src/kitemviews/kitemlistcontainer.cpp

   1 /*
   2  * SPDX-FileCopyrightText: 2011 Peter Penz <peter.penz19@gmail.com>
   3  *
   4  * Based on the Itemviews NG project from Trolltech Labs
   5  *
   6  * SPDX-License-Identifier: GPL-2.0-or-later
   7  */
   8
   9 #include "kitemlistcontainer.h"
  10
  11 #include "kitemlistcontroller.h"
  12 #include "kitemlistview.h"
  13 #include "private/kitemlistsmoothscroller.h"
  14
  15 #include <QApplication>
  16 #include <QFontMetrics>
  17 #include <QGraphicsScene>
  18 #include <QGraphicsView>
  19 #include <QScrollBar>
  20 #include <QScroller>
  21 #include <QStyleOption>
  22
  23 /**
  24  * Replaces the default viewport of KItemListContainer by a
  25  * non-scrollable viewport. The scrolling is done in an optimized
  26  * way by KItemListView internally.
  27  */
  28 class KItemListContainerViewport : public QGraphicsView
  29 {
  30     Q_OBJECT
  31
  32 public:
  33     KItemListContainerViewport(QGraphicsScene* scene, QWidget* parent);
  34 protected:
  35     void wheelEvent(QWheelEvent* event) override;
  36 };
  37
  38 KItemListContainerViewport::KItemListContainerViewport(QGraphicsScene* scene, QWidget* parent) :
  39     QGraphicsView(scene, parent)
  40 {
  41     setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
  42     setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
  43     setViewportMargins(0, 0, 0, 0);
  44     setFrameShape(QFrame::NoFrame);
  45 }
  46
  47 void KItemListContainerViewport::wheelEvent(QWheelEvent* event)
  48 {
  49     // Assure that the wheel-event gets forwarded to the parent
  50     // and not handled at all by QGraphicsView.
  51     event->ignore();
  52 }
  53
  54 KItemListContainer::KItemListContainer(KItemListController* controller, QWidget* parent) :
  55     QAbstractScrollArea(parent),
  56     m_controller(controller),
  57     m_horizontalSmoothScroller(nullptr),
  58     m_verticalSmoothScroller(nullptr),
  59     m_scroller(nullptr)
  60 {
  61     Q_ASSERT(controller);
  62     controller->setParent(this);
  63
  64     QGraphicsView* graphicsView = new KItemListContainerViewport(new QGraphicsScene(this), this);
  65     setViewport(graphicsView);
  66
  67     m_horizontalSmoothScroller = new KItemListSmoothScroller(horizontalScrollBar(), this);
  68     m_verticalSmoothScroller = new KItemListSmoothScroller(verticalScrollBar(), this);
  69
  70     if (controller->model()) {
  71         slotModelChanged(controller->model(), nullptr);
  72     }
  73     if (controller->view()) {
  74         slotViewChanged(controller->view(), nullptr);
  75     }
  76
  77     connect(controller, &KItemListController::modelChanged,
  78             this, &KItemListContainer::slotModelChanged);
  79     connect(controller, &KItemListController::viewChanged,
  80             this, &KItemListContainer::slotViewChanged);
  81
  82     m_scroller = QScroller::scroller(viewport());
  83     m_scroller->grabGesture(viewport());
  84     connect(controller, &KItemListController::scrollerStop,
  85             this, &KItemListContainer::stopScroller);
  86     connect(m_scroller, &QScroller::stateChanged,
  87             controller, &KItemListController::slotStateChanged);
  88 }
  89
  90 KItemListContainer::~KItemListContainer()
  91 {
  92     // Don't rely on the QObject-order to delete the controller, otherwise
  93     // the QGraphicsScene might get deleted before the view.
  94     delete m_controller;
  95     m_controller = nullptr;
  96 }
  97
  98 KItemListController* KItemListContainer::controller() const
  99 {
 100     return m_controller;
 101 }
 102
 103 void KItemListContainer::setEnabledFrame(bool enable)
 104 {
 105     QGraphicsView* graphicsView = qobject_cast<QGraphicsView*>(viewport());
 106     if (enable) {
 107         setFrameShape(QFrame::StyledPanel);
 108         graphicsView->setPalette(palette());
 109         graphicsView->viewport()->setAutoFillBackground(true);
 110     } else {
 111         setFrameShape(QFrame::NoFrame);
 112         // Make the background of the container transparent and apply the window-text color
 113         // to the text color, so that enough contrast is given for all color
 114         // schemes
 115         QPalette p = graphicsView->palette();
 116         p.setColor(QPalette::Active,   QPalette::Text, p.color(QPalette::Active,   QPalette::WindowText));
 117         p.setColor(QPalette::Inactive, QPalette::Text, p.color(QPalette::Inactive, QPalette::WindowText));
 118         p.setColor(QPalette::Disabled, QPalette::Text, p.color(QPalette::Disabled, QPalette::WindowText));
 119         graphicsView->setPalette(p);
 120         graphicsView->viewport()->setAutoFillBackground(false);
 121     }
 122 }
 123
 124 bool KItemListContainer::enabledFrame() const
 125 {
 126     const QGraphicsView* graphicsView = qobject_cast<QGraphicsView*>(viewport());
 127     return graphicsView->autoFillBackground();
 128 }
 129
 130 void KItemListContainer::keyPressEvent(QKeyEvent* event)
 131 {
 132     // TODO: We should find a better way to handle the key press events in the view.
 133     // The reasons why we need this hack are:
 134     // 1. Without reimplementing keyPressEvent() here, the event would not reach the QGraphicsView.
 135     // 2. By default, the KItemListView does not have the keyboard focus in the QGraphicsScene, so
 136     //    simply sending the event to the QGraphicsView which is the KItemListContainer's viewport
 137     //    does not work.
 138     KItemListView* view = m_controller->view();
 139     if (view) {
 140         QApplication::sendEvent(view, event);
 141     }
 142 }
 143
 144 void KItemListContainer::showEvent(QShowEvent* event)
 145 {
 146     QAbstractScrollArea::showEvent(event);
 147     updateGeometries();
 148 }
 149
 150 void KItemListContainer::resizeEvent(QResizeEvent* event)
 151 {
 152     QAbstractScrollArea::resizeEvent(event);
 153     updateGeometries();
 154 }
 155
 156 void KItemListContainer::scrollContentsBy(int dx, int dy)
 157 {
 158     m_horizontalSmoothScroller->scrollContentsBy(dx);
 159     m_verticalSmoothScroller->scrollContentsBy(dy);
 160 }
 161
 162 void KItemListContainer::wheelEvent(QWheelEvent* event)
 163 {
 164     if (event->modifiers().testFlag(Qt::ControlModifier)) {
 165         event->ignore();
 166         return;
 167     }
 168
 169     KItemListView* view = m_controller->view();
 170     if (!view) {
 171         event->ignore();
 172         return;
 173     }
 174
 175     const bool scrollHorizontally = (qAbs(event->angleDelta().y()) < qAbs(event->angleDelta().x())) ||
 176                                     (!verticalScrollBar()->isVisible());
 177     KItemListSmoothScroller* smoothScroller = scrollHorizontally ?
 178                                               m_horizontalSmoothScroller : m_verticalSmoothScroller;
 179
 180     smoothScroller->handleWheelEvent(event);
 181 }
 182
 183 void KItemListContainer::slotScrollOrientationChanged(Qt::Orientation current, Qt::Orientation previous)
 184 {
 185     Q_UNUSED(previous)
 186     updateSmoothScrollers(current);
 187 }
 188
 189 void KItemListContainer::slotModelChanged(KItemModelBase* current, KItemModelBase* previous)
 190 {
 191     Q_UNUSED(current)
 192     Q_UNUSED(previous)
 193 }
 194
 195 void KItemListContainer::slotViewChanged(KItemListView* current, KItemListView* previous)
 196 {
 197     QGraphicsScene* scene = static_cast<QGraphicsView*>(viewport())->scene();
 198     if (previous) {
 199         scene->removeItem(previous);
 200         disconnect(previous, &KItemListView::scrollOrientationChanged,
 201                    this, &KItemListContainer::slotScrollOrientationChanged);
 202         disconnect(previous, &KItemListView::scrollOffsetChanged,
 203                    this, &KItemListContainer::updateScrollOffsetScrollBar);
 204         disconnect(previous, &KItemListView::maximumScrollOffsetChanged,
 205                    this, &KItemListContainer::updateScrollOffsetScrollBar);
 206         disconnect(previous, &KItemListView::itemOffsetChanged,
 207                    this, &KItemListContainer::updateItemOffsetScrollBar);
 208         disconnect(previous, &KItemListView::maximumItemOffsetChanged,
 209                    this, &KItemListContainer::updateItemOffsetScrollBar);
 210         disconnect(previous, &KItemListView::scrollTo, this, &KItemListContainer::scrollTo);
 211         disconnect(m_horizontalSmoothScroller, &KItemListSmoothScroller::scrollingStopped, previous, &KItemListView::scrollingStopped);
 212         disconnect(m_verticalSmoothScroller, &KItemListSmoothScroller::scrollingStopped, previous, &KItemListView::scrollingStopped);
 213         m_horizontalSmoothScroller->setTargetObject(nullptr);
 214         m_verticalSmoothScroller->setTargetObject(nullptr);
 215     }
 216     if (current) {
 217         scene->addItem(current);
 218         connect(current, &KItemListView::scrollOrientationChanged,
 219                 this, &KItemListContainer::slotScrollOrientationChanged);
 220         connect(current, &KItemListView::scrollOffsetChanged,
 221                 this, &KItemListContainer::updateScrollOffsetScrollBar);
 222         connect(current, &KItemListView::maximumScrollOffsetChanged,
 223                 this, &KItemListContainer::updateScrollOffsetScrollBar);
 224         connect(current, &KItemListView::itemOffsetChanged,
 225                 this, &KItemListContainer::updateItemOffsetScrollBar);
 226         connect(current, &KItemListView::maximumItemOffsetChanged,
 227                 this, &KItemListContainer::updateItemOffsetScrollBar);
 228         connect(current, &KItemListView::scrollTo, this, &KItemListContainer::scrollTo);
 229         connect(m_horizontalSmoothScroller, &KItemListSmoothScroller::scrollingStopped, current, &KItemListView::scrollingStopped);
 230         connect(m_verticalSmoothScroller, &KItemListSmoothScroller::scrollingStopped, current, &KItemListView::scrollingStopped);
 231
 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::stopScroller()
 343 {
 344     m_scroller->stop();
 345 }
 346
 347 void KItemListContainer::updateGeometries()
 348 {
 349     QRect rect = geometry();
 350
 351     int extra = frameWidth() * 2;
 352     QStyleOption option;
 353     option.initFrom(this);
 354     int scrollbarSpacing = 0;
 355     if (style()->styleHint(QStyle::SH_ScrollView_FrameOnlyAroundContents, &option, this)) {
 356         scrollbarSpacing = style()->pixelMetric(QStyle::PM_ScrollView_ScrollBarSpacing, &option, this);
 357     }
 358
 359     const int widthDec = verticalScrollBar()->isVisible()
 360                          ? extra + scrollbarSpacing + style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this)
 361                          : extra;
 362
 363     const int heightDec = horizontalScrollBar()->isVisible()
 364                           ? extra + scrollbarSpacing + style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this)
 365                           : extra;
 366
 367     const QRectF newGeometry(0, 0, rect.width() - widthDec,
 368                              rect.height() - heightDec);
 369     if (m_controller->view()->geometry() != newGeometry) {
 370         m_controller->view()->setGeometry(newGeometry);
 371
 372         // Get the real geometry of the view again since the scrollbars
 373         // visibilities and the view geometry may have changed in re-layout.
 374         static_cast<KItemListContainerViewport*>(viewport())->scene()->setSceneRect(m_controller->view()->geometry());
 375         static_cast<KItemListContainerViewport*>(viewport())->viewport()->setGeometry(m_controller->view()->geometry().toRect());
 376
 377         updateScrollOffsetScrollBar();
 378         updateItemOffsetScrollBar();
 379     }
 380 }
 381
 382 void KItemListContainer::updateSmoothScrollers(Qt::Orientation orientation)
 383 {
 384     if (orientation == Qt::Vertical) {
 385         m_verticalSmoothScroller->setPropertyName("scrollOffset");
 386         m_horizontalSmoothScroller->setPropertyName("itemOffset");
 387     } else {
 388         m_horizontalSmoothScroller->setPropertyName("scrollOffset");
 389         m_verticalSmoothScroller->setPropertyName("itemOffset");
 390     }
 391 }
 392
 393 void KItemListContainer::updateScrollOffsetScrollBarPolicy()
 394 {
 395     const KItemListView* view = m_controller->view();
 396     Q_ASSERT(view);
 397     const bool vertical = (view->scrollOrientation() == Qt::Vertical);
 398
 399     QStyleOption option;
 400     option.initFrom(this);
 401     const int scrollBarInc = style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this);
 402
 403     QSizeF newViewSize = m_controller->view()->size();
 404     if (vertical) {
 405         newViewSize.rwidth() += scrollBarInc;
 406     } else {
 407         newViewSize.rheight() += scrollBarInc;
 408     }
 409
 410     const Qt::ScrollBarPolicy policy = view->scrollBarRequired(newViewSize)
 411                                        ? Qt::ScrollBarAlwaysOn : Qt::ScrollBarAsNeeded;
 412     if (vertical) {
 413         setVerticalScrollBarPolicy(policy);
 414     } else {
 415         setHorizontalScrollBarPolicy(policy);
 416     }
 417 }
 418
 419 #include "kitemlistcontainer.moc"