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 protected:
  35     void wheelEvent(QWheelEvent* event) override;
  36 };
  37
  38 KItemListContainerViewport::KItemListContainerViewport(QGraphicsScene* scene, QWidget* parent) :
  39     QGraphicsView(scene, parent)
  40 {
  41     setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
  42     setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
  43     setViewportMargins(0, 0, 0, 0);
  44     setFrameShape(QFrame::NoFrame);
  45 }
  46
  47 void KItemListContainerViewport::wheelEvent(QWheelEvent* event)
  48 {
  49     // Assure that the wheel-event gets forwarded to the parent
  50     // and not handled at all by QGraphicsView.
  51     event->ignore();
  52 }
  53
  54 KItemListContainer::KItemListContainer(KItemListController* controller, QWidget* parent) :
  55     QAbstractScrollArea(parent),
  56     m_controller(controller),
  57     m_horizontalSmoothScroller(nullptr),
  58     m_verticalSmoothScroller(nullptr),
  59     m_scroller(nullptr)
  60 {
  61     Q_ASSERT(controller);
  62     controller->setParent(this);
  63
  64     QGraphicsView* graphicsView = new KItemListContainerViewport(new QGraphicsScene(this), this);
  65     setViewport(graphicsView);
  66
  67     m_horizontalSmoothScroller = new KItemListSmoothScroller(horizontalScrollBar(), this);
  68     m_verticalSmoothScroller = new KItemListSmoothScroller(verticalScrollBar(), this);
  69
  70     if (controller->model()) {
  71         slotModelChanged(controller->model(), nullptr);
  72     }
  73     if (controller->view()) {
  74         slotViewChanged(controller->view(), nullptr);
  75     }
  76
  77     connect(controller, &KItemListController::modelChanged,
  78             this, &KItemListContainer::slotModelChanged);
  79     connect(controller, &KItemListController::viewChanged,
  80             this, &KItemListContainer::slotViewChanged);
  81
  82     m_scroller = QScroller::scroller(viewport());
  83     m_scroller->grabGesture(viewport());
  84     connect(controller, &KItemListController::scrollerStop,
  85             this, &KItemListContainer::stopScroller);
  86     connect(m_scroller, &QScroller::stateChanged,
  87             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::showEvent(QShowEvent* event)
 145 {
 146     QAbstractScrollArea::showEvent(event);
 147     updateGeometries();
 148 }
 149
 150 void KItemListContainer::resizeEvent(QResizeEvent* event)
 151 {
 152     QAbstractScrollArea::resizeEvent(event);
 153     updateGeometries();
 154 }
 155
 156 void KItemListContainer::scrollContentsBy(int dx, int dy)
 157 {
 158     m_horizontalSmoothScroller->scrollContentsBy(dx);
 159     m_verticalSmoothScroller->scrollContentsBy(dy);
 160 }
 161
 162 void KItemListContainer::wheelEvent(QWheelEvent* event)
 163 {
 164     if (event->modifiers().testFlag(Qt::ControlModifier)) {
 165         event->ignore();
 166         return;
 167     }
 168
 169     KItemListView* view = m_controller->view();
 170     if (!view) {
 171         event->ignore();
 172         return;
 173     }
 174
 175     const bool scrollHorizontally = (event->angleDelta().x() != 0) ||
 176                                     (event->angleDelta().y() != 0 && !verticalScrollBar()->isVisible());
 177     KItemListSmoothScroller* smoothScroller = scrollHorizontally ?
 178                                               m_horizontalSmoothScroller : m_verticalSmoothScroller;
 179
 180     smoothScroller->handleWheelEvent(event);
 181 }
 182
 183 void KItemListContainer::slotScrollOrientationChanged(Qt::Orientation current, Qt::Orientation previous)
 184 {
 185     Q_UNUSED(previous)
 186     updateSmoothScrollers(current);
 187 }
 188
 189 void KItemListContainer::slotModelChanged(KItemModelBase* current, KItemModelBase* previous)
 190 {
 191     Q_UNUSED(current)
 192     Q_UNUSED(previous)
 193 }
 194
 195 void KItemListContainer::slotViewChanged(KItemListView* current, KItemListView* previous)
 196 {
 197     QGraphicsScene* scene = static_cast<QGraphicsView*>(viewport())->scene();
 198     if (previous) {
 199         scene->removeItem(previous);
 200         disconnect(previous, &KItemListView::scrollOrientationChanged,
 201                    this, &KItemListContainer::slotScrollOrientationChanged);
 202         disconnect(previous, &KItemListView::scrollOffsetChanged,
 203                    this, &KItemListContainer::updateScrollOffsetScrollBar);
 204         disconnect(previous, &KItemListView::maximumScrollOffsetChanged,
 205                    this, &KItemListContainer::updateScrollOffsetScrollBar);
 206         disconnect(previous, &KItemListView::itemOffsetChanged,
 207                    this, &KItemListContainer::updateItemOffsetScrollBar);
 208         disconnect(previous, &KItemListView::maximumItemOffsetChanged,
 209                    this, &KItemListContainer::updateItemOffsetScrollBar);
 210         disconnect(previous, &KItemListView::scrollTo, this, &KItemListContainer::scrollTo);
 211         m_horizontalSmoothScroller->setTargetObject(nullptr);
 212         m_verticalSmoothScroller->setTargetObject(nullptr);
 213     }
 214     if (current) {
 215         scene->addItem(current);
 216         connect(current, &KItemListView::scrollOrientationChanged,
 217                 this, &KItemListContainer::slotScrollOrientationChanged);
 218         connect(current, &KItemListView::scrollOffsetChanged,
 219                 this, &KItemListContainer::updateScrollOffsetScrollBar);
 220         connect(current, &KItemListView::maximumScrollOffsetChanged,
 221                 this, &KItemListContainer::updateScrollOffsetScrollBar);
 222         connect(current, &KItemListView::itemOffsetChanged,
 223                 this, &KItemListContainer::updateItemOffsetScrollBar);
 224         connect(current, &KItemListView::maximumItemOffsetChanged,
 225                 this, &KItemListContainer::updateItemOffsetScrollBar);
 226         connect(current, &KItemListView::scrollTo, this, &KItemListContainer::scrollTo);
 227         m_horizontalSmoothScroller->setTargetObject(current);
 228         m_verticalSmoothScroller->setTargetObject(current);
 229         updateSmoothScrollers(current->scrollOrientation());
 230     }
 231 }
 232
 233 void KItemListContainer::scrollTo(qreal offset)
 234 {
 235     const KItemListView* view = m_controller->view();
 236     if (view) {
 237         if (view->scrollOrientation() == Qt::Vertical) {
 238             m_verticalSmoothScroller->scrollTo(offset);
 239         } else {
 240             m_horizontalSmoothScroller->scrollTo(offset);
 241         }
 242     }
 243 }
 244
 245 void KItemListContainer::updateScrollOffsetScrollBar()
 246 {
 247     const KItemListView* view = m_controller->view();
 248     if (!view) {
 249         return;
 250     }
 251
 252     KItemListSmoothScroller* smoothScroller = nullptr;
 253     QScrollBar* scrollOffsetScrollBar = nullptr;
 254     int singleStep = 0;
 255     int pageStep = 0;
 256     int maximum = 0;
 257     if (view->scrollOrientation() == Qt::Vertical) {
 258         smoothScroller = m_verticalSmoothScroller;
 259         scrollOffsetScrollBar = verticalScrollBar();
 260
 261         // Don't scroll super fast when using a wheel mouse:
 262         // We want to consider one "line" to be the text label which has a
 263         // roughly fixed height rather than using the height of the icon which
 264         // may be very tall
 265         const QFontMetrics metrics(font());
 266         singleStep = metrics.height() * QApplication::wheelScrollLines();
 267
 268         // We cannot use view->size().height() because this height might
 269         // include the header widget, which is not part of the scrolled area.
 270         pageStep = view->verticalPageStep();
 271
 272         // However, the total height of the view must be considered for the
 273         // maximum value of the scroll bar. Note that the view's scrollOffset()
 274         // refers to the offset of the top part of the view, which might be
 275         // hidden behind the header.
 276         maximum = qMax(0, int(view->maximumScrollOffset() - view->size().height()));
 277     } else {
 278         smoothScroller = m_horizontalSmoothScroller;
 279         scrollOffsetScrollBar = horizontalScrollBar();
 280         singleStep = view->itemSize().width();
 281         pageStep = view->size().width();
 282         maximum = qMax(0, int(view->maximumScrollOffset() - view->size().width()));
 283     }
 284
 285     const int value = view->scrollOffset();
 286     if (smoothScroller->requestScrollBarUpdate(maximum)) {
 287         const bool updatePolicy = (scrollOffsetScrollBar->maximum() > 0 && maximum == 0)
 288                                   || horizontalScrollBarPolicy() == Qt::ScrollBarAlwaysOn;
 289
 290         scrollOffsetScrollBar->setSingleStep(singleStep);
 291         scrollOffsetScrollBar->setPageStep(pageStep);
 292         scrollOffsetScrollBar->setMinimum(0);
 293         scrollOffsetScrollBar->setMaximum(maximum);
 294         scrollOffsetScrollBar->setValue(value);
 295
 296         if (updatePolicy) {
 297             // Prevent a potential endless layout loop (see bug #293318).
 298             updateScrollOffsetScrollBarPolicy();
 299         }
 300     }
 301 }
 302
 303 void KItemListContainer::updateItemOffsetScrollBar()
 304 {
 305     const KItemListView* view = m_controller->view();
 306     if (!view) {
 307         return;
 308     }
 309
 310     KItemListSmoothScroller* smoothScroller = nullptr;
 311     QScrollBar* itemOffsetScrollBar = nullptr;
 312     int singleStep = 0;
 313     int pageStep = 0;
 314     if (view->scrollOrientation() == Qt::Vertical) {
 315         smoothScroller = m_horizontalSmoothScroller;
 316         itemOffsetScrollBar = horizontalScrollBar();
 317         singleStep = view->size().width() / 10;
 318         pageStep = view->size().width();
 319     } else {
 320         smoothScroller = m_verticalSmoothScroller;
 321         itemOffsetScrollBar = verticalScrollBar();
 322         singleStep = view->size().height() / 10;
 323         pageStep = view->size().height();
 324     }
 325
 326     const int value = view->itemOffset();
 327     const int maximum = qMax(0, int(view->maximumItemOffset()) - pageStep);
 328     if (smoothScroller->requestScrollBarUpdate(maximum)) {
 329         itemOffsetScrollBar->setSingleStep(singleStep);
 330         itemOffsetScrollBar->setPageStep(pageStep);
 331         itemOffsetScrollBar->setMinimum(0);
 332         itemOffsetScrollBar->setMaximum(maximum);
 333         itemOffsetScrollBar->setValue(value);
 334     }
 335 }
 336
 337 void KItemListContainer::stopScroller()
 338 {
 339     m_scroller->stop();
 340 }
 341
 342 void KItemListContainer::updateGeometries()
 343 {
 344     QRect rect = geometry();
 345
 346     int extra = frameWidth() * 2;
 347     QStyleOption option;
 348     option.initFrom(this);
 349     int scrollbarSpacing = 0;
 350     if (style()->styleHint(QStyle::SH_ScrollView_FrameOnlyAroundContents, &option, this)) {
 351         scrollbarSpacing = style()->pixelMetric(QStyle::PM_ScrollView_ScrollBarSpacing, &option, this);
 352     }
 353
 354     const int widthDec = verticalScrollBar()->isVisible()
 355                          ? extra + scrollbarSpacing + style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this)
 356                          : extra;
 357
 358     const int heightDec = horizontalScrollBar()->isVisible()
 359                           ? extra + scrollbarSpacing + style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this)
 360                           : extra;
 361
 362     const QRectF newGeometry(0, 0, rect.width() - widthDec,
 363                              rect.height() - heightDec);
 364     if (m_controller->view()->geometry() != newGeometry) {
 365         m_controller->view()->setGeometry(newGeometry);
 366
 367         // Get the real geometry of the view again since the scrollbars
 368         // visibilities and the view geometry may have changed in re-layout.
 369         static_cast<KItemListContainerViewport*>(viewport())->scene()->setSceneRect(m_controller->view()->geometry());
 370         static_cast<KItemListContainerViewport*>(viewport())->viewport()->setGeometry(m_controller->view()->geometry().toRect());
 371
 372         updateScrollOffsetScrollBar();
 373         updateItemOffsetScrollBar();
 374     }
 375 }
 376
 377 void KItemListContainer::updateSmoothScrollers(Qt::Orientation orientation)
 378 {
 379     if (orientation == Qt::Vertical) {
 380         m_verticalSmoothScroller->setPropertyName("scrollOffset");
 381         m_horizontalSmoothScroller->setPropertyName("itemOffset");
 382     } else {
 383         m_horizontalSmoothScroller->setPropertyName("scrollOffset");
 384         m_verticalSmoothScroller->setPropertyName("itemOffset");
 385     }
 386 }
 387
 388 void KItemListContainer::updateScrollOffsetScrollBarPolicy()
 389 {
 390     const KItemListView* view = m_controller->view();
 391     Q_ASSERT(view);
 392     const bool vertical = (view->scrollOrientation() == Qt::Vertical);
 393
 394     QStyleOption option;
 395     option.initFrom(this);
 396     const int scrollBarInc = style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this);
 397
 398     QSizeF newViewSize = m_controller->view()->size();
 399     if (vertical) {
 400         newViewSize.rwidth() += scrollBarInc;
 401     } else {
 402         newViewSize.rheight() += scrollBarInc;
 403     }
 404
 405     const Qt::ScrollBarPolicy policy = view->scrollBarRequired(newViewSize)
 406                                        ? Qt::ScrollBarAlwaysOn : Qt::ScrollBarAsNeeded;
 407     if (vertical) {
 408         setVerticalScrollBarPolicy(policy);
 409     } else {
 410         setHorizontalScrollBarPolicy(policy);
 411     }
 412 }
 413
 414 #include "kitemlistcontainer.moc"