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         if (event->modifiers().testFlag(Qt::ShiftModifier)) {
 190             const int scrollingDirection = numPixels > 0 ? 1 : -1;
 191             smoothScroller->scrollTo(scrollBar->value() - scrollBar->pageStep() * scrollingDirection);
 192         } else {
 193             smoothScroller->scrollTo(scrollBar->value() - numPixels);
 194         }
 195     } else {
 196         const int numDegrees = event->angleDelta().y() / 8;
 197         const int numSteps = qApp->wheelScrollLines() * numDegrees / 15;
 198         if (event->modifiers().testFlag(Qt::ShiftModifier)) {
 199             const int scrollingDirection = numSteps > 0 ? 1 : -1;
 200             smoothScroller->scrollTo(scrollBar->value() - scrollBar->pageStep() * scrollingDirection);
 201         } else {
 202             smoothScroller->scrollTo(scrollBar->value() - numSteps * scrollBar->pageStep() / 12);
 203         }
 204     }
 205
 206     event->accept();
 207 }
 208
 209 void KItemListContainer::slotScrollOrientationChanged(Qt::Orientation current, Qt::Orientation previous)
 210 {
 211     Q_UNUSED(previous);
 212     updateSmoothScrollers(current);
 213 }
 214
 215 void KItemListContainer::slotModelChanged(KItemModelBase* current, KItemModelBase* previous)
 216 {
 217     Q_UNUSED(current);
 218     Q_UNUSED(previous);
 219 }
 220
 221 void KItemListContainer::slotViewChanged(KItemListView* current, KItemListView* previous)
 222 {
 223     QGraphicsScene* scene = static_cast<QGraphicsView*>(viewport())->scene();
 224     if (previous) {
 225         scene->removeItem(previous);
 226         disconnect(previous, &KItemListView::scrollOrientationChanged,
 227                    this, &KItemListContainer::slotScrollOrientationChanged);
 228         disconnect(previous, &KItemListView::scrollOffsetChanged,
 229                    this, &KItemListContainer::updateScrollOffsetScrollBar);
 230         disconnect(previous, &KItemListView::maximumScrollOffsetChanged,
 231                    this, &KItemListContainer::updateScrollOffsetScrollBar);
 232         disconnect(previous, &KItemListView::itemOffsetChanged,
 233                    this, &KItemListContainer::updateItemOffsetScrollBar);
 234         disconnect(previous, &KItemListView::maximumItemOffsetChanged,
 235                    this, &KItemListContainer::updateItemOffsetScrollBar);
 236         disconnect(previous, &KItemListView::scrollTo, this, &KItemListContainer::scrollTo);
 237         m_horizontalSmoothScroller->setTargetObject(0);
 238         m_verticalSmoothScroller->setTargetObject(0);
 239     }
 240     if (current) {
 241         scene->addItem(current);
 242         connect(current, &KItemListView::scrollOrientationChanged,
 243                 this, &KItemListContainer::slotScrollOrientationChanged);
 244         connect(current, &KItemListView::scrollOffsetChanged,
 245                 this, &KItemListContainer::updateScrollOffsetScrollBar);
 246         connect(current, &KItemListView::maximumScrollOffsetChanged,
 247                 this, &KItemListContainer::updateScrollOffsetScrollBar);
 248         connect(current, &KItemListView::itemOffsetChanged,
 249                 this, &KItemListContainer::updateItemOffsetScrollBar);
 250         connect(current, &KItemListView::maximumItemOffsetChanged,
 251                 this, &KItemListContainer::updateItemOffsetScrollBar);
 252         connect(current, &KItemListView::scrollTo, this, &KItemListContainer::scrollTo);
 253         m_horizontalSmoothScroller->setTargetObject(current);
 254         m_verticalSmoothScroller->setTargetObject(current);
 255         updateSmoothScrollers(current->scrollOrientation());
 256     }
 257 }
 258
 259 void KItemListContainer::scrollTo(qreal offset)
 260 {
 261     const KItemListView* view = m_controller->view();
 262     if (view) {
 263         if (view->scrollOrientation() == Qt::Vertical) {
 264             m_verticalSmoothScroller->scrollTo(offset);
 265         } else {
 266             m_horizontalSmoothScroller->scrollTo(offset);
 267         }
 268     }
 269 }
 270
 271 void KItemListContainer::updateScrollOffsetScrollBar()
 272 {
 273     const KItemListView* view = m_controller->view();
 274     if (!view) {
 275         return;
 276     }
 277
 278     KItemListSmoothScroller* smoothScroller = 0;
 279     QScrollBar* scrollOffsetScrollBar = 0;
 280     int singleStep = 0;
 281     int pageStep = 0;
 282     int maximum = 0;
 283     if (view->scrollOrientation() == Qt::Vertical) {
 284         smoothScroller = m_verticalSmoothScroller;
 285         scrollOffsetScrollBar = verticalScrollBar();
 286         singleStep = view->itemSize().height();
 287         // We cannot use view->size().height() because this height might
 288         // include the header widget, which is not part of the scrolled area.
 289         pageStep = view->verticalPageStep();
 290
 291         // However, the total height of the view must be considered for the
 292         // maximum value of the scroll bar. Note that the view's scrollOffset()
 293         // refers to the offset of the top part of the view, which might be
 294         // hidden behind the header.
 295         maximum = qMax(0, int(view->maximumScrollOffset() - view->size().height()));
 296     } else {
 297         smoothScroller = m_horizontalSmoothScroller;
 298         scrollOffsetScrollBar = horizontalScrollBar();
 299         singleStep = view->itemSize().width();
 300         pageStep = view->size().width();
 301         maximum = qMax(0, int(view->maximumScrollOffset() - view->size().width()));
 302     }
 303
 304     const int value = view->scrollOffset();
 305     if (smoothScroller->requestScrollBarUpdate(maximum)) {
 306         const bool updatePolicy = (scrollOffsetScrollBar->maximum() > 0 && maximum == 0)
 307                                   || horizontalScrollBarPolicy() == Qt::ScrollBarAlwaysOn;
 308
 309         scrollOffsetScrollBar->setSingleStep(singleStep);
 310         scrollOffsetScrollBar->setPageStep(pageStep);
 311         scrollOffsetScrollBar->setMinimum(0);
 312         scrollOffsetScrollBar->setMaximum(maximum);
 313         scrollOffsetScrollBar->setValue(value);
 314
 315         if (updatePolicy) {
 316             // Prevent a potential endless layout loop (see bug #293318).
 317             updateScrollOffsetScrollBarPolicy();
 318         }
 319     }
 320 }
 321
 322 void KItemListContainer::updateItemOffsetScrollBar()
 323 {
 324     const KItemListView* view = m_controller->view();
 325     if (!view) {
 326         return;
 327     }
 328
 329     KItemListSmoothScroller* smoothScroller = 0;
 330     QScrollBar* itemOffsetScrollBar = 0;
 331     int singleStep = 0;
 332     int pageStep = 0;
 333     if (view->scrollOrientation() == Qt::Vertical) {
 334         smoothScroller = m_horizontalSmoothScroller;
 335         itemOffsetScrollBar = horizontalScrollBar();
 336         singleStep = view->size().width() / 10;
 337         pageStep = view->size().width();
 338     } else {
 339         smoothScroller = m_verticalSmoothScroller;
 340         itemOffsetScrollBar = verticalScrollBar();
 341         singleStep = view->size().height() / 10;
 342         pageStep = view->size().height();
 343     }
 344
 345     const int value = view->itemOffset();
 346     const int maximum = qMax(0, int(view->maximumItemOffset()) - pageStep);
 347     if (smoothScroller->requestScrollBarUpdate(maximum)) {
 348         itemOffsetScrollBar->setSingleStep(singleStep);
 349         itemOffsetScrollBar->setPageStep(pageStep);
 350         itemOffsetScrollBar->setMinimum(0);
 351         itemOffsetScrollBar->setMaximum(maximum);
 352         itemOffsetScrollBar->setValue(value);
 353     }
 354 }
 355
 356 void KItemListContainer::updateGeometries()
 357 {
 358     QRect rect = geometry();
 359
 360     int extra = frameWidth() * 2;
 361     QStyleOption option;
 362     option.initFrom(this);
 363     int scrollbarSpacing = 0;
 364     if (style()->styleHint(QStyle::SH_ScrollView_FrameOnlyAroundContents, &option, this)) {
 365         scrollbarSpacing = style()->pixelMetric(QStyle::PM_ScrollView_ScrollBarSpacing, &option, this);
 366     }
 367
 368     const int widthDec = verticalScrollBar()->isVisible()
 369                          ? extra + scrollbarSpacing + style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this)
 370                          : extra;
 371
 372     const int heightDec = horizontalScrollBar()->isVisible()
 373                           ? extra + scrollbarSpacing + style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this)
 374                           : extra;
 375
 376     const QRectF newGeometry(0, 0, rect.width() - widthDec,
 377                              rect.height() - heightDec);
 378     if (m_controller->view()->geometry() != newGeometry) {
 379         m_controller->view()->setGeometry(newGeometry);
 380
 381         // Get the real geometry of the view again since the scrollbars
 382         // visibilities and the view geometry may have changed in re-layout.
 383         static_cast<KItemListContainerViewport*>(viewport())->scene()->setSceneRect(m_controller->view()->geometry());
 384         static_cast<KItemListContainerViewport*>(viewport())->viewport()->setGeometry(m_controller->view()->geometry().toRect());
 385
 386         updateScrollOffsetScrollBar();
 387         updateItemOffsetScrollBar();
 388     }
 389 }
 390
 391 void KItemListContainer::updateSmoothScrollers(Qt::Orientation orientation)
 392 {
 393     if (orientation == Qt::Vertical) {
 394         m_verticalSmoothScroller->setPropertyName("scrollOffset");
 395         m_horizontalSmoothScroller->setPropertyName("itemOffset");
 396     } else {
 397         m_horizontalSmoothScroller->setPropertyName("scrollOffset");
 398         m_verticalSmoothScroller->setPropertyName("itemOffset");
 399     }
 400 }
 401
 402 void KItemListContainer::updateScrollOffsetScrollBarPolicy()
 403 {
 404     const KItemListView* view = m_controller->view();
 405     Q_ASSERT(view);
 406     const bool vertical = (view->scrollOrientation() == Qt::Vertical);
 407
 408     QStyleOption option;
 409     option.initFrom(this);
 410     const int scrollBarInc = style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this);
 411
 412     QSizeF newViewSize = m_controller->view()->size();
 413     if (vertical) {
 414         newViewSize.rwidth() += scrollBarInc;
 415     } else {
 416         newViewSize.rheight() += scrollBarInc;
 417     }
 418
 419     const Qt::ScrollBarPolicy policy = view->scrollBarRequired(newViewSize)
 420                                        ? Qt::ScrollBarAlwaysOn : Qt::ScrollBarAsNeeded;
 421     if (vertical) {
 422         setVerticalScrollBarPolicy(policy);
 423     } else {
 424         setHorizontalScrollBarPolicy(policy);
 425     }
 426 }
 427