */ 0.f,
                         /* tilt_y */ 0.f);
 }
 
 bool GetScrollOffsets(const base::NativeEvent& native_event,
                       float* x_offset,
                       float* y_offset,
                       float* x_offset_ordinal,
                       float* y_offset_ordinal,
-                      int* finger_count) {
-  NOTIMPLEMENTED();
-  return false;
+                      int* finger_count,
+                      int* momentum_phase) {
+  gfx::Vector2d offset = GetMouseWheelOffset(native_event);
+  *x_offset_ordinal = offset.x();
+  *y_offset_ordinal = offset.y();
+
+  // For non-scrolling events, the finger count can be determined with
+  // [[native_event touchesMatchingPhase:NSTouchPhaseTouching inView:nil] count]
+  // but it's illegal to ask that of scroll events, so say two fingers.
+  *finger_count = 2;
+
+  // If a user just rests two fingers on the touchpad without moving, AppKit
+  // uses NSEventPhaseMayBegin. Treat this the same as NSEventPhaseBegan.
+  const NSUInteger kBeginPhaseMask = NSEventPhaseBegan | NSEventPhaseMayBegin;
+  const NSUInteger kEndPhaseMask = NSEventPhaseCancelled | NSEventPhaseEnded;
+
+  if ([native_event phase] & kBeginPhaseMask)
+    *momentum_phase |= EM_PHASE_MAY_BEGIN;
+
+  if (([native_event phase] | [native_event momentumPhase]) & kEndPhaseMask)
+    *momentum_phase |= EM_PHASE_END;
+  else if ([native_event momentumPhase] != NSEventPhaseNone)
+    *momentum_phase |= EM_PHASE_INERTIAL_UPDATE;
+
+  // If the event completely lacks phase information, there won't be further
+  // updates, so they must be treated as an end.
+  if (([native_event phase] | [native_event momentumPhase]) == NSEventPhaseNone)
+    *momentum_phase |= EM_PHASE_END;
+
+  return true;
 }
 
 bool GetFlingData(const base::NativeEvent& native_event,
                   float* vx,
                   float* vy,
                   float* vx_ordinal,
                   float* vy_ordinal,
                   bool* is_cancel) {
   NOTIMPLEMENTED();
   return false;
@@ skipping 47 matching lines @@
   uint16_t return_value;
   [text getCharacters:&return_value];
   return return_value;
 }
 
 bool IsCharFromNative(const base::NativeEvent& native_event) {
   return false;
 }
 
 }  // namespace ui