Differential D13901 Diff 53070 lib/touch/twofingerpan.cpp

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lib/touch/twofingerpan.cpp

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1		/*
2		Gwenview: an image viewer
3		Copyright 2019 Steffen Hartleib <steffenhartleib@t-online.de>
4
	ngrahamUnsubmitted Not Done Your copyright ngraham: Your copyright
5		This program is free software; you can redistribute it and/or
6		modify it under the terms of the GNU General Public License
7		as published by the Free Software Foundation; either version 2
8		of the License, or (at your option) any later version.
9
10		This program is distributed in the hope that it will be useful,
11		but WITHOUT ANY WARRANTY; without even the implied warranty of
12		MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13		GNU General Public License for more details.
14
15		You should have received a copy of the GNU General Public License
16		along with this program; if not, write to the Free Software
17		Foundation, Inc., 51 Franklin Street, Fifth Floor, Cambridge, MA 02110-1301, USA.
18
19		*/
20		// Self
21		#include "twofingerpan.h"
22
23		// Qt
24		#include <QTouchEvent>
25		#include <QDebug>
26		#include <QVector2D>
27		#include <QGraphicsWidget>
28
29		// KDE
30
31		// Local
32		#include "lib/touch/touch_helper.h"
33
34		namespace Gwenview
35		{
36
37		struct TwoFingerPanRecognizerPrivate
38		{
39		TwoFingerPanRecognizer* q;
40		bool mTargetIsGrapicsWidget = false;
41		qint64 mTouchBeginnTimestamp;
42		bool mGestureTriggered;
43		qint64 mLastTouchTimestamp;
44		};
45
46		TwoFingerPanRecognizer::TwoFingerPanRecognizer() : QGestureRecognizer()
47		, d (new TwoFingerPanRecognizerPrivate)
48		{
49		d->q = this;
50		}
51
52		TwoFingerPanRecognizer::~TwoFingerPanRecognizer()
53		{
54		delete d;
55		}
56
57		QGesture* TwoFingerPanRecognizer::create(QObject*)
58		{
59		return static_cast<QGesture*>(new TwoFingerPan());
60		}
61
62		QGestureRecognizer::Result TwoFingerPanRecognizer::recognize(QGesture* state, QObject* watched, QEvent* event)
63		{
64		//Because of a bug in Qt in a gesture event in a graphicsview, all gestures are trigger twice
65		//https://bugreports.qt.io/browse/QTBUG-13103
66		if (qobject_cast<QGraphicsWidget*>(watched)) d->mTargetIsGrapicsWidget = true;
67		if (d->mTargetIsGrapicsWidget && watched->isWidgetType()) return Ignore;
68
69		switch (event->type()) {
70		case QEvent::TouchBegin: {
71		QTouchEvent* touchEvent = static_cast<QTouchEvent*>(event);
72		d->mTouchBeginnTimestamp = touchEvent->timestamp();
73		d->mLastTouchTimestamp = touchEvent->timestamp();
74		d->mGestureTriggered = false;
75		state->setProperty("delayActive", true);
76		state->setHotSpot(touchEvent->touchPoints().first().screenPos());
77		return TriggerGesture;
78		}
79
80		case QEvent::TouchUpdate: {
81		QTouchEvent* touchEvent = static_cast<QTouchEvent*>(event);
82		const qint64 now = touchEvent->timestamp();
83		const QPointF pos = touchEvent->touchPoints().first().pos();
84		state->setHotSpot(touchEvent->touchPoints().first().screenPos());
85
86		if (touchEvent->touchPoints().size() >> 2) {
87		if (d->mGestureTriggered) {
88		d->mGestureTriggered = false;
89		}
90		return CancelGesture;
91		}
92
93		if (touchEvent->touchPoints().size() == 2) {
94		if (touchEvent->touchPointStates() & Qt::TouchPointReleased) {
95		if (d->mGestureTriggered) {
96		d->mGestureTriggered = false;
97		return FinishGesture;
98		}
99		}
100
101		if (now - d->mTouchBeginnTimestamp >= Touch_Helper::Touch::gestureDelay) {
102		state ->setProperty("delayActive", false);
103
104		//Check if both touch points moving in the same direction
105		const QVector2D vectorTouchPoint1 = QVector2D (touchEvent->touchPoints().at(0).startPos() - touchEvent->touchPoints().at(0).pos());
106		const QVector2D vectorTouchPoint2 = QVector2D (touchEvent->touchPoints().at(1).startPos() - touchEvent->touchPoints().at(1).pos());
107		QVector2D dotProduct = vectorTouchPoint1 * vectorTouchPoint2;
108
109		//The dot product is greater than zero if both touch points moving in the same direction
110		//special case if the touch point moving exact or almost exact in x or y axis
111		//one value of the dot product is zero or a little bit less than zero and
112		//the other value is bigger than zero
113		if (dotProduct.x() >= -500 && dotProduct.x() <= 0 && dotProduct.y() > 0) dotProduct.setX(1);
114		if (dotProduct.y() >= -500 && dotProduct.y() <= 0 && dotProduct.x() > 0) dotProduct.setY(1);
115
116		if (dotProduct.x() > 0 && dotProduct.y() > 0) {
117		const QPointF diff = (touchEvent->touchPoints().first().lastPos() - pos);
118		state->setProperty("delta", diff);
119		d->mGestureTriggered = true;
120		return TriggerGesture;
121		} else {
122		//special case if the user makes a very slow pan gesture, the vectors a very short. Sometimes the
123		//dot product is then zero, so we only want to cancel the gesture if the user makes a bigger wrong gesture
124		if (vectorTouchPoint1.toPoint().manhattanLength() > 50 \|\| vectorTouchPoint2.toPoint().manhattanLength() > 50 ) {
125		d->mGestureTriggered = false;
126		return CancelGesture;
127		} else {
128		const QPointF diff = (touchEvent->touchPoints().first().lastPos() - pos);
129		state->setProperty("delta", diff);
130		d->mGestureTriggered = true;
131		return TriggerGesture;
132		}
133		}
134		} else {
135		state->setProperty("delta", QPointF (0, 0));
136		state->setProperty("delayActive", true);
137		d->mGestureTriggered = false;
138		return TriggerGesture;
139		}
140		}
141		break;
142		}
143
144		case QEvent::TouchEnd: {
145		QTouchEvent* touchEvent = static_cast<QTouchEvent*>(event);
146		if (d->mGestureTriggered) {
147		d->mGestureTriggered = false;
148		state->setHotSpot(touchEvent->touchPoints().first().screenPos());
149		return FinishGesture;
150		}
151		break;
152		}
153
154		default:
155		return Ignore;
156		}
157		return Ignore;
158		}
159
160		TwoFingerPan::TwoFingerPan(QObject* parent)
161		: QGesture(parent)
162		{
163		}
164
165		} // namespace