Add GestureTapCancel gesture type

ui/base/gestures/gesture_sequence.cc

 // Copyright (c) 2012 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/base/gestures/gesture_sequence.h"
 
 #include <cmath>
 
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 350 matching lines @@
     case GST_INVALID:
       break;
 
     case GST_NO_GESTURE_FIRST_PRESSED:
       TouchDown(event, point, gestures.get());
       set_state(GS_PENDING_SYNTHETIC_CLICK);
       break;
     case GST_PENDING_SYNTHETIC_CLICK_FIRST_RELEASED:
       if (Click(event, point, gestures.get()))
         point.UpdateForTap();
+      else
+        AppendTapCancelGestureEvent(point, gestures.get());
       set_state(GS_NO_GESTURE);
       break;
     case GST_PENDING_SYNTHETIC_CLICK_FIRST_MOVED:
     case GST_PENDING_SYNTHETIC_CLICK_FIRST_STATIONARY:
       if (ScrollStart(event, point, gestures.get())) {
+        AppendTapCancelGestureEvent(point, gestures.get());

[sadrul, 2012/09/09 18:33:02]

This will add TAP_CANCEL after SCROLL_START. I think TAP_CANCEL should be before
SCROLL_START (and similarly, before PINCH_START). So AppendTapCancelGestureEvent
should be in ScrollStart, PinchStart (when state_ == PENDING_TAP), and
TwoFingerTouchDown (when state_ == PENDING_TAP)

[Rick Byers, 2012/09/10 00:56:26]

Yep, you're right - thanks.  I don't think it makes much difference in practice
which order they occur in, but I agree the order should be reversed.  I'll do
that.  

Since I was trying to make it clear that we send TapCancel (or Tap) on every
outgoing edge from the 'pending' state I wanted the sending of the event to be
next to the set_state calls (eg. it's not necessarily they case that we'll
always want to send this on every ScrollStart - in fact it gets more complicated
in this way in my fix for bug 146397), I'll come up with something.

BTW, this is something I don't like about our existing gesture recognizer unit
test infrastructure - it's too loose on what it validates (eg. makes it hard to
validate the order of events like this).  Tim's reworked log-based
infrastructure (that got reverted) was much better if I recall.  I'll see if
there's a small change I can make to validate this in the current infrastructure
without doing a major overhaul here.

         set_state(GS_SCROLL);
         if (ScrollUpdate(event, point, gestures.get()))
           point.UpdateForScroll();
       }
       break;
     case GST_PENDING_SYNTHETIC_CLICK_FIRST_RELEASED_HANDLED:
     case GST_PENDING_SYNTHETIC_CLICK_FIRST_CANCELLED:
+      AppendTapCancelGestureEvent(point, gestures.get());
       set_state(GS_NO_GESTURE);
       break;
     case GST_SCROLL_FIRST_MOVED:
       if (scroll_type_ == ST_VERTICAL ||
           scroll_type_ == ST_HORIZONTAL)
         BreakRailScroll(event, point, gestures.get());
       if (ScrollUpdate(event, point, gestures.get()))
         point.UpdateForScroll();
       break;
     case GST_SCROLL_FIRST_RELEASED:
     case GST_SCROLL_FIRST_CANCELLED:
       ScrollEnd(event, point, gestures.get());
       set_state(GS_NO_GESTURE);
       break;
+    case GST_PENDING_SYNTHETIC_CLICK_SECOND_PRESSED:
+      AppendTapCancelGestureEvent(point, gestures.get());
+      // fall through
     case GST_SCROLL_SECOND_PRESSED:
-    case GST_PENDING_SYNTHETIC_CLICK_SECOND_PRESSED:
       if (IsSecondTouchDownCloseEnoughForTwoFingerTap()) {
         TwoFingerTouchDown(event, point, gestures.get());
         set_state(GS_PENDING_TWO_FINGER_TAP);
       } else {
         PinchStart(event, point, gestures.get());
         set_state(GS_PINCH);
       }
       break;
     case GST_PENDING_TWO_FINGER_TAP_FIRST_RELEASED:
     case GST_PENDING_TWO_FINGER_TAP_SECOND_RELEASED:
@@ skipping 181 matching lines @@
 void GestureSequence::AppendTapDownGestureEvent(const GesturePoint& point,
                                                 Gestures* gestures) {
   gestures->push_back(CreateGestureEvent(
       GestureEventDetails(ui::ET_GESTURE_TAP_DOWN, 0, 0),
       point.first_touch_position(),
       flags_,
       base::Time::FromDoubleT(point.last_touch_time()),
       1 << point.touch_id()));
 }
 
+void GestureSequence::AppendTapCancelGestureEvent(const GesturePoint& point,
+                                            Gestures* gestures) {
+    gestures->push_back(CreateGestureEvent(
+      GestureEventDetails(ui::ET_GESTURE_TAP_CANCEL, 0, 0),
+      point.first_touch_position(),
+      flags_,
+      base::Time::FromDoubleT(point.last_touch_time()),
+      1 << point.touch_id()));
+}
+
 void GestureSequence::AppendBeginGestureEvent(const GesturePoint& point,
                                               Gestures* gestures) {
   gestures->push_back(CreateGestureEvent(
       GestureEventDetails(ui::ET_GESTURE_BEGIN, 0, 0),
       point.first_touch_position(),
       flags_,
       base::Time::FromDoubleT(point.last_touch_time()),
       1 << point.touch_id()));
 }
 
@@ skipping 443 matching lines @@
     return;
 
   // Since long press timer has been started, there should be a non-NULL point.
   const GesturePoint* point = GetPointByPointId(0);
   if (!ui::gestures::IsInsideManhattanSquare(point->first_touch_position(),
       event.location()))
     long_press_timer_->Stop();
 }
 
 }  // namespace ui