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::focusInEvent(QFocusEvent *event)
 179 {
 180     KItemListView *view = m_controller->view();
 181     if (view) {
 182         QApplication::sendEvent(view, event);
 183     }
 184 }
 185
 186 void KItemListContainer::focusOutEvent(QFocusEvent *event)
 187 {
 188     KItemListView *view = m_controller->view();
 189     if (view) {
 190         QApplication::sendEvent(view, event);
 191     }
 192 }
 193
 194 void KItemListContainer::slotScrollOrientationChanged(Qt::Orientation current, Qt::Orientation previous)
 195 {
 196     Q_UNUSED(previous)
 197     updateSmoothScrollers(current);
 198 }
 199
 200 void KItemListContainer::slotModelChanged(KItemModelBase *current, KItemModelBase *previous)
 201 {
 202     Q_UNUSED(current)
 203     Q_UNUSED(previous)
 204 }
 205
 206 void KItemListContainer::slotViewChanged(KItemListView *current, KItemListView *previous)
 207 {
 208     QGraphicsScene *scene = static_cast<QGraphicsView *>(viewport())->scene();
 209     if (previous) {
 210         scene->removeItem(previous);
 211         disconnect(previous, &KItemListView::scrollOrientationChanged, this, &KItemListContainer::slotScrollOrientationChanged);
 212         disconnect(previous, &KItemListView::scrollOffsetChanged, this, &KItemListContainer::updateScrollOffsetScrollBar);
 213         disconnect(previous, &KItemListView::maximumScrollOffsetChanged, this, &KItemListContainer::updateScrollOffsetScrollBar);
 214         disconnect(previous, &KItemListView::itemOffsetChanged, this, &KItemListContainer::updateItemOffsetScrollBar);
 215         disconnect(previous, &KItemListView::maximumItemOffsetChanged, this, &KItemListContainer::updateItemOffsetScrollBar);
 216         disconnect(previous, &KItemListView::scrollTo, this, &KItemListContainer::scrollTo);
 217         disconnect(m_horizontalSmoothScroller, &KItemListSmoothScroller::scrollingStopped, previous, &KItemListView::scrollingStopped);
 218         disconnect(m_verticalSmoothScroller, &KItemListSmoothScroller::scrollingStopped, previous, &KItemListView::scrollingStopped);
 219         m_horizontalSmoothScroller->setTargetObject(nullptr);
 220         m_verticalSmoothScroller->setTargetObject(nullptr);
 221     }
 222     if (current) {
 223         scene->addItem(current);
 224         connect(current, &KItemListView::scrollOrientationChanged, this, &KItemListContainer::slotScrollOrientationChanged);
 225         connect(current, &KItemListView::scrollOffsetChanged, this, &KItemListContainer::updateScrollOffsetScrollBar);
 226         connect(current, &KItemListView::maximumScrollOffsetChanged, this, &KItemListContainer::updateScrollOffsetScrollBar);
 227         connect(current, &KItemListView::itemOffsetChanged, this, &KItemListContainer::updateItemOffsetScrollBar);
 228         connect(current, &KItemListView::maximumItemOffsetChanged, this, &KItemListContainer::updateItemOffsetScrollBar);
 229         connect(current, &KItemListView::scrollTo, this, &KItemListContainer::scrollTo);
 230         connect(m_horizontalSmoothScroller, &KItemListSmoothScroller::scrollingStopped, current, &KItemListView::scrollingStopped);
 231         connect(m_verticalSmoothScroller, &KItemListSmoothScroller::scrollingStopped, current, &KItemListView::scrollingStopped);
 232
 233         m_horizontalSmoothScroller->setTargetObject(current);
 234         m_verticalSmoothScroller->setTargetObject(current);
 235         updateSmoothScrollers(current->scrollOrientation());
 236     }
 237 }
 238
 239 void KItemListContainer::scrollTo(qreal offset)
 240 {
 241     const KItemListView *view = m_controller->view();
 242     if (view) {
 243         if (view->scrollOrientation() == Qt::Vertical) {
 244             m_verticalSmoothScroller->scrollTo(offset);
 245         } else {
 246             m_horizontalSmoothScroller->scrollTo(offset);
 247         }
 248     }
 249 }
 250
 251 void KItemListContainer::updateScrollOffsetScrollBar()
 252 {
 253     const KItemListView *view = m_controller->view();
 254     if (!view) {
 255         return;
 256     }
 257
 258     KItemListSmoothScroller *smoothScroller = nullptr;
 259     QScrollBar *scrollOffsetScrollBar = nullptr;
 260     int singleStep = 0;
 261     int pageStep = 0;
 262     int maximum = 0;
 263     if (view->scrollOrientation() == Qt::Vertical) {
 264         smoothScroller = m_verticalSmoothScroller;
 265         scrollOffsetScrollBar = verticalScrollBar();
 266
 267         // Don't scroll super fast when using a wheel mouse:
 268         // We want to consider one "line" to be the text label which has a
 269         // roughly fixed height rather than using the height of the icon which
 270         // may be very tall
 271         const QFontMetrics metrics(font());
 272         singleStep = metrics.height() * QApplication::wheelScrollLines();
 273
 274         // We cannot use view->size().height() because this height might
 275         // include the header widget, which is not part of the scrolled area.
 276         pageStep = view->verticalPageStep();
 277
 278         // However, the total height of the view must be considered for the
 279         // maximum value of the scroll bar. Note that the view's scrollOffset()
 280         // refers to the offset of the top part of the view, which might be
 281         // hidden behind the header.
 282         maximum = qMax(0, int(view->maximumScrollOffset() - view->size().height()));
 283     } else {
 284         smoothScroller = m_horizontalSmoothScroller;
 285         scrollOffsetScrollBar = horizontalScrollBar();
 286         singleStep = view->itemSize().width();
 287         pageStep = view->size().width();
 288         maximum = qMax(0, int(view->maximumScrollOffset() - view->size().width()));
 289     }
 290
 291     const int value = view->scrollOffset();
 292     if (smoothScroller->requestScrollBarUpdate(maximum)) {
 293         const bool updatePolicy = (scrollOffsetScrollBar->maximum() > 0 && maximum == 0) || 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() ? extra + scrollbarSpacing + style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this) : extra;
 360
 361     const int heightDec =
 362         horizontalScrollBar()->isVisible() ? extra + scrollbarSpacing + style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this) : extra;
 363
 364     const QRectF newGeometry(0, 0, rect.width() - widthDec, rect.height() - heightDec);
 365     if (m_controller->view()->geometry() != newGeometry) {
 366         m_controller->view()->setGeometry(newGeometry);
 367
 368         // Get the real geometry of the view again since the scrollbars
 369         // visibilities and the view geometry may have changed in re-layout.
 370         static_cast<KItemListContainerViewport *>(viewport())->scene()->setSceneRect(m_controller->view()->geometry());
 371         static_cast<KItemListContainerViewport *>(viewport())->viewport()->setGeometry(m_controller->view()->geometry().toRect());
 372
 373         updateScrollOffsetScrollBar();
 374         updateItemOffsetScrollBar();
 375     }
 376 }
 377
 378 void KItemListContainer::updateSmoothScrollers(Qt::Orientation orientation)
 379 {
 380     if (orientation == Qt::Vertical) {
 381         m_verticalSmoothScroller->setPropertyName("scrollOffset");
 382         m_horizontalSmoothScroller->setPropertyName("itemOffset");
 383     } else {
 384         m_horizontalSmoothScroller->setPropertyName("scrollOffset");
 385         m_verticalSmoothScroller->setPropertyName("itemOffset");
 386     }
 387 }
 388
 389 void KItemListContainer::updateScrollOffsetScrollBarPolicy()
 390 {
 391     const KItemListView *view = m_controller->view();
 392     Q_ASSERT(view);
 393     const bool vertical = (view->scrollOrientation() == Qt::Vertical);
 394
 395     QStyleOption option;
 396     option.initFrom(this);
 397     const int scrollBarInc = style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this);
 398
 399     QSizeF newViewSize = m_controller->view()->size();
 400     if (vertical) {
 401         newViewSize.rwidth() += scrollBarInc;
 402     } else {
 403         newViewSize.rheight() += scrollBarInc;
 404     }
 405
 406     const Qt::ScrollBarPolicy policy = view->scrollBarRequired(newViewSize) ? Qt::ScrollBarAlwaysOn : Qt::ScrollBarAsNeeded;
 407     if (vertical) {
 408         setVerticalScrollBarPolicy(policy);
 409     } else {
 410         setHorizontalScrollBarPolicy(policy);
 411     }
 412 }
 413
 414 #include "kitemlistcontainer.moc"
 415 #include "moc_kitemlistcontainer.cpp"