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 <QAccessibleEvent>
  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             view->setFocus();
 206 #ifndef QT_NO_ACCESSIBILITY
 207             QAccessibleEvent accessibleFocusInEvent(this, QAccessible::Focus);
 208             accessibleFocusInEvent.setChild(0);
 209             QAccessible::updateAccessibility(&accessibleFocusInEvent);
 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         scrollOffsetScrollBar = verticalScrollBar();
 295
 296         // Don't scroll super fast when using a wheel mouse:
 297         // We want to consider one "line" to be the text label which has a
 298         // roughly fixed height rather than using the height of the icon which
 299         // may be very tall
 300         const QFontMetrics metrics(font());
 301         singleStep = metrics.height() * QApplication::wheelScrollLines();
 302
 303         // We cannot use view->size().height() because this height might
 304         // include the header widget, which is not part of the scrolled area.
 305         pageStep = view->verticalPageStep();
 306
 307         // However, the total height of the view must be considered for the
 308         // maximum value of the scroll bar. Note that the view's scrollOffset()
 309         // refers to the offset of the top part of the view, which might be
 310         // hidden behind the header.
 311         maximum = qMax(0, int(view->maximumScrollOffset() - view->size().height()));
 312     } else {
 313         smoothScroller = m_horizontalSmoothScroller;
 314         scrollOffsetScrollBar = horizontalScrollBar();
 315         singleStep = view->itemSize().width();
 316         pageStep = view->size().width();
 317         maximum = qMax(0, int(view->maximumScrollOffset() - view->size().width()));
 318     }
 319
 320     const int value = view->scrollOffset();
 321     if (smoothScroller->requestScrollBarUpdate(maximum)) {
 322         const bool updatePolicy = (scrollOffsetScrollBar->maximum() > 0 && maximum == 0) || horizontalScrollBarPolicy() == Qt::ScrollBarAlwaysOn;
 323
 324         scrollOffsetScrollBar->setSingleStep(singleStep);
 325         scrollOffsetScrollBar->setPageStep(pageStep);
 326         scrollOffsetScrollBar->setMinimum(0);
 327         scrollOffsetScrollBar->setMaximum(maximum);
 328         scrollOffsetScrollBar->setValue(value);
 329
 330         if (updatePolicy) {
 331             // Prevent a potential endless layout loop (see bug #293318).
 332             updateScrollOffsetScrollBarPolicy();
 333         }
 334     }
 335 }
 336
 337 void KItemListContainer::updateItemOffsetScrollBar()
 338 {
 339     const KItemListView *view = m_controller->view();
 340     if (!view) {
 341         return;
 342     }
 343
 344     KItemListSmoothScroller *smoothScroller = nullptr;
 345     QScrollBar *itemOffsetScrollBar = nullptr;
 346     int singleStep = 0;
 347     int pageStep = 0;
 348     if (view->scrollOrientation() == Qt::Vertical) {
 349         smoothScroller = m_horizontalSmoothScroller;
 350         itemOffsetScrollBar = horizontalScrollBar();
 351         singleStep = view->size().width() / 10;
 352         pageStep = view->size().width();
 353     } else {
 354         smoothScroller = m_verticalSmoothScroller;
 355         itemOffsetScrollBar = verticalScrollBar();
 356         singleStep = view->size().height() / 10;
 357         pageStep = view->size().height();
 358     }
 359
 360     const int value = view->itemOffset();
 361     const int maximum = qMax(0, int(view->maximumItemOffset()) - pageStep);
 362     if (smoothScroller->requestScrollBarUpdate(maximum)) {
 363         itemOffsetScrollBar->setSingleStep(singleStep);
 364         itemOffsetScrollBar->setPageStep(pageStep);
 365         itemOffsetScrollBar->setMinimum(0);
 366         itemOffsetScrollBar->setMaximum(maximum);
 367         itemOffsetScrollBar->setValue(value);
 368     }
 369 }
 370
 371 void KItemListContainer::stopScroller()
 372 {
 373     m_scroller->stop();
 374 }
 375
 376 void KItemListContainer::updateGeometries()
 377 {
 378     QRect rect = geometry();
 379
 380     int extra = frameWidth() * 2;
 381     QStyleOption option;
 382     option.initFrom(this);
 383     int scrollbarSpacing = 0;
 384     if (style()->styleHint(QStyle::SH_ScrollView_FrameOnlyAroundContents, &option, this)) {
 385         scrollbarSpacing = style()->pixelMetric(QStyle::PM_ScrollView_ScrollBarSpacing, &option, this);
 386     }
 387
 388     const int widthDec = verticalScrollBar()->isVisible() ? extra + scrollbarSpacing + style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this) : extra;
 389
 390     const int heightDec =
 391         horizontalScrollBar()->isVisible() ? extra + scrollbarSpacing + style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this) : extra;
 392
 393     const QRectF newGeometry(0, 0, rect.width() - widthDec, rect.height() - heightDec);
 394     if (m_controller->view()->geometry() != newGeometry) {
 395         m_controller->view()->setGeometry(newGeometry);
 396
 397         // Get the real geometry of the view again since the scrollbars
 398         // visibilities and the view geometry may have changed in re-layout.
 399         static_cast<KItemListContainerViewport *>(viewport())->scene()->setSceneRect(m_controller->view()->geometry());
 400         static_cast<KItemListContainerViewport *>(viewport())->viewport()->setGeometry(m_controller->view()->geometry().toRect());
 401
 402         updateScrollOffsetScrollBar();
 403         updateItemOffsetScrollBar();
 404     }
 405 }
 406
 407 void KItemListContainer::updateSmoothScrollers(Qt::Orientation orientation)
 408 {
 409     if (orientation == Qt::Vertical) {
 410         m_verticalSmoothScroller->setPropertyName("scrollOffset");
 411         m_horizontalSmoothScroller->setPropertyName("itemOffset");
 412     } else {
 413         m_horizontalSmoothScroller->setPropertyName("scrollOffset");
 414         m_verticalSmoothScroller->setPropertyName("itemOffset");
 415     }
 416
 417     const bool isRightToLeft = m_controller->view()->layoutDirection() == Qt::RightToLeft;
 418     QScrollBar *hScrollBar = horizontalScrollBar();
 419     hScrollBar->setInvertedAppearance(isRightToLeft && orientation == Qt::Vertical);
 420     hScrollBar->setInvertedControls(!isRightToLeft || orientation == Qt::Vertical);
 421 }
 422
 423 void KItemListContainer::updateScrollOffsetScrollBarPolicy()
 424 {
 425     const KItemListView *view = m_controller->view();
 426     Q_ASSERT(view);
 427     const bool vertical = (view->scrollOrientation() == Qt::Vertical);
 428
 429     QStyleOption option;
 430     option.initFrom(this);
 431     const int scrollBarInc = style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this);
 432
 433     QSizeF newViewSize = m_controller->view()->size();
 434     if (vertical) {
 435         newViewSize.rwidth() += scrollBarInc;
 436     } else {
 437         newViewSize.rheight() += scrollBarInc;
 438     }
 439
 440     const Qt::ScrollBarPolicy policy = view->scrollBarRequired(newViewSize) ? Qt::ScrollBarAlwaysOn : Qt::ScrollBarAsNeeded;
 441     if (vertical) {
 442         setVerticalScrollBarPolicy(policy);
 443     } else {
 444         setHorizontalScrollBarPolicy(policy);
 445     }
 446 }
 447
 448 #include "kitemlistcontainer.moc"
 449 #include "moc_kitemlistcontainer.cpp"