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_scrollBarPressed(false),
  63     m_smoothScrolling(false),
  64     m_smoothScrollingAnimation(0)
  65 {
  66     Q_ASSERT(controller);
  67     controller->setParent(this);
  68     initialize();
  69 }
  70
  71 KItemListContainer::KItemListContainer(QWidget* parent) :
  72     QAbstractScrollArea(parent),
  73     m_controller(0),
  74     m_scrollBarPressed(false),
  75     m_smoothScrolling(false),
  76     m_smoothScrollingAnimation(0)
  77 {
  78     initialize();
  79 }
  80
  81 KItemListContainer::~KItemListContainer()
  82 {
  83 }
  84
  85 KItemListController* KItemListContainer::controller() const
  86 {
  87     return m_controller;
  88 }
  89
  90 void KItemListContainer::keyPressEvent(QKeyEvent* event)
  91 {
  92     // TODO: We should find a better way to handle the key press events in the view.
  93     // The reasons why we need this hack are:
  94     // 1. Without reimplementing keyPressEvent() here, the event would not reach the QGraphicsView.
  95     // 2. By default, the KItemListView does not have the keyboard focus in the QGraphicsScene, so
  96     //    simply sending the event to the QGraphicsView which is the KItemListContainer's viewport
  97     //    does not work.
  98     KItemListView* view = m_controller->view();
  99     if (view) {
 100         QApplication::sendEvent(view, event);
 101     }
 102 }
 103
 104 void KItemListContainer::showEvent(QShowEvent* event)
 105 {
 106     QAbstractScrollArea::showEvent(event);
 107     updateGeometries();
 108 }
 109
 110 void KItemListContainer::resizeEvent(QResizeEvent* event)
 111 {
 112     QAbstractScrollArea::resizeEvent(event);
 113     updateGeometries();
 114 }
 115
 116 void KItemListContainer::scrollContentsBy(int dx, int dy)
 117 {
 118     KItemListView* view = m_controller->view();
 119     if (!view) {
 120         return;
 121     }
 122
 123     const qreal currentOffset = view->offset();
 124     qreal offsetDiff = (view->scrollOrientation() == Qt::Vertical) ? dy : dx;
 125
 126     const bool animRunning = (m_smoothScrollingAnimation->state() == QAbstractAnimation::Running);
 127     if (animRunning) {
 128         // Stopping a running animation means skipping the range from the current offset
 129         // until the target offset. To prevent skipping of the range the difference
 130         // is added to the new target offset.
 131         const qreal oldEndOffset = m_smoothScrollingAnimation->endValue().toReal();
 132         offsetDiff += (currentOffset - oldEndOffset);
 133     }
 134
 135     const qreal endOffset = currentOffset - offsetDiff;
 136
 137     if (m_smoothScrolling || animRunning) {
 138         qreal startOffset = currentOffset;
 139         if (animRunning) {
 140             // If the animation was running and has been interrupted by assigning a new end-offset
 141             // one frame must be added to the start-offset to keep the animation smooth. This also
 142             // assures that animation proceeds even in cases where new end-offset are triggered
 143             // within a very short timeslots.
 144             startOffset += (endOffset - currentOffset) * 1000 / (m_smoothScrollingAnimation->duration() * 60);
 145         }
 146
 147         m_smoothScrollingAnimation->stop();
 148         m_smoothScrollingAnimation->setStartValue(startOffset);
 149         m_smoothScrollingAnimation->setEndValue(endOffset);
 150         m_smoothScrollingAnimation->setEasingCurve(animRunning ? QEasingCurve::OutQuad : QEasingCurve::InOutQuad);
 151         m_smoothScrollingAnimation->start();
 152         view->setOffset(startOffset);
 153     } else {
 154         view->setOffset(endOffset);
 155     }
 156 }
 157
 158 bool KItemListContainer::eventFilter(QObject* obj, QEvent* event)
 159 {
 160     Q_ASSERT(obj == horizontalScrollBar() || obj == verticalScrollBar());
 161
 162     // Check whether the scrollbar has been adjusted by a mouse-event
 163     // triggered by the user and remember this in m_scrollBarPressed.
 164     // The smooth scrolling will only get active if m_scrollBarPressed
 165     // is true (see scrollContentsBy()).
 166     const bool scrollVertical = (m_controller->view()->scrollOrientation() == Qt::Vertical);
 167     const bool checkEvent = ( scrollVertical && obj == verticalScrollBar()) ||
 168                             (!scrollVertical && obj == horizontalScrollBar());
 169     if (checkEvent) {
 170         switch (event->type()) {
 171         case QEvent::MouseButtonPress:
 172             m_scrollBarPressed = true;
 173             m_smoothScrolling = true;
 174             break;
 175
 176         case QEvent::MouseButtonRelease:
 177             m_scrollBarPressed = false;
 178             m_smoothScrolling = false;
 179             break;
 180
 181         case QEvent::Wheel:
 182             wheelEvent(static_cast<QWheelEvent*>(event));
 183             break;
 184
 185         default:
 186             break;
 187         }
 188     }
 189
 190     return QAbstractScrollArea::eventFilter(obj, event);
 191 }
 192
 193 void KItemListContainer::wheelEvent(QWheelEvent* event)
 194 {
 195     KItemListView* view = m_controller->view();
 196     if (!view || event->orientation() != view->scrollOrientation()) {
 197         return;
 198     }
 199
 200     const int numDegrees = event->delta() / 8;
 201     const int numSteps = numDegrees / 15;
 202
 203     const bool previous = m_smoothScrolling;
 204     m_smoothScrolling = true;
 205     if (view->scrollOrientation() == Qt::Vertical) {
 206         const int value = verticalScrollBar()->value();
 207         verticalScrollBar()->setValue(value - numSteps * view->size().height());
 208     } else {
 209         const int value = horizontalScrollBar()->value();
 210         horizontalScrollBar()->setValue(value - numSteps * view->size().width());
 211     }
 212     m_smoothScrolling = previous;
 213
 214     event->accept();
 215 }
 216
 217 void KItemListContainer::slotModelChanged(KItemModelBase* current, KItemModelBase* previous)
 218 {
 219     Q_UNUSED(current);
 220     Q_UNUSED(previous);
 221 }
 222
 223 void KItemListContainer::slotViewChanged(KItemListView* current, KItemListView* previous)
 224 {
 225     QGraphicsScene* scene = static_cast<QGraphicsView*>(viewport())->scene();
 226     if (previous) {
 227         scene->removeItem(previous);
 228         disconnect(previous, SIGNAL(offsetChanged(qreal,qreal)), this, SLOT(updateScrollBars()));
 229         disconnect(previous, SIGNAL(maximumOffsetChanged(qreal,qreal)), this, SLOT(updateScrollBars()));
 230         disconnect(previous, SIGNAL(scrollTo(qreal)), this, SLOT(scrollTo(qreal)));
 231         m_smoothScrollingAnimation->setTargetObject(0);
 232     }
 233     if (current) {
 234         scene->addItem(current);
 235         connect(current, SIGNAL(offsetChanged(qreal,qreal)), this, SLOT(updateScrollBars()));
 236         connect(current, SIGNAL(maximumOffsetChanged(qreal,qreal)), this, SLOT(updateScrollBars()));
 237         connect(current, SIGNAL(scrollTo(qreal)), this, SLOT(scrollTo(qreal)));
 238         m_smoothScrollingAnimation->setTargetObject(current);
 239     }
 240 }
 241
 242 void KItemListContainer::slotAnimationStateChanged(QAbstractAnimation::State newState,
 243                                                    QAbstractAnimation::State oldState)
 244 {
 245     Q_UNUSED(oldState);
 246     if (newState == QAbstractAnimation::Stopped && m_smoothScrolling && !m_scrollBarPressed) {
 247         m_smoothScrolling = false;
 248     }
 249 }
 250
 251
 252 void KItemListContainer::scrollTo(qreal offset)
 253 {
 254     const KItemListView* view = m_controller->view();
 255     if (!view) {
 256         return;
 257     }
 258
 259     m_smoothScrolling = true;
 260     QScrollBar* scrollBar = (view->scrollOrientation() == Qt::Vertical)
 261                             ? verticalScrollBar() : horizontalScrollBar();
 262     scrollBar->setValue(offset);
 263 }
 264
 265 void KItemListContainer::updateScrollBars()
 266 {
 267     const KItemListView* view = m_controller->view();
 268     if (!view) {
 269         return;
 270     }
 271
 272     QScrollBar* scrollBar = 0;
 273     int singleStep = 0;
 274     int pageStep = 0;
 275     QScrollBar* otherScrollBar = 0;
 276     if (view->scrollOrientation() == Qt::Vertical) {
 277         scrollBar = verticalScrollBar();
 278         singleStep = view->itemSize().height();
 279         pageStep = view->size().height();
 280         otherScrollBar = horizontalScrollBar();
 281     } else {
 282         scrollBar = horizontalScrollBar();
 283         singleStep = view->itemSize().width();
 284         pageStep = view->size().width();
 285         otherScrollBar = verticalScrollBar();
 286     }
 287
 288     const int value = view->offset();
 289     const int maximum = qMax(0, int(view->maximumOffset() - pageStep));
 290     if (m_smoothScrollingAnimation->state() == QAbstractAnimation::Running) {
 291         if (maximum == scrollBar->maximum()) {
 292             // The value has been changed by the animation, no update
 293             // of the scrollbars is required as their target state will be
 294             // reached with the end of the animation.
 295             return;
 296         }
 297
 298         // The maximum has been changed which indicates that the content
 299         // of the view has been changed. Stop the animation in any case and
 300         // update the scrollbars immediately.
 301         m_smoothScrollingAnimation->stop();
 302     }
 303
 304     scrollBar->setSingleStep(singleStep);
 305     scrollBar->setPageStep(pageStep);
 306     scrollBar->setMinimum(0);
 307     scrollBar->setMaximum(maximum);
 308     scrollBar->setValue(value);
 309
 310     // Make sure that the other scroll bar is hidden
 311     otherScrollBar->setMaximum(0);
 312     otherScrollBar->setValue(0);
 313 }
 314
 315 void KItemListContainer::updateGeometries()
 316 {
 317     QRect rect = geometry();
 318
 319     int widthDec = frameWidth() * 2;
 320     if (verticalScrollBar()->isVisible()) {
 321         widthDec += style()->pixelMetric(QStyle::PM_ScrollBarExtent);
 322     }
 323
 324     int heightDec = frameWidth() * 2;
 325     if (horizontalScrollBar()->isVisible()) {
 326         heightDec += style()->pixelMetric(QStyle::PM_ScrollBarExtent);
 327     }
 328
 329     rect.adjust(0, 0, -widthDec, -heightDec);
 330
 331     m_controller->view()->setGeometry(QRect(0, 0, rect.width(), rect.height()));
 332
 333     static_cast<KItemListContainerViewport*>(viewport())->scene()->setSceneRect(0, 0, rect.width(), rect.height());
 334     static_cast<KItemListContainerViewport*>(viewport())->viewport()->setGeometry(QRect(0, 0, rect.width(), rect.height()));
 335
 336     updateScrollBars();
 337 }
 338
 339 void KItemListContainer::initialize()
 340 {
 341     if (!m_controller) {
 342         m_controller = new KItemListController(this);
 343     }
 344
 345     connect(m_controller, SIGNAL(modelChanged(KItemModelBase*,KItemModelBase*)),
 346             this, SLOT(slotModelChanged(KItemModelBase*,KItemModelBase*)));
 347     connect(m_controller, SIGNAL(viewChanged(KItemListView*,KItemListView*)),
 348             this, SLOT(slotViewChanged(KItemListView*,KItemListView*)));
 349
 350     QGraphicsView* graphicsView = new KItemListContainerViewport(new QGraphicsScene(this), this);
 351     setViewport(graphicsView);
 352
 353     m_smoothScrollingAnimation = new QPropertyAnimation(this, "offset");
 354     m_smoothScrollingAnimation->setDuration(300);
 355     connect(m_smoothScrollingAnimation, SIGNAL(stateChanged(QAbstractAnimation::State,QAbstractAnimation::State)),
 356             this, SLOT(slotAnimationStateChanged(QAbstractAnimation::State,QAbstractAnimation::State)));
 357
 358     horizontalScrollBar()->installEventFilter(this);
 359     verticalScrollBar()->installEventFilter(this);
 360 }
 361
 362 #include "kitemlistcontainer.moc"