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
  35 protected:
  36     void wheelEvent(QWheelEvent *event) override;
  37 };
  38
  39 KItemListContainerViewport::KItemListContainerViewport(QGraphicsScene *scene, QWidget *parent)
  40     : QGraphicsView(scene, parent)
  41 {
  42     setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
  43     setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
  44     setViewportMargins(0, 0, 0, 0);
  45     setFrameShape(QFrame::NoFrame);
  46 }
  47
  48 void KItemListContainerViewport::wheelEvent(QWheelEvent *event)
  49 {
  50     // Assure that the wheel-event gets forwarded to the parent
  51     // and not handled at all by QGraphicsView.
  52     event->ignore();
  53 }
  54
  55 KItemListContainer::KItemListContainer(KItemListController *controller, QWidget *parent)
  56     : QAbstractScrollArea(parent)
  57     , m_controller(controller)
  58     , m_horizontalSmoothScroller(nullptr)
  59     , m_verticalSmoothScroller(nullptr)
  60     , m_scroller(nullptr)
  61 {
  62     Q_ASSERT(controller);
  63     controller->setParent(this);
  64
  65     QGraphicsView *graphicsView = new KItemListContainerViewport(new QGraphicsScene(this), this);
  66     setViewport(graphicsView);
  67
  68     m_horizontalSmoothScroller = new KItemListSmoothScroller(horizontalScrollBar(), this);
  69     m_verticalSmoothScroller = new KItemListSmoothScroller(verticalScrollBar(), this);
  70
  71     if (controller->model()) {
  72         slotModelChanged(controller->model(), nullptr);
  73     }
  74     if (controller->view()) {
  75         slotViewChanged(controller->view(), nullptr);
  76     }
  77
  78     connect(controller, &KItemListController::modelChanged, this, &KItemListContainer::slotModelChanged);
  79     connect(controller, &KItemListController::viewChanged, this, &KItemListContainer::slotViewChanged);
  80
  81     m_scroller = QScroller::scroller(viewport());
  82     m_scroller->grabGesture(viewport());
  83     connect(controller, &KItemListController::scrollerStop, this, &KItemListContainer::stopScroller);
  84     connect(m_scroller, &QScroller::stateChanged, controller, &KItemListController::slotStateChanged);
  85 }
  86
  87 KItemListContainer::~KItemListContainer()
  88 {
  89     // Don't rely on the QObject-order to delete the controller, otherwise
  90     // the QGraphicsScene might get deleted before the view.
  91     delete m_controller;
  92     m_controller = nullptr;
  93 }
  94
  95 KItemListController *KItemListContainer::controller() const
  96 {
  97     return m_controller;
  98 }
  99
 100 void KItemListContainer::setEnabledFrame(bool enable)
 101 {
 102     QGraphicsView *graphicsView = qobject_cast<QGraphicsView *>(viewport());
 103     if (enable) {
 104         setFrameShape(QFrame::StyledPanel);
 105         graphicsView->setPalette(palette());
 106         graphicsView->viewport()->setAutoFillBackground(true);
 107     } else {
 108         setFrameShape(QFrame::NoFrame);
 109         // Make the background of the container transparent and apply the window-text color
 110         // to the text color, so that enough contrast is given for all color
 111         // schemes
 112         QPalette p = graphicsView->palette();
 113         p.setColor(QPalette::Active, QPalette::Text, p.color(QPalette::Active, QPalette::WindowText));
 114         p.setColor(QPalette::Inactive, QPalette::Text, p.color(QPalette::Inactive, QPalette::WindowText));
 115         p.setColor(QPalette::Disabled, QPalette::Text, p.color(QPalette::Disabled, QPalette::WindowText));
 116         graphicsView->setPalette(p);
 117         graphicsView->viewport()->setAutoFillBackground(false);
 118     }
 119 }
 120
 121 bool KItemListContainer::enabledFrame() const
 122 {
 123     const QGraphicsView *graphicsView = qobject_cast<QGraphicsView *>(viewport());
 124     return graphicsView->autoFillBackground();
 125 }
 126
 127 void KItemListContainer::keyPressEvent(QKeyEvent *event)
 128 {
 129     // TODO: We should find a better way to handle the key press events in the view.
 130     // The reasons why we need this hack are:
 131     // 1. Without reimplementing keyPressEvent() here, the event would not reach the QGraphicsView.
 132     // 2. By default, the KItemListView does not have the keyboard focus in the QGraphicsScene, so
 133     //    simply sending the event to the QGraphicsView which is the KItemListContainer's viewport
 134     //    does not work.
 135     KItemListView *view = m_controller->view();
 136     if (view) {
 137         QApplication::sendEvent(view, event);
 138     }
 139 }
 140
 141 void KItemListContainer::contextMenuEvent(QContextMenuEvent *event)
 142 {
 143     // Note copied from the keyPressEvent() method above because the same reasons probably also apply here.
 144     // TODO: We should find a better way to handle the context menu events in the view.
 145     // The reasons why we need this hack are:
 146     // 1. Without reimplementing contextMenuEvent() here, the event would not reach the QGraphicsView.
 147     // 2. By default, the KItemListView does not have the keyboard focus in the QGraphicsScene, so
 148     //    simply sending the event to the QGraphicsView which is the KItemListContainer's viewport
 149     //    does not work.
 150     KItemListView *view = m_controller->view();
 151     if (view) {
 152         QApplication::sendEvent(view, event);
 153     }
 154 }
 155
 156 void KItemListContainer::showEvent(QShowEvent *event)
 157 {
 158     QAbstractScrollArea::showEvent(event);
 159     updateGeometries();
 160 }
 161
 162 void KItemListContainer::resizeEvent(QResizeEvent *event)
 163 {
 164     QAbstractScrollArea::resizeEvent(event);
 165     updateGeometries();
 166 }
 167
 168 void KItemListContainer::scrollContentsBy(int dx, int dy)
 169 {
 170     m_horizontalSmoothScroller->scrollContentsBy(dx);
 171     m_verticalSmoothScroller->scrollContentsBy(dy);
 172 }
 173
 174 void KItemListContainer::wheelEvent(QWheelEvent *event)
 175 {
 176     if (event->modifiers().testFlag(Qt::ControlModifier)) {
 177         event->ignore();
 178         return;
 179     }
 180
 181     KItemListView *view = m_controller->view();
 182     if (!view) {
 183         event->ignore();
 184         return;
 185     }
 186
 187     const bool scrollHorizontally = (qAbs(event->angleDelta().y()) < qAbs(event->angleDelta().x())) || (!verticalScrollBar()->isVisible());
 188     KItemListSmoothScroller *smoothScroller = scrollHorizontally ? m_horizontalSmoothScroller : m_verticalSmoothScroller;
 189
 190     smoothScroller->handleWheelEvent(event);
 191 }
 192
 193 void KItemListContainer::focusInEvent(QFocusEvent *event)
 194 {
 195     KItemListView *view = m_controller->view();
 196     if (view) {
 197         QApplication::sendEvent(view, event);
 198     }
 199 }
 200
 201 void KItemListContainer::focusOutEvent(QFocusEvent *event)
 202 {
 203     KItemListView *view = m_controller->view();
 204     if (view) {
 205         QApplication::sendEvent(view, event);
 206     }
 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, this, &KItemListContainer::slotScrollOrientationChanged);
 227         disconnect(previous, &KItemListView::scrollOffsetChanged, this, &KItemListContainer::updateScrollOffsetScrollBar);
 228         disconnect(previous, &KItemListView::maximumScrollOffsetChanged, this, &KItemListContainer::updateScrollOffsetScrollBar);
 229         disconnect(previous, &KItemListView::itemOffsetChanged, this, &KItemListContainer::updateItemOffsetScrollBar);
 230         disconnect(previous, &KItemListView::maximumItemOffsetChanged, this, &KItemListContainer::updateItemOffsetScrollBar);
 231         disconnect(previous, &KItemListView::scrollTo, this, &KItemListContainer::scrollTo);
 232         disconnect(m_horizontalSmoothScroller, &KItemListSmoothScroller::scrollingStopped, previous, &KItemListView::scrollingStopped);
 233         disconnect(m_verticalSmoothScroller, &KItemListSmoothScroller::scrollingStopped, previous, &KItemListView::scrollingStopped);
 234         m_horizontalSmoothScroller->setTargetObject(nullptr);
 235         m_verticalSmoothScroller->setTargetObject(nullptr);
 236     }
 237     if (current) {
 238         scene->addItem(current);
 239         connect(current, &KItemListView::scrollOrientationChanged, this, &KItemListContainer::slotScrollOrientationChanged);
 240         connect(current, &KItemListView::scrollOffsetChanged, this, &KItemListContainer::updateScrollOffsetScrollBar);
 241         connect(current, &KItemListView::maximumScrollOffsetChanged, this, &KItemListContainer::updateScrollOffsetScrollBar);
 242         connect(current, &KItemListView::itemOffsetChanged, this, &KItemListContainer::updateItemOffsetScrollBar);
 243         connect(current, &KItemListView::maximumItemOffsetChanged, this, &KItemListContainer::updateItemOffsetScrollBar);
 244         connect(current, &KItemListView::scrollTo, this, &KItemListContainer::scrollTo);
 245         connect(m_horizontalSmoothScroller, &KItemListSmoothScroller::scrollingStopped, current, &KItemListView::scrollingStopped);
 246         connect(m_verticalSmoothScroller, &KItemListSmoothScroller::scrollingStopped, current, &KItemListView::scrollingStopped);
 247
 248         m_horizontalSmoothScroller->setTargetObject(current);
 249         m_verticalSmoothScroller->setTargetObject(current);
 250         updateSmoothScrollers(current->scrollOrientation());
 251     }
 252 }
 253
 254 void KItemListContainer::scrollTo(qreal offset)
 255 {
 256     const KItemListView *view = m_controller->view();
 257     if (view) {
 258         if (view->scrollOrientation() == Qt::Vertical) {
 259             m_verticalSmoothScroller->scrollTo(offset);
 260         } else {
 261             m_horizontalSmoothScroller->scrollTo(offset);
 262         }
 263     }
 264 }
 265
 266 void KItemListContainer::updateScrollOffsetScrollBar()
 267 {
 268     const KItemListView *view = m_controller->view();
 269     if (!view) {
 270         return;
 271     }
 272
 273     KItemListSmoothScroller *smoothScroller = nullptr;
 274     QScrollBar *scrollOffsetScrollBar = nullptr;
 275     int singleStep = 0;
 276     int pageStep = 0;
 277     int maximum = 0;
 278     if (view->scrollOrientation() == Qt::Vertical) {
 279         smoothScroller = m_verticalSmoothScroller;
 280         scrollOffsetScrollBar = verticalScrollBar();
 281
 282         // Don't scroll super fast when using a wheel mouse:
 283         // We want to consider one "line" to be the text label which has a
 284         // roughly fixed height rather than using the height of the icon which
 285         // may be very tall
 286         const QFontMetrics metrics(font());
 287         singleStep = metrics.height() * QApplication::wheelScrollLines();
 288
 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) || horizontalScrollBarPolicy() == Qt::ScrollBarAlwaysOn;
 309
 310         scrollOffsetScrollBar->setSingleStep(singleStep);
 311         scrollOffsetScrollBar->setPageStep(pageStep);
 312         scrollOffsetScrollBar->setMinimum(0);
 313         scrollOffsetScrollBar->setMaximum(maximum);
 314         scrollOffsetScrollBar->setValue(value);
 315
 316         if (updatePolicy) {
 317             // Prevent a potential endless layout loop (see bug #293318).
 318             updateScrollOffsetScrollBarPolicy();
 319         }
 320     }
 321 }
 322
 323 void KItemListContainer::updateItemOffsetScrollBar()
 324 {
 325     const KItemListView *view = m_controller->view();
 326     if (!view) {
 327         return;
 328     }
 329
 330     KItemListSmoothScroller *smoothScroller = nullptr;
 331     QScrollBar *itemOffsetScrollBar = nullptr;
 332     int singleStep = 0;
 333     int pageStep = 0;
 334     if (view->scrollOrientation() == Qt::Vertical) {
 335         smoothScroller = m_horizontalSmoothScroller;
 336         itemOffsetScrollBar = horizontalScrollBar();
 337         singleStep = view->size().width() / 10;
 338         pageStep = view->size().width();
 339     } else {
 340         smoothScroller = m_verticalSmoothScroller;
 341         itemOffsetScrollBar = verticalScrollBar();
 342         singleStep = view->size().height() / 10;
 343         pageStep = view->size().height();
 344     }
 345
 346     const int value = view->itemOffset();
 347     const int maximum = qMax(0, int(view->maximumItemOffset()) - pageStep);
 348     if (smoothScroller->requestScrollBarUpdate(maximum)) {
 349         itemOffsetScrollBar->setSingleStep(singleStep);
 350         itemOffsetScrollBar->setPageStep(pageStep);
 351         itemOffsetScrollBar->setMinimum(0);
 352         itemOffsetScrollBar->setMaximum(maximum);
 353         itemOffsetScrollBar->setValue(value);
 354     }
 355 }
 356
 357 void KItemListContainer::stopScroller()
 358 {
 359     m_scroller->stop();
 360 }
 361
 362 void KItemListContainer::updateGeometries()
 363 {
 364     QRect rect = geometry();
 365
 366     int extra = frameWidth() * 2;
 367     QStyleOption option;
 368     option.initFrom(this);
 369     int scrollbarSpacing = 0;
 370     if (style()->styleHint(QStyle::SH_ScrollView_FrameOnlyAroundContents, &option, this)) {
 371         scrollbarSpacing = style()->pixelMetric(QStyle::PM_ScrollView_ScrollBarSpacing, &option, this);
 372     }
 373
 374     const int widthDec = verticalScrollBar()->isVisible() ? extra + scrollbarSpacing + style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this) : extra;
 375
 376     const int heightDec =
 377         horizontalScrollBar()->isVisible() ? extra + scrollbarSpacing + style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this) : extra;
 378
 379     const QRectF newGeometry(0, 0, rect.width() - widthDec, 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     const bool isRightToLeft = m_controller->view()->layoutDirection() == Qt::RightToLeft;
 404     QScrollBar *hScrollBar = horizontalScrollBar();
 405     hScrollBar->setInvertedAppearance(isRightToLeft && orientation == Qt::Vertical);
 406     hScrollBar->setInvertedControls(!isRightToLeft || orientation == Qt::Vertical);
 407 }
 408
 409 void KItemListContainer::updateScrollOffsetScrollBarPolicy()
 410 {
 411     const KItemListView *view = m_controller->view();
 412     Q_ASSERT(view);
 413     const bool vertical = (view->scrollOrientation() == Qt::Vertical);
 414
 415     QStyleOption option;
 416     option.initFrom(this);
 417     const int scrollBarInc = style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this);
 418
 419     QSizeF newViewSize = m_controller->view()->size();
 420     if (vertical) {
 421         newViewSize.rwidth() += scrollBarInc;
 422     } else {
 423         newViewSize.rheight() += scrollBarInc;
 424     }
 425
 426     const Qt::ScrollBarPolicy policy = view->scrollBarRequired(newViewSize) ? Qt::ScrollBarAlwaysOn : Qt::ScrollBarAsNeeded;
 427     if (vertical) {
 428         setVerticalScrollBarPolicy(policy);
 429     } else {
 430         setHorizontalScrollBarPolicy(policy);
 431     }
 432 }
 433
 434 #include "kitemlistcontainer.moc"
 435 #include "moc_kitemlistcontainer.cpp"