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 "kitemlistsmoothscroller_p.h"
  27 #include "kitemlistview.h"
  28 #include "kitemmodelbase.h"
  29
  30 #include <QApplication>
  31 #include <QGraphicsScene>
  32 #include <QGraphicsView>
  33 #include <QPropertyAnimation>
  34 #include <QScrollBar>
  35 #include <QStyle>
  36 #include <QStyleOption>
  37
  38 #include <KDebug>
  39
  40 /**
  41  * Replaces the default viewport of KItemListContainer by a
  42  * non-scrollable viewport. The scrolling is done in an optimized
  43  * way by KItemListView internally.
  44  */
  45 class KItemListContainerViewport : public QGraphicsView
  46 {
  47 public:
  48     KItemListContainerViewport(QGraphicsScene* scene, QWidget* parent);
  49 protected:
  50     virtual void wheelEvent(QWheelEvent* event);
  51 };
  52
  53 KItemListContainerViewport::KItemListContainerViewport(QGraphicsScene* scene, QWidget* parent) :
  54     QGraphicsView(scene, parent)
  55 {
  56     setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
  57     setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
  58     setViewportMargins(0, 0, 0, 0);
  59     setFrameShape(QFrame::NoFrame);
  60 }
  61
  62 void KItemListContainerViewport::wheelEvent(QWheelEvent* event)
  63 {
  64     // Assure that the wheel-event gets forwarded to the parent
  65     // and not handled at all by QGraphicsView.
  66     event->ignore();
  67 }
  68
  69
  70
  71 KItemListContainer::KItemListContainer(KItemListController* controller, QWidget* parent) :
  72     QAbstractScrollArea(parent),
  73     m_controller(controller),
  74     m_horizontalSmoothScroller(0),
  75     m_verticalSmoothScroller(0)
  76 {
  77     Q_ASSERT(controller);
  78     controller->setParent(this);
  79     initialize();
  80 }
  81
  82 KItemListContainer::KItemListContainer(QWidget* parent) :
  83     QAbstractScrollArea(parent),
  84     m_controller(0),
  85     m_horizontalSmoothScroller(0),
  86     m_verticalSmoothScroller(0)
  87 {
  88     initialize();
  89 }
  90
  91 KItemListContainer::~KItemListContainer()
  92 {
  93 }
  94
  95 KItemListController* KItemListContainer::controller() const
  96 {
  97     return m_controller;
  98 }
  99
 100 void KItemListContainer::keyPressEvent(QKeyEvent* event)
 101 {
 102     // TODO: We should find a better way to handle the key press events in the view.
 103     // The reasons why we need this hack are:
 104     // 1. Without reimplementing keyPressEvent() here, the event would not reach the QGraphicsView.
 105     // 2. By default, the KItemListView does not have the keyboard focus in the QGraphicsScene, so
 106     //    simply sending the event to the QGraphicsView which is the KItemListContainer's viewport
 107     //    does not work.
 108     KItemListView* view = m_controller->view();
 109     if (view) {
 110         QApplication::sendEvent(view, event);
 111     }
 112 }
 113
 114 void KItemListContainer::showEvent(QShowEvent* event)
 115 {
 116     QAbstractScrollArea::showEvent(event);
 117     updateGeometries();
 118 }
 119
 120 void KItemListContainer::resizeEvent(QResizeEvent* event)
 121 {
 122     QAbstractScrollArea::resizeEvent(event);
 123     updateGeometries();
 124 }
 125
 126 void KItemListContainer::scrollContentsBy(int dx, int dy)
 127 {
 128     m_horizontalSmoothScroller->scrollContentsBy(dx);
 129     m_verticalSmoothScroller->scrollContentsBy(dy);
 130 }
 131
 132 void KItemListContainer::wheelEvent(QWheelEvent* event)
 133 {
 134     if (event->modifiers().testFlag(Qt::ControlModifier)) {
 135         event->ignore();
 136         return;
 137     }
 138
 139     KItemListView* view = m_controller->view();
 140     if (!view) {
 141         event->ignore();
 142         return;
 143     }
 144
 145     const bool scrollHorizontally = (event->orientation() == Qt::Horizontal) ||
 146                                     (event->orientation() == Qt::Vertical && !verticalScrollBar()->isVisible());
 147     KItemListSmoothScroller* smoothScroller = scrollHorizontally ?
 148                                               m_horizontalSmoothScroller : m_verticalSmoothScroller;
 149
 150     const int numDegrees = event->delta() / 8;
 151     const int numSteps = numDegrees / 15;
 152
 153     const QScrollBar* scrollBar = smoothScroller->scrollBar();
 154     smoothScroller->scrollTo(scrollBar->value() - numSteps * scrollBar->pageStep() / 4);
 155
 156     event->accept();
 157 }
 158
 159 void KItemListContainer::slotScrollOrientationChanged(Qt::Orientation current, Qt::Orientation previous)
 160 {
 161     Q_UNUSED(previous);
 162     updateSmoothScrollers(current);
 163 }
 164
 165 void KItemListContainer::slotModelChanged(KItemModelBase* current, KItemModelBase* previous)
 166 {
 167     Q_UNUSED(current);
 168     Q_UNUSED(previous);
 169 }
 170
 171 void KItemListContainer::slotViewChanged(KItemListView* current, KItemListView* previous)
 172 {
 173     QGraphicsScene* scene = static_cast<QGraphicsView*>(viewport())->scene();
 174     if (previous) {
 175         scene->removeItem(previous);
 176         disconnect(previous, SIGNAL(scrollOrientationChanged(Qt::Orientation,Qt::Orientation)), this, SLOT(slotScrollOrientationChanged(Qt::Orientation,Qt::Orientation)));
 177         disconnect(previous, SIGNAL(scrollOffsetChanged(qreal,qreal)),        this, SLOT(updateScrollOffsetScrollBar()));
 178         disconnect(previous, SIGNAL(maximumScrollOffsetChanged(qreal,qreal)), this, SLOT(updateScrollOffsetScrollBar()));
 179         disconnect(previous, SIGNAL(itemOffsetChanged(qreal,qreal)),          this, SLOT(updateItemOffsetScrollBar()));
 180         disconnect(previous, SIGNAL(maximumItemOffsetChanged(qreal,qreal)),   this, SLOT(updateItemOffsetScrollBar()));
 181         disconnect(previous, SIGNAL(scrollTo(qreal)),                         this, SLOT(scrollTo(qreal)));
 182         m_horizontalSmoothScroller->setTargetObject(0);
 183         m_verticalSmoothScroller->setTargetObject(0);
 184     }
 185     if (current) {
 186         scene->addItem(current);
 187         connect(current, SIGNAL(scrollOrientationChanged(Qt::Orientation,Qt::Orientation)), this, SLOT(slotScrollOrientationChanged(Qt::Orientation,Qt::Orientation)));
 188         connect(current, SIGNAL(scrollOffsetChanged(qreal,qreal)),        this, SLOT(updateScrollOffsetScrollBar()));
 189         connect(current, SIGNAL(maximumScrollOffsetChanged(qreal,qreal)), this, SLOT(updateScrollOffsetScrollBar()));
 190         connect(current, SIGNAL(itemOffsetChanged(qreal,qreal)),          this, SLOT(updateItemOffsetScrollBar()));
 191         connect(current, SIGNAL(maximumItemOffsetChanged(qreal,qreal)),   this, SLOT(updateItemOffsetScrollBar()));
 192         connect(current, SIGNAL(scrollTo(qreal)),                         this, SLOT(scrollTo(qreal)));
 193         m_horizontalSmoothScroller->setTargetObject(current);
 194         m_verticalSmoothScroller->setTargetObject(current);
 195         updateSmoothScrollers(current->scrollOrientation());
 196     }
 197 }
 198
 199 void KItemListContainer::scrollTo(qreal offset)
 200 {
 201     const KItemListView* view = m_controller->view();
 202     if (view) {
 203         if (view->scrollOrientation() == Qt::Vertical) {
 204             m_verticalSmoothScroller->scrollTo(offset);
 205         } else {
 206             m_horizontalSmoothScroller->scrollTo(offset);
 207         }
 208     }
 209 }
 210
 211 void KItemListContainer::updateScrollOffsetScrollBar()
 212 {
 213     const KItemListView* view = m_controller->view();
 214     if (!view) {
 215         return;
 216     }
 217
 218     KItemListSmoothScroller* smoothScroller = 0;
 219     QScrollBar* scrollOffsetScrollBar = 0;
 220     int singleStep = 0;
 221     int pageStep = 0;
 222     if (view->scrollOrientation() == Qt::Vertical) {
 223         smoothScroller = m_verticalSmoothScroller;
 224         scrollOffsetScrollBar = verticalScrollBar();
 225         singleStep = view->itemSize().height();
 226         pageStep = view->size().height();
 227     } else {
 228         smoothScroller = m_horizontalSmoothScroller;
 229         scrollOffsetScrollBar = horizontalScrollBar();
 230         singleStep = view->itemSize().width();
 231         pageStep = view->size().width();
 232     }
 233
 234     const int value = view->scrollOffset();
 235     const int maximum = qMax(0, int(view->maximumScrollOffset() - pageStep));
 236     if (smoothScroller->requestScrollBarUpdate(maximum)) {
 237         const bool updatePolicy = (scrollOffsetScrollBar->maximum() > 0 && maximum == 0)
 238                                   || horizontalScrollBarPolicy() == Qt::ScrollBarAlwaysOn;
 239
 240         scrollOffsetScrollBar->setSingleStep(singleStep);
 241         scrollOffsetScrollBar->setPageStep(pageStep);
 242         scrollOffsetScrollBar->setMinimum(0);
 243         scrollOffsetScrollBar->setMaximum(maximum);
 244         scrollOffsetScrollBar->setValue(value);
 245
 246         if (updatePolicy) {
 247             // Prevent a potential endless layout loop (see bug #293318).
 248             updateScrollOffsetScrollBarPolicy();
 249         }
 250     }
 251 }
 252
 253 void KItemListContainer::updateItemOffsetScrollBar()
 254 {
 255     const KItemListView* view = m_controller->view();
 256     if (!view) {
 257         return;
 258     }
 259
 260     KItemListSmoothScroller* smoothScroller = 0;
 261     QScrollBar* itemOffsetScrollBar = 0;
 262     int singleStep = 0;
 263     int pageStep = 0;
 264     if (view->scrollOrientation() == Qt::Vertical) {
 265         smoothScroller = m_horizontalSmoothScroller;
 266         itemOffsetScrollBar = horizontalScrollBar();
 267         singleStep = view->size().width() / 10;
 268         pageStep = view->size().width();
 269     } else {
 270         smoothScroller = m_verticalSmoothScroller;
 271         itemOffsetScrollBar = verticalScrollBar();
 272         singleStep = view->size().height() / 10;
 273         pageStep = view->size().height();
 274     }
 275
 276     const int value = view->itemOffset();
 277     const int maximum = qMax(0, int(view->maximumItemOffset()) - pageStep);
 278     if (smoothScroller->requestScrollBarUpdate(maximum)) {
 279         itemOffsetScrollBar->setSingleStep(singleStep);
 280         itemOffsetScrollBar->setPageStep(pageStep);
 281         itemOffsetScrollBar->setMinimum(0);
 282         itemOffsetScrollBar->setMaximum(maximum);
 283         itemOffsetScrollBar->setValue(value);
 284     }
 285 }
 286
 287 void KItemListContainer::updateGeometries()
 288 {
 289     QRect rect = geometry();
 290
 291     int extra = frameWidth() * 2;
 292     QStyleOption option;
 293     option.initFrom(this);
 294     if (style()->styleHint(QStyle::SH_ScrollView_FrameOnlyAroundContents, &option, this)) {
 295         extra += style()->pixelMetric(QStyle::PM_ScrollView_ScrollBarSpacing, &option, this);
 296     }
 297
 298     const int widthDec = verticalScrollBar()->isVisible()
 299                          ? extra + style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this)
 300                          : extra;
 301
 302     const int heightDec = horizontalScrollBar()->isVisible()
 303                           ? extra + style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this)
 304                           : extra;
 305
 306     rect.adjust(0, 0, -widthDec, -heightDec);
 307
 308     const QRectF newGeometry(0, 0, rect.width(), rect.height());
 309     if (m_controller->view()->geometry() != newGeometry) {
 310         m_controller->view()->setGeometry(newGeometry);
 311
 312         static_cast<KItemListContainerViewport*>(viewport())->scene()->setSceneRect(0, 0, rect.width(), rect.height());
 313         static_cast<KItemListContainerViewport*>(viewport())->viewport()->setGeometry(QRect(0, 0, rect.width(), rect.height()));
 314
 315         updateScrollOffsetScrollBar();
 316         updateItemOffsetScrollBar();
 317     }
 318 }
 319
 320 void KItemListContainer::updateSmoothScrollers(Qt::Orientation orientation)
 321 {
 322     if (orientation == Qt::Vertical) {
 323         m_verticalSmoothScroller->setPropertyName("scrollOffset");
 324         m_horizontalSmoothScroller->setPropertyName("itemOffset");
 325     } else {
 326         m_horizontalSmoothScroller->setPropertyName("scrollOffset");
 327         m_verticalSmoothScroller->setPropertyName("itemOffset");
 328     }
 329 }
 330
 331 void KItemListContainer::updateScrollOffsetScrollBarPolicy()
 332 {
 333     const KItemListView* view = m_controller->view();
 334     Q_ASSERT(view);
 335     const bool vertical = (view->scrollOrientation() == Qt::Vertical);
 336
 337     QStyleOption option;
 338     option.initFrom(this);
 339     const int scrollBarInc = style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this);
 340
 341     QSizeF newViewSize = m_controller->view()->size();
 342     if (vertical) {
 343         newViewSize.rwidth() += scrollBarInc;
 344     } else {
 345         newViewSize.rheight() += scrollBarInc;
 346     }
 347
 348     const Qt::ScrollBarPolicy policy = view->scrollBarRequired(newViewSize)
 349                                        ? Qt::ScrollBarAlwaysOn : Qt::ScrollBarAsNeeded;
 350     if (vertical) {
 351         setVerticalScrollBarPolicy(policy);
 352     } else {
 353         setHorizontalScrollBarPolicy(policy);
 354     }
 355 }
 356
 357 void KItemListContainer::initialize()
 358 {
 359     if (m_controller) {
 360         if (m_controller->model()) {
 361             slotModelChanged(m_controller->model(), 0);
 362         }
 363         if (m_controller->view()) {
 364             slotViewChanged(m_controller->view(), 0);
 365         }
 366     } else {
 367         m_controller = new KItemListController(this);
 368     }
 369
 370     connect(m_controller, SIGNAL(modelChanged(KItemModelBase*,KItemModelBase*)),
 371             this, SLOT(slotModelChanged(KItemModelBase*,KItemModelBase*)));
 372     connect(m_controller, SIGNAL(viewChanged(KItemListView*,KItemListView*)),
 373             this, SLOT(slotViewChanged(KItemListView*,KItemListView*)));
 374
 375     QGraphicsView* graphicsView = new KItemListContainerViewport(new QGraphicsScene(this), this);
 376     setViewport(graphicsView);
 377
 378     m_horizontalSmoothScroller = new KItemListSmoothScroller(horizontalScrollBar(), this);
 379     m_verticalSmoothScroller = new KItemListSmoothScroller(verticalScrollBar(), this);
 380 }
 381
 382 #include "kitemlistcontainer.moc"