gesture recognizer: Some cleanup and workaround for a crash.

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 280 matching lines @@
 
   // Set a limit on the number of simultaneous touches in a gesture.
   if (event.touch_id() >= kMaxGesturePoints)
     return NULL;
 
   if (event.type() == ui::ET_TOUCH_PRESSED) {
     if (point_count_ == kMaxGesturePoints)
       return NULL;
     GesturePoint* new_point = &points_[event.touch_id()];
     // We shouldn't be able to get two PRESSED events from the same
-    // finger without either a RELEASE or CANCEL in between.
-    DCHECK(!new_point->in_use());
+    // finger without either a RELEASE or CANCEL in between. But let's not crash
+    // in a release build.
+    if (new_point->in_use()) {
+      LOG(ERROR) << "Received a second press for a point: " << event.touch_id();
+      new_point->ResetVelocity();
+      new_point->UpdateValues(event);
+      return NULL;
+    }
     new_point->set_point_id(point_count_++);
     new_point->set_touch_id(event.touch_id());
   }
 
   GestureState last_state = state_;
 
   // NOTE: when modifying these state transitions, also update gestures.dot
   scoped_ptr<Gestures> gestures(new Gestures());
   GesturePoint& point = GesturePointForEvent(event);
   point.UpdateValues(event);
   RecreateBoundingBox();
   flags_ = event.flags();
   const int point_id = points_[event.touch_id()].point_id();

[varunjain, 2012/08/13 20:40:44]

also change this to point.point_id()?

[sadrul, 2012/08/13 20:43:55]

Good point. Done.

   if (point_id < 0)
     return NULL;
 
   // Send GESTURE_BEGIN for any touch pressed.
   if (event.type() == ui::ET_TOUCH_PRESSED)
     AppendBeginGestureEvent(point, gestures.get());
 
   TouchStatusInternal status_internal = (status == ui::TOUCH_STATUS_UNKNOWN) ?
       TSI_NOT_PROCESSED : TSI_PROCESSED;
 
@@ skipping 18 matching lines @@
       break;
     case GST_PENDING_SYNTHETIC_CLICK_FIRST_MOVED:
     case GST_PENDING_SYNTHETIC_CLICK_FIRST_STATIONARY:
       if (ScrollStart(event, point, gestures.get())) {
         set_state(GS_SCROLL);
         if (ScrollUpdate(event, point, gestures.get()))
           point.UpdateForScroll();
       }
       break;
     case GST_PENDING_SYNTHETIC_CLICK_FIRST_CANCELLED:
-      NoGesture(event, 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:
@@ skipping 86 matching lines @@
 
   if (last_state == GS_PENDING_SYNTHETIC_CLICK && state_ != last_state)
     long_press_timer_->Stop();
 
   // The set of point_ids must be contiguous and include 0.
   // When a touch point is released, all points with ids greater than the
   // released point must have their ids decremented, or the set of point_ids
   // could end up with gaps.
   if (event.type() == ui::ET_TOUCH_RELEASED ||
       event.type() == ui::ET_TOUCH_CANCELLED) {
-    GesturePoint& old_point = points_[event.touch_id()];
     for (int i = 0; i < kMaxGesturePoints; ++i) {
-      GesturePoint& point = points_[i];
-      if (point.point_id() > old_point.point_id())
-        point.set_point_id(point.point_id() - 1);
+      GesturePoint& iter_point = points_[i];
+      if (iter_point.point_id() > point.point_id())
+        iter_point.set_point_id(iter_point.point_id() - 1);
     }
 
-    if (old_point.in_use()) {
-      old_point.Reset();
-      --point_count_;
-      DCHECK_GE(point_count_, 0);
-      RecreateBoundingBox();
-      if (state_ == GS_PINCH) {
-        pinch_distance_current_ = BoundingBoxDiagonal(bounding_box_);
-        pinch_distance_start_ = pinch_distance_current_;
-      }
+    point.Reset();
+    --point_count_;
+    CHECK_GE(point_count_, 0);
+    RecreateBoundingBox();
+    if (state_ == GS_PINCH) {
+      pinch_distance_current_ = BoundingBoxDiagonal(bounding_box_);
+      pinch_distance_start_ = pinch_distance_current_;
     }
   }
-
   return gestures.release();
 }
 
-void GestureSequence::Reset() {
-  set_state(GS_NO_GESTURE);
-  for (int i = 0; i < kMaxGesturePoints; ++i)
-    points_[i].Reset();
-  point_count_ = 0;
-}
-
 void GestureSequence::RecreateBoundingBox() {
   // TODO(sad): Recreating the bounding box at every touch-event is not very
   // efficient. This should be made better.
   int left = INT_MAX, top = INT_MAX, right = INT_MIN, bottom = INT_MIN;
   for (int i = 0; i < kMaxGesturePoints; ++i) {
     if (!points_[i].in_use())
       continue;
     gfx::Rect rect = points_[i].enclosing_rectangle();
     if (left > rect.x())
       left = rect.x();
@@ skipping 293 matching lines @@
 
 bool GestureSequence::ScrollUpdate(const TouchEvent& event,
     const GesturePoint& point, Gestures* gestures) {
   DCHECK(state_ == GS_SCROLL);
   if (!point.DidScroll(event, 0))
     return false;
   AppendScrollGestureUpdate(point, point.last_touch_position(), gestures);
   return true;
 }
 
-bool GestureSequence::NoGesture(const TouchEvent&,
-    const GesturePoint& point, Gestures*) {
-  Reset();
-  return false;
-}
-
 bool GestureSequence::TouchDown(const TouchEvent& event,
     const GesturePoint& point, Gestures* gestures) {
   DCHECK(state_ == GS_NO_GESTURE);
   AppendTapDownGestureEvent(point, gestures);
   long_press_timer_->Start(
       FROM_HERE,
       base::TimeDelta::FromMilliseconds(
           GestureConfiguration::long_press_time_in_seconds() * 1000),
       this,
       &GestureSequence::AppendLongPressGestureEvent);
@@ skipping 209 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