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// 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 "content/browser/renderer_host/touch_event_queue.h"
#include "base/debug/trace_event.h"
#include "base/stl_util.h"
#include "content/browser/renderer_host/render_widget_host_impl.h"
#include "content/public/browser/render_widget_host_view.h"
#include "content/port/browser/render_widget_host_view_port.h"
namespace content {
typedef std::vector<WebKit::WebTouchEvent> WebTouchEventList;
// This class represents a single coalesced touch event. However, it also keeps
// track of all the original touch-events that were coalesced into a single
// event. The coalesced event is forwarded to the renderer, while the original
// touch-events are sent to the View (on ACK for the coalesced event) so that
// the View receives the event with their original timestamp.
class CoalescedWebTouchEvent {
public:
explicit CoalescedWebTouchEvent(const WebKit::WebTouchEvent& event)
: coalesced_event_(event) {
events_.push_back(event);
TRACE_EVENT_ASYNC_BEGIN0(
"input", "TouchEventQueue::QueueEvent", this);
}
~CoalescedWebTouchEvent() {
TRACE_EVENT_ASYNC_END0(
"input", "TouchEventQueue::QueueEvent", this);
}
// Coalesces the event with the existing event if possible. Returns whether
// the event was coalesced.
bool CoalesceEventIfPossible(const WebKit::WebTouchEvent& event) {
if (coalesced_event_.type == WebKit::WebInputEvent::TouchMove &&
event.type == WebKit::WebInputEvent::TouchMove &&
coalesced_event_.modifiers == event.modifiers &&
coalesced_event_.touchesLength == event.touchesLength) {
events_.push_back(event);
// The WebTouchPoints include absolute position information. So it is
// sufficient to simply replace the previous event with the new event.
// However, it is necessary to make sure that all the points have the
// correct state, i.e. the touch-points that moved in the last event, but
// didn't change in the current event, will have Stationary state. It is
// necessary to change them back to Moved state.
const WebKit::WebTouchEvent last_event = coalesced_event_;
coalesced_event_ = event;
for (unsigned i = 0; i < last_event.touchesLength; ++i) {
if (last_event.touches[i].state == WebKit::WebTouchPoint::StateMoved)
coalesced_event_.touches[i].state = WebKit::WebTouchPoint::StateMoved;
}
return true;
}
return false;
}
const WebKit::WebTouchEvent& coalesced_event() const {
return coalesced_event_;
}
WebTouchEventList::const_iterator begin() const {
return events_.begin();
}
WebTouchEventList::const_iterator end() const {
return events_.end();
}
size_t size() const { return events_.size(); }
private:
// This is the event that is forwarded to the renderer.
WebKit::WebTouchEvent coalesced_event_;
// This is the list of the original events that were coalesced.
WebTouchEventList events_;
DISALLOW_COPY_AND_ASSIGN(CoalescedWebTouchEvent);
};
TouchEventQueue::TouchEventQueue(RenderWidgetHostImpl* host)
: render_widget_host_(host) {
}
TouchEventQueue::~TouchEventQueue() {
if (!touch_queue_.empty())
STLDeleteElements(&touch_queue_);
}
void TouchEventQueue::QueueEvent(const WebKit::WebTouchEvent& event) {
if (touch_queue_.empty()) {
// There is no touch event in the queue. Forward it to the renderer
// immediately.
touch_queue_.push_back(new CoalescedWebTouchEvent(event));
if (ShouldForwardToRenderer(event))
render_widget_host_->ForwardTouchEventImmediately(event);
else
PopTouchEventToView(INPUT_EVENT_ACK_STATE_NO_CONSUMER_EXISTS);
return;
}
// If the last queued touch-event was a touch-move, and the current event is
// also a touch-move, then the events can be coalesced into a single event.
if (touch_queue_.size() > 1) {
CoalescedWebTouchEvent* last_event = touch_queue_.back();
if (last_event->CoalesceEventIfPossible(event))
return;
}
touch_queue_.push_back(new CoalescedWebTouchEvent(event));
}
void TouchEventQueue::ProcessTouchAck(InputEventAckState ack_result) {
if (touch_queue_.empty())
return;
// Update the ACK status for each touch point in the ACKed event.
const WebKit::WebTouchEvent& event = touch_queue_.front()->coalesced_event();
if (event.type == WebKit::WebInputEvent::TouchEnd ||
event.type == WebKit::WebInputEvent::TouchCancel) {
// The points have been released. Erase the ACK states.
for (unsigned i = 0; i < event.touchesLength; ++i) {
const WebKit::WebTouchPoint& point = event.touches[i];
if (point.state == WebKit::WebTouchPoint::StateReleased ||
point.state == WebKit::WebTouchPoint::StateCancelled)
touch_ack_states_.erase(point.id);
}
} else if (event.type == WebKit::WebInputEvent::TouchStart) {
for (unsigned i = 0; i < event.touchesLength; ++i) {
const WebKit::WebTouchPoint& point = event.touches[i];
if (point.state == WebKit::WebTouchPoint::StatePressed)
touch_ack_states_[point.id] = ack_result;
}
}
PopTouchEventToView(ack_result);
// If there are queued touch events, then try to forward them to the renderer
// immediately, or ACK the events back to the view if appropriate.
while (!touch_queue_.empty()) {
const WebKit::WebTouchEvent& touch =
touch_queue_.front()->coalesced_event();
if (ShouldForwardToRenderer(touch)) {
render_widget_host_->ForwardTouchEventImmediately(touch);
break;
}
PopTouchEventToView(INPUT_EVENT_ACK_STATE_NO_CONSUMER_EXISTS);
}
}
void TouchEventQueue::FlushQueue() {
while (!touch_queue_.empty())
PopTouchEventToView(INPUT_EVENT_ACK_STATE_NOT_CONSUMED);
}
void TouchEventQueue::Reset() {
touch_queue_.clear();
}
size_t TouchEventQueue::GetQueueSize() const {
return touch_queue_.size();
}
const WebKit::WebTouchEvent& TouchEventQueue::GetLatestEvent() const {
return touch_queue_.back()->coalesced_event();
}
void TouchEventQueue::PopTouchEventToView(InputEventAckState ack_result) {
if (touch_queue_.empty())
return;
scoped_ptr<CoalescedWebTouchEvent> acked_event(touch_queue_.front());
touch_queue_.pop_front();
// Note that acking the touch-event may result in multiple gestures being sent
// to the renderer.
RenderWidgetHostViewPort* view = RenderWidgetHostViewPort::FromRWHV(
render_widget_host_->GetView());
for (WebTouchEventList::const_iterator iter = acked_event->begin(),
end = acked_event->end();
iter != end; ++iter) {
view->ProcessAckedTouchEvent((*iter), ack_result);
}
}
bool TouchEventQueue::ShouldForwardToRenderer(
const WebKit::WebTouchEvent& event) const {
// Touch press events should always be forwarded to the renderer.
if (event.type == WebKit::WebInputEvent::TouchStart)
return true;
for (unsigned int i = 0; i < event.touchesLength; ++i) {
const WebKit::WebTouchPoint& point = event.touches[i];
// If a point has been stationary, then don't take it into account.
if (point.state == WebKit::WebTouchPoint::StateStationary)
continue;
if (touch_ack_states_.count(point.id) > 0) {
if (touch_ack_states_.find(point.id)->second !=
INPUT_EVENT_ACK_STATE_NO_CONSUMER_EXISTS)
return true;
} else {
// If the ACK status of a point is unknown, then the event should be
// forwarded to the renderer.
return true;
}
}
return false;
}
} // namespace content
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