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 <QScrollBar>
  35 #include <QStyle>
  36 #include <QStyleOption>
  37
  38
  39 /**
  40  * Replaces the default viewport of KItemListContainer by a
  41  * non-scrollable viewport. The scrolling is done in an optimized
  42  * way by KItemListView internally.
  43  */
  44 class KItemListContainerViewport : public QGraphicsView
  45 {
  46 public:
  47     KItemListContainerViewport(QGraphicsScene* scene, QWidget* parent);
  48 protected:
  49     virtual void wheelEvent(QWheelEvent* event);
  50 };
  51
  52 KItemListContainerViewport::KItemListContainerViewport(QGraphicsScene* scene, QWidget* parent) :
  53     QGraphicsView(scene, parent)
  54 {
  55     setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
  56     setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
  57     setViewportMargins(0, 0, 0, 0);
  58     setFrameShape(QFrame::NoFrame);
  59 }
  60
  61 void KItemListContainerViewport::wheelEvent(QWheelEvent* event)
  62 {
  63     // Assure that the wheel-event gets forwarded to the parent
  64     // and not handled at all by QGraphicsView.
  65     event->ignore();
  66 }
  67
  68 KItemListContainer::KItemListContainer(KItemListController* controller, QWidget* parent) :
  69     QAbstractScrollArea(parent),
  70     m_controller(controller),
  71     m_horizontalSmoothScroller(0),
  72     m_verticalSmoothScroller(0)
  73 {
  74     Q_ASSERT(controller);
  75     controller->setParent(this);
  76
  77     QGraphicsView* graphicsView = new KItemListContainerViewport(new QGraphicsScene(this), this);
  78     setViewport(graphicsView);
  79
  80     m_horizontalSmoothScroller = new KItemListSmoothScroller(horizontalScrollBar(), this);
  81     m_verticalSmoothScroller = new KItemListSmoothScroller(verticalScrollBar(), this);
  82
  83     if (controller->model()) {
  84         slotModelChanged(controller->model(), 0);
  85     }
  86     if (controller->view()) {
  87         slotViewChanged(controller->view(), 0);
  88     }
  89
  90     connect(controller, &KItemListController::modelChanged,
  91             this, &KItemListContainer::slotModelChanged);
  92     connect(controller, &KItemListController::viewChanged,
  93             this, &KItemListContainer::slotViewChanged);
  94 }
  95
  96 KItemListContainer::~KItemListContainer()
  97 {
  98     // Don't rely on the QObject-order to delete the controller, otherwise
  99     // the QGraphicsScene might get deleted before the view.
 100     delete m_controller;
 101     m_controller = 0;
 102 }
 103
 104 KItemListController* KItemListContainer::controller() const
 105 {
 106     return m_controller;
 107 }
 108
 109 void KItemListContainer::setEnabledFrame(bool enable)
 110 {
 111     QGraphicsView* graphicsView = qobject_cast<QGraphicsView*>(viewport());
 112     if (enable) {
 113         setFrameShape(QFrame::StyledPanel);
 114         graphicsView->setPalette(palette());
 115         graphicsView->viewport()->setAutoFillBackground(true);
 116     } else {
 117         setFrameShape(QFrame::NoFrame);
 118         // Make the background of the container transparent and apply the window-text color
 119         // to the text color, so that enough contrast is given for all color
 120         // schemes
 121         QPalette p = graphicsView->palette();
 122         p.setColor(QPalette::Active,   QPalette::Text, p.color(QPalette::Active,   QPalette::WindowText));
 123         p.setColor(QPalette::Inactive, QPalette::Text, p.color(QPalette::Inactive, QPalette::WindowText));
 124         p.setColor(QPalette::Disabled, QPalette::Text, p.color(QPalette::Disabled, QPalette::WindowText));
 125         graphicsView->setPalette(p);
 126         graphicsView->viewport()->setAutoFillBackground(false);
 127     }
 128 }
 129
 130 bool KItemListContainer::enabledFrame() const
 131 {
 132     const QGraphicsView* graphicsView = qobject_cast<QGraphicsView*>(viewport());
 133     return graphicsView->autoFillBackground();
 134 }
 135
 136 void KItemListContainer::keyPressEvent(QKeyEvent* event)
 137 {
 138     // TODO: We should find a better way to handle the key press events in the view.
 139     // The reasons why we need this hack are:
 140     // 1. Without reimplementing keyPressEvent() here, the event would not reach the QGraphicsView.
 141     // 2. By default, the KItemListView does not have the keyboard focus in the QGraphicsScene, so
 142     //    simply sending the event to the QGraphicsView which is the KItemListContainer's viewport
 143     //    does not work.
 144     KItemListView* view = m_controller->view();
 145     if (view) {
 146         QApplication::sendEvent(view, event);
 147     }
 148 }
 149
 150 void KItemListContainer::showEvent(QShowEvent* event)
 151 {
 152     QAbstractScrollArea::showEvent(event);
 153     updateGeometries();
 154 }
 155
 156 void KItemListContainer::resizeEvent(QResizeEvent* event)
 157 {
 158     QAbstractScrollArea::resizeEvent(event);
 159     updateGeometries();
 160 }
 161
 162 void KItemListContainer::scrollContentsBy(int dx, int dy)
 163 {
 164     m_horizontalSmoothScroller->scrollContentsBy(dx);
 165     m_verticalSmoothScroller->scrollContentsBy(dy);
 166 }
 167
 168 void KItemListContainer::wheelEvent(QWheelEvent* event)
 169 {
 170     if (event->modifiers().testFlag(Qt::ControlModifier)) {
 171         event->ignore();
 172         return;
 173     }
 174
 175     KItemListView* view = m_controller->view();
 176     if (!view) {
 177         event->ignore();
 178         return;
 179     }
 180
 181     const bool scrollHorizontally = (event->orientation() == Qt::Horizontal) ||
 182                                     (event->orientation() == Qt::Vertical && !verticalScrollBar()->isVisible());
 183     KItemListSmoothScroller* smoothScroller = scrollHorizontally ?
 184                                               m_horizontalSmoothScroller : m_verticalSmoothScroller;
 185
 186     const QScrollBar* scrollBar = smoothScroller->scrollBar();
 187     if (!event->pixelDelta().isNull()) {
 188         const int numPixels =  event->pixelDelta().y();
 189         smoothScroller->scrollTo(scrollBar->value() - numPixels);
 190     } else {
 191         const int numDegrees = event->angleDelta().y() / 8;
 192         const int numSteps = numDegrees / 15;
 193         smoothScroller->scrollTo(scrollBar->value() - numSteps * scrollBar->pageStep() / 4);
 194     }
 195
 196     event->accept();
 197 }
 198
 199 void KItemListContainer::slotScrollOrientationChanged(Qt::Orientation current, Qt::Orientation previous)
 200 {
 201     Q_UNUSED(previous);
 202     updateSmoothScrollers(current);
 203 }
 204
 205 void KItemListContainer::slotModelChanged(KItemModelBase* current, KItemModelBase* previous)
 206 {
 207     Q_UNUSED(current);
 208     Q_UNUSED(previous);
 209 }
 210
 211 void KItemListContainer::slotViewChanged(KItemListView* current, KItemListView* previous)
 212 {
 213     QGraphicsScene* scene = static_cast<QGraphicsView*>(viewport())->scene();
 214     if (previous) {
 215         scene->removeItem(previous);
 216         disconnect(previous, &KItemListView::scrollOrientationChanged,
 217                    this, &KItemListContainer::slotScrollOrientationChanged);
 218         disconnect(previous, &KItemListView::scrollOffsetChanged,
 219                    this, &KItemListContainer::updateScrollOffsetScrollBar);
 220         disconnect(previous, &KItemListView::maximumScrollOffsetChanged,
 221                    this, &KItemListContainer::updateScrollOffsetScrollBar);
 222         disconnect(previous, &KItemListView::itemOffsetChanged,
 223                    this, &KItemListContainer::updateItemOffsetScrollBar);
 224         disconnect(previous, &KItemListView::maximumItemOffsetChanged,
 225                    this, &KItemListContainer::updateItemOffsetScrollBar);
 226         disconnect(previous, &KItemListView::scrollTo, this, &KItemListContainer::scrollTo);
 227         m_horizontalSmoothScroller->setTargetObject(0);
 228         m_verticalSmoothScroller->setTargetObject(0);
 229     }
 230     if (current) {
 231         scene->addItem(current);
 232         connect(current, &KItemListView::scrollOrientationChanged,
 233                 this, &KItemListContainer::slotScrollOrientationChanged);
 234         connect(current, &KItemListView::scrollOffsetChanged,
 235                 this, &KItemListContainer::updateScrollOffsetScrollBar);
 236         connect(current, &KItemListView::maximumScrollOffsetChanged,
 237                 this, &KItemListContainer::updateScrollOffsetScrollBar);
 238         connect(current, &KItemListView::itemOffsetChanged,
 239                 this, &KItemListContainer::updateItemOffsetScrollBar);
 240         connect(current, &KItemListView::maximumItemOffsetChanged,
 241                 this, &KItemListContainer::updateItemOffsetScrollBar);
 242         connect(current, &KItemListView::scrollTo, this, &KItemListContainer::scrollTo);
 243         m_horizontalSmoothScroller->setTargetObject(current);
 244         m_verticalSmoothScroller->setTargetObject(current);
 245         updateSmoothScrollers(current->scrollOrientation());
 246     }
 247 }
 248
 249 void KItemListContainer::scrollTo(qreal offset)
 250 {
 251     const KItemListView* view = m_controller->view();
 252     if (view) {
 253         if (view->scrollOrientation() == Qt::Vertical) {
 254             m_verticalSmoothScroller->scrollTo(offset);
 255         } else {
 256             m_horizontalSmoothScroller->scrollTo(offset);
 257         }
 258     }
 259 }
 260
 261 void KItemListContainer::updateScrollOffsetScrollBar()
 262 {
 263     const KItemListView* view = m_controller->view();
 264     if (!view) {
 265         return;
 266     }
 267
 268     KItemListSmoothScroller* smoothScroller = 0;
 269     QScrollBar* scrollOffsetScrollBar = 0;
 270     int singleStep = 0;
 271     int pageStep = 0;
 272     int maximum = 0;
 273     if (view->scrollOrientation() == Qt::Vertical) {
 274         smoothScroller = m_verticalSmoothScroller;
 275         scrollOffsetScrollBar = verticalScrollBar();
 276         singleStep = view->itemSize().height();
 277         // We cannot use view->size().height() because this height might
 278         // include the header widget, which is not part of the scrolled area.
 279         pageStep = view->verticalPageStep();
 280
 281         // However, the total height of the view must be considered for the
 282         // maximum value of the scroll bar. Note that the view's scrollOffset()
 283         // refers to the offset of the top part of the view, which might be
 284         // hidden behind the header.
 285         maximum = qMax(0, int(view->maximumScrollOffset() - view->size().height()));
 286     } else {
 287         smoothScroller = m_horizontalSmoothScroller;
 288         scrollOffsetScrollBar = horizontalScrollBar();
 289         singleStep = view->itemSize().width();
 290         pageStep = view->size().width();
 291         maximum = qMax(0, int(view->maximumScrollOffset() - view->size().width()));
 292     }
 293
 294     const int value = view->scrollOffset();
 295     if (smoothScroller->requestScrollBarUpdate(maximum)) {
 296         const bool updatePolicy = (scrollOffsetScrollBar->maximum() > 0 && maximum == 0)
 297                                   || horizontalScrollBarPolicy() == Qt::ScrollBarAlwaysOn;
 298
 299         scrollOffsetScrollBar->setSingleStep(singleStep);
 300         scrollOffsetScrollBar->setPageStep(pageStep);
 301         scrollOffsetScrollBar->setMinimum(0);
 302         scrollOffsetScrollBar->setMaximum(maximum);
 303         scrollOffsetScrollBar->setValue(value);
 304
 305         if (updatePolicy) {
 306             // Prevent a potential endless layout loop (see bug #293318).
 307             updateScrollOffsetScrollBarPolicy();
 308         }
 309     }
 310 }
 311
 312 void KItemListContainer::updateItemOffsetScrollBar()
 313 {
 314     const KItemListView* view = m_controller->view();
 315     if (!view) {
 316         return;
 317     }
 318
 319     KItemListSmoothScroller* smoothScroller = 0;
 320     QScrollBar* itemOffsetScrollBar = 0;
 321     int singleStep = 0;
 322     int pageStep = 0;
 323     if (view->scrollOrientation() == Qt::Vertical) {
 324         smoothScroller = m_horizontalSmoothScroller;
 325         itemOffsetScrollBar = horizontalScrollBar();
 326         singleStep = view->size().width() / 10;
 327         pageStep = view->size().width();
 328     } else {
 329         smoothScroller = m_verticalSmoothScroller;
 330         itemOffsetScrollBar = verticalScrollBar();
 331         singleStep = view->size().height() / 10;
 332         pageStep = view->size().height();
 333     }
 334
 335     const int value = view->itemOffset();
 336     const int maximum = qMax(0, int(view->maximumItemOffset()) - pageStep);
 337     if (smoothScroller->requestScrollBarUpdate(maximum)) {
 338         itemOffsetScrollBar->setSingleStep(singleStep);
 339         itemOffsetScrollBar->setPageStep(pageStep);
 340         itemOffsetScrollBar->setMinimum(0);
 341         itemOffsetScrollBar->setMaximum(maximum);
 342         itemOffsetScrollBar->setValue(value);
 343     }
 344 }
 345
 346 void KItemListContainer::updateGeometries()
 347 {
 348     QRect rect = geometry();
 349
 350     int extra = frameWidth() * 2;
 351     QStyleOption option;
 352     option.initFrom(this);
 353     int scrollbarSpacing = 0;
 354     if (style()->styleHint(QStyle::SH_ScrollView_FrameOnlyAroundContents, &option, this)) {
 355         scrollbarSpacing = style()->pixelMetric(QStyle::PM_ScrollView_ScrollBarSpacing, &option, this);
 356     }
 357
 358     const int widthDec = verticalScrollBar()->isVisible()
 359                          ? extra + scrollbarSpacing + style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this)
 360                          : extra;
 361
 362     const int heightDec = horizontalScrollBar()->isVisible()
 363                           ? extra + scrollbarSpacing + style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this)
 364                           : extra;
 365
 366     const QRectF newGeometry(0, 0, rect.width() - widthDec,
 367                              rect.height() - heightDec);
 368     if (m_controller->view()->geometry() != newGeometry) {
 369         m_controller->view()->setGeometry(newGeometry);
 370
 371         // Get the real geometry of the view again since the scrollbars
 372         // visibilities and the view geometry may have changed in re-layout.
 373         static_cast<KItemListContainerViewport*>(viewport())->scene()->setSceneRect(m_controller->view()->geometry());
 374         static_cast<KItemListContainerViewport*>(viewport())->viewport()->setGeometry(m_controller->view()->geometry().toRect());
 375
 376         updateScrollOffsetScrollBar();
 377         updateItemOffsetScrollBar();
 378     }
 379 }
 380
 381 void KItemListContainer::updateSmoothScrollers(Qt::Orientation orientation)
 382 {
 383     if (orientation == Qt::Vertical) {
 384         m_verticalSmoothScroller->setPropertyName("scrollOffset");
 385         m_horizontalSmoothScroller->setPropertyName("itemOffset");
 386     } else {
 387         m_horizontalSmoothScroller->setPropertyName("scrollOffset");
 388         m_verticalSmoothScroller->setPropertyName("itemOffset");
 389     }
 390 }
 391
 392 void KItemListContainer::updateScrollOffsetScrollBarPolicy()
 393 {
 394     const KItemListView* view = m_controller->view();
 395     Q_ASSERT(view);
 396     const bool vertical = (view->scrollOrientation() == Qt::Vertical);
 397
 398     QStyleOption option;
 399     option.initFrom(this);
 400     const int scrollBarInc = style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this);
 401
 402     QSizeF newViewSize = m_controller->view()->size();
 403     if (vertical) {
 404         newViewSize.rwidth() += scrollBarInc;
 405     } else {
 406         newViewSize.rheight() += scrollBarInc;
 407     }
 408
 409     const Qt::ScrollBarPolicy policy = view->scrollBarRequired(newViewSize)
 410                                        ? Qt::ScrollBarAlwaysOn : Qt::ScrollBarAsNeeded;
 411     if (vertical) {
 412         setVerticalScrollBarPolicy(policy);
 413     } else {
 414         setHorizontalScrollBarPolicy(policy);
 415     }
 416 }
 417