169 lines
6.1 KiB
C++

/*
Gwenview: an image viewer
Copyright 2019 Steffen Hartleib <steffenhartleib@t-online.de>
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Cambridge, MA 02110-1301, USA.
*/
// Self
#include "twofingerpan.h"
// Qt
#include <QGraphicsWidget>
#include <QTouchEvent>
#include <QVector2D>
// KF
// Local
#include "gwenview_lib_debug.h"
#include "lib/touch/touch_helper.h"
namespace Gwenview
{
struct TwoFingerPanRecognizerPrivate {
TwoFingerPanRecognizer *q = nullptr;
bool mTargetIsGrapicsWidget = false;
qint64 mTouchBeginnTimestamp;
bool mGestureTriggered;
qint64 mLastTouchTimestamp;
};
TwoFingerPanRecognizer::TwoFingerPanRecognizer()
: QGestureRecognizer()
, d(new TwoFingerPanRecognizerPrivate)
{
d->q = this;
}
TwoFingerPanRecognizer::~TwoFingerPanRecognizer()
{
delete d;
}
QGesture *TwoFingerPanRecognizer::create(QObject *)
{
return static_cast<QGesture *>(new TwoFingerPan());
}
QGestureRecognizer::Result TwoFingerPanRecognizer::recognize(QGesture *state, QObject *watched, QEvent *event)
{
// Because of a bug in Qt in a gesture event in a graphicsview, all gestures are trigger twice
// https://bugreports.qt.io/browse/QTBUG-13103
if (qobject_cast<QGraphicsWidget *>(watched))
d->mTargetIsGrapicsWidget = true;
if (d->mTargetIsGrapicsWidget && watched->isWidgetType())
return Ignore;
switch (event->type()) {
case QEvent::TouchBegin: {
auto touchEvent = static_cast<QTouchEvent *>(event);
d->mTouchBeginnTimestamp = touchEvent->timestamp();
d->mLastTouchTimestamp = touchEvent->timestamp();
d->mGestureTriggered = false;
state->setProperty("delayActive", true);
state->setHotSpot(touchEvent->touchPoints().first().screenPos());
return TriggerGesture;
}
case QEvent::TouchUpdate: {
auto touchEvent = static_cast<QTouchEvent *>(event);
const qint64 now = touchEvent->timestamp();
const QPointF pos = touchEvent->touchPoints().first().pos();
state->setHotSpot(touchEvent->touchPoints().first().screenPos());
if (touchEvent->touchPoints().size() >> 2) {
if (d->mGestureTriggered) {
d->mGestureTriggered = false;
}
return CancelGesture;
}
if (touchEvent->touchPoints().size() == 2) {
if (touchEvent->touchPointStates() & Qt::TouchPointReleased) {
if (d->mGestureTriggered) {
d->mGestureTriggered = false;
return FinishGesture;
}
}
if (now - d->mTouchBeginnTimestamp >= Touch_Helper::Touch::gestureDelay) {
state->setProperty("delayActive", false);
// Check if both touch points moving in the same direction
const QVector2D vectorTouchPoint1 = QVector2D(touchEvent->touchPoints().at(0).startPos() - touchEvent->touchPoints().at(0).pos());
const QVector2D vectorTouchPoint2 = QVector2D(touchEvent->touchPoints().at(1).startPos() - touchEvent->touchPoints().at(1).pos());
QVector2D dotProduct = vectorTouchPoint1 * vectorTouchPoint2;
// The dot product is greater than zero if both touch points moving in the same direction
// special case if the touch point moving exact or almost exact in x or y axis
// one value of the dot product is zero or a little bit less than zero and
// the other value is bigger than zero
if (dotProduct.x() >= -500 && dotProduct.x() <= 0 && dotProduct.y() > 0)
dotProduct.setX(1);
if (dotProduct.y() >= -500 && dotProduct.y() <= 0 && dotProduct.x() > 0)
dotProduct.setY(1);
if (dotProduct.x() > 0 && dotProduct.y() > 0) {
const QPointF diff = (touchEvent->touchPoints().first().lastPos() - pos);
state->setProperty("delta", diff);
d->mGestureTriggered = true;
return TriggerGesture;
} else {
// special case if the user makes a very slow pan gesture, the vectors a very short. Sometimes the
// dot product is then zero, so we only want to cancel the gesture if the user makes a bigger wrong gesture
if (vectorTouchPoint1.toPoint().manhattanLength() > 50 || vectorTouchPoint2.toPoint().manhattanLength() > 50) {
d->mGestureTriggered = false;
return CancelGesture;
} else {
const QPointF diff = (touchEvent->touchPoints().first().lastPos() - pos);
state->setProperty("delta", diff);
d->mGestureTriggered = true;
return TriggerGesture;
}
}
} else {
state->setProperty("delta", QPointF(0, 0));
state->setProperty("delayActive", true);
d->mGestureTriggered = false;
return TriggerGesture;
}
}
break;
}
case QEvent::TouchEnd: {
auto touchEvent = static_cast<QTouchEvent *>(event);
if (d->mGestureTriggered) {
d->mGestureTriggered = false;
state->setHotSpot(touchEvent->touchPoints().first().screenPos());
return FinishGesture;
}
break;
}
default:
return Ignore;
}
return Ignore;
}
TwoFingerPan::TwoFingerPan(QObject *parent)
: QGesture(parent)
{
}
} // namespace