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 <QApplication>
  30 #include <QGraphicsScene>
  31 #include <QGraphicsView>
  32 #include <QPropertyAnimation>
  33 #include <QScrollBar>
  34 #include <QStyle>
  35
  36 #include <KDebug>
  37
  38 class KItemListContainerViewport : public QGraphicsView
  39 {
  40 public:
  41     KItemListContainerViewport(QGraphicsScene* scene, QWidget* parent)
  42         : QGraphicsView(scene, parent)
  43     {
  44         setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
  45         setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
  46         setViewportMargins(0, 0, 0, 0);
  47         setFrameShape(QFrame::NoFrame);
  48     }
  49
  50     void scrollContentsBy(int dx, int dy)
  51     {
  52         Q_UNUSED(dx);
  53         Q_UNUSED(dy);
  54         // Do nothing. This prevents that e.g. the wheel-event
  55         // results in a moving of the scene items.
  56     }
  57 };
  58
  59 KItemListContainer::KItemListContainer(KItemListController* controller, QWidget* parent) :
  60     QAbstractScrollArea(parent),
  61     m_controller(controller),
  62     m_smoothScrolling(false),
  63     m_smoothScrollingAnimation(0)
  64 {
  65     Q_ASSERT(controller);
  66     controller->setParent(this);
  67     initialize();
  68 }
  69
  70 KItemListContainer::KItemListContainer(QWidget* parent) :
  71     QAbstractScrollArea(parent),
  72     m_controller(0),
  73     m_smoothScrolling(false),
  74     m_smoothScrollingAnimation(0)
  75 {
  76     initialize();
  77 }
  78
  79 KItemListContainer::~KItemListContainer()
  80 {
  81 }
  82
  83 KItemListController* KItemListContainer::controller() const
  84 {
  85     return m_controller;
  86 }
  87
  88 void KItemListContainer::keyPressEvent(QKeyEvent* event)
  89 {
  90     // TODO: We should find a better way to handle the key press events in the view.
  91     // The reasons why we need this hack are:
  92     // 1. Without reimplementing keyPressEvent() here, the event would not reach the QGraphicsView.
  93     // 2. By default, the KItemListView does not have the keyboard focus in the QGraphicsScene, so
  94     //    simply sending the event to the QGraphicsView which is the KItemListContainer's viewport
  95     //    does not work.
  96     KItemListView* view = m_controller->view();
  97     if (view) {
  98         QApplication::sendEvent(view, event);
  99     }
 100 }
 101
 102 void KItemListContainer::showEvent(QShowEvent* event)
 103 {
 104     QAbstractScrollArea::showEvent(event);
 105     updateGeometries();
 106 }
 107
 108 void KItemListContainer::resizeEvent(QResizeEvent* event)
 109 {
 110     QAbstractScrollArea::resizeEvent(event);
 111     updateGeometries();
 112 }
 113
 114 void KItemListContainer::scrollContentsBy(int dx, int dy)
 115 {
 116     KItemListView* view = m_controller->view();
 117     if (!view) {
 118         return;
 119     }
 120
 121     const qreal currentOffset = view->offset();
 122     qreal offsetDiff = (view->scrollOrientation() == Qt::Vertical) ? dy : dx;
 123
 124     const bool animRunning = (m_smoothScrollingAnimation->state() == QAbstractAnimation::Running);
 125     if (animRunning) {
 126         // Stopping a running animation means skipping the range from the current offset
 127         // until the target offset. To prevent skipping of the range the difference
 128         // is added to the new target offset.
 129         const qreal targetOffset = m_smoothScrollingAnimation->endValue().toReal();
 130         offsetDiff += (currentOffset - targetOffset);
 131     }
 132
 133     const qreal newOffset = currentOffset - offsetDiff;
 134
 135     if (m_smoothScrolling || animRunning) {
 136         m_smoothScrollingAnimation->stop();
 137         m_smoothScrollingAnimation->setStartValue(currentOffset);
 138         m_smoothScrollingAnimation->setEndValue(newOffset);
 139         m_smoothScrollingAnimation->setEasingCurve(animRunning ? QEasingCurve::OutQuad : QEasingCurve::InOutQuad);
 140         m_smoothScrollingAnimation->start();
 141         view->setOffset(currentOffset);
 142     } else {
 143         view->setOffset(newOffset);
 144     }
 145 }
 146
 147 bool KItemListContainer::eventFilter(QObject* obj, QEvent* event)
 148 {
 149     Q_ASSERT(obj == horizontalScrollBar() || obj == verticalScrollBar());
 150
 151     // Check whether the scrollbar has been adjusted by a mouse-event
 152     // triggered by the user and remember this in m_smoothScrolling.
 153     // The smooth scrolling will only get active if m_smoothScrolling
 154     // is true (see scrollContentsBy()).
 155     const bool scrollVertical = (m_controller->view()->scrollOrientation() == Qt::Vertical);
 156     const bool checkEvent = ( scrollVertical && obj == verticalScrollBar()) ||
 157                             (!scrollVertical && obj == horizontalScrollBar());
 158     if (checkEvent) {
 159         switch (event->type()) {
 160         case QEvent::MouseButtonPress:
 161             m_smoothScrolling = true;
 162             break;
 163
 164         case QEvent::MouseButtonRelease:
 165             m_smoothScrolling = false;
 166             break;
 167
 168         case QEvent::Wheel:
 169             wheelEvent(static_cast<QWheelEvent*>(event));
 170             break;
 171
 172         default:
 173             break;
 174         }
 175     }
 176
 177     return QAbstractScrollArea::eventFilter(obj, event);
 178 }
 179
 180 void KItemListContainer::wheelEvent(QWheelEvent* event)
 181 {
 182     KItemListView* view = m_controller->view();
 183     if (!view || event->orientation() != view->scrollOrientation()) {
 184         return;
 185     }
 186
 187     const int numDegrees = event->delta() / 8;
 188     const int numSteps = numDegrees / 15;
 189
 190     const bool previous = m_smoothScrolling;
 191     m_smoothScrolling = true;
 192     if (view->scrollOrientation() == Qt::Vertical) {
 193         const int value = verticalScrollBar()->value();
 194         verticalScrollBar()->setValue(value - numSteps * view->size().height());
 195     } else {
 196         const int value = horizontalScrollBar()->value();
 197         horizontalScrollBar()->setValue(value - numSteps * view->size().width());
 198     }
 199     m_smoothScrolling = previous;
 200
 201     event->accept();
 202 }
 203
 204 void KItemListContainer::slotModelChanged(KItemModelBase* current, KItemModelBase* previous)
 205 {
 206     Q_UNUSED(current);
 207     Q_UNUSED(previous);
 208 }
 209
 210 void KItemListContainer::slotViewChanged(KItemListView* current, KItemListView* previous)
 211 {
 212     QGraphicsScene* scene = static_cast<QGraphicsView*>(viewport())->scene();
 213     if (previous) {
 214         scene->removeItem(previous);
 215         disconnect(previous, SIGNAL(offsetChanged(qreal,qreal)), this, SLOT(updateScrollBars()));
 216         disconnect(previous, SIGNAL(maximumOffsetChanged(qreal,qreal)), this, SLOT(updateScrollBars()));
 217         disconnect(previous, SIGNAL(scrollTo(qreal)), this, SLOT(scrollTo(qreal)));
 218         m_smoothScrollingAnimation->setTargetObject(0);
 219     }
 220     if (current) {
 221         scene->addItem(current);
 222         connect(current, SIGNAL(offsetChanged(qreal,qreal)), this, SLOT(updateScrollBars()));
 223         connect(current, SIGNAL(maximumOffsetChanged(qreal,qreal)), this, SLOT(updateScrollBars()));
 224         connect(current, SIGNAL(scrollTo(qreal)), this, SLOT(scrollTo(qreal)));
 225         m_smoothScrollingAnimation->setTargetObject(current);
 226     }
 227 }
 228
 229 void KItemListContainer::slotAnimationStateChanged(QAbstractAnimation::State newState,
 230                                                    QAbstractAnimation::State oldState)
 231 {
 232     Q_UNUSED(oldState);
 233     if (newState == QAbstractAnimation::Stopped) {
 234         m_smoothScrolling = false;
 235     }
 236 }
 237
 238
 239 void KItemListContainer::scrollTo(qreal offset)
 240 {
 241     const KItemListView* view = m_controller->view();
 242     if (!view) {
 243         return;
 244     }
 245
 246     m_smoothScrolling = true;
 247     QScrollBar* scrollBar = (view->scrollOrientation() == Qt::Vertical)
 248                             ? verticalScrollBar() : horizontalScrollBar();
 249     scrollBar->setValue(offset);
 250 }
 251
 252 void KItemListContainer::updateScrollBars()
 253 {
 254     const KItemListView* view = m_controller->view();
 255     if (!view) {
 256         return;
 257     }
 258
 259     QScrollBar* scrollBar = 0;
 260     int singleStep = 0;
 261     int pageStep = 0;
 262     QScrollBar* otherScrollBar = 0;
 263     if (view->scrollOrientation() == Qt::Vertical) {
 264         scrollBar = verticalScrollBar();
 265         singleStep = view->itemSize().height();
 266         pageStep = view->size().height();
 267         otherScrollBar = horizontalScrollBar();
 268     } else {
 269         scrollBar = horizontalScrollBar();
 270         singleStep = view->itemSize().width();
 271         pageStep = view->size().width();
 272         otherScrollBar = verticalScrollBar();
 273     }
 274
 275     const int value = view->offset();
 276     const int maximum = qMax(0, int(view->maximumOffset() - pageStep));
 277     if (m_smoothScrollingAnimation->state() == QAbstractAnimation::Running) {
 278         if (maximum == scrollBar->maximum()) {
 279             // The value has been changed by the animation, no update
 280             // of the scrollbars is required as their target state will be
 281             // reached with the end of the animation.
 282             return;
 283         }
 284
 285         // The maximum has been changed which indicates that the content
 286         // of the view has been changed. Stop the animation in any case and
 287         // update the scrollbars immediately.
 288         m_smoothScrollingAnimation->stop();
 289     }
 290
 291     scrollBar->setSingleStep(singleStep);
 292     scrollBar->setPageStep(pageStep);
 293     scrollBar->setMinimum(0);
 294     scrollBar->setMaximum(maximum);
 295     scrollBar->setValue(value);
 296
 297     // Make sure that the other scroll bar is hidden
 298     otherScrollBar->setMaximum(0);
 299     otherScrollBar->setValue(0);
 300 }
 301
 302 void KItemListContainer::updateGeometries()
 303 {
 304     QRect rect = geometry();
 305
 306     int widthDec = frameWidth() * 2;
 307     if (verticalScrollBar()->isVisible()) {
 308         widthDec += style()->pixelMetric(QStyle::PM_ScrollBarExtent);
 309     }
 310
 311     int heightDec = frameWidth() * 2;
 312     if (horizontalScrollBar()->isVisible()) {
 313         heightDec += style()->pixelMetric(QStyle::PM_ScrollBarExtent);
 314     }
 315
 316     rect.adjust(0, 0, -widthDec, -heightDec);
 317
 318     m_controller->view()->setGeometry(QRect(0, 0, rect.width(), rect.height()));
 319
 320     static_cast<KItemListContainerViewport*>(viewport())->scene()->setSceneRect(0, 0, rect.width(), rect.height());
 321     static_cast<KItemListContainerViewport*>(viewport())->viewport()->setGeometry(QRect(0, 0, rect.width(), rect.height()));
 322
 323     updateScrollBars();
 324 }
 325
 326 void KItemListContainer::initialize()
 327 {
 328     if (!m_controller) {
 329         m_controller = new KItemListController(this);
 330     }
 331
 332     connect(m_controller, SIGNAL(modelChanged(KItemModelBase*,KItemModelBase*)),
 333             this, SLOT(slotModelChanged(KItemModelBase*,KItemModelBase*)));
 334     connect(m_controller, SIGNAL(viewChanged(KItemListView*,KItemListView*)),
 335             this, SLOT(slotViewChanged(KItemListView*,KItemListView*)));
 336
 337     QGraphicsView* graphicsView = new KItemListContainerViewport(new QGraphicsScene(this), this);
 338     setViewport(graphicsView);
 339
 340     m_smoothScrollingAnimation = new QPropertyAnimation(this, "offset");
 341     m_smoothScrollingAnimation->setDuration(300);
 342     connect(m_smoothScrollingAnimation, SIGNAL(stateChanged(QAbstractAnimation::State,QAbstractAnimation::State)),
 343             this, SLOT(slotAnimationStateChanged(QAbstractAnimation::State,QAbstractAnimation::State)));
 344
 345     horizontalScrollBar()->installEventFilter(this);
 346     verticalScrollBar()->installEventFilter(this);
 347 }
 348
 349 #include "kitemlistcontainer.moc"