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 "private/kitemlistsmoothscroller.h"
  30
  31 #include <QApplication>
  32 #include <QGraphicsScene>
  33 #include <QGraphicsView>
  34 #include <QPropertyAnimation>
  35 #include <QScrollBar>
  36 #include <QStyle>
  37 #include <QStyleOption>
  38
  39 #include <KDebug>
  40
  41 /**
  42  * Replaces the default viewport of KItemListContainer by a
  43  * non-scrollable viewport. The scrolling is done in an optimized
  44  * way by KItemListView internally.
  45  */
  46 class KItemListContainerViewport : public QGraphicsView
  47 {
  48 public:
  49     KItemListContainerViewport(QGraphicsScene* scene, QWidget* parent);
  50 protected:
  51     virtual void wheelEvent(QWheelEvent* event);
  52 };
  53
  54 KItemListContainerViewport::KItemListContainerViewport(QGraphicsScene* scene, QWidget* parent) :
  55     QGraphicsView(scene, parent)
  56 {
  57     setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
  58     setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
  59     setViewportMargins(0, 0, 0, 0);
  60     setFrameShape(QFrame::NoFrame);
  61 }
  62
  63 void KItemListContainerViewport::wheelEvent(QWheelEvent* event)
  64 {
  65     // Assure that the wheel-event gets forwarded to the parent
  66     // and not handled at all by QGraphicsView.
  67     event->ignore();
  68 }
  69
  70
  71
  72 KItemListContainer::KItemListContainer(KItemListController* controller, QWidget* parent) :
  73     QAbstractScrollArea(parent),
  74     m_controller(controller),
  75     m_horizontalSmoothScroller(0),
  76     m_verticalSmoothScroller(0)
  77 {
  78     Q_ASSERT(controller);
  79     controller->setParent(this);
  80     initialize();
  81 }
  82
  83 KItemListContainer::KItemListContainer(QWidget* parent) :
  84     QAbstractScrollArea(parent),
  85     m_controller(0),
  86     m_horizontalSmoothScroller(0),
  87     m_verticalSmoothScroller(0)
  88 {
  89     initialize();
  90 }
  91
  92 KItemListContainer::~KItemListContainer()
  93 {
  94 }
  95
  96 KItemListController* KItemListContainer::controller() const
  97 {
  98     return m_controller;
  99 }
 100
 101 void KItemListContainer::keyPressEvent(QKeyEvent* event)
 102 {
 103     // TODO: We should find a better way to handle the key press events in the view.
 104     // The reasons why we need this hack are:
 105     // 1. Without reimplementing keyPressEvent() here, the event would not reach the QGraphicsView.
 106     // 2. By default, the KItemListView does not have the keyboard focus in the QGraphicsScene, so
 107     //    simply sending the event to the QGraphicsView which is the KItemListContainer's viewport
 108     //    does not work.
 109     KItemListView* view = m_controller->view();
 110     if (view) {
 111         QApplication::sendEvent(view, event);
 112     }
 113 }
 114
 115 void KItemListContainer::showEvent(QShowEvent* event)
 116 {
 117     QAbstractScrollArea::showEvent(event);
 118     updateGeometries();
 119 }
 120
 121 void KItemListContainer::resizeEvent(QResizeEvent* event)
 122 {
 123     QAbstractScrollArea::resizeEvent(event);
 124     updateGeometries();
 125 }
 126
 127 void KItemListContainer::scrollContentsBy(int dx, int dy)
 128 {
 129     m_horizontalSmoothScroller->scrollContentsBy(dx);
 130     m_verticalSmoothScroller->scrollContentsBy(dy);
 131 }
 132
 133 void KItemListContainer::wheelEvent(QWheelEvent* event)
 134 {
 135     if (event->modifiers().testFlag(Qt::ControlModifier)) {
 136         event->ignore();
 137         return;
 138     }
 139
 140     KItemListView* view = m_controller->view();
 141     if (!view) {
 142         event->ignore();
 143         return;
 144     }
 145
 146     const bool scrollHorizontally = (event->orientation() == Qt::Horizontal) ||
 147                                     (event->orientation() == Qt::Vertical && !verticalScrollBar()->isVisible());
 148     KItemListSmoothScroller* smoothScroller = scrollHorizontally ?
 149                                               m_horizontalSmoothScroller : m_verticalSmoothScroller;
 150
 151     const int numDegrees = event->delta() / 8;
 152     const int numSteps = numDegrees / 15;
 153
 154     const QScrollBar* scrollBar = smoothScroller->scrollBar();
 155     smoothScroller->scrollTo(scrollBar->value() - numSteps * scrollBar->pageStep() / 4);
 156
 157     event->accept();
 158 }
 159
 160 void KItemListContainer::slotScrollOrientationChanged(Qt::Orientation current, Qt::Orientation previous)
 161 {
 162     Q_UNUSED(previous);
 163     updateSmoothScrollers(current);
 164 }
 165
 166 void KItemListContainer::slotModelChanged(KItemModelBase* current, KItemModelBase* previous)
 167 {
 168     Q_UNUSED(current);
 169     Q_UNUSED(previous);
 170 }
 171
 172 void KItemListContainer::slotViewChanged(KItemListView* current, KItemListView* previous)
 173 {
 174     QGraphicsScene* scene = static_cast<QGraphicsView*>(viewport())->scene();
 175     if (previous) {
 176         scene->removeItem(previous);
 177         disconnect(previous, SIGNAL(scrollOrientationChanged(Qt::Orientation,Qt::Orientation)), this, SLOT(slotScrollOrientationChanged(Qt::Orientation,Qt::Orientation)));
 178         disconnect(previous, SIGNAL(scrollOffsetChanged(qreal,qreal)),        this, SLOT(updateScrollOffsetScrollBar()));
 179         disconnect(previous, SIGNAL(maximumScrollOffsetChanged(qreal,qreal)), this, SLOT(updateScrollOffsetScrollBar()));
 180         disconnect(previous, SIGNAL(itemOffsetChanged(qreal,qreal)),          this, SLOT(updateItemOffsetScrollBar()));
 181         disconnect(previous, SIGNAL(maximumItemOffsetChanged(qreal,qreal)),   this, SLOT(updateItemOffsetScrollBar()));
 182         disconnect(previous, SIGNAL(scrollTo(qreal)),                         this, SLOT(scrollTo(qreal)));
 183         m_horizontalSmoothScroller->setTargetObject(0);
 184         m_verticalSmoothScroller->setTargetObject(0);
 185     }
 186     if (current) {
 187         scene->addItem(current);
 188         connect(current, SIGNAL(scrollOrientationChanged(Qt::Orientation,Qt::Orientation)), this, SLOT(slotScrollOrientationChanged(Qt::Orientation,Qt::Orientation)));
 189         connect(current, SIGNAL(scrollOffsetChanged(qreal,qreal)),        this, SLOT(updateScrollOffsetScrollBar()));
 190         connect(current, SIGNAL(maximumScrollOffsetChanged(qreal,qreal)), this, SLOT(updateScrollOffsetScrollBar()));
 191         connect(current, SIGNAL(itemOffsetChanged(qreal,qreal)),          this, SLOT(updateItemOffsetScrollBar()));
 192         connect(current, SIGNAL(maximumItemOffsetChanged(qreal,qreal)),   this, SLOT(updateItemOffsetScrollBar()));
 193         connect(current, SIGNAL(scrollTo(qreal)),                         this, SLOT(scrollTo(qreal)));
 194         m_horizontalSmoothScroller->setTargetObject(current);
 195         m_verticalSmoothScroller->setTargetObject(current);
 196         updateSmoothScrollers(current->scrollOrientation());
 197     }
 198 }
 199
 200 void KItemListContainer::scrollTo(qreal offset)
 201 {
 202     const KItemListView* view = m_controller->view();
 203     if (view) {
 204         if (view->scrollOrientation() == Qt::Vertical) {
 205             m_verticalSmoothScroller->scrollTo(offset);
 206         } else {
 207             m_horizontalSmoothScroller->scrollTo(offset);
 208         }
 209     }
 210 }
 211
 212 void KItemListContainer::updateScrollOffsetScrollBar()
 213 {
 214     const KItemListView* view = m_controller->view();
 215     if (!view) {
 216         return;
 217     }
 218
 219     KItemListSmoothScroller* smoothScroller = 0;
 220     QScrollBar* scrollOffsetScrollBar = 0;
 221     int singleStep = 0;
 222     int pageStep = 0;
 223     if (view->scrollOrientation() == Qt::Vertical) {
 224         smoothScroller = m_verticalSmoothScroller;
 225         scrollOffsetScrollBar = verticalScrollBar();
 226         singleStep = view->itemSize().height();
 227         pageStep = view->size().height();
 228     } else {
 229         smoothScroller = m_horizontalSmoothScroller;
 230         scrollOffsetScrollBar = horizontalScrollBar();
 231         singleStep = view->itemSize().width();
 232         pageStep = view->size().width();
 233     }
 234
 235     const int value = view->scrollOffset();
 236     const int maximum = qMax(0, int(view->maximumScrollOffset() - pageStep));
 237     if (smoothScroller->requestScrollBarUpdate(maximum)) {
 238         const bool updatePolicy = (scrollOffsetScrollBar->maximum() > 0 && maximum == 0)
 239                                   || horizontalScrollBarPolicy() == Qt::ScrollBarAlwaysOn;
 240
 241         scrollOffsetScrollBar->setSingleStep(singleStep);
 242         scrollOffsetScrollBar->setPageStep(pageStep);
 243         scrollOffsetScrollBar->setMinimum(0);
 244         scrollOffsetScrollBar->setMaximum(maximum);
 245         scrollOffsetScrollBar->setValue(value);
 246
 247         if (updatePolicy) {
 248             // Prevent a potential endless layout loop (see bug #293318).
 249             updateScrollOffsetScrollBarPolicy();
 250         }
 251     }
 252 }
 253
 254 void KItemListContainer::updateItemOffsetScrollBar()
 255 {
 256     const KItemListView* view = m_controller->view();
 257     if (!view) {
 258         return;
 259     }
 260
 261     KItemListSmoothScroller* smoothScroller = 0;
 262     QScrollBar* itemOffsetScrollBar = 0;
 263     int singleStep = 0;
 264     int pageStep = 0;
 265     if (view->scrollOrientation() == Qt::Vertical) {
 266         smoothScroller = m_horizontalSmoothScroller;
 267         itemOffsetScrollBar = horizontalScrollBar();
 268         singleStep = view->size().width() / 10;
 269         pageStep = view->size().width();
 270     } else {
 271         smoothScroller = m_verticalSmoothScroller;
 272         itemOffsetScrollBar = verticalScrollBar();
 273         singleStep = view->size().height() / 10;
 274         pageStep = view->size().height();
 275     }
 276
 277     const int value = view->itemOffset();
 278     const int maximum = qMax(0, int(view->maximumItemOffset()) - pageStep);
 279     if (smoothScroller->requestScrollBarUpdate(maximum)) {
 280         itemOffsetScrollBar->setSingleStep(singleStep);
 281         itemOffsetScrollBar->setPageStep(pageStep);
 282         itemOffsetScrollBar->setMinimum(0);
 283         itemOffsetScrollBar->setMaximum(maximum);
 284         itemOffsetScrollBar->setValue(value);
 285     }
 286 }
 287
 288 void KItemListContainer::updateGeometries()
 289 {
 290     QRect rect = geometry();
 291
 292     int extra = frameWidth() * 2;
 293     QStyleOption option;
 294     option.initFrom(this);
 295     if (style()->styleHint(QStyle::SH_ScrollView_FrameOnlyAroundContents, &option, this)) {
 296         extra += style()->pixelMetric(QStyle::PM_ScrollView_ScrollBarSpacing, &option, this);
 297     }
 298
 299     const int widthDec = verticalScrollBar()->isVisible()
 300                          ? extra + style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this)
 301                          : extra;
 302
 303     const int heightDec = horizontalScrollBar()->isVisible()
 304                           ? extra + style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this)
 305                           : extra;
 306
 307     rect.adjust(0, 0, -widthDec, -heightDec);
 308
 309     const QRectF newGeometry(0, 0, rect.width(), rect.height());
 310     if (m_controller->view()->geometry() != newGeometry) {
 311         m_controller->view()->setGeometry(newGeometry);
 312
 313         static_cast<KItemListContainerViewport*>(viewport())->scene()->setSceneRect(0, 0, rect.width(), rect.height());
 314         static_cast<KItemListContainerViewport*>(viewport())->viewport()->setGeometry(QRect(0, 0, rect.width(), rect.height()));
 315
 316         updateScrollOffsetScrollBar();
 317         updateItemOffsetScrollBar();
 318     }
 319 }
 320
 321 void KItemListContainer::updateSmoothScrollers(Qt::Orientation orientation)
 322 {
 323     if (orientation == Qt::Vertical) {
 324         m_verticalSmoothScroller->setPropertyName("scrollOffset");
 325         m_horizontalSmoothScroller->setPropertyName("itemOffset");
 326     } else {
 327         m_horizontalSmoothScroller->setPropertyName("scrollOffset");
 328         m_verticalSmoothScroller->setPropertyName("itemOffset");
 329     }
 330 }
 331
 332 void KItemListContainer::updateScrollOffsetScrollBarPolicy()
 333 {
 334     const KItemListView* view = m_controller->view();
 335     Q_ASSERT(view);
 336     const bool vertical = (view->scrollOrientation() == Qt::Vertical);
 337
 338     QStyleOption option;
 339     option.initFrom(this);
 340     const int scrollBarInc = style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this);
 341
 342     QSizeF newViewSize = m_controller->view()->size();
 343     if (vertical) {
 344         newViewSize.rwidth() += scrollBarInc;
 345     } else {
 346         newViewSize.rheight() += scrollBarInc;
 347     }
 348
 349     const Qt::ScrollBarPolicy policy = view->scrollBarRequired(newViewSize)
 350                                        ? Qt::ScrollBarAlwaysOn : Qt::ScrollBarAsNeeded;
 351     if (vertical) {
 352         setVerticalScrollBarPolicy(policy);
 353     } else {
 354         setHorizontalScrollBarPolicy(policy);
 355     }
 356 }
 357
 358 void KItemListContainer::initialize()
 359 {
 360     if (m_controller) {
 361         if (m_controller->model()) {
 362             slotModelChanged(m_controller->model(), 0);
 363         }
 364         if (m_controller->view()) {
 365             slotViewChanged(m_controller->view(), 0);
 366         }
 367     } else {
 368         m_controller = new KItemListController(this);
 369     }
 370
 371     connect(m_controller, SIGNAL(modelChanged(KItemModelBase*,KItemModelBase*)),
 372             this, SLOT(slotModelChanged(KItemModelBase*,KItemModelBase*)));
 373     connect(m_controller, SIGNAL(viewChanged(KItemListView*,KItemListView*)),
 374             this, SLOT(slotViewChanged(KItemListView*,KItemListView*)));
 375
 376     QGraphicsView* graphicsView = new KItemListContainerViewport(new QGraphicsScene(this), this);
 377     setViewport(graphicsView);
 378
 379     m_horizontalSmoothScroller = new KItemListSmoothScroller(horizontalScrollBar(), this);
 380     m_verticalSmoothScroller = new KItemListSmoothScroller(verticalScrollBar(), this);
 381 }
 382
 383 #include "kitemlistcontainer.moc"