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 <QStyleOption>
  21
  22 /**
  23  * Replaces the default viewport of KItemListContainer by a
  24  * non-scrollable viewport. The scrolling is done in an optimized
  25  * way by KItemListView internally.
  26  */
  27 class KItemListContainerViewport : public QGraphicsView
  28 {
  29     Q_OBJECT
  30
  31 public:
  32     KItemListContainerViewport(QGraphicsScene* scene, QWidget* parent);
  33 protected:
  34     void wheelEvent(QWheelEvent* event) override;
  35 };
  36
  37 KItemListContainerViewport::KItemListContainerViewport(QGraphicsScene* scene, QWidget* parent) :
  38     QGraphicsView(scene, parent)
  39 {
  40     setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
  41     setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
  42     setViewportMargins(0, 0, 0, 0);
  43     setFrameShape(QFrame::NoFrame);
  44 }
  45
  46 void KItemListContainerViewport::wheelEvent(QWheelEvent* event)
  47 {
  48     // Assure that the wheel-event gets forwarded to the parent
  49     // and not handled at all by QGraphicsView.
  50     event->ignore();
  51 }
  52
  53 KItemListContainer::KItemListContainer(KItemListController* controller, QWidget* parent) :
  54     QAbstractScrollArea(parent),
  55     m_controller(controller),
  56     m_horizontalSmoothScroller(nullptr),
  57     m_verticalSmoothScroller(nullptr)
  58 {
  59     Q_ASSERT(controller);
  60     controller->setParent(this);
  61
  62     QGraphicsView* graphicsView = new KItemListContainerViewport(new QGraphicsScene(this), this);
  63     setViewport(graphicsView);
  64
  65     m_horizontalSmoothScroller = new KItemListSmoothScroller(horizontalScrollBar(), this);
  66     m_verticalSmoothScroller = new KItemListSmoothScroller(verticalScrollBar(), this);
  67
  68     if (controller->model()) {
  69         slotModelChanged(controller->model(), nullptr);
  70     }
  71     if (controller->view()) {
  72         slotViewChanged(controller->view(), nullptr);
  73     }
  74
  75     connect(controller, &KItemListController::modelChanged,
  76             this, &KItemListContainer::slotModelChanged);
  77     connect(controller, &KItemListController::viewChanged,
  78             this, &KItemListContainer::slotViewChanged);
  79 }
  80
  81 KItemListContainer::~KItemListContainer()
  82 {
  83     // Don't rely on the QObject-order to delete the controller, otherwise
  84     // the QGraphicsScene might get deleted before the view.
  85     delete m_controller;
  86     m_controller = nullptr;
  87 }
  88
  89 KItemListController* KItemListContainer::controller() const
  90 {
  91     return m_controller;
  92 }
  93
  94 void KItemListContainer::setEnabledFrame(bool enable)
  95 {
  96     QGraphicsView* graphicsView = qobject_cast<QGraphicsView*>(viewport());
  97     if (enable) {
  98         setFrameShape(QFrame::StyledPanel);
  99         graphicsView->setPalette(palette());
 100         graphicsView->viewport()->setAutoFillBackground(true);
 101     } else {
 102         setFrameShape(QFrame::NoFrame);
 103         // Make the background of the container transparent and apply the window-text color
 104         // to the text color, so that enough contrast is given for all color
 105         // schemes
 106         QPalette p = graphicsView->palette();
 107         p.setColor(QPalette::Active,   QPalette::Text, p.color(QPalette::Active,   QPalette::WindowText));
 108         p.setColor(QPalette::Inactive, QPalette::Text, p.color(QPalette::Inactive, QPalette::WindowText));
 109         p.setColor(QPalette::Disabled, QPalette::Text, p.color(QPalette::Disabled, QPalette::WindowText));
 110         graphicsView->setPalette(p);
 111         graphicsView->viewport()->setAutoFillBackground(false);
 112     }
 113 }
 114
 115 bool KItemListContainer::enabledFrame() const
 116 {
 117     const QGraphicsView* graphicsView = qobject_cast<QGraphicsView*>(viewport());
 118     return graphicsView->autoFillBackground();
 119 }
 120
 121 void KItemListContainer::keyPressEvent(QKeyEvent* event)
 122 {
 123     // TODO: We should find a better way to handle the key press events in the view.
 124     // The reasons why we need this hack are:
 125     // 1. Without reimplementing keyPressEvent() here, the event would not reach the QGraphicsView.
 126     // 2. By default, the KItemListView does not have the keyboard focus in the QGraphicsScene, so
 127     //    simply sending the event to the QGraphicsView which is the KItemListContainer's viewport
 128     //    does not work.
 129     KItemListView* view = m_controller->view();
 130     if (view) {
 131         QApplication::sendEvent(view, event);
 132     }
 133 }
 134
 135 void KItemListContainer::showEvent(QShowEvent* event)
 136 {
 137     QAbstractScrollArea::showEvent(event);
 138     updateGeometries();
 139 }
 140
 141 void KItemListContainer::resizeEvent(QResizeEvent* event)
 142 {
 143     QAbstractScrollArea::resizeEvent(event);
 144     updateGeometries();
 145 }
 146
 147 void KItemListContainer::scrollContentsBy(int dx, int dy)
 148 {
 149     m_horizontalSmoothScroller->scrollContentsBy(dx);
 150     m_verticalSmoothScroller->scrollContentsBy(dy);
 151 }
 152
 153 void KItemListContainer::wheelEvent(QWheelEvent* event)
 154 {
 155     if (event->modifiers().testFlag(Qt::ControlModifier)) {
 156         event->ignore();
 157         return;
 158     }
 159
 160     KItemListView* view = m_controller->view();
 161     if (!view) {
 162         event->ignore();
 163         return;
 164     }
 165
 166     const bool scrollHorizontally = (event->angleDelta().x() != 0) ||
 167                                     (event->angleDelta().y() != 0 && !verticalScrollBar()->isVisible());
 168     KItemListSmoothScroller* smoothScroller = scrollHorizontally ?
 169                                               m_horizontalSmoothScroller : m_verticalSmoothScroller;
 170
 171     smoothScroller->handleWheelEvent(event);
 172 }
 173
 174 void KItemListContainer::slotScrollOrientationChanged(Qt::Orientation current, Qt::Orientation previous)
 175 {
 176     Q_UNUSED(previous)
 177     updateSmoothScrollers(current);
 178 }
 179
 180 void KItemListContainer::slotModelChanged(KItemModelBase* current, KItemModelBase* previous)
 181 {
 182     Q_UNUSED(current)
 183     Q_UNUSED(previous)
 184 }
 185
 186 void KItemListContainer::slotViewChanged(KItemListView* current, KItemListView* previous)
 187 {
 188     QGraphicsScene* scene = static_cast<QGraphicsView*>(viewport())->scene();
 189     if (previous) {
 190         scene->removeItem(previous);
 191         disconnect(previous, &KItemListView::scrollOrientationChanged,
 192                    this, &KItemListContainer::slotScrollOrientationChanged);
 193         disconnect(previous, &KItemListView::scrollOffsetChanged,
 194                    this, &KItemListContainer::updateScrollOffsetScrollBar);
 195         disconnect(previous, &KItemListView::maximumScrollOffsetChanged,
 196                    this, &KItemListContainer::updateScrollOffsetScrollBar);
 197         disconnect(previous, &KItemListView::itemOffsetChanged,
 198                    this, &KItemListContainer::updateItemOffsetScrollBar);
 199         disconnect(previous, &KItemListView::maximumItemOffsetChanged,
 200                    this, &KItemListContainer::updateItemOffsetScrollBar);
 201         disconnect(previous, &KItemListView::scrollTo, this, &KItemListContainer::scrollTo);
 202         m_horizontalSmoothScroller->setTargetObject(nullptr);
 203         m_verticalSmoothScroller->setTargetObject(nullptr);
 204     }
 205     if (current) {
 206         scene->addItem(current);
 207         connect(current, &KItemListView::scrollOrientationChanged,
 208                 this, &KItemListContainer::slotScrollOrientationChanged);
 209         connect(current, &KItemListView::scrollOffsetChanged,
 210                 this, &KItemListContainer::updateScrollOffsetScrollBar);
 211         connect(current, &KItemListView::maximumScrollOffsetChanged,
 212                 this, &KItemListContainer::updateScrollOffsetScrollBar);
 213         connect(current, &KItemListView::itemOffsetChanged,
 214                 this, &KItemListContainer::updateItemOffsetScrollBar);
 215         connect(current, &KItemListView::maximumItemOffsetChanged,
 216                 this, &KItemListContainer::updateItemOffsetScrollBar);
 217         connect(current, &KItemListView::scrollTo, this, &KItemListContainer::scrollTo);
 218         m_horizontalSmoothScroller->setTargetObject(current);
 219         m_verticalSmoothScroller->setTargetObject(current);
 220         updateSmoothScrollers(current->scrollOrientation());
 221     }
 222 }
 223
 224 void KItemListContainer::scrollTo(qreal offset)
 225 {
 226     const KItemListView* view = m_controller->view();
 227     if (view) {
 228         if (view->scrollOrientation() == Qt::Vertical) {
 229             m_verticalSmoothScroller->scrollTo(offset);
 230         } else {
 231             m_horizontalSmoothScroller->scrollTo(offset);
 232         }
 233     }
 234 }
 235
 236 void KItemListContainer::updateScrollOffsetScrollBar()
 237 {
 238     const KItemListView* view = m_controller->view();
 239     if (!view) {
 240         return;
 241     }
 242
 243     KItemListSmoothScroller* smoothScroller = nullptr;
 244     QScrollBar* scrollOffsetScrollBar = nullptr;
 245     int singleStep = 0;
 246     int pageStep = 0;
 247     int maximum = 0;
 248     if (view->scrollOrientation() == Qt::Vertical) {
 249         smoothScroller = m_verticalSmoothScroller;
 250         scrollOffsetScrollBar = verticalScrollBar();
 251
 252         // Don't scroll super fast when using a wheel mouse:
 253         // We want to consider one "line" to be the text label which has a
 254         // roughly fixed height rather than using the height of the icon which
 255         // may be very tall
 256         const QFontMetrics metrics(font());
 257         singleStep = metrics.height() * QApplication::wheelScrollLines();
 258
 259         // We cannot use view->size().height() because this height might
 260         // include the header widget, which is not part of the scrolled area.
 261         pageStep = view->verticalPageStep();
 262
 263         // However, the total height of the view must be considered for the
 264         // maximum value of the scroll bar. Note that the view's scrollOffset()
 265         // refers to the offset of the top part of the view, which might be
 266         // hidden behind the header.
 267         maximum = qMax(0, int(view->maximumScrollOffset() - view->size().height()));
 268     } else {
 269         smoothScroller = m_horizontalSmoothScroller;
 270         scrollOffsetScrollBar = horizontalScrollBar();
 271         singleStep = view->itemSize().width();
 272         pageStep = view->size().width();
 273         maximum = qMax(0, int(view->maximumScrollOffset() - view->size().width()));
 274     }
 275
 276     const int value = view->scrollOffset();
 277     if (smoothScroller->requestScrollBarUpdate(maximum)) {
 278         const bool updatePolicy = (scrollOffsetScrollBar->maximum() > 0 && maximum == 0)
 279                                   || horizontalScrollBarPolicy() == Qt::ScrollBarAlwaysOn;
 280
 281         scrollOffsetScrollBar->setSingleStep(singleStep);
 282         scrollOffsetScrollBar->setPageStep(pageStep);
 283         scrollOffsetScrollBar->setMinimum(0);
 284         scrollOffsetScrollBar->setMaximum(maximum);
 285         scrollOffsetScrollBar->setValue(value);
 286
 287         if (updatePolicy) {
 288             // Prevent a potential endless layout loop (see bug #293318).
 289             updateScrollOffsetScrollBarPolicy();
 290         }
 291     }
 292 }
 293
 294 void KItemListContainer::updateItemOffsetScrollBar()
 295 {
 296     const KItemListView* view = m_controller->view();
 297     if (!view) {
 298         return;
 299     }
 300
 301     KItemListSmoothScroller* smoothScroller = nullptr;
 302     QScrollBar* itemOffsetScrollBar = nullptr;
 303     int singleStep = 0;
 304     int pageStep = 0;
 305     if (view->scrollOrientation() == Qt::Vertical) {
 306         smoothScroller = m_horizontalSmoothScroller;
 307         itemOffsetScrollBar = horizontalScrollBar();
 308         singleStep = view->size().width() / 10;
 309         pageStep = view->size().width();
 310     } else {
 311         smoothScroller = m_verticalSmoothScroller;
 312         itemOffsetScrollBar = verticalScrollBar();
 313         singleStep = view->size().height() / 10;
 314         pageStep = view->size().height();
 315     }
 316
 317     const int value = view->itemOffset();
 318     const int maximum = qMax(0, int(view->maximumItemOffset()) - pageStep);
 319     if (smoothScroller->requestScrollBarUpdate(maximum)) {
 320         itemOffsetScrollBar->setSingleStep(singleStep);
 321         itemOffsetScrollBar->setPageStep(pageStep);
 322         itemOffsetScrollBar->setMinimum(0);
 323         itemOffsetScrollBar->setMaximum(maximum);
 324         itemOffsetScrollBar->setValue(value);
 325     }
 326 }
 327
 328 void KItemListContainer::updateGeometries()
 329 {
 330     QRect rect = geometry();
 331
 332     int extra = frameWidth() * 2;
 333     QStyleOption option;
 334     option.initFrom(this);
 335     int scrollbarSpacing = 0;
 336     if (style()->styleHint(QStyle::SH_ScrollView_FrameOnlyAroundContents, &option, this)) {
 337         scrollbarSpacing = style()->pixelMetric(QStyle::PM_ScrollView_ScrollBarSpacing, &option, this);
 338     }
 339
 340     const int widthDec = verticalScrollBar()->isVisible()
 341                          ? extra + scrollbarSpacing + style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this)
 342                          : extra;
 343
 344     const int heightDec = horizontalScrollBar()->isVisible()
 345                           ? extra + scrollbarSpacing + style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this)
 346                           : extra;
 347
 348     const QRectF newGeometry(0, 0, rect.width() - widthDec,
 349                              rect.height() - heightDec);
 350     if (m_controller->view()->geometry() != newGeometry) {
 351         m_controller->view()->setGeometry(newGeometry);
 352
 353         // Get the real geometry of the view again since the scrollbars
 354         // visibilities and the view geometry may have changed in re-layout.
 355         static_cast<KItemListContainerViewport*>(viewport())->scene()->setSceneRect(m_controller->view()->geometry());
 356         static_cast<KItemListContainerViewport*>(viewport())->viewport()->setGeometry(m_controller->view()->geometry().toRect());
 357
 358         updateScrollOffsetScrollBar();
 359         updateItemOffsetScrollBar();
 360     }
 361 }
 362
 363 void KItemListContainer::updateSmoothScrollers(Qt::Orientation orientation)
 364 {
 365     if (orientation == Qt::Vertical) {
 366         m_verticalSmoothScroller->setPropertyName("scrollOffset");
 367         m_horizontalSmoothScroller->setPropertyName("itemOffset");
 368     } else {
 369         m_horizontalSmoothScroller->setPropertyName("scrollOffset");
 370         m_verticalSmoothScroller->setPropertyName("itemOffset");
 371     }
 372 }
 373
 374 void KItemListContainer::updateScrollOffsetScrollBarPolicy()
 375 {
 376     const KItemListView* view = m_controller->view();
 377     Q_ASSERT(view);
 378     const bool vertical = (view->scrollOrientation() == Qt::Vertical);
 379
 380     QStyleOption option;
 381     option.initFrom(this);
 382     const int scrollBarInc = style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this);
 383
 384     QSizeF newViewSize = m_controller->view()->size();
 385     if (vertical) {
 386         newViewSize.rwidth() += scrollBarInc;
 387     } else {
 388         newViewSize.rheight() += scrollBarInc;
 389     }
 390
 391     const Qt::ScrollBarPolicy policy = view->scrollBarRequired(newViewSize)
 392                                        ? Qt::ScrollBarAlwaysOn : Qt::ScrollBarAsNeeded;
 393     if (vertical) {
 394         setVerticalScrollBarPolicy(policy);
 395     } else {
 396         setHorizontalScrollBarPolicy(policy);
 397     }
 398 }
 399
 400 #include "kitemlistcontainer.moc"