content/common/input/gesture_event_stream_validator.cc

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "content/common/input/gesture_event_stream_validator.h"
   6
   7 #include "base/logging.h"
   8 #include "third_party/WebKit/public/web/WebInputEvent.h"
   9
  10 using blink::WebInputEvent;
  11
  12 namespace content {
  13
  14 GestureEventStreamValidator::GestureEventStreamValidator()
  15     : scrolling_(false), pinching_(false), waiting_for_tap_end_(false) {
  16 }
  17
  18 GestureEventStreamValidator::~GestureEventStreamValidator() {
  19 }
  20
  21 bool GestureEventStreamValidator::Validate(const blink::WebGestureEvent& event,
  22                                            std::string* error_msg) {
  23   DCHECK(error_msg);
  24   error_msg->clear();
  25   switch (event.type) {
  26     case WebInputEvent::GestureScrollBegin:
  27       if (scrolling_)
  28         error_msg->append("Scroll begin during scroll\n");
  29       if (pinching_)
  30         error_msg->append("Scroll begin during pinch\n");
  31       scrolling_ = true;
  32       break;
  33     case WebInputEvent::GestureScrollUpdate:
  34     case WebInputEvent::GestureScrollUpdateWithoutPropagation:
  35       if (!scrolling_)
  36         error_msg->append("Scroll update outside of scroll\n");
  37       break;
  38     case WebInputEvent::GestureScrollEnd:
  39     case WebInputEvent::GestureFlingStart:
  40       if (!scrolling_)
  41         error_msg->append("Scroll end outside of scroll\n");
  42       if (pinching_)
  43         error_msg->append("Ending scroll while pinching\n");
  44       scrolling_ = false;
  45       break;
  46     case WebInputEvent::GesturePinchBegin:
  47       if (pinching_)
  48         error_msg->append("Pinch begin during pinch\n");
  49       pinching_ = true;
  50       break;
  51     case WebInputEvent::GesturePinchUpdate:
  52       if (!pinching_)
  53         error_msg->append("Pinch update outside of pinch\n");
  54       break;
  55     case WebInputEvent::GesturePinchEnd:
  56       if (!pinching_)
  57         error_msg->append("Pinch end outside of pinch\n");
  58       pinching_ = false;
  59       break;
  60     case WebInputEvent::GestureTapDown:
  61       if (waiting_for_tap_end_)
  62         error_msg->append("Missing tap end event\n");
  63       waiting_for_tap_end_ = true;
  64       break;
  65     case WebInputEvent::GestureTapUnconfirmed:
  66       if (!waiting_for_tap_end_)
  67         error_msg->append("Missing TapDown event before TapUnconfirmed\n");
  68       break;
  69     case WebInputEvent::GestureTapCancel:
  70       if (!waiting_for_tap_end_)
  71         error_msg->append("Missing TapDown event before TapCancel\n");
  72       waiting_for_tap_end_ = false;
  73       break;
  74     case WebInputEvent::GestureTap:
  75     case WebInputEvent::GestureDoubleTap:
  76       // Both Tap and DoubleTap gestures may be synthetically inserted, and do
  77       // not require a preceding TapDown.
  78       waiting_for_tap_end_ = false;
  79       break;
  80     default:
  81       break;
  82   }
  83   return error_msg->empty();
  84 }
  85
  86 }  // namespace content