File indexing completed on 2024-04-28 04:21:28

 // SPDX-FileCopyrightText: 2003-2010 Jesper K. Pedersen <blackie@kde.org>
 // SPDX-FileCopyrightText: 2022 Johannes Zarl-Zierl <johannes@zarl-zierl.at>
 //
 // SPDX-License-Identifier: GPL-2.0-or-later
 
 #include "ViewHandler.h"
 
 #include <QMouseEvent>
 #include <QRubberBand>
 #include <qapplication.h>
 #include <qcursor.h>
 #include <qpainter.h>
 
 /**
  * \class Viewer::ViewHandler
  * \brief Mouse handler used during zooming and panning actions
  */
 
 Viewer::ViewHandler::ViewHandler(Viewer::ImageDisplay *display)
     : QObject(display)
     , m_scale(false)
     , m_pan(false)
     , m_errorX(0)
     , m_errorY(0)
     , m_rubberBand(new QRubberBand(QRubberBand::Rectangle, display))
     , m_display(display)
 {
 }
 
 bool Viewer::ViewHandler::mousePressEvent(QMouseEvent *e, const QPoint &unTranslatedPos, double /*scaleFactor*/)
 {
     m_pan = false;
     m_scale = false;
 
     if ((e->button() & Qt::LeftButton)) {
         if ((e->modifiers() & Qt::ControlModifier)) {
             m_pan = true;
         } else {
             m_scale = true;
         }
     } else if (e->button() & Qt::MiddleButton) {
         m_pan = true;
     }
 
     if (m_pan) {
         // panning
         m_last = unTranslatedPos;
         qApp->setOverrideCursor(Qt::SizeAllCursor);
         m_errorX = 0;
         m_errorY = 0;
         return true;
     } else if (m_scale) {
         // scaling
         m_start = e->pos();
         m_untranslatedStart = unTranslatedPos;
         qApp->setOverrideCursor(Qt::CrossCursor);
         return true;
     } else {
         return true;
     }
 }
 
 bool Viewer::ViewHandler::mouseMoveEvent(QMouseEvent *,
                                          const QPoint &unTranslatedPos, double scaleFactor)
 {
     if (m_scale) {
         m_rubberBand->setGeometry(QRect(m_untranslatedStart, unTranslatedPos).normalized());
         m_rubberBand->show();
         return true;
     } else if (m_pan) {
         // This code need to be taking the error into account, consider this situation:
         // The user moves the mouse very slowly, only 1 pixel at a time, scale factor is 3
         // Then translated delta would be 1/3 which every time would be
         // rounded down to 0, and the panning would never move any pixels.
         double deltaX = m_errorX + (m_last.x() - unTranslatedPos.x()) / scaleFactor;
         double deltaY = m_errorY + (m_last.y() - unTranslatedPos.y()) / scaleFactor;
         QPoint deltaPoint = QPoint((int)deltaX, (int)deltaY);
         m_errorX = deltaX - ((double)((int)deltaX));
         m_errorY = deltaY - ((double)((int)deltaY));
 
         m_display->pan(deltaPoint);
         m_last = unTranslatedPos;
         return true;
     } else
         return false;
 }
 
 bool Viewer::ViewHandler::mouseReleaseEvent(QMouseEvent *e, const QPoint & /*unTranslatedPos*/, double /*scaleFactor*/)
 {
     if (m_scale) {
         qApp->restoreOverrideCursor();
         m_rubberBand->hide();
         m_scale = false;
         if ((e->pos() - m_start).manhattanLength() > 1) {
             m_display->zoom(m_start, e->pos());
             return true;
         } else
             return false;
     } else if (m_pan) {
         qApp->restoreOverrideCursor();
         m_pan = false;
         return true;
     } else
         return false;
 }
 
 void Viewer::ViewHandler::hideEvent()
 {
     // In case the escape key is pressed while viewing or scaling, then we need to restore the override cursor
     // (As in that case we will not see a key release event)
     if (m_pan || m_scale) {
         qApp->restoreOverrideCursor();
         m_pan = false;
         m_scale = false;
     }
 }
 // vi:expandtab:tabstop=4 shiftwidth=4:
 
 #include "moc_ViewHandler.cpp"