src/kitemviews/kitemlistcontainer.cpp

   1 /***************************************************************************
   2  *   Copyright (C) 2011 by Peter Penz <peter.penz19@gmail.com>             *
   3  *                                                                         *
   4  *   Based on the Itemviews NG project from Trolltech Labs:                *
   5  *   http://qt.gitorious.org/qt-labs/itemviews-ng                          *
   6  *                                                                         *
   7  *   This program is free software; you can redistribute it and/or modify  *
   8  *   it under the terms of the GNU General Public License as published by  *
   9  *   the Free Software Foundation; either version 2 of the License, or     *
  10  *   (at your option) any later version.                                   *
  11  *                                                                         *
  12  *   This program is distributed in the hope that it will be useful,       *
  13  *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
  14  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
  15  *   GNU General Public License for more details.                          *
  16  *                                                                         *
  17  *   You should have received a copy of the GNU General Public License     *
  18  *   along with this program; if not, write to the                         *
  19  *   Free Software Foundation, Inc.,                                       *
  20  *   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA            *
  21  ***************************************************************************/
  22
  23 #include "kitemlistcontainer.h"
  24
  25 #include "kitemlistcontroller.h"
  26 #include "kitemlistview.h"
  27 #include "kitemmodelbase.h"
  28
  29 #include <QGraphicsScene>
  30 #include <QGraphicsView>
  31 #include <QPropertyAnimation>
  32 #include <QScrollBar>
  33 #include <QStyle>
  34
  35 #include <KDebug>
  36
  37 class KItemListContainerViewport : public QGraphicsView
  38 {
  39 public:
  40     KItemListContainerViewport(QGraphicsScene* scene, QWidget* parent)
  41         : QGraphicsView(scene, parent)
  42     {
  43         setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
  44         setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
  45         setViewportMargins(0, 0, 0, 0);
  46         setFrameShape(QFrame::NoFrame);
  47     }
  48
  49     void scrollContentsBy(int dx, int dy)
  50     {
  51         Q_UNUSED(dx);
  52         Q_UNUSED(dy);
  53         // Do nothing. This prevents that e.g. the wheel-event
  54         // results in a moving of the scene items.
  55     }
  56 };
  57
  58 KItemListContainer::KItemListContainer(KItemListController* controller, QWidget* parent) :
  59     QAbstractScrollArea(parent),
  60     m_controller(controller),
  61     m_sliderMovedByUser(false),
  62     m_viewOffsetAnimation(0)
  63 {
  64     Q_ASSERT(controller);
  65     controller->setParent(this);
  66     initialize();
  67 }
  68
  69 KItemListContainer::KItemListContainer(QWidget* parent) :
  70     QAbstractScrollArea(parent),
  71     m_controller(0)
  72 {
  73     initialize();
  74 }
  75
  76 KItemListContainer::~KItemListContainer()
  77 {
  78 }
  79
  80 KItemListController* KItemListContainer::controller() const
  81 {
  82     return m_controller;
  83 }
  84
  85 void KItemListContainer::showEvent(QShowEvent* event)
  86 {
  87     QAbstractScrollArea::showEvent(event);
  88     updateGeometries();
  89 }
  90
  91 void KItemListContainer::resizeEvent(QResizeEvent* event)
  92 {
  93     QAbstractScrollArea::resizeEvent(event);
  94     updateGeometries();
  95 }
  96
  97 void KItemListContainer::scrollContentsBy(int dx, int dy)
  98 {
  99     KItemListView* view = m_controller->view();
 100     if (!view) {
 101         return;
 102     }
 103
 104     const qreal currentOffset = view->offset();
 105     qreal offsetDiff = (view->scrollOrientation() == Qt::Vertical) ? dy : dx;
 106
 107     const bool animRunning = (m_viewOffsetAnimation->state() == QAbstractAnimation::Running);
 108     if (animRunning) {
 109         // Stopping a running animation means skipping the range from the current offset
 110         // until the target offset. To prevent skipping of the range the difference
 111         // is added to the new target offset.
 112         m_viewOffsetAnimation->stop();
 113         const qreal targetOffset = m_viewOffsetAnimation->endValue().toReal();
 114         offsetDiff += (currentOffset - targetOffset);
 115     }
 116
 117     const qreal newOffset = currentOffset - offsetDiff;
 118
 119     if (m_sliderMovedByUser || animRunning) {
 120         m_viewOffsetAnimation->stop();
 121         m_viewOffsetAnimation->setStartValue(currentOffset);
 122         m_viewOffsetAnimation->setEndValue(newOffset);
 123         m_viewOffsetAnimation->setEasingCurve(animRunning ? QEasingCurve::OutQuad : QEasingCurve::InOutQuad);
 124         m_viewOffsetAnimation->start();
 125     } else {
 126         view->setOffset(newOffset);
 127     }
 128 }
 129
 130 bool KItemListContainer::eventFilter(QObject* obj, QEvent* event)
 131 {
 132     Q_ASSERT(obj == horizontalScrollBar() || obj == verticalScrollBar());
 133
 134     // Check whether the scrollbar has been adjusted by a mouse-event
 135     // triggered by the user and remember this in m_sliderMovedByUser.
 136     // The smooth scrolling will only get active if m_sliderMovedByUser
 137     // is true (see scrollContentsBy()).
 138     const bool scrollVertical = (m_controller->view()->scrollOrientation() == Qt::Vertical);
 139     const bool checkEvent = ( scrollVertical && obj == verticalScrollBar()) ||
 140                             (!scrollVertical && obj == horizontalScrollBar());
 141     if (checkEvent) {
 142         switch (event->type()) {
 143         case QEvent::MouseButtonPress:
 144             m_sliderMovedByUser = true;
 145            break;
 146
 147         case QEvent::MouseButtonRelease:
 148             m_sliderMovedByUser = false;
 149             break;
 150
 151         case QEvent::Wheel:
 152             wheelEvent(static_cast<QWheelEvent*>(event));
 153             break;
 154
 155         default:
 156             break;
 157          }
 158     }
 159
 160     return QAbstractScrollArea::eventFilter(obj, event);
 161 }
 162
 163 void KItemListContainer::wheelEvent(QWheelEvent* event)
 164 {
 165     KItemListView* view = m_controller->view();
 166     if (!view || event->orientation() != view->scrollOrientation()) {
 167         return;
 168     }
 169
 170     const int numDegrees = event->delta() / 8;
 171     const int numSteps = numDegrees / 15;
 172
 173     const bool previous = m_sliderMovedByUser;
 174     m_sliderMovedByUser = true;
 175     if (view->scrollOrientation() == Qt::Vertical) {
 176         const int value = verticalScrollBar()->value();
 177         verticalScrollBar()->setValue(value - numSteps * view->size().height());
 178     } else {
 179         const int value = horizontalScrollBar()->value();
 180         horizontalScrollBar()->setValue(value - numSteps * view->size().width());
 181     }
 182     m_sliderMovedByUser = previous;
 183
 184     event->accept();
 185 }
 186
 187 void KItemListContainer::slotModelChanged(KItemModelBase* current, KItemModelBase* previous)
 188 {
 189     Q_UNUSED(current);
 190     Q_UNUSED(previous);
 191 }
 192
 193 void KItemListContainer::slotViewChanged(KItemListView* current, KItemListView* previous)
 194 {
 195     QGraphicsScene* scene = static_cast<QGraphicsView*>(viewport())->scene();
 196     if (previous) {
 197         scene->removeItem(previous);
 198         disconnect(previous, SIGNAL(offsetChanged(int,int)), this, SLOT(updateScrollBars()));
 199         disconnect(previous, SIGNAL(maximumOffsetChanged(int,int)), this, SLOT(updateScrollBars()));
 200         m_viewOffsetAnimation->setTargetObject(0);
 201     }
 202     if (current) {
 203         scene->addItem(current);
 204         connect(current, SIGNAL(offsetChanged(int,int)), this, SLOT(updateScrollBars()));
 205         connect(current, SIGNAL(maximumOffsetChanged(int,int)), this, SLOT(updateScrollBars()));
 206         m_viewOffsetAnimation->setTargetObject(current);
 207     }
 208 }
 209
 210 void KItemListContainer::updateScrollBars()
 211 {
 212     const KItemListView* view = m_controller->view();
 213     if (!view) {
 214         return;
 215     }
 216
 217     QScrollBar* scrollBar = 0;
 218     int singleStep = 0;
 219     int pageStep = 0;
 220     if (view->scrollOrientation() == Qt::Vertical) {
 221         scrollBar = verticalScrollBar();
 222         singleStep = view->itemSize().height();
 223         pageStep = view->size().height();
 224     } else {
 225         scrollBar = horizontalScrollBar();
 226         singleStep = view->itemSize().width();
 227         pageStep = view->size().width();
 228     }
 229
 230     const int value = view->offset();
 231     const int maximum = qMax(0, int(view->maximumOffset() - pageStep));
 232     if (m_viewOffsetAnimation->state() == QAbstractAnimation::Running) {
 233         if (maximum == scrollBar->maximum()) {
 234             // The value has been changed by the animation, no update
 235             // of the scrollbars is required as their target state will be
 236             // reached with the end of the animation.
 237             return;
 238         }
 239
 240         // The maximum has been changed which indicates that the content
 241         // of the view has been changed. Stop the animation in any case and
 242         // update the scrollbars immediately.
 243         m_viewOffsetAnimation->stop();
 244     }
 245
 246     scrollBar->setSingleStep(singleStep);
 247     scrollBar->setPageStep(pageStep);
 248     scrollBar->setMinimum(0);
 249     scrollBar->setMaximum(maximum);
 250     scrollBar->setValue(value);
 251 }
 252
 253 void KItemListContainer::updateGeometries()
 254 {
 255     QRect rect = geometry();
 256
 257     int widthDec = frameWidth() * 2;
 258     if (verticalScrollBar()->isVisible()) {
 259         widthDec += style()->pixelMetric(QStyle::PM_ScrollBarExtent);
 260     }
 261
 262     int heightDec = frameWidth() * 2;
 263     if (horizontalScrollBar()->isVisible()) {
 264         heightDec += style()->pixelMetric(QStyle::PM_ScrollBarExtent);
 265     }
 266
 267     rect.adjust(0, 0, -widthDec, -heightDec);
 268
 269     m_controller->view()->setGeometry(QRect(0, 0, rect.width(), rect.height()));
 270
 271     static_cast<KItemListContainerViewport*>(viewport())->scene()->setSceneRect(0, 0, rect.width(), rect.height());
 272     static_cast<KItemListContainerViewport*>(viewport())->viewport()->setGeometry(QRect(0, 0, rect.width(), rect.height()));
 273
 274     updateScrollBars();
 275 }
 276
 277 void KItemListContainer::initialize()
 278 {
 279     if (!m_controller) {
 280         m_controller = new KItemListController(this);
 281     }
 282
 283     connect(m_controller, SIGNAL(modelChanged(KItemModelBase*,KItemModelBase*)),
 284             this, SLOT(slotModelChanged(KItemModelBase*,KItemModelBase*)));
 285     connect(m_controller, SIGNAL(viewChanged(KItemListView*,KItemListView*)),
 286             this, SLOT(slotViewChanged(KItemListView*,KItemListView*)));
 287
 288     QGraphicsView* graphicsView = new KItemListContainerViewport(new QGraphicsScene(this), this);
 289     setViewport(graphicsView);
 290
 291     m_viewOffsetAnimation = new QPropertyAnimation(this, "offset");
 292     m_viewOffsetAnimation->setDuration(500);
 293
 294     horizontalScrollBar()->installEventFilter(this);
 295     verticalScrollBar()->installEventFilter(this);
 296 }
 297
 298 #include "kitemlistcontainer.moc"