File indexing completed on 2024-05-12 04:19:51

 /*
 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 "doubletap.h"
 
 // Qt
 #include <QGraphicsWidget>
 #include <QTouchEvent>
 
 // KF
 
 // Local
 #include "gwenview_lib_debug.h"
 #include "lib/touch/touch_helper.h"
 
 namespace Gwenview
 {
 struct DoubleTapRecognizerPrivate {
     DoubleTapRecognizer *q = nullptr;
     bool mTargetIsGrapicsWidget = false;
     qint64 mTouchBeginnTimestamp;
     bool mIsOnlyTap;
     qint64 mLastTapTimestamp = 0;
     qint64 mLastDoupleTapTimestamp = 0;
 };
 
 DoubleTapRecognizer::DoubleTapRecognizer()
     : QGestureRecognizer()
     , d(new DoubleTapRecognizerPrivate)
 {
     d->q = this;
 }
 
 DoubleTapRecognizer::~DoubleTapRecognizer()
 {
     delete d;
 }
 
 QGesture *DoubleTapRecognizer::create(QObject *)
 {
     return static_cast<QGesture *>(new DoubleTap());
 }
 
 QGestureRecognizer::Result DoubleTapRecognizer::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->mIsOnlyTap = true;
         if (d->mLastDoupleTapTimestamp == 0)
             d->mLastDoupleTapTimestamp = touchEvent->timestamp() - Touch_Helper::Touch::doubleTapInterval;
         state->setHotSpot(touchEvent->touchPoints().first().screenPos());
         return MayBeGesture;
     }
 
     case QEvent::TouchUpdate: {
         auto touchEvent = static_cast<QTouchEvent *>(event);
         const qint64 now = touchEvent->timestamp();
         state->setHotSpot(touchEvent->touchPoints().first().screenPos());
 
         if (d->mIsOnlyTap && now - d->mTouchBeginnTimestamp < Touch_Helper::Touch::maxTimeForTap && Touch_Helper::touchStationary(event)) {
             d->mIsOnlyTap = true;
             return MayBeGesture;
         } else {
             d->mIsOnlyTap = false;
             return CancelGesture;
         }
         break;
     }
 
     case QEvent::TouchEnd: {
         auto touchEvent = static_cast<QTouchEvent *>(event);
         const qint64 now = touchEvent->timestamp();
 
         if (now - d->mLastTapTimestamp <= Touch_Helper::Touch::doubleTapInterval && d->mIsOnlyTap) {
             // Interval between two double tap gesture need to be bigger than Touch_Helper::Touch::doupleTapIntervall,
             // to suppress fast successively double tap gestures
             if (now - d->mLastDoupleTapTimestamp > Touch_Helper::Touch::doubleTapInterval) {
                 d->mLastTapTimestamp = 0;
                 state->setHotSpot(touchEvent->touchPoints().first().screenPos());
                 d->mLastDoupleTapTimestamp = now;
                 return FinishGesture;
             }
         }
 
         if (d->mIsOnlyTap)
             d->mLastTapTimestamp = now;
 
         break;
     }
 
     default:
         return Ignore;
     }
     return Ignore;
 }
 
 DoubleTap::DoubleTap(QObject *parent)
     : QGesture(parent)
 {
 }
 
 } // namespace