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 "private/kitemlistsmoothscroller.h"
  28
  29 #include <QApplication>
  30 #include <QFontMetrics>
  31 #include <QGraphicsScene>
  32 #include <QGraphicsView>
  33 #include <QScrollBar>
  34 #include <QStyleOption>
  35
  36 /**
  37  * Replaces the default viewport of KItemListContainer by a
  38  * non-scrollable viewport. The scrolling is done in an optimized
  39  * way by KItemListView internally.
  40  */
  41 class KItemListContainerViewport : public QGraphicsView
  42 {
  43     Q_OBJECT
  44
  45 public:
  46     KItemListContainerViewport(QGraphicsScene* scene, QWidget* parent);
  47 protected:
  48     void wheelEvent(QWheelEvent* event) override;
  49 };
  50
  51 KItemListContainerViewport::KItemListContainerViewport(QGraphicsScene* scene, QWidget* parent) :
  52     QGraphicsView(scene, parent)
  53 {
  54     setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
  55     setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
  56     setViewportMargins(0, 0, 0, 0);
  57     setFrameShape(QFrame::NoFrame);
  58 }
  59
  60 void KItemListContainerViewport::wheelEvent(QWheelEvent* event)
  61 {
  62     // Assure that the wheel-event gets forwarded to the parent
  63     // and not handled at all by QGraphicsView.
  64     event->ignore();
  65 }
  66
  67 KItemListContainer::KItemListContainer(KItemListController* controller, QWidget* parent) :
  68     QAbstractScrollArea(parent),
  69     m_controller(controller),
  70     m_horizontalSmoothScroller(nullptr),
  71     m_verticalSmoothScroller(nullptr)
  72 {
  73     Q_ASSERT(controller);
  74     controller->setParent(this);
  75
  76     QGraphicsView* graphicsView = new KItemListContainerViewport(new QGraphicsScene(this), this);
  77     setViewport(graphicsView);
  78
  79     m_horizontalSmoothScroller = new KItemListSmoothScroller(horizontalScrollBar(), this);
  80     m_verticalSmoothScroller = new KItemListSmoothScroller(verticalScrollBar(), this);
  81
  82     if (controller->model()) {
  83         slotModelChanged(controller->model(), nullptr);
  84     }
  85     if (controller->view()) {
  86         slotViewChanged(controller->view(), nullptr);
  87     }
  88
  89     connect(controller, &KItemListController::modelChanged,
  90             this, &KItemListContainer::slotModelChanged);
  91     connect(controller, &KItemListController::viewChanged,
  92             this, &KItemListContainer::slotViewChanged);
  93 }
  94
  95 KItemListContainer::~KItemListContainer()
  96 {
  97     // Don't rely on the QObject-order to delete the controller, otherwise
  98     // the QGraphicsScene might get deleted before the view.
  99     delete m_controller;
 100     m_controller = nullptr;
 101 }
 102
 103 KItemListController* KItemListContainer::controller() const
 104 {
 105     return m_controller;
 106 }
 107
 108 void KItemListContainer::setEnabledFrame(bool enable)
 109 {
 110     QGraphicsView* graphicsView = qobject_cast<QGraphicsView*>(viewport());
 111     if (enable) {
 112         setFrameShape(QFrame::StyledPanel);
 113         graphicsView->setPalette(palette());
 114         graphicsView->viewport()->setAutoFillBackground(true);
 115     } else {
 116         setFrameShape(QFrame::NoFrame);
 117         // Make the background of the container transparent and apply the window-text color
 118         // to the text color, so that enough contrast is given for all color
 119         // schemes
 120         QPalette p = graphicsView->palette();
 121         p.setColor(QPalette::Active,   QPalette::Text, p.color(QPalette::Active,   QPalette::WindowText));
 122         p.setColor(QPalette::Inactive, QPalette::Text, p.color(QPalette::Inactive, QPalette::WindowText));
 123         p.setColor(QPalette::Disabled, QPalette::Text, p.color(QPalette::Disabled, QPalette::WindowText));
 124         graphicsView->setPalette(p);
 125         graphicsView->viewport()->setAutoFillBackground(false);
 126     }
 127 }
 128
 129 bool KItemListContainer::enabledFrame() const
 130 {
 131     const QGraphicsView* graphicsView = qobject_cast<QGraphicsView*>(viewport());
 132     return graphicsView->autoFillBackground();
 133 }
 134
 135 void KItemListContainer::keyPressEvent(QKeyEvent* event)
 136 {
 137     // TODO: We should find a better way to handle the key press events in the view.
 138     // The reasons why we need this hack are:
 139     // 1. Without reimplementing keyPressEvent() here, the event would not reach the QGraphicsView.
 140     // 2. By default, the KItemListView does not have the keyboard focus in the QGraphicsScene, so
 141     //    simply sending the event to the QGraphicsView which is the KItemListContainer's viewport
 142     //    does not work.
 143     KItemListView* view = m_controller->view();
 144     if (view) {
 145         QApplication::sendEvent(view, event);
 146     }
 147 }
 148
 149 void KItemListContainer::showEvent(QShowEvent* event)
 150 {
 151     QAbstractScrollArea::showEvent(event);
 152     updateGeometries();
 153 }
 154
 155 void KItemListContainer::resizeEvent(QResizeEvent* event)
 156 {
 157     QAbstractScrollArea::resizeEvent(event);
 158     updateGeometries();
 159 }
 160
 161 void KItemListContainer::scrollContentsBy(int dx, int dy)
 162 {
 163     m_horizontalSmoothScroller->scrollContentsBy(dx);
 164     m_verticalSmoothScroller->scrollContentsBy(dy);
 165 }
 166
 167 void KItemListContainer::wheelEvent(QWheelEvent* event)
 168 {
 169     if (event->modifiers().testFlag(Qt::ControlModifier)) {
 170         event->ignore();
 171         return;
 172     }
 173
 174     KItemListView* view = m_controller->view();
 175     if (!view) {
 176         event->ignore();
 177         return;
 178     }
 179
 180     const bool scrollHorizontally = (event->orientation() == Qt::Horizontal) ||
 181                                     (event->orientation() == Qt::Vertical && !verticalScrollBar()->isVisible());
 182     KItemListSmoothScroller* smoothScroller = scrollHorizontally ?
 183                                               m_horizontalSmoothScroller : m_verticalSmoothScroller;
 184
 185     smoothScroller->handleWheelEvent(event);
 186 }
 187
 188 void KItemListContainer::slotScrollOrientationChanged(Qt::Orientation current, Qt::Orientation previous)
 189 {
 190     Q_UNUSED(previous)
 191     updateSmoothScrollers(current);
 192 }
 193
 194 void KItemListContainer::slotModelChanged(KItemModelBase* current, KItemModelBase* previous)
 195 {
 196     Q_UNUSED(current)
 197     Q_UNUSED(previous)
 198 }
 199
 200 void KItemListContainer::slotViewChanged(KItemListView* current, KItemListView* previous)
 201 {
 202     QGraphicsScene* scene = static_cast<QGraphicsView*>(viewport())->scene();
 203     if (previous) {
 204         scene->removeItem(previous);
 205         disconnect(previous, &KItemListView::scrollOrientationChanged,
 206                    this, &KItemListContainer::slotScrollOrientationChanged);
 207         disconnect(previous, &KItemListView::scrollOffsetChanged,
 208                    this, &KItemListContainer::updateScrollOffsetScrollBar);
 209         disconnect(previous, &KItemListView::maximumScrollOffsetChanged,
 210                    this, &KItemListContainer::updateScrollOffsetScrollBar);
 211         disconnect(previous, &KItemListView::itemOffsetChanged,
 212                    this, &KItemListContainer::updateItemOffsetScrollBar);
 213         disconnect(previous, &KItemListView::maximumItemOffsetChanged,
 214                    this, &KItemListContainer::updateItemOffsetScrollBar);
 215         disconnect(previous, &KItemListView::scrollTo, this, &KItemListContainer::scrollTo);
 216         m_horizontalSmoothScroller->setTargetObject(nullptr);
 217         m_verticalSmoothScroller->setTargetObject(nullptr);
 218     }
 219     if (current) {
 220         scene->addItem(current);
 221         connect(current, &KItemListView::scrollOrientationChanged,
 222                 this, &KItemListContainer::slotScrollOrientationChanged);
 223         connect(current, &KItemListView::scrollOffsetChanged,
 224                 this, &KItemListContainer::updateScrollOffsetScrollBar);
 225         connect(current, &KItemListView::maximumScrollOffsetChanged,
 226                 this, &KItemListContainer::updateScrollOffsetScrollBar);
 227         connect(current, &KItemListView::itemOffsetChanged,
 228                 this, &KItemListContainer::updateItemOffsetScrollBar);
 229         connect(current, &KItemListView::maximumItemOffsetChanged,
 230                 this, &KItemListContainer::updateItemOffsetScrollBar);
 231         connect(current, &KItemListView::scrollTo, this, &KItemListContainer::scrollTo);
 232         m_horizontalSmoothScroller->setTargetObject(current);
 233         m_verticalSmoothScroller->setTargetObject(current);
 234         updateSmoothScrollers(current->scrollOrientation());
 235     }
 236 }
 237
 238 void KItemListContainer::scrollTo(qreal offset)
 239 {
 240     const KItemListView* view = m_controller->view();
 241     if (view) {
 242         if (view->scrollOrientation() == Qt::Vertical) {
 243             m_verticalSmoothScroller->scrollTo(offset);
 244         } else {
 245             m_horizontalSmoothScroller->scrollTo(offset);
 246         }
 247     }
 248 }
 249
 250 void KItemListContainer::updateScrollOffsetScrollBar()
 251 {
 252     const KItemListView* view = m_controller->view();
 253     if (!view) {
 254         return;
 255     }
 256
 257     KItemListSmoothScroller* smoothScroller = nullptr;
 258     QScrollBar* scrollOffsetScrollBar = nullptr;
 259     int singleStep = 0;
 260     int pageStep = 0;
 261     int maximum = 0;
 262     if (view->scrollOrientation() == Qt::Vertical) {
 263         smoothScroller = m_verticalSmoothScroller;
 264         scrollOffsetScrollBar = verticalScrollBar();
 265
 266         // Don't scroll super fast when using a wheel mouse:
 267         // We want to consider one "line" to be the text label which has a
 268         // roughly fixed height rather than using the height of the icon which
 269         // may be very tall
 270         const QFontMetrics metrics(font());
 271         singleStep = metrics.height() * QApplication::wheelScrollLines();
 272
 273         // We cannot use view->size().height() because this height might
 274         // include the header widget, which is not part of the scrolled area.
 275         pageStep = view->verticalPageStep();
 276
 277         // However, the total height of the view must be considered for the
 278         // maximum value of the scroll bar. Note that the view's scrollOffset()
 279         // refers to the offset of the top part of the view, which might be
 280         // hidden behind the header.
 281         maximum = qMax(0, int(view->maximumScrollOffset() - view->size().height()));
 282     } else {
 283         smoothScroller = m_horizontalSmoothScroller;
 284         scrollOffsetScrollBar = horizontalScrollBar();
 285         singleStep = view->itemSize().width();
 286         pageStep = view->size().width();
 287         maximum = qMax(0, int(view->maximumScrollOffset() - view->size().width()));
 288     }
 289
 290     const int value = view->scrollOffset();
 291     if (smoothScroller->requestScrollBarUpdate(maximum)) {
 292         const bool updatePolicy = (scrollOffsetScrollBar->maximum() > 0 && maximum == 0)
 293                                   || horizontalScrollBarPolicy() == Qt::ScrollBarAlwaysOn;
 294
 295         scrollOffsetScrollBar->setSingleStep(singleStep);
 296         scrollOffsetScrollBar->setPageStep(pageStep);
 297         scrollOffsetScrollBar->setMinimum(0);
 298         scrollOffsetScrollBar->setMaximum(maximum);
 299         scrollOffsetScrollBar->setValue(value);
 300
 301         if (updatePolicy) {
 302             // Prevent a potential endless layout loop (see bug #293318).
 303             updateScrollOffsetScrollBarPolicy();
 304         }
 305     }
 306 }
 307
 308 void KItemListContainer::updateItemOffsetScrollBar()
 309 {
 310     const KItemListView* view = m_controller->view();
 311     if (!view) {
 312         return;
 313     }
 314
 315     KItemListSmoothScroller* smoothScroller = nullptr;
 316     QScrollBar* itemOffsetScrollBar = nullptr;
 317     int singleStep = 0;
 318     int pageStep = 0;
 319     if (view->scrollOrientation() == Qt::Vertical) {
 320         smoothScroller = m_horizontalSmoothScroller;
 321         itemOffsetScrollBar = horizontalScrollBar();
 322         singleStep = view->size().width() / 10;
 323         pageStep = view->size().width();
 324     } else {
 325         smoothScroller = m_verticalSmoothScroller;
 326         itemOffsetScrollBar = verticalScrollBar();
 327         singleStep = view->size().height() / 10;
 328         pageStep = view->size().height();
 329     }
 330
 331     const int value = view->itemOffset();
 332     const int maximum = qMax(0, int(view->maximumItemOffset()) - pageStep);
 333     if (smoothScroller->requestScrollBarUpdate(maximum)) {
 334         itemOffsetScrollBar->setSingleStep(singleStep);
 335         itemOffsetScrollBar->setPageStep(pageStep);
 336         itemOffsetScrollBar->setMinimum(0);
 337         itemOffsetScrollBar->setMaximum(maximum);
 338         itemOffsetScrollBar->setValue(value);
 339     }
 340 }
 341
 342 void KItemListContainer::updateGeometries()
 343 {
 344     QRect rect = geometry();
 345
 346     int extra = frameWidth() * 2;
 347     QStyleOption option;
 348     option.initFrom(this);
 349     int scrollbarSpacing = 0;
 350     if (style()->styleHint(QStyle::SH_ScrollView_FrameOnlyAroundContents, &option, this)) {
 351         scrollbarSpacing = style()->pixelMetric(QStyle::PM_ScrollView_ScrollBarSpacing, &option, this);
 352     }
 353
 354     const int widthDec = verticalScrollBar()->isVisible()
 355                          ? extra + scrollbarSpacing + style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this)
 356                          : extra;
 357
 358     const int heightDec = horizontalScrollBar()->isVisible()
 359                           ? extra + scrollbarSpacing + style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this)
 360                           : extra;
 361
 362     const QRectF newGeometry(0, 0, rect.width() - widthDec,
 363                              rect.height() - heightDec);
 364     if (m_controller->view()->geometry() != newGeometry) {
 365         m_controller->view()->setGeometry(newGeometry);
 366
 367         // Get the real geometry of the view again since the scrollbars
 368         // visibilities and the view geometry may have changed in re-layout.
 369         static_cast<KItemListContainerViewport*>(viewport())->scene()->setSceneRect(m_controller->view()->geometry());
 370         static_cast<KItemListContainerViewport*>(viewport())->viewport()->setGeometry(m_controller->view()->geometry().toRect());
 371
 372         updateScrollOffsetScrollBar();
 373         updateItemOffsetScrollBar();
 374     }
 375 }
 376
 377 void KItemListContainer::updateSmoothScrollers(Qt::Orientation orientation)
 378 {
 379     if (orientation == Qt::Vertical) {
 380         m_verticalSmoothScroller->setPropertyName("scrollOffset");
 381         m_horizontalSmoothScroller->setPropertyName("itemOffset");
 382     } else {
 383         m_horizontalSmoothScroller->setPropertyName("scrollOffset");
 384         m_verticalSmoothScroller->setPropertyName("itemOffset");
 385     }
 386 }
 387
 388 void KItemListContainer::updateScrollOffsetScrollBarPolicy()
 389 {
 390     const KItemListView* view = m_controller->view();
 391     Q_ASSERT(view);
 392     const bool vertical = (view->scrollOrientation() == Qt::Vertical);
 393
 394     QStyleOption option;
 395     option.initFrom(this);
 396     const int scrollBarInc = style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this);
 397
 398     QSizeF newViewSize = m_controller->view()->size();
 399     if (vertical) {
 400         newViewSize.rwidth() += scrollBarInc;
 401     } else {
 402         newViewSize.rheight() += scrollBarInc;
 403     }
 404
 405     const Qt::ScrollBarPolicy policy = view->scrollBarRequired(newViewSize)
 406                                        ? Qt::ScrollBarAlwaysOn : Qt::ScrollBarAsNeeded;
 407     if (vertical) {
 408         setVerticalScrollBarPolicy(policy);
 409     } else {
 410         setHorizontalScrollBarPolicy(policy);
 411     }
 412 }
 413
 414 #include "kitemlistcontainer.moc"