1/*
2 * Copyright (C) 2011 Benjamin Poulain <benjamin@webkit.org>
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 *    notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 *    notice, this list of conditions and the following disclaimer in the
11 *    documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
14 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
15 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
17 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
18 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
19 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
20 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
21 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
22 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
23 * THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#include "config.h"
27#include "QtPinchGestureRecognizer.h"
28
29
30#include "PageViewportControllerClientQt.h"
31#include "QtWebPageEventHandler.h"
32#include <QtCore/QLineF>
33
34namespace WebKit {
35
36const qreal pinchInitialTriggerDistanceThreshold = 5.;
37
38static inline QPointF computePinchCenter(const QTouchEvent::TouchPoint& point1, const QTouchEvent::TouchPoint& point2)
39{
40    return (point1.pos() + point2.pos()) / 2.0f;
41}
42
43QtPinchGestureRecognizer::QtPinchGestureRecognizer(QtWebPageEventHandler* eventHandler)
44    : QtGestureRecognizer(eventHandler)
45{
46    reset();
47}
48
49bool QtPinchGestureRecognizer::update(const QTouchEvent::TouchPoint& point1, const QTouchEvent::TouchPoint& point2)
50{
51    const qreal currentFingerDistance = QLineF(point1.screenPos(), point2.screenPos()).length();
52    switch (m_state) {
53    case NoGesture:
54        m_initialFingerDistance = currentFingerDistance;
55        m_state = GestureRecognitionStarted;
56        return false;
57    case GestureRecognitionStarted: {
58        const qreal pinchDistance = qAbs(currentFingerDistance - m_initialFingerDistance);
59        if (pinchDistance < pinchInitialTriggerDistanceThreshold)
60            return false;
61        m_state = GestureRecognized;
62        if (viewportController())
63            viewportController()->pinchGestureStarted(computePinchCenter(point1, point2));
64
65        // We reset the initial span distance to the current distance of the
66        // touch points in order to avoid the jump caused by the events which
67        // were skipped between the recognition start and the actual recognition.
68        m_initialFingerDistance = currentFingerDistance;
69
70        // fall through
71    }
72    case GestureRecognized:
73        const qreal totalScaleFactor = currentFingerDistance / m_initialFingerDistance;
74        const QPointF touchCenterInViewCoordinates = computePinchCenter(point1, point2);
75        if (viewportController())
76            viewportController()->pinchGestureRequestUpdate(touchCenterInViewCoordinates, totalScaleFactor);
77        return true;
78        break;
79    }
80
81    ASSERT_NOT_REACHED();
82    return false;
83}
84
85void QtPinchGestureRecognizer::finish()
86{
87    if (m_state == NoGesture)
88        return;
89
90    if (viewportController())
91        viewportController()->pinchGestureEnded();
92    reset();
93}
94
95void QtPinchGestureRecognizer::cancel()
96{
97    if (m_state == NoGesture)
98        return;
99
100    if (viewportController())
101        viewportController()->pinchGestureCancelled();
102    reset();
103}
104
105} // namespace WebKit
106
107