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::showEvent(QShowEvent *event)
 142 {
 143     QAbstractScrollArea::showEvent(event);
 144     updateGeometries();
 145 }
 146
 147 void KItemListContainer::resizeEvent(QResizeEvent *event)
 148 {
 149     QAbstractScrollArea::resizeEvent(event);
 150     updateGeometries();
 151 }
 152
 153 void KItemListContainer::scrollContentsBy(int dx, int dy)
 154 {
 155     m_horizontalSmoothScroller->scrollContentsBy(dx);
 156     m_verticalSmoothScroller->scrollContentsBy(dy);
 157 }
 158
 159 void KItemListContainer::wheelEvent(QWheelEvent *event)
 160 {
 161     if (event->modifiers().testFlag(Qt::ControlModifier)) {
 162         event->ignore();
 163         return;
 164     }
 165
 166     KItemListView *view = m_controller->view();
 167     if (!view) {
 168         event->ignore();
 169         return;
 170     }
 171
 172     const bool scrollHorizontally = (qAbs(event->angleDelta().y()) < qAbs(event->angleDelta().x())) || (!verticalScrollBar()->isVisible());
 173     KItemListSmoothScroller *smoothScroller = scrollHorizontally ? m_horizontalSmoothScroller : m_verticalSmoothScroller;
 174
 175     smoothScroller->handleWheelEvent(event);
 176 }
 177
 178 void KItemListContainer::slotScrollOrientationChanged(Qt::Orientation current, Qt::Orientation previous)
 179 {
 180     Q_UNUSED(previous)
 181     updateSmoothScrollers(current);
 182 }
 183
 184 void KItemListContainer::slotModelChanged(KItemModelBase *current, KItemModelBase *previous)
 185 {
 186     Q_UNUSED(current)
 187     Q_UNUSED(previous)
 188 }
 189
 190 void KItemListContainer::slotViewChanged(KItemListView *current, KItemListView *previous)
 191 {
 192     QGraphicsScene *scene = static_cast<QGraphicsView *>(viewport())->scene();
 193     if (previous) {
 194         scene->removeItem(previous);
 195         disconnect(previous, &KItemListView::scrollOrientationChanged, this, &KItemListContainer::slotScrollOrientationChanged);
 196         disconnect(previous, &KItemListView::scrollOffsetChanged, this, &KItemListContainer::updateScrollOffsetScrollBar);
 197         disconnect(previous, &KItemListView::maximumScrollOffsetChanged, this, &KItemListContainer::updateScrollOffsetScrollBar);
 198         disconnect(previous, &KItemListView::itemOffsetChanged, this, &KItemListContainer::updateItemOffsetScrollBar);
 199         disconnect(previous, &KItemListView::maximumItemOffsetChanged, this, &KItemListContainer::updateItemOffsetScrollBar);
 200         disconnect(previous, &KItemListView::scrollTo, this, &KItemListContainer::scrollTo);
 201         disconnect(m_horizontalSmoothScroller, &KItemListSmoothScroller::scrollingStopped, previous, &KItemListView::scrollingStopped);
 202         disconnect(m_verticalSmoothScroller, &KItemListSmoothScroller::scrollingStopped, previous, &KItemListView::scrollingStopped);
 203         m_horizontalSmoothScroller->setTargetObject(nullptr);
 204         m_verticalSmoothScroller->setTargetObject(nullptr);
 205     }
 206     if (current) {
 207         scene->addItem(current);
 208         connect(current, &KItemListView::scrollOrientationChanged, this, &KItemListContainer::slotScrollOrientationChanged);
 209         connect(current, &KItemListView::scrollOffsetChanged, this, &KItemListContainer::updateScrollOffsetScrollBar);
 210         connect(current, &KItemListView::maximumScrollOffsetChanged, this, &KItemListContainer::updateScrollOffsetScrollBar);
 211         connect(current, &KItemListView::itemOffsetChanged, this, &KItemListContainer::updateItemOffsetScrollBar);
 212         connect(current, &KItemListView::maximumItemOffsetChanged, this, &KItemListContainer::updateItemOffsetScrollBar);
 213         connect(current, &KItemListView::scrollTo, this, &KItemListContainer::scrollTo);
 214         connect(m_horizontalSmoothScroller, &KItemListSmoothScroller::scrollingStopped, current, &KItemListView::scrollingStopped);
 215         connect(m_verticalSmoothScroller, &KItemListSmoothScroller::scrollingStopped, current, &KItemListView::scrollingStopped);
 216
 217         m_horizontalSmoothScroller->setTargetObject(current);
 218         m_verticalSmoothScroller->setTargetObject(current);
 219         updateSmoothScrollers(current->scrollOrientation());
 220     }
 221 }
 222
 223 void KItemListContainer::scrollTo(qreal offset)
 224 {
 225     const KItemListView *view = m_controller->view();
 226     if (view) {
 227         if (view->scrollOrientation() == Qt::Vertical) {
 228             m_verticalSmoothScroller->scrollTo(offset);
 229         } else {
 230             m_horizontalSmoothScroller->scrollTo(offset);
 231         }
 232     }
 233 }
 234
 235 void KItemListContainer::updateScrollOffsetScrollBar()
 236 {
 237     const KItemListView *view = m_controller->view();
 238     if (!view) {
 239         return;
 240     }
 241
 242     KItemListSmoothScroller *smoothScroller = nullptr;
 243     QScrollBar *scrollOffsetScrollBar = nullptr;
 244     int singleStep = 0;
 245     int pageStep = 0;
 246     int maximum = 0;
 247     if (view->scrollOrientation() == Qt::Vertical) {
 248         smoothScroller = m_verticalSmoothScroller;
 249         scrollOffsetScrollBar = verticalScrollBar();
 250
 251         // Don't scroll super fast when using a wheel mouse:
 252         // We want to consider one "line" to be the text label which has a
 253         // roughly fixed height rather than using the height of the icon which
 254         // may be very tall
 255         const QFontMetrics metrics(font());
 256         singleStep = metrics.height() * QApplication::wheelScrollLines();
 257
 258         // We cannot use view->size().height() because this height might
 259         // include the header widget, which is not part of the scrolled area.
 260         pageStep = view->verticalPageStep();
 261
 262         // However, the total height of the view must be considered for the
 263         // maximum value of the scroll bar. Note that the view's scrollOffset()
 264         // refers to the offset of the top part of the view, which might be
 265         // hidden behind the header.
 266         maximum = qMax(0, int(view->maximumScrollOffset() - view->size().height()));
 267     } else {
 268         smoothScroller = m_horizontalSmoothScroller;
 269         scrollOffsetScrollBar = horizontalScrollBar();
 270         singleStep = view->itemSize().width();
 271         pageStep = view->size().width();
 272         maximum = qMax(0, int(view->maximumScrollOffset() - view->size().width()));
 273     }
 274
 275     const int value = view->scrollOffset();
 276     if (smoothScroller->requestScrollBarUpdate(maximum)) {
 277         const bool updatePolicy = (scrollOffsetScrollBar->maximum() > 0 && maximum == 0) || horizontalScrollBarPolicy() == Qt::ScrollBarAlwaysOn;
 278
 279         scrollOffsetScrollBar->setSingleStep(singleStep);
 280         scrollOffsetScrollBar->setPageStep(pageStep);
 281         scrollOffsetScrollBar->setMinimum(0);
 282         scrollOffsetScrollBar->setMaximum(maximum);
 283         scrollOffsetScrollBar->setValue(value);
 284
 285         if (updatePolicy) {
 286             // Prevent a potential endless layout loop (see bug #293318).
 287             updateScrollOffsetScrollBarPolicy();
 288         }
 289     }
 290 }
 291
 292 void KItemListContainer::updateItemOffsetScrollBar()
 293 {
 294     const KItemListView *view = m_controller->view();
 295     if (!view) {
 296         return;
 297     }
 298
 299     KItemListSmoothScroller *smoothScroller = nullptr;
 300     QScrollBar *itemOffsetScrollBar = nullptr;
 301     int singleStep = 0;
 302     int pageStep = 0;
 303     if (view->scrollOrientation() == Qt::Vertical) {
 304         smoothScroller = m_horizontalSmoothScroller;
 305         itemOffsetScrollBar = horizontalScrollBar();
 306         singleStep = view->size().width() / 10;
 307         pageStep = view->size().width();
 308     } else {
 309         smoothScroller = m_verticalSmoothScroller;
 310         itemOffsetScrollBar = verticalScrollBar();
 311         singleStep = view->size().height() / 10;
 312         pageStep = view->size().height();
 313     }
 314
 315     const int value = view->itemOffset();
 316     const int maximum = qMax(0, int(view->maximumItemOffset()) - pageStep);
 317     if (smoothScroller->requestScrollBarUpdate(maximum)) {
 318         itemOffsetScrollBar->setSingleStep(singleStep);
 319         itemOffsetScrollBar->setPageStep(pageStep);
 320         itemOffsetScrollBar->setMinimum(0);
 321         itemOffsetScrollBar->setMaximum(maximum);
 322         itemOffsetScrollBar->setValue(value);
 323     }
 324 }
 325
 326 void KItemListContainer::stopScroller()
 327 {
 328     m_scroller->stop();
 329 }
 330
 331 void KItemListContainer::updateGeometries()
 332 {
 333     QRect rect = geometry();
 334
 335     int extra = frameWidth() * 2;
 336     QStyleOption option;
 337     option.initFrom(this);
 338     int scrollbarSpacing = 0;
 339     if (style()->styleHint(QStyle::SH_ScrollView_FrameOnlyAroundContents, &option, this)) {
 340         scrollbarSpacing = style()->pixelMetric(QStyle::PM_ScrollView_ScrollBarSpacing, &option, this);
 341     }
 342
 343     const int widthDec = verticalScrollBar()->isVisible() ? extra + scrollbarSpacing + style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this) : extra;
 344
 345     const int heightDec =
 346         horizontalScrollBar()->isVisible() ? extra + scrollbarSpacing + style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this) : extra;
 347
 348     const QRectF newGeometry(0, 0, rect.width() - widthDec, rect.height() - heightDec);
 349     if (m_controller->view()->geometry() != newGeometry) {
 350         m_controller->view()->setGeometry(newGeometry);
 351
 352         // Get the real geometry of the view again since the scrollbars
 353         // visibilities and the view geometry may have changed in re-layout.
 354         static_cast<KItemListContainerViewport *>(viewport())->scene()->setSceneRect(m_controller->view()->geometry());
 355         static_cast<KItemListContainerViewport *>(viewport())->viewport()->setGeometry(m_controller->view()->geometry().toRect());
 356
 357         updateScrollOffsetScrollBar();
 358         updateItemOffsetScrollBar();
 359     }
 360 }
 361
 362 void KItemListContainer::updateSmoothScrollers(Qt::Orientation orientation)
 363 {
 364     if (orientation == Qt::Vertical) {
 365         m_verticalSmoothScroller->setPropertyName("scrollOffset");
 366         m_horizontalSmoothScroller->setPropertyName("itemOffset");
 367     } else {
 368         m_horizontalSmoothScroller->setPropertyName("scrollOffset");
 369         m_verticalSmoothScroller->setPropertyName("itemOffset");
 370     }
 371 }
 372
 373 void KItemListContainer::updateScrollOffsetScrollBarPolicy()
 374 {
 375     const KItemListView *view = m_controller->view();
 376     Q_ASSERT(view);
 377     const bool vertical = (view->scrollOrientation() == Qt::Vertical);
 378
 379     QStyleOption option;
 380     option.initFrom(this);
 381     const int scrollBarInc = style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this);
 382
 383     QSizeF newViewSize = m_controller->view()->size();
 384     if (vertical) {
 385         newViewSize.rwidth() += scrollBarInc;
 386     } else {
 387         newViewSize.rheight() += scrollBarInc;
 388     }
 389
 390     const Qt::ScrollBarPolicy policy = view->scrollBarRequired(newViewSize) ? Qt::ScrollBarAlwaysOn : Qt::ScrollBarAsNeeded;
 391     if (vertical) {
 392         setVerticalScrollBarPolicy(policy);
 393     } else {
 394         setHorizontalScrollBarPolicy(policy);
 395     }
 396 }
 397
 398 #include "kitemlistcontainer.moc"
 399 #include "moc_kitemlistcontainer.cpp"