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// Copyright 2014 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "components/input/gesture_event_stream_validator.h"
#include "base/check.h"
#include "base/strings/stringprintf.h"
#include "third_party/blink/public/common/input/web_gesture_event.h"
#include "third_party/blink/public/common/input/web_input_event.h"
#include "ui/events/blink/web_input_event_traits.h"
using blink::WebInputEvent;
namespace input {
GestureEventStreamValidator::GestureEventStreamValidator()
: scrolling_(false), pinching_(false), waiting_for_tap_end_(false) {
}
GestureEventStreamValidator::~GestureEventStreamValidator() {
}
bool GestureEventStreamValidator::Validate(
const blink::WebGestureEvent& event,
std::string* error_msg) {
DCHECK(error_msg);
error_msg->clear();
if (!WebInputEvent::IsGestureEventType(event.GetType())) {
error_msg->append(base::StringPrintf(
"Invalid gesture type: %s", WebInputEvent::GetName(event.GetType())));
}
switch (event.GetType()) {
case WebInputEvent::Type::kGestureScrollBegin:
if (scrolling_)
error_msg->append("Scroll begin during scroll\n");
if (pinching_)
error_msg->append("Scroll begin during pinch\n");
scrolling_ = true;
break;
case WebInputEvent::Type::kGestureScrollUpdate:
if (!scrolling_)
error_msg->append("Scroll update outside of scroll\n");
break;
case WebInputEvent::Type::kGestureFlingStart:
if (event.SourceDevice() == blink::WebGestureDevice::kTouchscreen &&
!event.data.fling_start.velocity_x &&
!event.data.fling_start.velocity_y) {
error_msg->append("Zero velocity touchscreen fling\n");
}
if (!scrolling_)
error_msg->append("Fling start outside of scroll\n");
if (pinching_)
error_msg->append("Flinging while pinching\n");
// Don't reset scrolling_ since the GSE sent by the fling_controller_ at
// the end of the fling resets it.
break;
case WebInputEvent::Type::kGestureScrollEnd:
if (!scrolling_)
error_msg->append("Scroll end outside of scroll\n");
if (pinching_)
error_msg->append("Ending scroll while pinching\n");
scrolling_ = false;
break;
case WebInputEvent::Type::kGesturePinchBegin:
if (pinching_)
error_msg->append("Pinch begin during pinch\n");
pinching_ = true;
break;
case WebInputEvent::Type::kGesturePinchUpdate:
if (!pinching_)
error_msg->append("Pinch update outside of pinch\n");
break;
case WebInputEvent::Type::kGesturePinchEnd:
if (!pinching_)
error_msg->append("Pinch end outside of pinch\n");
pinching_ = false;
break;
case WebInputEvent::Type::kGestureTapDown:
if (waiting_for_tap_end_)
error_msg->append("Missing tap ending event before TapDown\n");
waiting_for_tap_end_ = true;
break;
case WebInputEvent::Type::kGestureTapUnconfirmed:
if (!waiting_for_tap_end_)
error_msg->append("Missing TapDown event before TapUnconfirmed\n");
break;
case WebInputEvent::Type::kGestureTapCancel:
if (!waiting_for_tap_end_)
error_msg->append("Missing TapDown event before TapCancel\n");
waiting_for_tap_end_ = false;
break;
case WebInputEvent::Type::kGestureTap:
if (!waiting_for_tap_end_)
error_msg->append("Missing TapDown event before Tap\n");
waiting_for_tap_end_ = false;
break;
case WebInputEvent::Type::kGestureDoubleTap:
// DoubleTap gestures may be synthetically inserted, and do not require a
// preceding TapDown.
waiting_for_tap_end_ = false;
break;
default:
break;
}
// TODO(wjmaclean): At some future point we may wish to consider adding a
// 'continuity check', requiring that all events between an initial tap-down
// and whatever terminates the sequence to have the same source device type,
// and that touchpad gestures are only found on ScrollEvents.
if (event.SourceDevice() == blink::WebGestureDevice::kUninitialized)
error_msg->append("Gesture event source is uninitialized.\n");
return error_msg->empty();
}
} // namespace input
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