Touch Events - changedTouches list includes non-changed touch points on Android

content/browser/renderer_host/input/touch_event_queue.cc

 // Copyright 2013 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 "content/browser/renderer_host/input/touch_event_queue.h"
 
 #include "base/auto_reset.h"
 #include "base/debug/trace_event.h"
 #include "base/stl_util.h"
 #include "content/browser/renderer_host/input/timeout_monitor.h"
@@ skipping 89 matching lines @@
       case PENDING_ACK_NONE:
         if (ack_result == INPUT_EVENT_ACK_STATE_CONSUMED)
           enabled_for_current_sequence_ = false;
         timeout_monitor_.Stop();
         return false;
       case PENDING_ACK_ORIGINAL_EVENT:
         if (AckedTimeoutEventRequiresCancel(ack_result)) {
           SetPendingAckState(PENDING_ACK_CANCEL_EVENT);
           TouchEventWithLatencyInfo cancel_event =
               ObtainCancelEventForTouchEvent(timeout_event_);
-          touch_queue_->SendTouchEventImmediately(cancel_event);
+          touch_queue_->SendTouchEventImmediately(&cancel_event);
         } else {
           SetPendingAckState(PENDING_ACK_NONE);
           touch_queue_->UpdateTouchConsumerStates(timeout_event_.event,
                                                   ack_result);
         }
         return true;
       case PENDING_ACK_CANCEL_EVENT:
         SetPendingAckState(PENDING_ACK_NONE);
         return true;
     }
@@ skipping 397 matching lines @@
     if (pending_async_touchmove_->CanCoalesceWith(touch)) {
       pending_async_touchmove_->CoalesceWith(touch);
       pending_async_touchmove_->event.cancelable = !send_touch_events_async_;
       touch = *pending_async_touchmove_;
       pending_async_touchmove_.reset();
     } else {
       scoped_ptr<TouchEventWithLatencyInfo> async_move =
           pending_async_touchmove_.Pass();
       async_move->event.cancelable = false;
       touch_queue_.push_front(new CoalescedWebTouchEvent(*async_move, true));
-      SendTouchEventImmediately(*async_move);
+      SendTouchEventImmediately(async_move.get());
       return;
     }
   }
 
   // Note: Marking touchstart events as not-cancelable prevents them from
   // blocking subsequent gestures, but it may not be the best long term solution
   // for tracking touch point dispatch.
   if (send_touch_events_async_)
     touch.event.cancelable = false;
 
   // A synchronous ack will reset |dispatching_touch_|, in which case
   // the touch timeout should not be started.
   base::AutoReset<bool> dispatching_touch(&dispatching_touch_, true);
-  SendTouchEventImmediately(touch);
+  SendTouchEventImmediately(&touch);
   if (dispatching_touch_ && timeout_handler_)
     timeout_handler_->StartIfNecessary(touch);
 }
 
 void TouchEventQueue::OnGestureScrollEvent(
     const GestureEventWithLatencyInfo& gesture_event) {
   if (gesture_event.event.type == blink::WebInputEvent::GestureScrollBegin) {
     if (!touch_consumer_states_.is_empty() &&
         !drop_remaining_touches_in_sequence_) {
       DCHECK(!touchmove_slop_suppressor_->suppressing_touchmoves())
@@ skipping 143 matching lines @@
 }
 
 scoped_ptr<CoalescedWebTouchEvent> TouchEventQueue::PopTouchEvent() {
   DCHECK(!touch_queue_.empty());
   scoped_ptr<CoalescedWebTouchEvent> event(touch_queue_.front());
   touch_queue_.pop_front();
   return event.Pass();
 }
 
 void TouchEventQueue::SendTouchEventImmediately(
-    const TouchEventWithLatencyInfo& touch) {
+    TouchEventWithLatencyInfo* touch) {
   if (needs_async_touchmove_for_outer_slop_region_) {
     // Any event other than a touchmove (e.g., touchcancel or secondary
     // touchstart) after a scroll has started will interrupt the need to send a
     // an outer slop-region exceeding touchmove.
-    if (touch.event.type != WebInputEvent::TouchMove ||
-        OutsideApplicationSlopRegion(touch.event,
+    if (touch->event.type != WebInputEvent::TouchMove ||
+        OutsideApplicationSlopRegion(touch->event,
                                      touch_sequence_start_position_))
       needs_async_touchmove_for_outer_slop_region_ = false;
   }
 
-  client_->SendTouchEventImmediately(touch);
+  // For touchmove events, compare touch points position from current event
+  // to last sent event and update touch points state.
+  if (touch->event.type == WebInputEvent::TouchMove) {
+    CHECK(last_sent_touchevent_);
+    for (unsigned int i = 0; i < last_sent_touchevent_->touchesLength; ++i) {
+      const WebTouchPoint& last_touch_point =
+          last_sent_touchevent_->touches[i];
+      // Touches with same id may not have same index in Touches array.
+      for (unsigned int j = 0; j < touch->event.touchesLength; ++j) {
+        const WebTouchPoint& current_touchmove_point = touch->event.touches[j];
+        if (last_touch_point.id == current_touchmove_point.id) {

[jdduke (slow), 2015/01/09 17:33:05]

Style nit: With this many nested levels, let's invert the condition for
readability:

if (last_touch_point.id != current_touchmove_point.id)
  continue;
...

[USE s.singapati at gmail.com, 2015/01/12 19:30:26]

Done.

+          if (current_touchmove_point.position.x == last_touch_point.position.x

[jdduke (slow), 2015/01/09 17:33:05]

I think this can just be:

if (current_touchmove_point.position == last_touch_point.position)
  touch->event.touches[j].state = WebTouchPoint::Stationary;
...

[USE s.singapati at gmail.com, 2015/01/12 19:30:26]

Done.

+              && current_touchmove_point.position.y ==
+                  last_touch_point.position.y) {
+            touch->event.touches[j].state = WebTouchPoint::StateStationary;
+          }
+          break;
+        }
+      }
+    }
+  }
+
+  if (last_sent_touchevent_)
+    *last_sent_touchevent_ = touch->event;
+  else
+    last_sent_touchevent_.reset(new WebTouchEvent(touch->event));
+
+  client_->SendTouchEventImmediately(*touch);
 }
 
 TouchEventQueue::PreFilterResult
 TouchEventQueue::FilterBeforeForwarding(const WebTouchEvent& event) {
   if (timeout_handler_ && timeout_handler_->FilterEvent(event))
     return ACK_WITH_NO_CONSUMER_EXISTS;
 
   if (touchmove_slop_suppressor_->FilterEvent(event))
     return ACK_WITH_NOT_CONSUMED;
 
   if (WebTouchEventTraits::IsTouchSequenceStart(event)) {
     touch_consumer_states_.clear();
     send_touch_events_async_ = false;
     pending_async_touchmove_.reset();
+    last_sent_touchevent_.reset();
+
     touch_sequence_start_position_ = gfx::PointF(event.touches[0].position);
     drop_remaining_touches_in_sequence_ = false;
     if (!has_handlers_) {
       drop_remaining_touches_in_sequence_ = true;
       return ACK_WITH_NO_CONSUMER_EXISTS;
     }
   }
 
   if (drop_remaining_touches_in_sequence_ &&
       event.type != WebInputEvent::TouchCancel) {
@@ skipping 35 matching lines @@
         if (ack_result != INPUT_EVENT_ACK_STATE_NO_CONSUMER_EXISTS)
           touch_consumer_states_.mark_bit(point.id);
         else
           touch_consumer_states_.clear_bit(point.id);
       }
     }
   }
 }
 
 }  // namespace content