blob: 85bc469443315e516f26d4b362b75fdbd1146903 [file] [log] [blame]
// 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 "content/common/input/touch_event_stream_validator.h"
#include "base/logging.h"
#include "content/common/input/web_touch_event_traits.h"
using blink::WebInputEvent;
using blink::WebTouchEvent;
using blink::WebTouchPoint;
namespace content {
namespace {
const WebTouchPoint* FindTouchPoint(const WebTouchEvent& event, int id) {
for (unsigned i = 0; i < event.touchesLength; ++i) {
if (event.touches[i].id == id)
return &event.touches[i];
return NULL;
} // namespace
TouchEventStreamValidator::TouchEventStreamValidator() {
TouchEventStreamValidator::~TouchEventStreamValidator() {
bool TouchEventStreamValidator::Validate(const WebTouchEvent& event,
std::string* error_msg) {
WebTouchEvent previous_event = previous_event_;
previous_event_ = event;
// Allow "hard" restarting of touch stream validation. This is necessary
// in cases where touch event forwarding ceases in response to the event ack
// or removal of touch handlers.
if (WebTouchEventTraits::IsTouchSequenceStart(event))
previous_event = WebTouchEvent();
// Unreleased points from the previous event should exist in the latest event.
for (unsigned i = 0; i < previous_event.touchesLength; ++i) {
const WebTouchPoint& previous_point = previous_event.touches[i];
if (previous_point.state == WebTouchPoint::StateCancelled ||
previous_point.state == WebTouchPoint::StateReleased)
const WebTouchPoint* point = FindTouchPoint(event,;
if (!point)
error_msg->append("Previously active touch point not in new event.\n");
for (unsigned i = 0; i < event.touchesLength; ++i) {
const WebTouchPoint& point = event.touches[i];
const WebTouchPoint* previous_point =
// The point should exist in the previous event if it is not a new point.
if (!previous_point) {
if (point.state != WebTouchPoint::StatePressed)
error_msg->append("Active touch point not found in previous event.\n");
} else {
if (point.state == WebTouchPoint::StatePressed &&
previous_point->state != WebTouchPoint::StateCancelled &&
previous_point->state != WebTouchPoint::StateReleased) {
error_msg->append("Pressed touch point id already exists.\n");
switch (point.state) {
case WebTouchPoint::StateUndefined:
error_msg->append("Undefined WebTouchPoint state.\n");
case WebTouchPoint::StateReleased:
if (event.type != WebInputEvent::TouchEnd)
error_msg->append("Released touch point outside touchend.\n");
case WebTouchPoint::StatePressed:
if (event.type != WebInputEvent::TouchStart)
error_msg->append("Pressed touch point outside touchstart.\n");
case WebTouchPoint::StateMoved:
if (event.type != WebInputEvent::TouchMove)
error_msg->append("Moved touch point outside touchmove.\n");
case WebTouchPoint::StateStationary:
case WebTouchPoint::StateCancelled:
if (event.type != WebInputEvent::TouchCancel)
error_msg->append("Cancelled touch point outside touchcancel.\n");
return error_msg->empty();
} // namespace content