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     Q_OBJECT
  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 KItemListContainer::KItemListContainer(KItemListController* controller, QWidget* parent) :
  71     QAbstractScrollArea(parent),
  72     m_controller(controller),
  73     m_horizontalSmoothScroller(0),
  74     m_verticalSmoothScroller(0)
  75 {
  76     Q_ASSERT(controller);
  77     controller->setParent(this);
  78
  79     QGraphicsView* graphicsView = new KItemListContainerViewport(new QGraphicsScene(this), this);
  80     setViewport(graphicsView);
  81
  82     m_horizontalSmoothScroller = new KItemListSmoothScroller(horizontalScrollBar(), this);
  83     m_verticalSmoothScroller = new KItemListSmoothScroller(verticalScrollBar(), this);
  84
  85     if (controller->model()) {
  86         slotModelChanged(controller->model(), 0);
  87     }
  88     if (controller->view()) {
  89         slotViewChanged(controller->view(), 0);
  90     }
  91
  92     connect(controller, &KItemListController::modelChanged,
  93             this, &KItemListContainer::slotModelChanged);
  94     connect(controller, &KItemListController::viewChanged,
  95             this, &KItemListContainer::slotViewChanged);
  96 }
  97
  98 KItemListContainer::~KItemListContainer()
  99 {
 100     // Don't rely on the QObject-order to delete the controller, otherwise
 101     // the QGraphicsScene might get deleted before the view.
 102     delete m_controller;
 103     m_controller = 0;
 104 }
 105
 106 KItemListController* KItemListContainer::controller() const
 107 {
 108     return m_controller;
 109 }
 110
 111 void KItemListContainer::setEnabledFrame(bool enable)
 112 {
 113     QGraphicsView* graphicsView = qobject_cast<QGraphicsView*>(viewport());
 114     if (enable) {
 115         setFrameShape(QFrame::StyledPanel);
 116         graphicsView->setPalette(palette());
 117         graphicsView->viewport()->setAutoFillBackground(true);
 118     } else {
 119         setFrameShape(QFrame::NoFrame);
 120         // Make the background of the container transparent and apply the window-text color
 121         // to the text color, so that enough contrast is given for all color
 122         // schemes
 123         QPalette p = graphicsView->palette();
 124         p.setColor(QPalette::Active,   QPalette::Text, p.color(QPalette::Active,   QPalette::WindowText));
 125         p.setColor(QPalette::Inactive, QPalette::Text, p.color(QPalette::Inactive, QPalette::WindowText));
 126         p.setColor(QPalette::Disabled, QPalette::Text, p.color(QPalette::Disabled, QPalette::WindowText));
 127         graphicsView->setPalette(p);
 128         graphicsView->viewport()->setAutoFillBackground(false);
 129     }
 130 }
 131
 132 bool KItemListContainer::enabledFrame() const
 133 {
 134     const QGraphicsView* graphicsView = qobject_cast<QGraphicsView*>(viewport());
 135     return graphicsView->autoFillBackground();
 136 }
 137
 138 void KItemListContainer::keyPressEvent(QKeyEvent* event)
 139 {
 140     // TODO: We should find a better way to handle the key press events in the view.
 141     // The reasons why we need this hack are:
 142     // 1. Without reimplementing keyPressEvent() here, the event would not reach the QGraphicsView.
 143     // 2. By default, the KItemListView does not have the keyboard focus in the QGraphicsScene, so
 144     //    simply sending the event to the QGraphicsView which is the KItemListContainer's viewport
 145     //    does not work.
 146     KItemListView* view = m_controller->view();
 147     if (view) {
 148         QApplication::sendEvent(view, event);
 149     }
 150 }
 151
 152 void KItemListContainer::showEvent(QShowEvent* event)
 153 {
 154     QAbstractScrollArea::showEvent(event);
 155     updateGeometries();
 156 }
 157
 158 void KItemListContainer::resizeEvent(QResizeEvent* event)
 159 {
 160     QAbstractScrollArea::resizeEvent(event);
 161     updateGeometries();
 162 }
 163
 164 void KItemListContainer::scrollContentsBy(int dx, int dy)
 165 {
 166     m_horizontalSmoothScroller->scrollContentsBy(dx);
 167     m_verticalSmoothScroller->scrollContentsBy(dy);
 168 }
 169
 170 void KItemListContainer::wheelEvent(QWheelEvent* event)
 171 {
 172     if (event->modifiers().testFlag(Qt::ControlModifier)) {
 173         event->ignore();
 174         return;
 175     }
 176
 177     KItemListView* view = m_controller->view();
 178     if (!view) {
 179         event->ignore();
 180         return;
 181     }
 182
 183     const bool scrollHorizontally = (event->orientation() == Qt::Horizontal) ||
 184                                     (event->orientation() == Qt::Vertical && !verticalScrollBar()->isVisible());
 185     KItemListSmoothScroller* smoothScroller = scrollHorizontally ?
 186                                               m_horizontalSmoothScroller : m_verticalSmoothScroller;
 187
 188     const QScrollBar* scrollBar = smoothScroller->scrollBar();
 189     if (!event->pixelDelta().isNull()) {
 190         const int numPixels =  event->pixelDelta().y();
 191         if (event->modifiers().testFlag(Qt::ShiftModifier)) {
 192             const int scrollingDirection = numPixels > 0 ? 1 : -1;
 193             smoothScroller->scrollTo(scrollBar->value() - scrollBar->pageStep() * scrollingDirection);
 194         } else {
 195             smoothScroller->scrollTo(scrollBar->value() - numPixels);
 196         }
 197     } else {
 198         const int numDegrees = event->angleDelta().y() / 8;
 199         const int numSteps = qApp->wheelScrollLines() * numDegrees / 15;
 200         if (event->modifiers().testFlag(Qt::ShiftModifier)) {
 201             const int scrollingDirection = numSteps > 0 ? 1 : -1;
 202             smoothScroller->scrollTo(scrollBar->value() - scrollBar->pageStep() * scrollingDirection);
 203         } else {
 204             smoothScroller->scrollTo(scrollBar->value() - numSteps * scrollBar->pageStep() / 12);
 205         }
 206     }
 207
 208     event->accept();
 209 }
 210
 211 void KItemListContainer::slotScrollOrientationChanged(Qt::Orientation current, Qt::Orientation previous)
 212 {
 213     Q_UNUSED(previous);
 214     updateSmoothScrollers(current);
 215 }
 216
 217 void KItemListContainer::slotModelChanged(KItemModelBase* current, KItemModelBase* previous)
 218 {
 219     Q_UNUSED(current);
 220     Q_UNUSED(previous);
 221 }
 222
 223 void KItemListContainer::slotViewChanged(KItemListView* current, KItemListView* previous)
 224 {
 225     QGraphicsScene* scene = static_cast<QGraphicsView*>(viewport())->scene();
 226     if (previous) {
 227         scene->removeItem(previous);
 228         disconnect(previous, &KItemListView::scrollOrientationChanged,
 229                    this, &KItemListContainer::slotScrollOrientationChanged);
 230         disconnect(previous, &KItemListView::scrollOffsetChanged,
 231                    this, &KItemListContainer::updateScrollOffsetScrollBar);
 232         disconnect(previous, &KItemListView::maximumScrollOffsetChanged,
 233                    this, &KItemListContainer::updateScrollOffsetScrollBar);
 234         disconnect(previous, &KItemListView::itemOffsetChanged,
 235                    this, &KItemListContainer::updateItemOffsetScrollBar);
 236         disconnect(previous, &KItemListView::maximumItemOffsetChanged,
 237                    this, &KItemListContainer::updateItemOffsetScrollBar);
 238         disconnect(previous, &KItemListView::scrollTo, this, &KItemListContainer::scrollTo);
 239         m_horizontalSmoothScroller->setTargetObject(0);
 240         m_verticalSmoothScroller->setTargetObject(0);
 241     }
 242     if (current) {
 243         scene->addItem(current);
 244         connect(current, &KItemListView::scrollOrientationChanged,
 245                 this, &KItemListContainer::slotScrollOrientationChanged);
 246         connect(current, &KItemListView::scrollOffsetChanged,
 247                 this, &KItemListContainer::updateScrollOffsetScrollBar);
 248         connect(current, &KItemListView::maximumScrollOffsetChanged,
 249                 this, &KItemListContainer::updateScrollOffsetScrollBar);
 250         connect(current, &KItemListView::itemOffsetChanged,
 251                 this, &KItemListContainer::updateItemOffsetScrollBar);
 252         connect(current, &KItemListView::maximumItemOffsetChanged,
 253                 this, &KItemListContainer::updateItemOffsetScrollBar);
 254         connect(current, &KItemListView::scrollTo, this, &KItemListContainer::scrollTo);
 255         m_horizontalSmoothScroller->setTargetObject(current);
 256         m_verticalSmoothScroller->setTargetObject(current);
 257         updateSmoothScrollers(current->scrollOrientation());
 258     }
 259 }
 260
 261 void KItemListContainer::scrollTo(qreal offset)
 262 {
 263     const KItemListView* view = m_controller->view();
 264     if (view) {
 265         if (view->scrollOrientation() == Qt::Vertical) {
 266             m_verticalSmoothScroller->scrollTo(offset);
 267         } else {
 268             m_horizontalSmoothScroller->scrollTo(offset);
 269         }
 270     }
 271 }
 272
 273 void KItemListContainer::updateScrollOffsetScrollBar()
 274 {
 275     const KItemListView* view = m_controller->view();
 276     if (!view) {
 277         return;
 278     }
 279
 280     KItemListSmoothScroller* smoothScroller = 0;
 281     QScrollBar* scrollOffsetScrollBar = 0;
 282     int singleStep = 0;
 283     int pageStep = 0;
 284     int maximum = 0;
 285     if (view->scrollOrientation() == Qt::Vertical) {
 286         smoothScroller = m_verticalSmoothScroller;
 287         scrollOffsetScrollBar = verticalScrollBar();
 288         singleStep = view->itemSize().height();
 289         // We cannot use view->size().height() because this height might
 290         // include the header widget, which is not part of the scrolled area.
 291         pageStep = view->verticalPageStep();
 292
 293         // However, the total height of the view must be considered for the
 294         // maximum value of the scroll bar. Note that the view's scrollOffset()
 295         // refers to the offset of the top part of the view, which might be
 296         // hidden behind the header.
 297         maximum = qMax(0, int(view->maximumScrollOffset() - view->size().height()));
 298     } else {
 299         smoothScroller = m_horizontalSmoothScroller;
 300         scrollOffsetScrollBar = horizontalScrollBar();
 301         singleStep = view->itemSize().width();
 302         pageStep = view->size().width();
 303         maximum = qMax(0, int(view->maximumScrollOffset() - view->size().width()));
 304     }
 305
 306     const int value = view->scrollOffset();
 307     if (smoothScroller->requestScrollBarUpdate(maximum)) {
 308         const bool updatePolicy = (scrollOffsetScrollBar->maximum() > 0 && maximum == 0)
 309                                   || horizontalScrollBarPolicy() == Qt::ScrollBarAlwaysOn;
 310
 311         scrollOffsetScrollBar->setSingleStep(singleStep);
 312         scrollOffsetScrollBar->setPageStep(pageStep);
 313         scrollOffsetScrollBar->setMinimum(0);
 314         scrollOffsetScrollBar->setMaximum(maximum);
 315         scrollOffsetScrollBar->setValue(value);
 316
 317         if (updatePolicy) {
 318             // Prevent a potential endless layout loop (see bug #293318).
 319             updateScrollOffsetScrollBarPolicy();
 320         }
 321     }
 322 }
 323
 324 void KItemListContainer::updateItemOffsetScrollBar()
 325 {
 326     const KItemListView* view = m_controller->view();
 327     if (!view) {
 328         return;
 329     }
 330
 331     KItemListSmoothScroller* smoothScroller = 0;
 332     QScrollBar* itemOffsetScrollBar = 0;
 333     int singleStep = 0;
 334     int pageStep = 0;
 335     if (view->scrollOrientation() == Qt::Vertical) {
 336         smoothScroller = m_horizontalSmoothScroller;
 337         itemOffsetScrollBar = horizontalScrollBar();
 338         singleStep = view->size().width() / 10;
 339         pageStep = view->size().width();
 340     } else {
 341         smoothScroller = m_verticalSmoothScroller;
 342         itemOffsetScrollBar = verticalScrollBar();
 343         singleStep = view->size().height() / 10;
 344         pageStep = view->size().height();
 345     }
 346
 347     const int value = view->itemOffset();
 348     const int maximum = qMax(0, int(view->maximumItemOffset()) - pageStep);
 349     if (smoothScroller->requestScrollBarUpdate(maximum)) {
 350         itemOffsetScrollBar->setSingleStep(singleStep);
 351         itemOffsetScrollBar->setPageStep(pageStep);
 352         itemOffsetScrollBar->setMinimum(0);
 353         itemOffsetScrollBar->setMaximum(maximum);
 354         itemOffsetScrollBar->setValue(value);
 355     }
 356 }
 357
 358 void KItemListContainer::updateGeometries()
 359 {
 360     QRect rect = geometry();
 361
 362     int extra = frameWidth() * 2;
 363     QStyleOption option;
 364     option.initFrom(this);
 365     int scrollbarSpacing = 0;
 366     if (style()->styleHint(QStyle::SH_ScrollView_FrameOnlyAroundContents, &option, this)) {
 367         scrollbarSpacing = style()->pixelMetric(QStyle::PM_ScrollView_ScrollBarSpacing, &option, this);
 368     }
 369
 370     const int widthDec = verticalScrollBar()->isVisible()
 371                          ? extra + scrollbarSpacing + style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this)
 372                          : extra;
 373
 374     const int heightDec = horizontalScrollBar()->isVisible()
 375                           ? extra + scrollbarSpacing + style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this)
 376                           : extra;
 377
 378     const QRectF newGeometry(0, 0, rect.width() - widthDec,
 379                              rect.height() - heightDec);
 380     if (m_controller->view()->geometry() != newGeometry) {
 381         m_controller->view()->setGeometry(newGeometry);
 382
 383         // Get the real geometry of the view again since the scrollbars
 384         // visibilities and the view geometry may have changed in re-layout.
 385         static_cast<KItemListContainerViewport*>(viewport())->scene()->setSceneRect(m_controller->view()->geometry());
 386         static_cast<KItemListContainerViewport*>(viewport())->viewport()->setGeometry(m_controller->view()->geometry().toRect());
 387
 388         updateScrollOffsetScrollBar();
 389         updateItemOffsetScrollBar();
 390     }
 391 }
 392
 393 void KItemListContainer::updateSmoothScrollers(Qt::Orientation orientation)
 394 {
 395     if (orientation == Qt::Vertical) {
 396         m_verticalSmoothScroller->setPropertyName("scrollOffset");
 397         m_horizontalSmoothScroller->setPropertyName("itemOffset");
 398     } else {
 399         m_horizontalSmoothScroller->setPropertyName("scrollOffset");
 400         m_verticalSmoothScroller->setPropertyName("itemOffset");
 401     }
 402 }
 403
 404 void KItemListContainer::updateScrollOffsetScrollBarPolicy()
 405 {
 406     const KItemListView* view = m_controller->view();
 407     Q_ASSERT(view);
 408     const bool vertical = (view->scrollOrientation() == Qt::Vertical);
 409
 410     QStyleOption option;
 411     option.initFrom(this);
 412     const int scrollBarInc = style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this);
 413
 414     QSizeF newViewSize = m_controller->view()->size();
 415     if (vertical) {
 416         newViewSize.rwidth() += scrollBarInc;
 417     } else {
 418         newViewSize.rheight() += scrollBarInc;
 419     }
 420
 421     const Qt::ScrollBarPolicy policy = view->scrollBarRequired(newViewSize)
 422                                        ? Qt::ScrollBarAlwaysOn : Qt::ScrollBarAsNeeded;
 423     if (vertical) {
 424         setVerticalScrollBarPolicy(policy);
 425     } else {
 426         setHorizontalScrollBarPolicy(policy);
 427     }
 428 }
 429
 430 #include "kitemlistcontainer.moc"