WheelHandler Class Reference

#include <wheelhandler.h>

Inheritance diagram for WheelHandler:

Properties
bool	blockTargetWheel
bool	filterMouseEvents
qreal	horizontalStepSize
bool	keyNavigationEnabled
Qt::KeyboardModifiers	pageScrollModifiers
Qt::Orientation	primaryOrientation
bool	scrollFlickableTarget
QML_ELEMENTQQuickItem *	target
qreal	verticalStepSize
Properties inherited from QObject
	objectName

Signals
void	blockTargetWheelChanged ()
void	filterMouseEventsChanged ()
void	horizontalStepSizeChanged ()
void	keyNavigationEnabledChanged ()
void	pageScrollModifiersChanged ()
void	primaryOrientationChanged ()
void	scrollFlickableTargetChanged ()
void	targetChanged ()
void	verticalStepSizeChanged ()
void	wheel (KirigamiWheelEvent *wheel)

Public Member Functions
	WheelHandler (QObject *parent=nullptr)
bool	filterMouseEvents () const
qreal	horizontalStepSize () const
bool	keyNavigationEnabled () const
Qt::KeyboardModifiers	pageScrollModifiers () const
Qt::Orientation	primaryOrientation () const
void	resetHorizontalStepSize ()
void	resetPageScrollModifiers ()
void	resetVerticalStepSize ()
Q_INVOKABLE bool	scrollDown (qreal stepSize=-1)
Q_INVOKABLE bool	scrollLeft (qreal stepSize=-1)
Q_INVOKABLE bool	scrollRight (qreal stepSize=-1)
Q_INVOKABLE bool	scrollUp (qreal stepSize=-1)
void	setFilterMouseEvents (bool enabled)
void	setHorizontalStepSize (qreal stepSize)
void	setKeyNavigationEnabled (bool enabled)
void	setPageScrollModifiers (Qt::KeyboardModifiers modifiers)
void	setPrimaryOrientation (Qt::Orientation orientation)
void	setTarget (QQuickItem *target)
void	setVerticalStepSize (qreal stepSize)
QQuickItem *	target () const
qreal	verticalStepSize () const
Public Member Functions inherited from QObject
	QObject (QObject *parent)
QBindable< QString >	bindableObjectName ()
bool	blockSignals (bool block)
const QObjectList &	children () const const
QMetaObject::Connection	connect (const QObject *sender, const char *signal, const char *method, Qt::ConnectionType type) const const
void	deleteLater ()
void	destroyed (QObject *obj)
bool	disconnect (const char *signal, const QObject *receiver, const char *method) const const
bool	disconnect (const QObject *receiver, const char *method) const const
void	dumpObjectInfo () const const
void	dumpObjectTree () const const
QList< QByteArray >	dynamicPropertyNames () const const
virtual bool	event (QEvent *e)
T	findChild (const QString &name, Qt::FindChildOptions options) const const
QList< T >	findChildren (const QRegularExpression &re, Qt::FindChildOptions options) const const
QList< T >	findChildren (const QString &name, Qt::FindChildOptions options) const const
QList< T >	findChildren (Qt::FindChildOptions options) const const
bool	inherits (const char *className) const const
void	installEventFilter (QObject *filterObj)
bool	isQuickItemType () const const
bool	isWidgetType () const const
bool	isWindowType () const const
void	killTimer (int id)
virtual const QMetaObject *	metaObject () const const
void	moveToThread (QThread *targetThread)
QString	objectName () const const
void	objectNameChanged (const QString &objectName)
QObject *	parent () const const
QVariant	property (const char *name) const const
	Q_CLASSINFO (Name, Value)
	Q_EMIT Q_EMIT
	Q_ENUM (...)
	Q_ENUM_NS (...)
	Q_ENUMS (...)
	Q_FLAG (...)
	Q_FLAG_NS (...)
	Q_FLAGS (...)
	Q_GADGET Q_GADGET
	Q_GADGET_EXPORT (EXPORT_MACRO)
	Q_INTERFACES (...)
	Q_INVOKABLE Q_INVOKABLE
	Q_MOC_INCLUDE Q_MOC_INCLUDE
	Q_NAMESPACE Q_NAMESPACE
	Q_NAMESPACE_EXPORT (EXPORT_MACRO)
	Q_OBJECT Q_OBJECT
	Q_PROPERTY (...)
	Q_REVISION Q_REVISION
	Q_SET_OBJECT_NAME (Object)
	Q_SIGNAL Q_SIGNAL
	Q_SIGNALS Q_SIGNALS
	Q_SLOT Q_SLOT
	Q_SLOTS Q_SLOTS
T	qobject_cast (const QObject *object)
T	qobject_cast (QObject *object)
	QT_NO_NARROWING_CONVERSIONS_IN_CONNECT QT_NO_NARROWING_CONVERSIONS_IN_CONNECT
void	removeEventFilter (QObject *obj)
void	setObjectName (const QString &name)
void	setObjectName (QAnyStringView name)
void	setParent (QObject *parent)
bool	setProperty (const char *name, const QVariant &value)
bool	setProperty (const char *name, QVariant &&value)
bool	signalsBlocked () const const
int	startTimer (int interval, Qt::TimerType timerType)
int	startTimer (std::chrono::milliseconds interval, Qt::TimerType timerType)
QThread *	thread () const const

Protected Member Functions
bool	eventFilter (QObject *watched, QEvent *event) override
Protected Member Functions inherited from QObject
virtual void	childEvent (QChildEvent *event)
virtual void	connectNotify (const QMetaMethod &signal)
virtual void	customEvent (QEvent *event)
virtual void	disconnectNotify (const QMetaMethod &signal)
bool	isSignalConnected (const QMetaMethod &signal) const const
int	receivers (const char *signal) const const
QObject *	sender () const const
int	senderSignalIndex () const const
virtual void	timerEvent (QTimerEvent *event)

Additional Inherited Members
Static Public Member Functions inherited from QObject
QMetaObject::Connection	connect (const QObject *sender, const char *signal, const QObject *receiver, const char *method, Qt::ConnectionType type)
QMetaObject::Connection	connect (const QObject *sender, const QMetaMethod &signal, const QObject *receiver, const QMetaMethod &method, Qt::ConnectionType type)
QMetaObject::Connection	connect (const QObject *sender, PointerToMemberFunction signal, const QObject *context, Functor functor, Qt::ConnectionType type)
QMetaObject::Connection	connect (const QObject *sender, PointerToMemberFunction signal, const QObject *receiver, PointerToMemberFunction method, Qt::ConnectionType type)
QMetaObject::Connection	connect (const QObject *sender, PointerToMemberFunction signal, Functor functor)
bool	disconnect (const QMetaObject::Connection &connection)
bool	disconnect (const QObject *sender, const char *signal, const QObject *receiver, const char *method)
bool	disconnect (const QObject *sender, const QMetaMethod &signal, const QObject *receiver, const QMetaMethod &method)
bool	disconnect (const QObject *sender, PointerToMemberFunction signal, const QObject *receiver, PointerToMemberFunction method)
QString	tr (const char *sourceText, const char *disambiguation, int n)
Public Attributes inherited from QObject
typedef	QObjectList

Detailed Description

Handles scrolling for a Flickable and 2 attached ScrollBars.

WheelHandler filters events from a Flickable, a vertical ScrollBar and a horizontal 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 interactive property of the scrollbars to 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:

Common usage inside of a ScrollView template:

Definition at line 170 of file wheelhandler.h.

Property Documentation

blockTargetWheel

bool WheelHandler::blockTargetWheel

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.

The default value is true.

Definition at line 263 of file wheelhandler.h.

filterMouseEvents

bool WheelHandler::filterMouseEvents

readwrite

This property holds whether the WheelHandler filters mouse events like a Qt Quick 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.

The default value is false.

Since

KDE Frameworks 5.89

Definition at line 231 of file wheelhandler.h.

horizontalStepSize

qreal WheelHandler::horizontalStepSize

readwrite

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 also

verticalStepSize

Since

KDE Frameworks 5.89

Definition at line 203 of file wheelhandler.h.

keyNavigationEnabled

bool WheelHandler::keyNavigationEnabled

readwrite

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.

The default value is false.

Since

KDE Frameworks 5.89

Definition at line 251 of file wheelhandler.h.

pageScrollModifiers

Qt::KeyboardModifiers WheelHandler::pageScrollModifiers

readwrite

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

Definition at line 214 of file wheelhandler.h.

primaryOrientation

Qt::Orientation WheelHandler::primaryOrientation

readwrite

Definition at line 272 of file wheelhandler.h.

scrollFlickableTarget

bool WheelHandler::scrollFlickableTarget

This property holds whether the WheelHandler can use wheel events to scroll the Flickable.

The default value is true.

Definition at line 270 of file wheelhandler.h.

target

QML_ELEMENTQQuickItem * WheelHandler::target

readwrite

This property holds the Qt Quick Flickable that the WheelHandler will control.

Definition at line 179 of file wheelhandler.h.

verticalStepSize

qreal WheelHandler::verticalStepSize

readwrite

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 also

horizontalStepSize

Since

KDE Frameworks 5.89

Definition at line 190 of file wheelhandler.h.

Constructor & Destructor Documentation

WheelHandler()

WheelHandler::WheelHandler ( QObject * parent = nullptr )

explicit

Definition at line 87 of file wheelhandler.cpp.

~WheelHandler()

WheelHandler::~WheelHandler ( )

override

Definition at line 114 of file wheelhandler.cpp.

Member Function Documentation

eventFilter()

bool WheelHandler::eventFilter ( QObject * watched, QEvent * event )

overrideprotectedvirtual

Reimplemented from QObject.

Definition at line 567 of file wheelhandler.cpp.

filterMouseEvents()

bool WheelHandler::filterMouseEvents

(

)

const

Definition at line 356 of file wheelhandler.cpp.

horizontalStepSize()

qreal WheelHandler::horizontalStepSize

(

)

const

Definition at line 307 of file wheelhandler.cpp.

keyNavigationEnabled()

bool WheelHandler::keyNavigationEnabled

(

)

const

Definition at line 370 of file wheelhandler.cpp.

pageScrollModifiers()

Qt::KeyboardModifiers WheelHandler::pageScrollModifiers

(

)

const

Definition at line 337 of file wheelhandler.cpp.

primaryOrientation()

Qt::Orientation WheelHandler::primaryOrientation

(

)

const

Definition at line 411 of file wheelhandler.cpp.

resetHorizontalStepSize()

void WheelHandler::resetHorizontalStepSize

(

)

Definition at line 327 of file wheelhandler.cpp.

resetPageScrollModifiers()

void WheelHandler::resetPageScrollModifiers

(

)

Definition at line 351 of file wheelhandler.cpp.

resetVerticalStepSize()

void WheelHandler::resetVerticalStepSize

(

)

Definition at line 297 of file wheelhandler.cpp.

scrollDown()

bool WheelHandler::scrollDown

(

qreal

stepSize = -1

)

Scroll down one step.

If the stepSize parameter is less than 0, the verticalStepSize will be used.

returns true if the contentItem was moved.

Since

KDE Frameworks 5.89

Definition at line 534 of file wheelhandler.cpp.

scrollLeft()

bool WheelHandler::scrollLeft

(

qreal

stepSize = -1

)

Scroll left one step.

If the stepSize parameter is less than 0, the horizontalStepSize will be used.

returns true if the contentItem was moved.

Since

KDE Frameworks 5.89

Definition at line 545 of file wheelhandler.cpp.

scrollRight()

bool WheelHandler::scrollRight

(

qreal

stepSize = -1

)

Scroll right one step.

If the stepSize parameter is less than 0, the horizontalStepSize will be used.

returns true if the contentItem was moved.

Since

KDE Frameworks 5.89

Definition at line 556 of file wheelhandler.cpp.

scrollUp()

bool WheelHandler::scrollUp

(

qreal

stepSize = -1

)

Scroll up one step.

If the stepSize parameter is less than 0, the verticalStepSize will be used.

returns true if the contentItem was moved.

Since

KDE Frameworks 5.89

Definition at line 523 of file wheelhandler.cpp.

setFilterMouseEvents()

void WheelHandler::setFilterMouseEvents

(

bool

enabled

)

Definition at line 361 of file wheelhandler.cpp.

setHorizontalStepSize()

void WheelHandler::setHorizontalStepSize

(

qreal

stepSize

)

Definition at line 312 of file wheelhandler.cpp.

setKeyNavigationEnabled()

void WheelHandler::setKeyNavigationEnabled

(

bool

enabled

)

Definition at line 375 of file wheelhandler.cpp.

setPageScrollModifiers()

void WheelHandler::setPageScrollModifiers

(

Qt::KeyboardModifiers

modifiers

)

Definition at line 342 of file wheelhandler.cpp.

setPrimaryOrientation()

void WheelHandler::setPrimaryOrientation

(

Qt::Orientation

orientation

)

Definition at line 416 of file wheelhandler.cpp.

setTarget()

void WheelHandler::setTarget

(

QQuickItem *

target

)

Definition at line 124 of file wheelhandler.cpp.

setVerticalStepSize()

void WheelHandler::setVerticalStepSize

(

qreal

stepSize

)

Definition at line 282 of file wheelhandler.cpp.

target()

QQuickItem * WheelHandler::target

(

)

const

Definition at line 119 of file wheelhandler.cpp.

verticalStepSize()

qreal WheelHandler::verticalStepSize

(

)

const

Definition at line 277 of file wheelhandler.cpp.

wheel

void WheelHandler::wheel ( KirigamiWheelEvent * wheel )

signal

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.

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The documentation for this class was generated from the following files:

• wheelhandler.h
• wheelhandler.cpp