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 "base/strings/stringprintf.h"
   9 #include "content/common/input/web_input_event_traits.h"
  10 #include "third_party/WebKit/public/web/WebInputEvent.h"
  11
  12 using blink::WebInputEvent;
  13
  14 namespace content {
  15
  16 GestureEventStreamValidator::GestureEventStreamValidator()
  17     : scrolling_(false), pinching_(false), waiting_for_tap_end_(false) {
  18 }
  19
  20 GestureEventStreamValidator::~GestureEventStreamValidator() {
  21 }
  22
  23 bool GestureEventStreamValidator::Validate(const blink::WebGestureEvent& event,
  24                                            std::string* error_msg) {
  25   DCHECK(error_msg);
  26   error_msg->clear();
  27   if (!WebInputEvent::isGestureEventType(event.type)) {
  28     error_msg->append(base::StringPrintf(
  29         "Invalid gesture type: %s", WebInputEventTraits::GetName(event.type)));
  30   }
  31   switch (event.type) {
  32     case WebInputEvent::GestureScrollBegin:
  33       if (scrolling_)
  34         error_msg->append("Scroll begin during scroll\n");
  35       if (pinching_)
  36         error_msg->append("Scroll begin during pinch\n");
  37       scrolling_ = true;
  38       break;
  39     case WebInputEvent::GestureScrollUpdate:
  40       if (!scrolling_)
  41         error_msg->append("Scroll update outside of scroll\n");
  42       break;
  43     case WebInputEvent::GestureFlingStart:
  44       if (event.sourceDevice == blink::WebGestureDeviceTouchscreen &&
  45           !event.data.flingStart.velocityX &&
  46           !event.data.flingStart.velocityY) {
  47         error_msg->append("Zero velocity touchscreen fling\n");
  48       }
  49       if (!scrolling_)
  50         error_msg->append("Fling start outside of scroll\n");
  51       if (pinching_)
  52         error_msg->append("Flinging while pinching\n");
  53       scrolling_ = false;
  54       break;
  55     case WebInputEvent::GestureScrollEnd:
  56       if (!scrolling_)
  57         error_msg->append("Scroll end outside of scroll\n");
  58       if (pinching_)
  59         error_msg->append("Ending scroll while pinching\n");
  60       scrolling_ = false;
  61       break;
  62     case WebInputEvent::GesturePinchBegin:
  63       if (pinching_)
  64         error_msg->append("Pinch begin during pinch\n");
  65       pinching_ = true;
  66       break;
  67     case WebInputEvent::GesturePinchUpdate:
  68       if (!pinching_)
  69         error_msg->append("Pinch update outside of pinch\n");
  70       break;
  71     case WebInputEvent::GesturePinchEnd:
  72       if (!pinching_)
  73         error_msg->append("Pinch end outside of pinch\n");
  74       pinching_ = false;
  75       break;
  76     case WebInputEvent::GestureTapDown:
  77       if (waiting_for_tap_end_)
  78         error_msg->append("Missing tap ending event before TapDown\n");
  79       waiting_for_tap_end_ = true;
  80       break;
  81     case WebInputEvent::GestureTapUnconfirmed:
  82       if (!waiting_for_tap_end_)
  83         error_msg->append("Missing TapDown event before TapUnconfirmed\n");
  84       break;
  85     case WebInputEvent::GestureTapCancel:
  86       if (!waiting_for_tap_end_)
  87         error_msg->append("Missing TapDown event before TapCancel\n");
  88       waiting_for_tap_end_ = false;
  89       break;
  90     case WebInputEvent::GestureTap:
  91       if (!waiting_for_tap_end_)
  92         error_msg->append("Missing TapDown event before Tap\n");
  93       waiting_for_tap_end_ = false;
  94       break;
  95     case WebInputEvent::GestureDoubleTap:
  96       // DoubleTap gestures may be synthetically inserted, and do not require a
  97       // preceding TapDown.
  98       waiting_for_tap_end_ = false;
  99       break;
 100     default:
 101       break;
 102   }
 103   return error_msg->empty();
 104 }
 105
 106 }  // namespace content