File indexing completed on 2024-04-21 11:33:54

 /*
  *  SPDX-FileCopyrightText: 2019 Marco Martin <mart@kde.org>
  *
  *  SPDX-License-Identifier: LGPL-2.0-or-later
  */
 
 #include "wheelhandler.h"
 #include "settings.h"
 #include <QQmlInfo>
 #include <QQuickItem>
 #include <QQuickWindow>
 #include <QWheelEvent>
 
 #include <cmath>
 
 KirigamiWheelEvent::KirigamiWheelEvent(QObject *parent)
     : QObject(parent)
 {
 }
 
 KirigamiWheelEvent::~KirigamiWheelEvent()
 {
 }
 
 void KirigamiWheelEvent::initializeFromEvent(QWheelEvent *event)
 {
     m_x = event->position().x();
     m_y = event->position().y();
     m_angleDelta = event->angleDelta();
     m_pixelDelta = event->pixelDelta();
     m_buttons = event->buttons();
     m_modifiers = event->modifiers();
     m_accepted = false;
     m_inverted = event->inverted();
 }
 
 qreal KirigamiWheelEvent::x() const
 {
     return m_x;
 }
 
 qreal KirigamiWheelEvent::y() const
 {
     return m_y;
 }
 
 QPointF KirigamiWheelEvent::angleDelta() const
 {
     return m_angleDelta;
 }
 
 QPointF KirigamiWheelEvent::pixelDelta() const
 {
     return m_pixelDelta;
 }
 
 int KirigamiWheelEvent::buttons() const
 {
     return m_buttons;
 }
 
 int KirigamiWheelEvent::modifiers() const
 {
     return m_modifiers;
 }
 
 bool KirigamiWheelEvent::inverted() const
 {
     return m_inverted;
 }
 
 bool KirigamiWheelEvent::isAccepted()
 {
     return m_accepted;
 }
 
 void KirigamiWheelEvent::setAccepted(bool accepted)
 {
     m_accepted = accepted;
 }
 
 ///////////////////////////////
 
 WheelFilterItem::WheelFilterItem(QQuickItem *parent)
     : QQuickItem(parent)
 {
     setEnabled(false);
 }
 
 ///////////////////////////////
 
 WheelHandler::WheelHandler(QObject *parent)
     : QObject(parent)
     , m_filterItem(new WheelFilterItem(nullptr))
 {
     m_filterItem->installEventFilter(this);
 
     m_wheelScrollingTimer.setSingleShot(true);
     m_wheelScrollingTimer.setInterval(m_wheelScrollingDuration);
     m_wheelScrollingTimer.callOnTimeout([this]() {
         setScrolling(false);
     });
 
     connect(QGuiApplication::styleHints(), &QStyleHints::wheelScrollLinesChanged, this, [this](int scrollLines) {
         m_defaultPixelStepSize = 20 * scrollLines;
         if (!m_explicitVStepSize && m_verticalStepSize != m_defaultPixelStepSize) {
             m_verticalStepSize = m_defaultPixelStepSize;
             Q_EMIT verticalStepSizeChanged();
         }
         if (!m_explicitHStepSize && m_horizontalStepSize != m_defaultPixelStepSize) {
             m_horizontalStepSize = m_defaultPixelStepSize;
             Q_EMIT horizontalStepSizeChanged();
         }
     });
 }
 
 WheelHandler::~WheelHandler()
 {
     delete m_filterItem;
 }
 
 QQuickItem *WheelHandler::target() const
 {
     return m_flickable;
 }
 
 void WheelHandler::setTarget(QQuickItem *target)
 {
     if (m_flickable == target) {
         return;
     }
 
     if (target && !target->inherits("QQuickFlickable")) {
         qmlWarning(this) << "target must be a QQuickFlickable";
         return;
     }
 
     if (m_flickable) {
         m_flickable->removeEventFilter(this);
         disconnect(m_flickable, nullptr, m_filterItem, nullptr);
         disconnect(m_flickable, &QQuickItem::parentChanged, this, &WheelHandler::_k_rebindScrollBars);
     }
 
     m_flickable = target;
     m_filterItem->setParentItem(target);
 
     if (target) {
         target->installEventFilter(this);
 
         // Stack WheelFilterItem over the Flickable's scrollable content
         m_filterItem->stackAfter(target->property("contentItem").value<QQuickItem*>());
         // Make it fill the Flickable
         m_filterItem->setWidth(target->width());
         m_filterItem->setHeight(target->height());
         connect(target, &QQuickItem::widthChanged, m_filterItem, [this, target]() {
             m_filterItem->setWidth(target->width());
         });
         connect(target, &QQuickItem::heightChanged, m_filterItem, [this, target]() {
             m_filterItem->setHeight(target->height());
         });
     }
 
     _k_rebindScrollBars();
 
     Q_EMIT targetChanged();
 }
 
 void WheelHandler::_k_rebindScrollBars()
 {
     struct ScrollBarAttached {
         QObject *attached = nullptr;
         QQuickItem *vertical = nullptr;
         QQuickItem *horizontal = nullptr;
     };
 
     ScrollBarAttached attachedToFlickable;
     ScrollBarAttached attachedToScrollView;
 
     if (m_flickable) {
         // Get ScrollBars so that we can filter them too, even if they're not
         // in the bounds of the Flickable
         const auto flickableChildren = m_flickable->children();
         for (const auto child : flickableChildren) {
             if (child->inherits("QQuickScrollBarAttached")) {
                 attachedToFlickable.attached = child;
                 attachedToFlickable.vertical = child->property("vertical").value<QQuickItem *>();
                 attachedToFlickable.horizontal = child->property("horizontal").value<QQuickItem *>();
                 break;
             }
         }
 
         // Check ScrollView if there are no scrollbars attached to the Flickable.
         // We need to check if the parent inherits QQuickScrollView in case the
         // parent is another Flickable that already has a Kirigami WheelHandler.
         auto flickableParent = m_flickable->parentItem();
         if (flickableParent && flickableParent->inherits("QQuickScrollView")) {
             const auto siblings = flickableParent->children();
             for (const auto child : siblings) {
                 if (child->inherits("QQuickScrollBarAttached")) {
                     attachedToScrollView.attached = child;
                     attachedToScrollView.vertical = child->property("vertical").value<QQuickItem *>();
                     attachedToScrollView.horizontal = child->property("horizontal").value<QQuickItem *>();
                     break;
                 }
             }
         }
     }
 
     // Dilemma: ScrollBars can be attached to both ScrollView and Flickable,
     // but only one of them should be shown anyway. Let's prefer Flickable.
 
     struct ChosenScrollBar {
         QObject *attached = nullptr;
         QQuickItem *scrollBar = nullptr;
     };
 
     ChosenScrollBar vertical;
     if (attachedToFlickable.vertical) {
         vertical.attached = attachedToFlickable.attached;
         vertical.scrollBar = attachedToFlickable.vertical;
     } else if (attachedToScrollView.vertical) {
         vertical.attached = attachedToScrollView.attached;
         vertical.scrollBar = attachedToScrollView.vertical;
     }
 
     ChosenScrollBar horizontal;
     if (attachedToFlickable.horizontal) {
         horizontal.attached = attachedToFlickable.attached;
         horizontal.scrollBar = attachedToFlickable.horizontal;
     } else if (attachedToScrollView.horizontal) {
         horizontal.attached = attachedToScrollView.attached;
         horizontal.scrollBar = attachedToScrollView.horizontal;
     }
 
     // Flickable may get re-parented to or out of a ScrollView, so we need to
     // redo the discovery process. This is especially important for
     // Kirigami.ScrollablePage component.
     if (m_flickable) {
         if (attachedToFlickable.horizontal && attachedToFlickable.vertical) {
             // But if both scrollbars are already those from the preferred
             // Flickable, there's no need for rediscovery.
             disconnect(m_flickable, &QQuickItem::parentChanged, this, &WheelHandler::_k_rebindScrollBars);
         } else {
             connect(m_flickable, &QQuickItem::parentChanged, this, &WheelHandler::_k_rebindScrollBars, Qt::UniqueConnection);
         }
     }
 
     if (m_verticalScrollBar != vertical.scrollBar) {
         if (m_verticalScrollBar) {
             m_verticalScrollBar->removeEventFilter(this);
             disconnect(m_verticalChangedConnection);
         }
         m_verticalScrollBar = vertical.scrollBar;
         if (vertical.scrollBar) {
             vertical.scrollBar->installEventFilter(this);
             m_verticalChangedConnection = connect(vertical.attached, SIGNAL(verticalChanged()), this, SLOT(_k_rebindScrollBars()));
         }
     }
 
     if (m_horizontalScrollBar != horizontal.scrollBar) {
         if (m_horizontalScrollBar) {
             m_horizontalScrollBar->removeEventFilter(this);
             disconnect(m_horizontalChangedConnection);
         }
         m_horizontalScrollBar = horizontal.scrollBar;
         if (horizontal.scrollBar) {
             horizontal.scrollBar->installEventFilter(this);
             m_horizontalChangedConnection = connect(horizontal.attached, SIGNAL(horizontalChanged()), this, SLOT(_k_rebindScrollBars()));
         }
     }
 }
 
 qreal WheelHandler::verticalStepSize() const
 {
     return m_verticalStepSize;
 }
 
 void WheelHandler::setVerticalStepSize(qreal stepSize)
 {
     m_explicitVStepSize = true;
     if (qFuzzyCompare(m_verticalStepSize, stepSize)) {
         return;
     }
     // Mimic the behavior of QQuickScrollBar when stepSize is 0
     if (qFuzzyIsNull(stepSize)) {
         resetVerticalStepSize();
         return;
     }
     m_verticalStepSize = stepSize;
     Q_EMIT verticalStepSizeChanged();
 }
 
 void WheelHandler::resetVerticalStepSize()
 {
     m_explicitVStepSize = false;
     if (qFuzzyCompare(m_verticalStepSize, m_defaultPixelStepSize)) {
         return;
     }
     m_verticalStepSize = m_defaultPixelStepSize;
     Q_EMIT verticalStepSizeChanged();
 }
 
 qreal WheelHandler::horizontalStepSize() const
 {
     return m_horizontalStepSize;
 }
 
 void WheelHandler::setHorizontalStepSize(qreal stepSize)
 {
     m_explicitHStepSize = true;
     if (qFuzzyCompare(m_horizontalStepSize, stepSize)) {
         return;
     }
     // Mimic the behavior of QQuickScrollBar when stepSize is 0
     if (qFuzzyIsNull(stepSize)) {
         resetHorizontalStepSize();
         return;
     }
     m_horizontalStepSize = stepSize;
     Q_EMIT horizontalStepSizeChanged();
 }
 
 void WheelHandler::resetHorizontalStepSize()
 {
     m_explicitHStepSize = false;
     if (qFuzzyCompare(m_horizontalStepSize, m_defaultPixelStepSize)) {
         return;
     }
     m_horizontalStepSize = m_defaultPixelStepSize;
     Q_EMIT horizontalStepSizeChanged();
 }
 
 Qt::KeyboardModifiers WheelHandler::pageScrollModifiers() const
 {
     return m_pageScrollModifiers;
 }
 
 void WheelHandler::setPageScrollModifiers(Qt::KeyboardModifiers modifiers)
 {
     if (m_pageScrollModifiers == modifiers) {
         return;
     }
     m_pageScrollModifiers = modifiers;
     Q_EMIT pageScrollModifiersChanged();
 }
 
 void WheelHandler::resetPageScrollModifiers()
 {
     setPageScrollModifiers(m_defaultPageScrollModifiers);
 }
 
 bool WheelHandler::filterMouseEvents() const
 {
     return m_filterMouseEvents;
 }
 
 void WheelHandler::setFilterMouseEvents(bool enabled)
 {
     if (m_filterMouseEvents == enabled) {
         return;
     }
     m_filterMouseEvents = enabled;
     Q_EMIT filterMouseEventsChanged();
 }
 
 bool WheelHandler::keyNavigationEnabled() const
 {
     return m_keyNavigationEnabled;
 }
 
 void WheelHandler::setKeyNavigationEnabled(bool enabled)
 {
     if (m_keyNavigationEnabled == enabled) {
         return;
     }
     m_keyNavigationEnabled = enabled;
     Q_EMIT keyNavigationEnabledChanged();
 }
 
 void WheelHandler::setScrolling(bool scrolling)
 {
     if (m_wheelScrolling == scrolling) {
         if (m_wheelScrolling) {
             m_wheelScrollingTimer.start();
         }
         return;
     }
     m_wheelScrolling = scrolling;
     m_filterItem->setEnabled(m_wheelScrolling);
 }
 
 bool WheelHandler::scrollFlickable(QPointF pixelDelta, QPointF angleDelta, Qt::KeyboardModifiers modifiers)
 {
     if (!m_flickable || (pixelDelta.isNull() && angleDelta.isNull())) {
         return false;
     }
 
     const qreal width = m_flickable->width();
     const qreal height = m_flickable->height();
     const qreal contentWidth = m_flickable->property("contentWidth").toReal();
     const qreal contentHeight = m_flickable->property("contentHeight").toReal();
     const qreal contentX = m_flickable->property("contentX").toReal();
     const qreal contentY = m_flickable->property("contentY").toReal();
     const qreal topMargin = m_flickable->property("topMargin").toReal();
     const qreal bottomMargin = m_flickable->property("bottomMargin").toReal();
     const qreal leftMargin = m_flickable->property("leftMargin").toReal();
     const qreal rightMargin = m_flickable->property("rightMargin").toReal();
     const qreal originX = m_flickable->property("originX").toReal();
     const qreal originY = m_flickable->property("originY").toReal();
     const qreal pageWidth = width - leftMargin - rightMargin;
     const qreal pageHeight = height - topMargin - bottomMargin;
     const auto window = m_flickable->window();
     const qreal devicePixelRatio = window != nullptr ? window->devicePixelRatio() : qGuiApp->devicePixelRatio();
 
     // HACK: Only transpose deltas when not using xcb in order to not conflict with xcb's own delta transposing
     if (modifiers & m_defaultHorizontalScrollModifiers && qGuiApp->platformName() != QLatin1String("xcb")) {
         angleDelta = angleDelta.transposed();
         pixelDelta = pixelDelta.transposed();
     }
 
     const qreal xTicks = angleDelta.x() / 120;
     const qreal yTicks = angleDelta.y() / 120;
     qreal xChange;
     qreal yChange;
     bool scrolled = false;
 
     // Scroll X
     if (contentWidth > pageWidth) {
         // Use page size with pageScrollModifiers. Matches QScrollBar, which uses QAbstractSlider behavior.
         if (modifiers & m_pageScrollModifiers) {
             xChange = qBound(-pageWidth, xTicks * pageWidth, pageWidth);
         } else if (pixelDelta.x() != 0) {
             xChange = pixelDelta.x();
         } else {
             xChange = xTicks * m_horizontalStepSize;
         }
 
         // contentX and contentY use reversed signs from what x and y would normally use, so flip the signs
 
         qreal minXExtent = leftMargin - originX;
         qreal maxXExtent = width - (contentWidth + rightMargin + originX);
 
         qreal newContentX = qBound(-minXExtent, contentX - xChange, -maxXExtent);
         // Flickable::pixelAligned rounds the position, so round to mimic that behavior.
         // Rounding prevents fractional positioning from causing text to be
         // clipped off on the top and bottom.
         // Multiply by devicePixelRatio before rounding and divide by devicePixelRatio
         // after to make position match pixels on the screen more closely.
         newContentX = std::round(newContentX * devicePixelRatio) / devicePixelRatio;
         if (contentX != newContentX) {
             scrolled = true;
             m_flickable->setProperty("contentX", newContentX);
         }
     }
 
     // Scroll Y
     if (contentHeight > pageHeight) {
         if (modifiers & m_pageScrollModifiers) {
             yChange = qBound(-pageHeight, yTicks * pageHeight, pageHeight);
         } else if (pixelDelta.y() != 0) {
             yChange = pixelDelta.y();
         } else {
             yChange = yTicks * m_verticalStepSize;
         }
 
         // contentX and contentY use reversed signs from what x and y would normally use, so flip the signs
 
         qreal minYExtent = topMargin - originY;
         qreal maxYExtent = height - (contentHeight + bottomMargin + originY);
 
         qreal newContentY = qBound(-minYExtent, contentY - yChange, -maxYExtent);
         // Flickable::pixelAligned rounds the position, so round to mimic that behavior.
         // Rounding prevents fractional positioning from causing text to be
         // clipped off on the top and bottom.
         // Multiply by devicePixelRatio before rounding and divide by devicePixelRatio
         // after to make position match pixels on the screen more closely.
         newContentY = std::round(newContentY * devicePixelRatio) / devicePixelRatio;
         if (contentY != newContentY) {
             scrolled = true;
             m_flickable->setProperty("contentY", newContentY);
         }
     }
 
     return scrolled;
 }
 
 bool WheelHandler::scrollUp(qreal stepSize)
 {
     if (qFuzzyIsNull(stepSize)) {
         return false;
     } else if (stepSize < 0) {
         stepSize = m_verticalStepSize;
     }
     // contentY uses reversed sign
     return scrollFlickable(QPointF(0, stepSize));
 }
 
 bool WheelHandler::scrollDown(qreal stepSize)
 {
     if (qFuzzyIsNull(stepSize)) {
         return false;
     } else if (stepSize < 0) {
         stepSize = m_verticalStepSize;
     }
     // contentY uses reversed sign
     return scrollFlickable(QPointF(0, -stepSize));
 }
 
 bool WheelHandler::scrollLeft(qreal stepSize)
 {
     if (qFuzzyIsNull(stepSize)) {
         return false;
     } else if (stepSize < 0) {
         stepSize = m_horizontalStepSize;
     }
     // contentX uses reversed sign
     return scrollFlickable(QPoint(stepSize, 0));
 }
 
 bool WheelHandler::scrollRight(qreal stepSize)
 {
     if (qFuzzyIsNull(stepSize)) {
         return false;
     } else if (stepSize < 0) {
         stepSize = m_horizontalStepSize;
     }
     // contentX uses reversed sign
     return scrollFlickable(QPoint(-stepSize, 0));
 }
 
 bool WheelHandler::eventFilter(QObject *watched, QEvent *event)
 {
     auto item = qobject_cast<QQuickItem*>(watched);
     if (!item || !item->isEnabled()) {
         return false;
     }
 
     qreal contentWidth = 0;
     qreal contentHeight = 0;
     qreal pageWidth = 0;
     qreal pageHeight = 0;
     if (m_flickable) {
         contentWidth = m_flickable->property("contentWidth").toReal();
         contentHeight = m_flickable->property("contentHeight").toReal();
         pageWidth = m_flickable->width() - m_flickable->property("leftMargin").toReal() - m_flickable->property("rightMargin").toReal();
         pageHeight = m_flickable->height() - m_flickable->property("topMargin").toReal() - m_flickable->property("bottomMargin").toReal();
     }
 
     // The code handling touch, mouse and hover events is mostly copied/adapted from QQuickScrollView::childMouseEventFilter()
     switch (event->type()) {
     case QEvent::Wheel: {
         // QQuickScrollBar::interactive handling Matches behavior in QQuickScrollView::eventFilter()
         if (m_filterMouseEvents) {
             if (m_verticalScrollBar) {
                 m_verticalScrollBar->setProperty("interactive", true);
             }
             if (m_horizontalScrollBar) {
                 m_horizontalScrollBar->setProperty("interactive", true);
             }
         }
         QWheelEvent *wheelEvent = static_cast<QWheelEvent *>(event);
 
         // NOTE: On X11 with libinput, pixelDelta is identical to angleDelta when using a mouse that shouldn't use pixelDelta.
         // If faulty pixelDelta, reset pixelDelta to (0,0).
         if (wheelEvent->pixelDelta() == wheelEvent->angleDelta()) {
             // In order to change any of the data, we have to create a whole new QWheelEvent from its constructor.
             QWheelEvent newWheelEvent(
                 wheelEvent->position(),
                 wheelEvent->globalPosition(),
                 QPoint(0,0), // pixelDelta
                 wheelEvent->angleDelta(),
                 wheelEvent->buttons(),
                 wheelEvent->modifiers(),
                 wheelEvent->phase(),
                 wheelEvent->inverted(),
                 wheelEvent->source()
             );
             m_kirigamiWheelEvent.initializeFromEvent(&newWheelEvent);
         } else {
             m_kirigamiWheelEvent.initializeFromEvent(wheelEvent);
         }
 
         Q_EMIT wheel(&m_kirigamiWheelEvent);
 
         if (m_kirigamiWheelEvent.isAccepted()) {
             return true;
         }
 
         bool scrolled = false;
         if (m_scrollFlickableTarget || (contentHeight <= pageHeight && contentWidth <= pageWidth)) {
             // Don't use pixelDelta from the event unless angleDelta is not available
             // because scrolling by pixelDelta is too slow on Wayland with libinput.
             QPointF pixelDelta = m_kirigamiWheelEvent.angleDelta().isNull() ? m_kirigamiWheelEvent.pixelDelta() : QPoint(0, 0);
             scrolled = scrollFlickable(pixelDelta,
                                        m_kirigamiWheelEvent.angleDelta(),
                                        Qt::KeyboardModifiers(m_kirigamiWheelEvent.modifiers()));
         }
         setScrolling(scrolled);
 
         // NOTE: Wheel events created by touchpad gestures with pixel deltas will cause scrolling to jump back
         // to where scrolling started unless the event is always accepted before it reaches the Flickable.
         bool flickableWillUseGestureScrolling = !(wheelEvent->source() == Qt::MouseEventNotSynthesized || wheelEvent->pixelDelta().isNull());
         return scrolled || m_blockTargetWheel || flickableWillUseGestureScrolling;
     }
 
     case QEvent::TouchBegin: {
         m_wasTouched = true;
         if (!m_filterMouseEvents) {
             break;
         }
         if (m_verticalScrollBar) {
             m_verticalScrollBar->setProperty("interactive", false);
         }
         if (m_horizontalScrollBar) {
             m_horizontalScrollBar->setProperty("interactive", false);
         }
         break;
     }
 
     case QEvent::TouchEnd: {
         m_wasTouched = false;
         break;
     }
 
     case QEvent::MouseButtonPress: {
         // NOTE: Flickable does not handle touch events, only synthesized mouse events
         m_wasTouched = static_cast<QMouseEvent *>(event)->source() != Qt::MouseEventNotSynthesized;
         if (!m_filterMouseEvents) {
             break;
         }
         if (!m_wasTouched) {
             if (m_verticalScrollBar) {
                 m_verticalScrollBar->setProperty("interactive", true);
             }
             if (m_horizontalScrollBar) {
                 m_horizontalScrollBar->setProperty("interactive", true);
             }
             break;
         }
         return !m_wasTouched && item == m_flickable;
     }
 
     case QEvent::MouseMove:
     case QEvent::MouseButtonRelease: {
         setScrolling(false);
         if (!m_filterMouseEvents) {
             break;
         }
         if (static_cast<QMouseEvent *>(event)->source() == Qt::MouseEventNotSynthesized && item == m_flickable) {
             return true;
         }
         break;
     }
 
     case QEvent::HoverEnter:
     case QEvent::HoverMove: {
         if (!m_filterMouseEvents) {
             break;
         }
         if (m_wasTouched && (item == m_verticalScrollBar || item == m_horizontalScrollBar)) {
             if (m_verticalScrollBar) {
                 m_verticalScrollBar->setProperty("interactive", true);
             }
             if (m_horizontalScrollBar) {
                 m_horizontalScrollBar->setProperty("interactive", true);
             }
         }
         break;
     }
 
     case QEvent::KeyPress: {
         if (!m_keyNavigationEnabled) {
             break;
         }
         QKeyEvent *keyEvent = static_cast<QKeyEvent *>(event);
         bool horizontalScroll = keyEvent->modifiers() & m_defaultHorizontalScrollModifiers;
         switch (keyEvent->key()) {
         case Qt::Key_Up: return scrollUp();
         case Qt::Key_Down: return scrollDown();
         case Qt::Key_Left: return scrollLeft();
         case Qt::Key_Right: return scrollRight();
         case Qt::Key_PageUp: return horizontalScroll ? scrollLeft(pageWidth) : scrollUp(pageHeight);
         case Qt::Key_PageDown: return horizontalScroll ? scrollRight(pageWidth) : scrollDown(pageHeight);
         case Qt::Key_Home: return horizontalScroll ? scrollLeft(contentWidth) : scrollUp(contentHeight);
         case Qt::Key_End: return horizontalScroll ? scrollRight(contentWidth) : scrollDown(contentHeight);
         default: break;
         }
         break;
     }
 
     default: break;
     }
 
     return false;
 }
 
 #include "moc_wheelhandler.cpp"