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 targetOffset = m_smoothScrollingAnimation->endValue().toReal();
 132         offsetDiff += (currentOffset - targetOffset);
 133     }
 134
 135     const qreal newOffset = currentOffset - offsetDiff;
 136
 137     if (m_smoothScrolling || animRunning) {
 138         m_smoothScrollingAnimation->stop();
 139         m_smoothScrollingAnimation->setStartValue(currentOffset);
 140         m_smoothScrollingAnimation->setEndValue(newOffset);
 141         m_smoothScrollingAnimation->setEasingCurve(animRunning ? QEasingCurve::OutQuad : QEasingCurve::InOutQuad);
 142         m_smoothScrollingAnimation->start();
 143         view->setOffset(currentOffset);
 144     } else {
 145         view->setOffset(newOffset);
 146     }
 147 }
 148
 149 bool KItemListContainer::eventFilter(QObject* obj, QEvent* event)
 150 {
 151     Q_ASSERT(obj == horizontalScrollBar() || obj == verticalScrollBar());
 152
 153     // Check whether the scrollbar has been adjusted by a mouse-event
 154     // triggered by the user and remember this in m_scrollBarPressed.
 155     // The smooth scrolling will only get active if m_scrollBarPressed
 156     // is true (see scrollContentsBy()).
 157     const bool scrollVertical = (m_controller->view()->scrollOrientation() == Qt::Vertical);
 158     const bool checkEvent = ( scrollVertical && obj == verticalScrollBar()) ||
 159                             (!scrollVertical && obj == horizontalScrollBar());
 160     if (checkEvent) {
 161         switch (event->type()) {
 162         case QEvent::MouseButtonPress:
 163             m_scrollBarPressed = true;
 164             m_smoothScrolling = true;
 165             break;
 166
 167         case QEvent::MouseButtonRelease:
 168             m_scrollBarPressed = false;
 169             m_smoothScrolling = false;
 170             break;
 171
 172         case QEvent::Wheel:
 173             wheelEvent(static_cast<QWheelEvent*>(event));
 174             break;
 175
 176         default:
 177             break;
 178         }
 179     }
 180
 181     return QAbstractScrollArea::eventFilter(obj, event);
 182 }
 183
 184 void KItemListContainer::wheelEvent(QWheelEvent* event)
 185 {
 186     KItemListView* view = m_controller->view();
 187     if (!view || event->orientation() != view->scrollOrientation()) {
 188         return;
 189     }
 190
 191     const int numDegrees = event->delta() / 8;
 192     const int numSteps = numDegrees / 15;
 193
 194     const bool previous = m_smoothScrolling;
 195     m_smoothScrolling = true;
 196     if (view->scrollOrientation() == Qt::Vertical) {
 197         const int value = verticalScrollBar()->value();
 198         verticalScrollBar()->setValue(value - numSteps * view->size().height());
 199     } else {
 200         const int value = horizontalScrollBar()->value();
 201         horizontalScrollBar()->setValue(value - numSteps * view->size().width());
 202     }
 203     m_smoothScrolling = previous;
 204
 205     event->accept();
 206 }
 207
 208 void KItemListContainer::slotModelChanged(KItemModelBase* current, KItemModelBase* previous)
 209 {
 210     Q_UNUSED(current);
 211     Q_UNUSED(previous);
 212 }
 213
 214 void KItemListContainer::slotViewChanged(KItemListView* current, KItemListView* previous)
 215 {
 216     QGraphicsScene* scene = static_cast<QGraphicsView*>(viewport())->scene();
 217     if (previous) {
 218         scene->removeItem(previous);
 219         disconnect(previous, SIGNAL(offsetChanged(qreal,qreal)), this, SLOT(updateScrollBars()));
 220         disconnect(previous, SIGNAL(maximumOffsetChanged(qreal,qreal)), this, SLOT(updateScrollBars()));
 221         disconnect(previous, SIGNAL(scrollTo(qreal)), this, SLOT(scrollTo(qreal)));
 222         m_smoothScrollingAnimation->setTargetObject(0);
 223     }
 224     if (current) {
 225         scene->addItem(current);
 226         connect(current, SIGNAL(offsetChanged(qreal,qreal)), this, SLOT(updateScrollBars()));
 227         connect(current, SIGNAL(maximumOffsetChanged(qreal,qreal)), this, SLOT(updateScrollBars()));
 228         connect(current, SIGNAL(scrollTo(qreal)), this, SLOT(scrollTo(qreal)));
 229         m_smoothScrollingAnimation->setTargetObject(current);
 230     }
 231 }
 232
 233 void KItemListContainer::slotAnimationStateChanged(QAbstractAnimation::State newState,
 234                                                    QAbstractAnimation::State oldState)
 235 {
 236     Q_UNUSED(oldState);
 237     if (newState == QAbstractAnimation::Stopped && m_smoothScrolling && !m_scrollBarPressed) {
 238         m_smoothScrolling = false;
 239     }
 240 }
 241
 242
 243 void KItemListContainer::scrollTo(qreal offset)
 244 {
 245     const KItemListView* view = m_controller->view();
 246     if (!view) {
 247         return;
 248     }
 249
 250     m_smoothScrolling = true;
 251     QScrollBar* scrollBar = (view->scrollOrientation() == Qt::Vertical)
 252                             ? verticalScrollBar() : horizontalScrollBar();
 253     scrollBar->setValue(offset);
 254 }
 255
 256 void KItemListContainer::updateScrollBars()
 257 {
 258     const KItemListView* view = m_controller->view();
 259     if (!view) {
 260         return;
 261     }
 262
 263     QScrollBar* scrollBar = 0;
 264     int singleStep = 0;
 265     int pageStep = 0;
 266     QScrollBar* otherScrollBar = 0;
 267     if (view->scrollOrientation() == Qt::Vertical) {
 268         scrollBar = verticalScrollBar();
 269         singleStep = view->itemSize().height();
 270         pageStep = view->size().height();
 271         otherScrollBar = horizontalScrollBar();
 272     } else {
 273         scrollBar = horizontalScrollBar();
 274         singleStep = view->itemSize().width();
 275         pageStep = view->size().width();
 276         otherScrollBar = verticalScrollBar();
 277     }
 278
 279     const int value = view->offset();
 280     const int maximum = qMax(0, int(view->maximumOffset() - pageStep));
 281     if (m_smoothScrollingAnimation->state() == QAbstractAnimation::Running) {
 282         if (maximum == scrollBar->maximum()) {
 283             // The value has been changed by the animation, no update
 284             // of the scrollbars is required as their target state will be
 285             // reached with the end of the animation.
 286             return;
 287         }
 288
 289         // The maximum has been changed which indicates that the content
 290         // of the view has been changed. Stop the animation in any case and
 291         // update the scrollbars immediately.
 292         m_smoothScrollingAnimation->stop();
 293     }
 294
 295     scrollBar->setSingleStep(singleStep);
 296     scrollBar->setPageStep(pageStep);
 297     scrollBar->setMinimum(0);
 298     scrollBar->setMaximum(maximum);
 299     scrollBar->setValue(value);
 300
 301     // Make sure that the other scroll bar is hidden
 302     otherScrollBar->setMaximum(0);
 303     otherScrollBar->setValue(0);
 304 }
 305
 306 void KItemListContainer::updateGeometries()
 307 {
 308     QRect rect = geometry();
 309
 310     int widthDec = frameWidth() * 2;
 311     if (verticalScrollBar()->isVisible()) {
 312         widthDec += style()->pixelMetric(QStyle::PM_ScrollBarExtent);
 313     }
 314
 315     int heightDec = frameWidth() * 2;
 316     if (horizontalScrollBar()->isVisible()) {
 317         heightDec += style()->pixelMetric(QStyle::PM_ScrollBarExtent);
 318     }
 319
 320     rect.adjust(0, 0, -widthDec, -heightDec);
 321
 322     m_controller->view()->setGeometry(QRect(0, 0, rect.width(), rect.height()));
 323
 324     static_cast<KItemListContainerViewport*>(viewport())->scene()->setSceneRect(0, 0, rect.width(), rect.height());
 325     static_cast<KItemListContainerViewport*>(viewport())->viewport()->setGeometry(QRect(0, 0, rect.width(), rect.height()));
 326
 327     updateScrollBars();
 328 }
 329
 330 void KItemListContainer::initialize()
 331 {
 332     if (!m_controller) {
 333         m_controller = new KItemListController(this);
 334     }
 335
 336     connect(m_controller, SIGNAL(modelChanged(KItemModelBase*,KItemModelBase*)),
 337             this, SLOT(slotModelChanged(KItemModelBase*,KItemModelBase*)));
 338     connect(m_controller, SIGNAL(viewChanged(KItemListView*,KItemListView*)),
 339             this, SLOT(slotViewChanged(KItemListView*,KItemListView*)));
 340
 341     QGraphicsView* graphicsView = new KItemListContainerViewport(new QGraphicsScene(this), this);
 342     setViewport(graphicsView);
 343
 344     m_smoothScrollingAnimation = new QPropertyAnimation(this, "offset");
 345     m_smoothScrollingAnimation->setDuration(300);
 346     connect(m_smoothScrollingAnimation, SIGNAL(stateChanged(QAbstractAnimation::State,QAbstractAnimation::State)),
 347             this, SLOT(slotAnimationStateChanged(QAbstractAnimation::State,QAbstractAnimation::State)));
 348
 349     horizontalScrollBar()->installEventFilter(this);
 350     verticalScrollBar()->installEventFilter(this);
 351 }
 352
 353 #include "kitemlistcontainer.moc"