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