1 | /* $Id: QIGraphicsView.cpp 101565 2023-10-24 00:08:46Z vboxsync $ */
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2 | /** @file
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3 | * VBox Qt GUI - Qt extensions: QIGraphicsView class implementation.
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4 | */
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5 |
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6 | /*
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7 | * Copyright (C) 2015-2023 Oracle and/or its affiliates.
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8 | *
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9 | * This file is part of VirtualBox base platform packages, as
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10 | * available from https://www.virtualbox.org.
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11 | *
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12 | * This program is free software; you can redistribute it and/or
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13 | * modify it under the terms of the GNU General Public License
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14 | * as published by the Free Software Foundation, in version 3 of the
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15 | * License.
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16 | *
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17 | * This program is distributed in the hope that it will be useful, but
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18 | * WITHOUT ANY WARRANTY; without even the implied warranty of
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19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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20 | * General Public License for more details.
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21 | *
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22 | * You should have received a copy of the GNU General Public License
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23 | * along with this program; if not, see <https://www.gnu.org/licenses>.
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24 | *
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25 | * SPDX-License-Identifier: GPL-3.0-only
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26 | */
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27 |
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28 | /* Qt includes: */
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29 | #include <QScrollBar>
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30 | #include <QTouchEvent>
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31 |
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32 | /* GUI includes: */
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33 | #include "QIGraphicsView.h"
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34 |
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35 | /* Other VBox includes: */
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36 | #include "iprt/assert.h"
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37 |
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38 |
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39 | QIGraphicsView::QIGraphicsView(QWidget *pParent /* = 0 */)
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40 | : QGraphicsView(pParent)
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41 | , m_iVerticalScrollBarPosition(0)
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42 | {
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43 | /* Enable multi-touch support: */
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44 | setAttribute(Qt::WA_AcceptTouchEvents);
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45 | viewport()->setAttribute(Qt::WA_AcceptTouchEvents);
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46 | }
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47 |
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48 | bool QIGraphicsView::event(QEvent *pEvent)
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49 | {
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50 | /* Handle known event types: */
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51 | switch (pEvent->type())
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52 | {
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53 | case QEvent::TouchBegin:
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54 | {
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55 | /* Parse the touch event: */
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56 | QTouchEvent *pTouchEvent = static_cast<QTouchEvent*>(pEvent);
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57 | AssertPtrReturn(pTouchEvent, QGraphicsView::event(pEvent));
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58 | /* For touch-screen event we have something special: */
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59 | if (pTouchEvent->device()->type() == QInputDevice::DeviceType::TouchScreen)
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60 | {
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61 | /* Remember where the scrolling was started: */
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62 | m_iVerticalScrollBarPosition = verticalScrollBar()->value();
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63 | /* Allow further touch events: */
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64 | pEvent->accept();
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65 | /* Mark event handled: */
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66 | return true;
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67 | }
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68 | break;
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69 | }
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70 | case QEvent::TouchUpdate:
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71 | {
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72 | /* Parse the touch-event: */
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73 | QTouchEvent *pTouchEvent = static_cast<QTouchEvent*>(pEvent);
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74 | AssertPtrReturn(pTouchEvent, QGraphicsView::event(pEvent));
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75 | /* For touch-screen event we have something special: */
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76 | if (pTouchEvent->device()->type() == QInputDevice::DeviceType::TouchScreen)
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77 | {
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78 | /* Determine vertical shift (inverted): */
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79 | const QEventPoint point = pTouchEvent->points().first();
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80 | const int iShift = (int)(point.pressPosition().y() - point.position().y());
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81 | /* Calculate new scroll-bar value according calculated shift: */
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82 | int iNewScrollBarValue = m_iVerticalScrollBarPosition + iShift;
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83 | /* Make sure new scroll-bar value is within the minimum/maximum bounds: */
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84 | iNewScrollBarValue = qMax(verticalScrollBar()->minimum(), iNewScrollBarValue);
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85 | iNewScrollBarValue = qMin(verticalScrollBar()->maximum(), iNewScrollBarValue);
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86 | /* Apply calculated scroll-bar shift finally: */
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87 | verticalScrollBar()->setValue(iNewScrollBarValue);
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88 | /* Mark event handled: */
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89 | return true;
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90 | }
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91 | break;
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92 | }
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93 | case QEvent::TouchEnd:
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94 | {
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95 | /* Parse the touch event: */
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96 | QTouchEvent *pTouchEvent = static_cast<QTouchEvent*>(pEvent);
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97 | AssertPtrReturn(pTouchEvent, QGraphicsView::event(pEvent));
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98 | /* For touch-screen event we have something special: */
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99 | if (pTouchEvent->device()->type() == QInputDevice::DeviceType::TouchScreen)
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100 | {
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101 | /* Reset the scrolling start position: */
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102 | m_iVerticalScrollBarPosition = 0;
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103 | /* Mark event handled: */
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104 | return true;
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105 | }
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106 | break;
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107 | }
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108 | default:
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109 | break;
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110 | }
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111 | /* Call to base-class: */
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112 | return QGraphicsView::event(pEvent);
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113 | }
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