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 QScrollBar* scrollBar = (view->scrollOrientation() == Qt::Vertical)
 124                                   ? verticalScrollBar() : horizontalScrollBar();
 125     const qreal currentOffset = view->offset();
 126     if (static_cast<int>(currentOffset) == scrollBar->value()) {
 127         // The current offset is already synchronous to the scrollbar
 128         return;
 129     }
 130
 131     qreal offsetDiff = (view->scrollOrientation() == Qt::Vertical) ? dy : dx;
 132
 133     const bool animRunning = (m_smoothScrollingAnimation->state() == QAbstractAnimation::Running);
 134     if (animRunning) {
 135         // Stopping a running animation means skipping the range from the current offset
 136         // until the target offset. To prevent skipping of the range the difference
 137         // is added to the new target offset.
 138         const qreal oldEndOffset = m_smoothScrollingAnimation->endValue().toReal();
 139         offsetDiff += (currentOffset - oldEndOffset);
 140     }
 141
 142     const qreal endOffset = currentOffset - offsetDiff;
 143
 144     if (m_smoothScrolling || animRunning) {
 145         qreal startOffset = currentOffset;
 146         if (animRunning) {
 147             // If the animation was running and has been interrupted by assigning a new end-offset
 148             // one frame must be added to the start-offset to keep the animation smooth. This also
 149             // assures that animation proceeds even in cases where new end-offset are triggered
 150             // within a very short timeslots.
 151             startOffset += (endOffset - currentOffset) * 1000 / (m_smoothScrollingAnimation->duration() * 60);
 152         }
 153
 154         m_smoothScrollingAnimation->stop();
 155         m_smoothScrollingAnimation->setStartValue(startOffset);
 156         m_smoothScrollingAnimation->setEndValue(endOffset);
 157         m_smoothScrollingAnimation->setEasingCurve(animRunning ? QEasingCurve::OutQuad : QEasingCurve::InOutQuad);
 158         m_smoothScrollingAnimation->start();
 159         view->setOffset(startOffset);
 160     } else {
 161         view->setOffset(endOffset);
 162     }
 163 }
 164
 165 bool KItemListContainer::eventFilter(QObject* obj, QEvent* event)
 166 {
 167     Q_ASSERT(obj == horizontalScrollBar() || obj == verticalScrollBar());
 168
 169     // Check whether the scrollbar has been adjusted by a mouse-event
 170     // triggered by the user and remember this in m_scrollBarPressed.
 171     // The smooth scrolling will only get active if m_scrollBarPressed
 172     // is true (see scrollContentsBy()).
 173     const bool scrollVertical = (m_controller->view()->scrollOrientation() == Qt::Vertical);
 174     const bool checkEvent = ( scrollVertical && obj == verticalScrollBar()) ||
 175                             (!scrollVertical && obj == horizontalScrollBar());
 176     if (checkEvent) {
 177         switch (event->type()) {
 178         case QEvent::MouseButtonPress:
 179             m_scrollBarPressed = true;
 180             m_smoothScrolling = true;
 181             break;
 182
 183         case QEvent::MouseButtonRelease:
 184             m_scrollBarPressed = false;
 185             m_smoothScrolling = false;
 186             break;
 187
 188         case QEvent::Wheel:
 189             wheelEvent(static_cast<QWheelEvent*>(event));
 190             break;
 191
 192         default:
 193             break;
 194         }
 195     }
 196
 197     return QAbstractScrollArea::eventFilter(obj, event);
 198 }
 199
 200 void KItemListContainer::wheelEvent(QWheelEvent* event)
 201 {
 202     if (event->modifiers().testFlag(Qt::ControlModifier)) {
 203         event->ignore();
 204         return;
 205     }
 206
 207     KItemListView* view = m_controller->view();
 208
 209     if (!view || event->orientation() != view->scrollOrientation()) {
 210         return;
 211     }
 212
 213     const int numDegrees = event->delta() / 8;
 214     const int numSteps = numDegrees / 15;
 215
 216     const bool previous = m_smoothScrolling;
 217     m_smoothScrolling = true;
 218     if (view->scrollOrientation() == Qt::Vertical) {
 219         const int value = verticalScrollBar()->value();
 220         verticalScrollBar()->setValue(value - numSteps * view->size().height());
 221     } else {
 222         const int value = horizontalScrollBar()->value();
 223         horizontalScrollBar()->setValue(value - numSteps * view->size().width());
 224     }
 225     m_smoothScrolling = previous;
 226
 227     event->accept();
 228 }
 229
 230 void KItemListContainer::slotModelChanged(KItemModelBase* current, KItemModelBase* previous)
 231 {
 232     Q_UNUSED(current);
 233     Q_UNUSED(previous);
 234 }
 235
 236 void KItemListContainer::slotViewChanged(KItemListView* current, KItemListView* previous)
 237 {
 238     QGraphicsScene* scene = static_cast<QGraphicsView*>(viewport())->scene();
 239     if (previous) {
 240         scene->removeItem(previous);
 241         disconnect(previous, SIGNAL(offsetChanged(qreal,qreal)), this, SLOT(updateScrollBars()));
 242         disconnect(previous, SIGNAL(maximumOffsetChanged(qreal,qreal)), this, SLOT(updateScrollBars()));
 243         disconnect(previous, SIGNAL(scrollTo(qreal)), this, SLOT(scrollTo(qreal)));
 244         m_smoothScrollingAnimation->setTargetObject(0);
 245     }
 246     if (current) {
 247         scene->addItem(current);
 248         connect(current, SIGNAL(offsetChanged(qreal,qreal)), this, SLOT(updateScrollBars()));
 249         connect(current, SIGNAL(maximumOffsetChanged(qreal,qreal)), this, SLOT(updateScrollBars()));
 250         connect(current, SIGNAL(scrollTo(qreal)), this, SLOT(scrollTo(qreal)));
 251         m_smoothScrollingAnimation->setTargetObject(current);
 252     }
 253 }
 254
 255 void KItemListContainer::slotAnimationStateChanged(QAbstractAnimation::State newState,
 256                                                    QAbstractAnimation::State oldState)
 257 {
 258     Q_UNUSED(oldState);
 259     if (newState == QAbstractAnimation::Stopped && m_smoothScrolling && !m_scrollBarPressed) {
 260         m_smoothScrolling = false;
 261     }
 262 }
 263
 264
 265 void KItemListContainer::scrollTo(qreal offset)
 266 {
 267     const KItemListView* view = m_controller->view();
 268     if (!view) {
 269         return;
 270     }
 271
 272     m_smoothScrolling = true;
 273     QScrollBar* scrollBar = (view->scrollOrientation() == Qt::Vertical)
 274                             ? verticalScrollBar() : horizontalScrollBar();
 275     scrollBar->setValue(offset);
 276 }
 277
 278 void KItemListContainer::updateScrollBars()
 279 {
 280     const KItemListView* view = m_controller->view();
 281     if (!view) {
 282         return;
 283     }
 284
 285     QScrollBar* scrollBar = 0;
 286     int singleStep = 0;
 287     int pageStep = 0;
 288     QScrollBar* otherScrollBar = 0;
 289     if (view->scrollOrientation() == Qt::Vertical) {
 290         scrollBar = verticalScrollBar();
 291         singleStep = view->itemSize().height();
 292         pageStep = view->size().height();
 293         otherScrollBar = horizontalScrollBar();
 294     } else {
 295         scrollBar = horizontalScrollBar();
 296         singleStep = view->itemSize().width();
 297         pageStep = view->size().width();
 298         otherScrollBar = verticalScrollBar();
 299     }
 300
 301     const int value = view->offset();
 302     const int maximum = qMax(0, int(view->maximumOffset() - pageStep));
 303     if (m_smoothScrollingAnimation->state() == QAbstractAnimation::Running) {
 304         if (maximum == scrollBar->maximum()) {
 305             // The value has been changed by the animation, no update
 306             // of the scrollbars is required as their target state will be
 307             // reached with the end of the animation.
 308             return;
 309         }
 310
 311         // The maximum has been changed which indicates that the content
 312         // of the view has been changed. Stop the animation in any case and
 313         // update the scrollbars immediately.
 314         m_smoothScrollingAnimation->stop();
 315     }
 316
 317     scrollBar->setSingleStep(singleStep);
 318     scrollBar->setPageStep(pageStep);
 319     scrollBar->setMinimum(0);
 320     scrollBar->setMaximum(maximum);
 321     scrollBar->setValue(value);
 322
 323     // Make sure that the other scroll bar is hidden
 324     otherScrollBar->setMaximum(0);
 325     otherScrollBar->setValue(0);
 326 }
 327
 328 void KItemListContainer::updateGeometries()
 329 {
 330     QRect rect = geometry();
 331
 332     const int widthDec = verticalScrollBar()->isVisible()
 333                          ? frameWidth() + style()->pixelMetric(QStyle::PM_ScrollBarExtent)
 334                          : frameWidth() * 2;
 335
 336     const int heightDec = horizontalScrollBar()->isVisible()
 337                           ? frameWidth() + style()->pixelMetric(QStyle::PM_ScrollBarExtent)
 338                           : frameWidth() * 2;
 339
 340     rect.adjust(0, 0, -widthDec, -heightDec);
 341
 342     m_controller->view()->setGeometry(QRect(0, 0, rect.width(), rect.height()));
 343
 344     static_cast<KItemListContainerViewport*>(viewport())->scene()->setSceneRect(0, 0, rect.width(), rect.height());
 345     static_cast<KItemListContainerViewport*>(viewport())->viewport()->setGeometry(QRect(0, 0, rect.width(), rect.height()));
 346
 347     updateScrollBars();
 348 }
 349
 350 void KItemListContainer::initialize()
 351 {
 352     if (!m_controller) {
 353         m_controller = new KItemListController(this);
 354     }
 355
 356     connect(m_controller, SIGNAL(modelChanged(KItemModelBase*,KItemModelBase*)),
 357             this, SLOT(slotModelChanged(KItemModelBase*,KItemModelBase*)));
 358     connect(m_controller, SIGNAL(viewChanged(KItemListView*,KItemListView*)),
 359             this, SLOT(slotViewChanged(KItemListView*,KItemListView*)));
 360
 361     QGraphicsView* graphicsView = new KItemListContainerViewport(new QGraphicsScene(this), this);
 362     setViewport(graphicsView);
 363
 364     m_smoothScrollingAnimation = new QPropertyAnimation(this, "offset");
 365     m_smoothScrollingAnimation->setDuration(300);
 366     connect(m_smoothScrollingAnimation, SIGNAL(stateChanged(QAbstractAnimation::State,QAbstractAnimation::State)),
 367             this, SLOT(slotAnimationStateChanged(QAbstractAnimation::State,QAbstractAnimation::State)));
 368
 369     horizontalScrollBar()->installEventFilter(this);
 370     verticalScrollBar()->installEventFilter(this);
 371 }
 372
 373 #include "kitemlistcontainer.moc"