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 #ifndef QT_NO_ACCESSIBILITY
  16 #include "accessibility/kitemlistviewaccessible.h"
  17 #endif
  18 #include <QApplication>
  19 #include <QFontMetrics>
  20 #include <QGraphicsScene>
  21 #include <QGraphicsView>
  22 #include <QScrollBar>
  23 #include <QScroller>
  24 #include <QStyleOption>
  25
  26 /**
  27  * Replaces the default viewport of KItemListContainer by a
  28  * non-scrollable viewport. The scrolling is done in an optimized
  29  * way by KItemListView internally.
  30  */
  31 class KItemListContainerViewport : public QGraphicsView
  32 {
  33     Q_OBJECT
  34
  35 public:
  36     KItemListContainerViewport(QGraphicsScene *scene, QWidget *parent);
  37
  38 protected:
  39     void wheelEvent(QWheelEvent *event) override;
  40 };
  41
  42 KItemListContainerViewport::KItemListContainerViewport(QGraphicsScene *scene, QWidget *parent)
  43     : QGraphicsView(scene, parent)
  44 {
  45     setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
  46     setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
  47     setViewportMargins(0, 0, 0, 0);
  48     setFrameShape(QFrame::NoFrame);
  49 }
  50
  51 void KItemListContainerViewport::wheelEvent(QWheelEvent *event)
  52 {
  53     // Assure that the wheel-event gets forwarded to the parent
  54     // and not handled at all by QGraphicsView.
  55     event->ignore();
  56 }
  57
  58 KItemListContainer::KItemListContainer(KItemListController *controller, QWidget *parent)
  59     : QAbstractScrollArea(parent)
  60     , m_controller(controller)
  61     , m_horizontalSmoothScroller(nullptr)
  62     , m_verticalSmoothScroller(nullptr)
  63     , m_scroller(nullptr)
  64 {
  65     Q_ASSERT(controller);
  66     controller->setParent(this);
  67
  68     QGraphicsView *graphicsView = new KItemListContainerViewport(new QGraphicsScene(this), this);
  69     setViewport(graphicsView);
  70
  71     m_horizontalSmoothScroller = new KItemListSmoothScroller(horizontalScrollBar(), this);
  72     m_verticalSmoothScroller = new KItemListSmoothScroller(verticalScrollBar(), this);
  73
  74     if (controller->model()) {
  75         slotModelChanged(controller->model(), nullptr);
  76     }
  77     if (controller->view()) {
  78         slotViewChanged(controller->view(), nullptr);
  79     }
  80
  81     connect(controller, &KItemListController::modelChanged, this, &KItemListContainer::slotModelChanged);
  82     connect(controller, &KItemListController::viewChanged, this, &KItemListContainer::slotViewChanged);
  83
  84     m_scroller = QScroller::scroller(viewport());
  85     m_scroller->grabGesture(viewport());
  86     connect(controller, &KItemListController::scrollerStop, this, &KItemListContainer::stopScroller);
  87     connect(m_scroller, &QScroller::stateChanged, 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::contextMenuEvent(QContextMenuEvent *event)
 145 {
 146     // Note copied from the keyPressEvent() method above because the same reasons probably also apply here.
 147     // TODO: We should find a better way to handle the context menu events in the view.
 148     // The reasons why we need this hack are:
 149     // 1. Without reimplementing contextMenuEvent() here, the event would not reach the QGraphicsView.
 150     // 2. By default, the KItemListView does not have the keyboard focus in the QGraphicsScene, so
 151     //    simply sending the event to the QGraphicsView which is the KItemListContainer's viewport
 152     //    does not work.
 153     KItemListView *view = m_controller->view();
 154     if (view) {
 155         QApplication::sendEvent(view, event);
 156     }
 157 }
 158
 159 void KItemListContainer::showEvent(QShowEvent *event)
 160 {
 161     QAbstractScrollArea::showEvent(event);
 162     updateGeometries();
 163 }
 164
 165 void KItemListContainer::resizeEvent(QResizeEvent *event)
 166 {
 167     QAbstractScrollArea::resizeEvent(event);
 168     updateGeometries();
 169 }
 170
 171 void KItemListContainer::scrollContentsBy(int dx, int dy)
 172 {
 173     m_horizontalSmoothScroller->scrollContentsBy(dx);
 174     m_verticalSmoothScroller->scrollContentsBy(dy);
 175 }
 176
 177 void KItemListContainer::wheelEvent(QWheelEvent *event)
 178 {
 179     if (event->modifiers().testFlag(Qt::ControlModifier)) {
 180         event->ignore();
 181         return;
 182     }
 183
 184     KItemListView *view = m_controller->view();
 185     if (!view) {
 186         event->ignore();
 187         return;
 188     }
 189
 190     const bool scrollHorizontally = (qAbs(event->angleDelta().y()) < qAbs(event->angleDelta().x())) || (!verticalScrollBar()->isVisible());
 191     KItemListSmoothScroller *smoothScroller = scrollHorizontally ? m_horizontalSmoothScroller : m_verticalSmoothScroller;
 192
 193     smoothScroller->handleWheelEvent(event);
 194 }
 195
 196 void KItemListContainer::focusInEvent(QFocusEvent *event)
 197 {
 198     KItemListView *view = m_controller->view();
 199     if (view) {
 200         QApplication::sendEvent(view, event);
 201
 202         // We need to set the focus to the view or accessibility software will only announce the container (which has no information available itself).
 203         // For some reason actively setting the focus to the view needs to be delayed or the focus will immediately go back to this container.
 204         QTimer::singleShot(0, this, [this, view]() {
 205             if (!isAncestorOf(QApplication::focusWidget())) {
 206                 view->setFocus();
 207             }
 208 #ifndef QT_NO_ACCESSIBILITY
 209             static_cast<KItemListViewAccessible *>(QAccessible::queryAccessibleInterface(view))->setAccessibleFocusAndAnnounceAll();
 210 #endif
 211         });
 212     }
 213 }
 214
 215 void KItemListContainer::focusOutEvent(QFocusEvent *event)
 216 {
 217     KItemListView *view = m_controller->view();
 218     if (view) {
 219         QApplication::sendEvent(view, event);
 220     }
 221 }
 222
 223 void KItemListContainer::slotScrollOrientationChanged(Qt::Orientation current, Qt::Orientation previous)
 224 {
 225     Q_UNUSED(previous)
 226     updateSmoothScrollers(current);
 227 }
 228
 229 void KItemListContainer::slotModelChanged(KItemModelBase *current, KItemModelBase *previous)
 230 {
 231     Q_UNUSED(current)
 232     Q_UNUSED(previous)
 233 }
 234
 235 void KItemListContainer::slotViewChanged(KItemListView *current, KItemListView *previous)
 236 {
 237     QGraphicsScene *scene = static_cast<QGraphicsView *>(viewport())->scene();
 238     if (previous) {
 239         scene->removeItem(previous);
 240         disconnect(previous, &KItemListView::scrollOrientationChanged, this, &KItemListContainer::slotScrollOrientationChanged);
 241         disconnect(previous, &KItemListView::scrollOffsetChanged, this, &KItemListContainer::updateScrollOffsetScrollBar);
 242         disconnect(previous, &KItemListView::maximumScrollOffsetChanged, this, &KItemListContainer::updateScrollOffsetScrollBar);
 243         disconnect(previous, &KItemListView::itemOffsetChanged, this, &KItemListContainer::updateItemOffsetScrollBar);
 244         disconnect(previous, &KItemListView::maximumItemOffsetChanged, this, &KItemListContainer::updateItemOffsetScrollBar);
 245         disconnect(previous, &KItemListView::scrollTo, this, &KItemListContainer::scrollTo);
 246         disconnect(m_horizontalSmoothScroller, &KItemListSmoothScroller::scrollingStopped, previous, &KItemListView::scrollingStopped);
 247         disconnect(m_verticalSmoothScroller, &KItemListSmoothScroller::scrollingStopped, previous, &KItemListView::scrollingStopped);
 248         m_horizontalSmoothScroller->setTargetObject(nullptr);
 249         m_verticalSmoothScroller->setTargetObject(nullptr);
 250     }
 251     if (current) {
 252         scene->addItem(current);
 253         connect(current, &KItemListView::scrollOrientationChanged, this, &KItemListContainer::slotScrollOrientationChanged);
 254         connect(current, &KItemListView::scrollOffsetChanged, this, &KItemListContainer::updateScrollOffsetScrollBar);
 255         connect(current, &KItemListView::maximumScrollOffsetChanged, this, &KItemListContainer::updateScrollOffsetScrollBar);
 256         connect(current, &KItemListView::itemOffsetChanged, this, &KItemListContainer::updateItemOffsetScrollBar);
 257         connect(current, &KItemListView::maximumItemOffsetChanged, this, &KItemListContainer::updateItemOffsetScrollBar);
 258         connect(current, &KItemListView::scrollTo, this, &KItemListContainer::scrollTo);
 259         connect(m_horizontalSmoothScroller, &KItemListSmoothScroller::scrollingStopped, current, &KItemListView::scrollingStopped);
 260         connect(m_verticalSmoothScroller, &KItemListSmoothScroller::scrollingStopped, current, &KItemListView::scrollingStopped);
 261
 262         m_horizontalSmoothScroller->setTargetObject(current);
 263         m_verticalSmoothScroller->setTargetObject(current);
 264         updateSmoothScrollers(current->scrollOrientation());
 265     }
 266 }
 267
 268 void KItemListContainer::scrollTo(qreal offset)
 269 {
 270     const KItemListView *view = m_controller->view();
 271     if (view) {
 272         if (view->scrollOrientation() == Qt::Vertical) {
 273             m_verticalSmoothScroller->scrollTo(offset);
 274         } else {
 275             m_horizontalSmoothScroller->scrollTo(offset);
 276         }
 277     }
 278 }
 279
 280 void KItemListContainer::updateScrollOffsetScrollBar()
 281 {
 282     const KItemListView *view = m_controller->view();
 283     if (!view) {
 284         return;
 285     }
 286
 287     KItemListSmoothScroller *smoothScroller = nullptr;
 288     QScrollBar *scrollOffsetScrollBar = nullptr;
 289     int singleStep = 0;
 290     int pageStep = 0;
 291     int maximum = 0;
 292     if (view->scrollOrientation() == Qt::Vertical) {
 293         smoothScroller = m_verticalSmoothScroller;
 294         if (smoothScroller->isAnimating()) {
 295             return;
 296         }
 297         scrollOffsetScrollBar = verticalScrollBar();
 298
 299         // Don't scroll super fast when using a wheel mouse:
 300         // We want to consider one "line" to be the text label which has a
 301         // roughly fixed height rather than using the height of the icon which
 302         // may be very tall
 303         const QFontMetrics metrics(font());
 304         singleStep = metrics.height() * QApplication::wheelScrollLines();
 305
 306         // We cannot use view->size().height() because this height might
 307         // include the header widget, which is not part of the scrolled area.
 308         pageStep = view->verticalPageStep();
 309
 310         // However, the total height of the view must be considered for the
 311         // maximum value of the scroll bar. Note that the view's scrollOffset()
 312         // refers to the offset of the top part of the view, which might be
 313         // hidden behind the header.
 314         maximum = qMax(0, int(view->maximumScrollOffset() - view->size().height()));
 315     } else {
 316         smoothScroller = m_horizontalSmoothScroller;
 317         if (smoothScroller->isAnimating()) {
 318             return;
 319         }
 320         scrollOffsetScrollBar = horizontalScrollBar();
 321         singleStep = view->itemSize().width();
 322         pageStep = view->size().width();
 323         maximum = qMax(0, int(view->maximumScrollOffset() - view->size().width()));
 324     }
 325
 326     const int value = view->scrollOffset();
 327     if (smoothScroller->requestScrollBarUpdate(maximum)) {
 328         const bool updatePolicy = (scrollOffsetScrollBar->maximum() > 0 && maximum == 0) || horizontalScrollBarPolicy() == Qt::ScrollBarAlwaysOn;
 329
 330         scrollOffsetScrollBar->setSingleStep(singleStep);
 331         scrollOffsetScrollBar->setPageStep(pageStep);
 332         scrollOffsetScrollBar->setMinimum(0);
 333         scrollOffsetScrollBar->setMaximum(maximum);
 334         scrollOffsetScrollBar->setValue(value);
 335
 336         if (updatePolicy) {
 337             // Prevent a potential endless layout loop (see bug #293318).
 338             updateScrollOffsetScrollBarPolicy();
 339         }
 340     }
 341 }
 342
 343 void KItemListContainer::updateItemOffsetScrollBar()
 344 {
 345     const KItemListView *view = m_controller->view();
 346     if (!view) {
 347         return;
 348     }
 349
 350     KItemListSmoothScroller *smoothScroller = nullptr;
 351     QScrollBar *itemOffsetScrollBar = nullptr;
 352     int singleStep = 0;
 353     int pageStep = 0;
 354     if (view->scrollOrientation() == Qt::Vertical) {
 355         smoothScroller = m_horizontalSmoothScroller;
 356         if (smoothScroller->isAnimating()) {
 357             return;
 358         }
 359         itemOffsetScrollBar = horizontalScrollBar();
 360         singleStep = view->size().width() / 10;
 361         pageStep = view->size().width();
 362     } else {
 363         smoothScroller = m_verticalSmoothScroller;
 364         if (smoothScroller->isAnimating()) {
 365             return;
 366         }
 367         itemOffsetScrollBar = verticalScrollBar();
 368         singleStep = view->size().height() / 10;
 369         pageStep = view->size().height();
 370     }
 371
 372     const int value = view->itemOffset();
 373     const int maximum = qMax(0, int(view->maximumItemOffset()) - pageStep);
 374     if (smoothScroller->requestScrollBarUpdate(maximum)) {
 375         itemOffsetScrollBar->setSingleStep(singleStep);
 376         itemOffsetScrollBar->setPageStep(pageStep);
 377         itemOffsetScrollBar->setMinimum(0);
 378         itemOffsetScrollBar->setMaximum(maximum);
 379         itemOffsetScrollBar->setValue(value);
 380     }
 381 }
 382
 383 void KItemListContainer::stopScroller()
 384 {
 385     m_scroller->stop();
 386 }
 387
 388 void KItemListContainer::updateGeometries()
 389 {
 390     QRect rect = geometry();
 391
 392     int extra = frameWidth() * 2;
 393     QStyleOption option;
 394     option.initFrom(this);
 395     int scrollbarSpacing = 0;
 396     if (style()->styleHint(QStyle::SH_ScrollView_FrameOnlyAroundContents, &option, this)) {
 397         scrollbarSpacing = style()->pixelMetric(QStyle::PM_ScrollView_ScrollBarSpacing, &option, this);
 398     }
 399
 400     const int widthDec = verticalScrollBar()->isVisible() ? extra + scrollbarSpacing + style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this) : extra;
 401
 402     const int heightDec =
 403         horizontalScrollBar()->isVisible() ? extra + scrollbarSpacing + style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this) : extra;
 404
 405     const QRectF newGeometry(0, 0, rect.width() - widthDec, rect.height() - heightDec);
 406     if (m_controller->view()->geometry() != newGeometry) {
 407         m_controller->view()->setGeometry(newGeometry);
 408
 409         // Get the real geometry of the view again since the scrollbars
 410         // visibilities and the view geometry may have changed in re-layout.
 411         static_cast<KItemListContainerViewport *>(viewport())->scene()->setSceneRect(m_controller->view()->geometry());
 412         static_cast<KItemListContainerViewport *>(viewport())->viewport()->setGeometry(m_controller->view()->geometry().toRect());
 413
 414         updateScrollOffsetScrollBar();
 415         updateItemOffsetScrollBar();
 416     }
 417 }
 418
 419 void KItemListContainer::updateSmoothScrollers(Qt::Orientation orientation)
 420 {
 421     if (orientation == Qt::Vertical) {
 422         m_verticalSmoothScroller->setPropertyName("scrollOffset");
 423         m_horizontalSmoothScroller->setPropertyName("itemOffset");
 424     } else {
 425         m_horizontalSmoothScroller->setPropertyName("scrollOffset");
 426         m_verticalSmoothScroller->setPropertyName("itemOffset");
 427     }
 428
 429     const bool isRightToLeft = m_controller->view()->layoutDirection() == Qt::RightToLeft;
 430     QScrollBar *hScrollBar = horizontalScrollBar();
 431     hScrollBar->setInvertedAppearance(isRightToLeft && orientation == Qt::Vertical);
 432     hScrollBar->setInvertedControls(!isRightToLeft || orientation == Qt::Vertical);
 433 }
 434
 435 void KItemListContainer::updateScrollOffsetScrollBarPolicy()
 436 {
 437     const KItemListView *view = m_controller->view();
 438     Q_ASSERT(view);
 439     const bool vertical = (view->scrollOrientation() == Qt::Vertical);
 440
 441     QStyleOption option;
 442     option.initFrom(this);
 443     const int scrollBarInc = style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this);
 444
 445     QSizeF newViewSize = m_controller->view()->size();
 446     if (vertical) {
 447         newViewSize.rwidth() += scrollBarInc;
 448     } else {
 449         newViewSize.rheight() += scrollBarInc;
 450     }
 451
 452     const Qt::ScrollBarPolicy policy = view->scrollBarRequired(newViewSize) ? Qt::ScrollBarAlwaysOn : Qt::ScrollBarAsNeeded;
 453     if (vertical) {
 454         setVerticalScrollBarPolicy(policy);
 455     } else {
 456         setHorizontalScrollBarPolicy(policy);
 457     }
 458 }
 459
 460 #include "kitemlistcontainer.moc"
 461 #include "moc_kitemlistcontainer.cpp"