File indexing completed on 2024-04-28 15:27:45

 /* SPDX-FileCopyrightText: 2019 Marco Martin <mart@kde.org>
  * SPDX-FileCopyrightText: 2021 Noah Davis <noahadvs@gmail.com>
  * SPDX-License-Identifier: LGPL-2.0-or-later
  */
 
 #pragma once
 
 #include <QGuiApplication>
 #include <QObject>
 #include <QPoint>
 #include <QQuickItem>
 #include <QStyleHints>
 #include <QTimer>
 
 class QWheelEvent;
 class WheelHandler;
 
 /**
  * Describes the mouse wheel event
  */
 class KirigamiWheelEvent : public QObject
 {
     Q_OBJECT
 
     /**
      * @brief This property holds the x coordinate of the mouse pointer.
      */
     Q_PROPERTY(qreal x READ x CONSTANT)
 
     /**
      * @brief This property holds the y coordinate of the mouse pointer.
      */
     Q_PROPERTY(qreal y READ y CONSTANT)
 
     /**
      * @brief This property holds the distance the wheel is rotated in degrees.
      *
      * The x and y coordinates indicate the horizontal and vertical wheels respectively.
      * A positive value indicates it was rotated up/right, negative, bottom/left
      * This value is more likely to be set in traditional mice.
      */
     Q_PROPERTY(QPointF angleDelta READ angleDelta CONSTANT)
 
     /**
      * @brief This property provides the delta in screen pixels available on high resolution trackpads.
      */
     Q_PROPERTY(QPointF pixelDelta READ pixelDelta CONSTANT)
 
     /**
      * @brief This property contains an OR combination of the buttons that were pressed during the wheel.
      *
      * Possible values in a combination are:
      * * ``Qt.LeftButton``
      * * ``Qt.MiddleButton``
      * * ``Qt.RightButton``
      */
     Q_PROPERTY(int buttons READ buttons CONSTANT)
 
     /**
      * @brief This property holds the keyboard modifiers that were pressed during the wheel event.
      *
      * Possible values in a combination are:
      * * ``Qt.NoModifier`` (default, no modifiers)
      * * ``Qt.ControlModifier``
      * * ``Qt.ShiftModifier``
      * ...
      */
     Q_PROPERTY(int modifiers READ modifiers CONSTANT)
 
     /**
      * @brief This property holds whether the delta values are inverted.
      *
      * The returned delta may be inverted on some platforms, so positive values would mean bottom/left.
      */
     Q_PROPERTY(bool inverted READ inverted CONSTANT)
 
     /**
      * @brief This property sets whether the event should be accepted or dropped.
      * If set, the event shouldn't be managed anymore, for instance it can be used
      * to block the handler to manage the scroll of a view on some scenarios.
      *
      * @code
      * // This handler handles automatically the scroll of
      * // flickableItem, unless Ctrl is pressed, in this case the
      * // app has custom code to handle Ctrl+wheel zooming
      * Kirigami.WheelHandler {
      *   target: flickableItem
      *   blockTargetWheel: true
      *   scrollFlickableTarget: true
      *   onWheel: {
      *        if (wheel.modifiers & Qt.ControlModifier) {
      *            wheel.accepted = true;
      *            // Handle scaling of the view
      *       }
      *   }
      * }
      * @endcode
      *
      */
     Q_PROPERTY(bool accepted READ isAccepted WRITE setAccepted)
 
 public:
     KirigamiWheelEvent(QObject *parent = nullptr);
     ~KirigamiWheelEvent() override;
 
     void initializeFromEvent(QWheelEvent *event);
 
     qreal x() const;
     qreal y() const;
     QPointF angleDelta() const;
     QPointF pixelDelta() const;
     int buttons() const;
     int modifiers() const;
     bool inverted() const;
     bool isAccepted();
     void setAccepted(bool accepted);
 
 private:
     qreal m_x = 0;
     qreal m_y = 0;
     QPointF m_angleDelta;
     QPointF m_pixelDelta;
     Qt::MouseButtons m_buttons = Qt::NoButton;
     Qt::KeyboardModifiers m_modifiers = Qt::NoModifier;
     bool m_inverted = false;
     bool m_accepted = false;
 };
 
 class WheelFilterItem : public QQuickItem
 {
     Q_OBJECT
 public:
     WheelFilterItem(QQuickItem *parent = nullptr);
 };
 
 /**
  * @brief Handles scrolling for a Flickable and 2 attached ScrollBars.
  *
  * WheelHandler filters events from a QtQuick.Flickable,
  * a vertical QtQuick.Controls.ScrollBar and a horizontal QtQuick.Controls.ScrollBar.
  * Wheel and KeyPress events (when ::keyNavigationEnabled is true) are
  * used to scroll the Flickable. When ::filterMouseEvents is true, WheelHandler blocks mouse button
  * input from reaching the Flickable and sets the
  * <a href="https://doc.qt.io/qt-5/qml-qtquick-controls2-scrollbar.html#interactive-prop">interactive</a>
  * property of the scrollbars to @c false when touch input is used.
  *
  * Wheel event handling behavior:
  *
  * - Pixel delta is ignored unless angle delta is not available because pixel delta scrolling is too slow. Qt Widgets doesn't use pixel delta either, so the
  * default scroll speed should be consistent with Qt Widgets.
  * - When using angle delta, scroll using the step increments defined by ::verticalStepSize and ::horizontalStepSize.
  * - When one of the keyboard modifiers in ::pageScrollModifiers is used, scroll by pages.
  * - When using a device that doesn't use 120 angle delta unit increments such as a touchpad, the ::verticalStepSize, ::horizontalStepSize and page increments
  * (if using page scrolling) will be multiplied by `angle delta / 120` to keep scrolling smooth.
  * - If scrolling has happened in the last 400ms, use an internal QQuickItem stacked over the Flickable's contentItem to catch wheel events and use those wheel
  * events to scroll, if possible. This prevents controls inside the Flickable's contentItem that allow scrolling to change the value (e.g., Sliders, SpinBoxes)
  * from conflicting with scrolling the page.
  *
  * Common usage with a Flickable:
  *
  * @include wheelhandler/FlickableUsage.qml
  *
  * Common usage inside of a ScrollView template:
  *
  * @include wheelhandler/ScrollViewUsage.qml
  *
  */
 class WheelHandler : public QObject
 {
     Q_OBJECT
 
     /**
      * @brief This property holds the Flickable that the WheelHandler will control.
      */
     Q_PROPERTY(QQuickItem *target READ target WRITE setTarget NOTIFY targetChanged FINAL)
 
     /**
      * @brief This property holds the vertical step size.
      *
      * The default value is equivalent to `20 * Qt.styleHints.wheelScrollLines`.
      * This is consistent with the default increment for QScrollArea.
      *
      * @see ::horizontalStepSize
      * @since KDE Frameworks 5.89
      */
     Q_PROPERTY(qreal verticalStepSize READ verticalStepSize
                WRITE setVerticalStepSize RESET resetVerticalStepSize
                NOTIFY verticalStepSizeChanged FINAL)
 
     /**
      * @brief This property holds the horizontal step size.
      *
      * The default value is equivalent to `20 * Qt.styleHints.wheelScrollLines`.
      * This is consistent with the default increment for QScrollArea.
      *
      * @see ::verticalStepSize
      * @since KDE Frameworks 5.89
      */
     Q_PROPERTY(qreal horizontalStepSize READ horizontalStepSize
                WRITE setHorizontalStepSize RESET resetHorizontalStepSize
                NOTIFY horizontalStepSizeChanged FINAL)
 
     /**
      * @brief This property holds the keyboard modifiers that will be used to start page scrolling.
      *
      * The default value is equivalent to `Qt.ControlModifier | Qt.ShiftModifier`. This matches QScrollBar,
      * which uses QAbstractSlider behavior.
      *
      * @since KDE Frameworks 5.89
      */
     Q_PROPERTY(Qt::KeyboardModifiers pageScrollModifiers READ pageScrollModifiers
                WRITE setPageScrollModifiers RESET resetPageScrollModifiers
                NOTIFY pageScrollModifiersChanged FINAL)
 
     /**
      * @brief This property holds whether the WheelHandler filters mouse events like a QtQuick.Controls.ScrollView would.
      *
      * Touch events are allowed to flick the view and they make the scrollbars not interactive.
      *
      * Mouse events are not allowed to flick the view and they make the scrollbars interactive.
      *
      * Hover events on the scrollbars and wheel events on anything also make the scrollbars interactive when this property is set to true.
      *
      * default: ``false``
      *
      * @since KDE Frameworks 5.89
      */
     Q_PROPERTY(bool filterMouseEvents READ filterMouseEvents
                WRITE setFilterMouseEvents NOTIFY filterMouseEventsChanged FINAL)
 
     /**
      * @brief This property holds whether the WheelHandler handles keyboard scrolling.
      *
      * - Left arrow scrolls a step to the left.
      * - Right arrow scrolls a step to the right.
      * - Up arrow scrolls a step upwards.
      * - Down arrow scrolls a step downwards.
      * - PageUp scrolls to the previous page.
      * - PageDown scrolls to the next page.
      * - Home scrolls to the beginning.
      * - End scrolls to the end.
      * - When Alt is held, scroll horizontally when using PageUp, PageDown, Home or End.
      *
      * default: ``false``
      *
      * @since KDE Frameworks 5.89
      */
     Q_PROPERTY(bool keyNavigationEnabled READ keyNavigationEnabled
                WRITE setKeyNavigationEnabled NOTIFY keyNavigationEnabledChanged FINAL)
 
     /**
      * @brief This property holds whether the WheelHandler blocks all wheel events from reaching the Flickable.
      *
      * When this property is false, scrolling the Flickable with WheelHandler will only block an event from reaching the Flickable if the Flickable is actually
      * scrolled by WheelHandler.
      *
      * NOTE: Wheel events created by touchpad gestures with pixel deltas will always be accepted no matter what. This is because they will cause the Flickable
      * to jump back to where scrolling started unless the events are always accepted before they reach the Flickable.
      *
      * default: ``true``
      */
     Q_PROPERTY(bool blockTargetWheel MEMBER m_blockTargetWheel NOTIFY blockTargetWheelChanged)
 
     /**
      * @brief This property holds whether the WheelHandler can use wheel events to scroll the Flickable.
      *
      * default: ``true``
      */
     Q_PROPERTY(bool scrollFlickableTarget MEMBER m_scrollFlickableTarget NOTIFY scrollFlickableTargetChanged)
 
 public:
     explicit WheelHandler(QObject *parent = nullptr);
     ~WheelHandler() override;
 
     QQuickItem *target() const;
     void setTarget(QQuickItem *target);
 
     qreal verticalStepSize() const;
     void setVerticalStepSize(qreal stepSize);
     void resetVerticalStepSize();
 
     qreal horizontalStepSize() const;
     void setHorizontalStepSize(qreal stepSize);
     void resetHorizontalStepSize();
 
     Qt::KeyboardModifiers pageScrollModifiers() const;
     void setPageScrollModifiers(Qt::KeyboardModifiers modifiers);
     void resetPageScrollModifiers();
 
     bool filterMouseEvents() const;
     void setFilterMouseEvents(bool enabled);
 
     bool keyNavigationEnabled() const;
     void setKeyNavigationEnabled(bool enabled);
 
     /**
      * Scroll up one step. If the ::stepSize parameter is less than 0, the ::verticalStepSize will be used.
      *
      * returns @c true if the contentItem was moved.
      *
      * @since KDE Frameworks 5.89
      */
     Q_INVOKABLE bool scrollUp(qreal stepSize = -1);
 
     /**
      * Scroll down one step. If the ::stepSize parameter is less than 0, the ::verticalStepSize will be used.
      *
      * returns @c true if the contentItem was moved.
      *
      * @since KDE Frameworks 5.89
      */
     Q_INVOKABLE bool scrollDown(qreal stepSize = -1);
 
     /**
      * Scroll left one step. If the ::stepSize parameter is less than 0, the ::horizontalStepSize will be used.
      *
      * returns @c true if the contentItem was moved.
      *
      * @since KDE Frameworks 5.89
      */
     Q_INVOKABLE bool scrollLeft(qreal stepSize = -1);
 
     /**
      * Scroll right one step. If the ::stepSize parameter is less than 0, the ::horizontalStepSize will be used.
      *
      * returns @c true if the contentItem was moved.
      *
      * @since KDE Frameworks 5.89
      */
     Q_INVOKABLE bool scrollRight(qreal stepSize = -1);
 
 Q_SIGNALS:
     void targetChanged();
     void verticalStepSizeChanged();
     void horizontalStepSizeChanged();
     void pageScrollModifiersChanged();
     void filterMouseEventsChanged();
     void keyNavigationEnabledChanged();
     void blockTargetWheelChanged();
     void scrollFlickableTargetChanged();
 
     /**
      * @brief This signal is emitted when a wheel event reaches the event filter, just before scrolling is handled.
      *
      * Accepting the wheel event in the `onWheel` signal handler prevents scrolling from happening.
      */
     void wheel(KirigamiWheelEvent *wheel);
 
 protected:
     bool eventFilter(QObject *watched, QEvent *event) override;
 
 private Q_SLOTS:
     void _k_rebindScrollBars();
 
 private:
     void setScrolling(bool scrolling);
     bool scrollFlickable(QPointF pixelDelta,
                          QPointF angleDelta = {},
                          Qt::KeyboardModifiers modifiers = Qt::NoModifier);
 
     QPointer<QQuickItem> m_flickable;
     QPointer<QQuickItem> m_verticalScrollBar;
     QPointer<QQuickItem> m_horizontalScrollBar;
     QMetaObject::Connection m_verticalChangedConnection;
     QMetaObject::Connection m_horizontalChangedConnection;
     QPointer<QQuickItem> m_filterItem;
     // Matches QScrollArea and QTextEdit
     qreal m_defaultPixelStepSize = 20 * QGuiApplication::styleHints()->wheelScrollLines();
     qreal m_verticalStepSize = m_defaultPixelStepSize;
     qreal m_horizontalStepSize = m_defaultPixelStepSize;
     bool m_explicitVStepSize = false;
     bool m_explicitHStepSize = false;
     bool m_wheelScrolling = false;
     constexpr static qreal m_wheelScrollingDuration = 400;
     bool m_filterMouseEvents = false;
     bool m_keyNavigationEnabled = false;
     bool m_wasTouched = false;
     bool m_blockTargetWheel = true;
     bool m_scrollFlickableTarget = true;
     // Same as QXcbWindow.
     constexpr static Qt::KeyboardModifiers m_defaultHorizontalScrollModifiers = Qt::AltModifier;
     // Same as QScrollBar/QAbstractSlider.
     constexpr static Qt::KeyboardModifiers m_defaultPageScrollModifiers = Qt::ControlModifier | Qt::ShiftModifier;
     Qt::KeyboardModifiers m_pageScrollModifiers = m_defaultPageScrollModifiers;
     QTimer m_wheelScrollingTimer;
     KirigamiWheelEvent m_kirigamiWheelEvent;
 };