ScrollableContainer

A ScrollableContainer is a container that allows its contents to be scrolled. It will intercept drag operations and move child nodes accordingly.

A standard Container will simply clip children that are either larger than the container itself, or children that extend beyond the borders of the container or children that are placed outside the borders of the container. A ScrollableContainer behaves much like a Container, except it enables the user to scroll the children and thereby act like a viewport. When the contents of the ScrollableContainer is scrollable, scrollbars can be seen near the edge of the ScrollableContainer.

See: Container

Note: The ScrollableContainer will consume all DragEvents in the area covered by the container.

Inherits from: Container, Drawable

Public Functions

virtual void	add(Drawable & d)
	Adds a Drawable instance as child to this Container.
virtual void	childGeometryChanged()
	Used to signal that the size or position of one or more children have changed.
void	enableHorizontalScroll(bool enable)
	Enables horizontal scrolling.
void	enableVerticalScroll(bool enable)
	Enables vertical scrolling.
virtual Rect	getContainedArea() const
	Gets the area that contains all children added to the ScrollableContainer.
virtual void	getLastChild(int16_t x, int16_t y, Drawable ** last)
	Gets the last child in the list of children in this Container.
uint16_t	getScrollDurationSlowdown() const
	Gets scroll duration speedup divisor.
uint16_t	getScrollDurationSpeedup() const
	Gets scroll duration speedup multiplier.
int16_t	getScrolledX() const
	Gets the distance scrolled for the x-axis.
int16_t	getScrolledY() const
	Gets the distance scrolled for the y-axis.
virtual void	handleClickEvent(const ClickEvent & event)
	Defines the event handler interface for ClickEvents.
virtual void	handleDragEvent(const DragEvent & event)
	Defines the event handler interface for DragEvents.
virtual void	handleGestureEvent(const GestureEvent & event)
	Defines the event handler interface for GestureEvents.
virtual void	handleTickEvent()
	Called periodically by the framework if the Drawable instance has subscribed to timer ticks.
virtual void	isScrollableXY(bool & scrollX, bool & scrollY)
	Is the ClickableContainer scrollable in either direction? Takes the width of the contained elements into account and also checks to see if horizontal or vertical scrolling is allowed.
virtual void	moveChildrenRelative(int16_t deltaX, int16_t deltaY)
	Calls moveRelative on all children.
void	reset()
	Resets the ScrollableContainer to its original state, before the user started dragging the contents.
	ScrollableContainer()
void	setMaxVelocity(uint16_t max)
	Sets the maximum velocity of a scroll due to a swipe.
void	setScrollbarPadding(uint8_t padding)
	Sets the amount of space between the scrollbar and the edge of the ScrollableContainer.
void	setScrollbarsAlpha(uint8_t alpha)
	Sets the alpha value (transparency) of the scrollbars.
void	setScrollbarsColor(colortype color)
	Sets the color of the scrollbars.
void	setScrollbarsPermanentlyVisible(bool permanentlyVisible =true)
	Make scrollbars permanently visible regardless of the size and position of the children of the ScrollableContainer.
void	setScrollbarsVisible(bool newVisible)
	Sets the visibility of the scrollbars, when the scrollable area is pressed.
void	setScrollbarWidth(uint8_t width)
	Sets the width of the scrollbar measured in pixels.
void	setScrollDurationSlowdown(uint16_t slowdown)
	Sets scroll duration speedup divisor.
void	setScrollDurationSpeedup(uint16_t speedup)
	Sets scroll duration speedup multiplier.
void	setScrollThreshold(int16_t t)
	Change the threshold which the first drag event received must exceed before initiating a scroll.

Protected Functions

virtual bool	doScroll(int16_t deltaX, int16_t deltaY)
	Method to actually scroll the container.
Rect	getXBorder(const Rect & xBar, const Rect & yBar) const
	Gets the area where the horizontal scrollbar can move.
Rect	getXScrollbar() const
	Gets x coordinate of the scrollbar.
Rect	getYBorder(const Rect & xBar, const Rect & yBar) const
	Gets the area where the vertical scrollbar can move.
Rect	getYScrollbar() const
	Gets y coordinate of the scrollbar.
void	invalidateScrollbars()
	Invalidate the scrollbars.

Protected Attributes

GestureEvent::GestureEventType	accelDirection
	The current direction (horizontal or vertical) of scroll.
bool	animate
	Is scroll animation currently active.
uint16_t	animationCounter
	Current step/tick in scroll animation.
int16_t	beginningValue
	Initial X or Y for calculated values in scroll animation.
int16_t	fingerAdjustmentX
	How much should the finger be adjusted horizontally.
int16_t	fingerAdjustmentY
	and how much vertically
bool	hasIssuedCancelEvent
	true if the pressed drawable has received cancel event
bool	isPressed
	Is the container currently pressed (maybe show scrollbars)
bool	isScrolling
	Is the container scrolling (i.e. has overcome the initial larger drag that is required to initiate a scroll).
Drawable *	lastDraggableChild
	The drawable child of this container which should receive drag events. Note that only drag events in directions which cannot be scrolled by this ScrollableContainer will be forwarded to children.
uint16_t	maxVelocity
	The maximum velocity of a scroll (due to a swipe)
Drawable *	pressedDrawable
	The drawable child of this container which received the last ClickEvent::PRESSED notification. When scrolling, send this drawable a CANCEL event if the new x/y coords no longer matches this drawable.
int16_t	pressedX
	The x coordinate where the last ClickEvent::PRESSED was received.
int16_t	pressedY
	The y coordinate where the last ClickEvent::PRESSED was received.
bool	scrollableX
	Is the container scrollable in the horizontal direction.
bool	scrollableY
	Is the container scrollable in the vertical direction.
uint8_t	scrollbarAlpha
	The scrollbar is semitransparent.
colortype	scrollbarColor
	The color of the scrollbar.
uint8_t	scrollbarPadding
	The amount of padding. The scrollbar will have a bit of space to the borders of the container.
bool	scrollbarsPermanentlyVisible
	Are scrollbars always visible.
bool	scrollbarsVisible
	Are scrollbars visible.
uint8_t	scrollbarWidth
	The width of the scrollbar.
uint16_t	scrollDuration
	Number of ticks the scroll animation should use.
uint16_t	scrollDurationSlowdown
	The scroll durations is divided by this number.
uint16_t	scrollDurationSpeedup
	The scroll durations is multipled by this number.
int16_t	scrolledXDistance
	The scrolled horizontal distance.
int16_t	scrolledYDistance
	The scrolled vertical distance.
int16_t	scrollThreshold
	The threshold which the first drag event received must exceed before scrolling. Default is 5.
int16_t	targetValue
	Target X or Y value for scroll animation.
Box	xSlider
	The horizontal scrollbar drawable.
Box	ySlider
	The vertical scrollbar drawable.
const uint8_t	SCROLLBAR_LINE
	The scrollbar line.
const uint16_t	SCROLLBAR_MAX_VELOCITY
	The (default) maximum velocity of a scroll due to a swipe.
const uint16_t	SCROLLBAR_MIN_VELOCITY
	The minimum velocity of a scroll due to a swipe.

Additional inherited members

Public Functions inherited from Container

	Container()
virtual bool	contains(const Drawable & d)
	Query if a given Drawable has been added directly to this Container.
virtual void	draw(const Rect & invalidatedArea) const
	Draw this drawable.
virtual void	forEachChild(GenericCallback< Drawable & > * function)
	Executes the specified callback function for each child in the Container.
virtual Drawable *	getFirstChild()
	Obtain a pointer to the first child of this container.
virtual Rect	getSolidRect() const
	Get (the largest possible) rectangle that is guaranteed to be solid (opaque).
virtual void	insert(Drawable * previous, Drawable & d)
	Inserts a Drawable after a specific child node.
virtual void	remove(Drawable & d)
	Removes a Drawable from the container by removing it from the linked list of children.
virtual void	removeAll()
	Removes all children in the Container by resetting their parent and sibling pointers.
virtual void	unlink()
	Removes all children by unlinking the first child.

Protected Attributes inherited from Container

Drawable *	firstChild
	Pointer to the first child of this container. Subsequent children can be found through firstChild's nextSibling.

Public Functions inherited from Drawable

virtual void	draw(const Rect & invalidatedArea) const =0
	Draw this drawable.
	Drawable()
	Initializes a new instance of the Drawable class.
void	drawToDynamicBitmap(BitmapId id)
	Render the Drawable object into a dynamic bitmap.
Rect	getAbsoluteRect() const
	Helper function for obtaining the rectangle this Drawable covers, expressed in absolute coordinates.
virtual Drawable *	getFirstChild()
	Function for obtaining the first child of this drawable if any.
int16_t	getHeight() const
	Gets the height of this Drawable.
Drawable *	getNextSibling()
	Gets the next sibling node.
Drawable *	getParent() const
	Returns the parent node.
const Rect &	getRect() const
	Gets the rectangle this Drawable covers, in coordinates relative to its parent.
virtual Rect	getSolidRect() const =0
	Get (the largest possible) rectangle that is guaranteed to be solid (opaque).
virtual Rect	getSolidRectAbsolute()
	Helper function for obtaining the largest solid rect (as implemented by getSolidRect()) expressed in absolute coordinates.
virtual void	getVisibleRect(Rect & rect) const
	Function for finding the visible part of this drawable.
int16_t	getWidth() const
	Gets the width of this Drawable.
int16_t	getX() const
	Gets the x coordinate of this Drawable, relative to its parent.
int16_t	getY() const
	Gets the y coordinate of this Drawable, relative to its parent.
virtual void	invalidate() const
	Tell the framework that this entire Drawable needs to be redrawn.
virtual void	invalidateRect(Rect & invalidatedArea) const
	Request that a region of this drawable is redrawn.
bool	isTouchable() const
	Gets whether this Drawable receives touch events or not.
bool	isVisible() const
	Gets whether this Drawable is visible.
virtual void	moveRelative(int16_t x, int16_t y)
	Moves the drawable.
virtual void	moveTo(int16_t x, int16_t y)
	Moves the drawable.
virtual void	setHeight(int16_t height)
	Sets the height of this drawable.
void	setPosition(const Drawable & drawable)
	Sets the position of the Drawable to the same as the given Drawable.
void	setPosition(int16_t x, int16_t y, int16_t width, int16_t height)
	Sets the size and position of this Drawable, relative to its parent.
void	setTouchable(bool touch)
	Controls whether this Drawable receives touch events or not.
void	setVisible(bool vis)
	Controls whether this Drawable should be visible.
virtual void	setWidth(int16_t width)
	Sets the width of this drawable.
void	setWidthHeight(const Bitmap & bitmap)
	Sets the dimensions (width and height) of the Drawable without changing the x and y coordinates).
void	setWidthHeight(const Drawable & drawable)
	Sets the dimensions (width and height) of the Drawable without changing the x and y coordinates).
void	setWidthHeight(const Rect & rect)
	Sets the dimensions (width and height) of the Drawable without changing the x and y coordinates).
void	setWidthHeight(int16_t width, int16_t height)
	Sets the dimensions (width and height) of the Drawable without changing the x and y coordinates).
virtual void	setX(int16_t x)
	Sets the x coordinate of this Drawable, relative to its parent.
void	setXY(const Drawable & drawable)
	Sets the x and y coordinates of this Drawable.
void	setXY(int16_t x, int16_t y)
	Sets the x and y coordinates of this Drawable, relative to its parent.
virtual void	setY(int16_t y)
	Sets the y coordinate of this Drawable, relative to its parent.
virtual void	translateRectToAbsolute(Rect & r) const
	Helper function for converting a region of this Drawable to absolute coordinates.
virtual	~Drawable()
	Finalizes an instance of the Drawable class.

Protected Attributes inherited from Drawable

Drawable *	nextSibling
	Pointer to the next Drawable.
Drawable *	parent
	Pointer to this drawable's parent.
Rect	rect
	The coordinates of this Drawable, relative to its parent.
bool	touchable
	True if this drawable should receive touch events.
bool	visible
	True if this drawable should be drawn.

Public Functions Documentation

add

virtual void add	(	Drawable &	d	)

Adds a Drawable instance as child to this Container.

The Drawable added will be placed as the element to be drawn last, and thus appear on top of all previously added drawables in the Container.

Parameters:

d	The Drawable to add.

Note

Never add a drawable more than once!

Reimplements: touchgfx::Container::add

childGeometryChanged

virtual void childGeometryChanged	(			)

Used to signal that the size or position of one or more children have changed.

This function can be called on parent nodes to signal that the size of one or more of its children have changed.

Reimplements: touchgfx::Drawable::childGeometryChanged

enableHorizontalScroll

void enableHorizontalScroll	(	bool	enable	)

Enables horizontal scrolling.

By default, scrolling in either direction is enabled, provided that the content is larger than the size of the ScrollableContainer. This function can be used to explicitly (dis)allow horizontal scrolling, even if the content is larger than the container.

Parameters:

enable	If true (default), horizontal scrolling is enabled. If false, horizontal scrolling is disabled.

See also:

enableVerticalScroll

enableVerticalScroll

void enableVerticalScroll	(	bool	enable	)

Enables vertical scrolling.

By default, scrolling in either direction is enabled, provided that the content is larger than the size of the ScrollableContainer. This function can be used to explicitly (dis)allow vertical scrolling, even if the content is larger than the container.

Parameters:

enable	If true (default), vertical scrolling is enabled. If false, vertical scrolling is disabled.

See also:

enableHorizontalScroll

getContainedArea

virtual Rect getContainedArea	(			)	const

Gets the area that contains all children added to the ScrollableContainer.

The scrollbars are not considered in this operation.

Returns:

The contained area.

Reimplements: touchgfx::Container::getContainedArea

getLastChild

virtual void getLastChild	(	int16_t	x ,
		int16_t	y ,
		Drawable **	last
		)

Gets the last child in the list of children in this Container.

If this Container is touchable (isTouchable()), it will be passed back as the result. Otherwise all visible children are traversed recursively to find the Drawable that intersects with the given coordinate.

Parameters:

x	The x coordinate of the intersection.
y	The y coordinate of the intersection.
last	out parameter in which the result is placed.

See also:

isVisible, isTouchable

Reimplements: touchgfx::Container::getLastChild

getScrollDurationSlowdown

uint16_t getScrollDurationSlowdown	(			)	const

Gets scroll duration speedup divisor.

Returns:

The scroll duration speedup divisor.

See also:

setScrollDurationSlowdown

getScrollDurationSpeedup

uint16_t getScrollDurationSpeedup	(			)	const

Gets scroll duration speedup multiplier.

Returns:

The swipe acceleration.

See also:

setScrollDurationSpeedup, getScrollDurationSlowdown

getScrolledX

int16_t getScrolledX	(			)	const

Gets the distance scrolled for the x-axis.

Returns:

the distance scrolled for the x-axis.

getScrolledY

int16_t getScrolledY	(			)	const

Gets the distance scrolled for the y-axis.

Returns:

the distance scrolled for the y-axis.

handleClickEvent

virtual void handleClickEvent	(	const ClickEvent &	event	)

Defines the event handler interface for ClickEvents.

The default implementation ignores the event. The event is only received if the Drawable is touchable and visible.

Parameters:

event	The ClickEvent received from the HAL.

Reimplements: touchgfx::Drawable::handleClickEvent

handleDragEvent

virtual void handleDragEvent	(	const DragEvent &	event	)

Defines the event handler interface for DragEvents.

The default implementation ignores the event. The event is only received if the drawable is touchable and visible.

Parameters:

event	The DragEvent received from the HAL.

Reimplements: touchgfx::Drawable::handleDragEvent

handleGestureEvent

virtual void handleGestureEvent	(	const GestureEvent &	event	)

Defines the event handler interface for GestureEvents.

The default implementation ignores the event. The event is only received if the Drawable is touchable and visible.

Parameters:

event	The GestureEvent received from the HAL.

Reimplements: touchgfx::Drawable::handleGestureEvent

handleTickEvent

virtual void handleTickEvent	(			)

Called periodically by the framework if the Drawable instance has subscribed to timer ticks.

See also:

Application::registerTimerWidget

Reimplements: touchgfx::Drawable::handleTickEvent

isScrollableXY

virtual void isScrollableXY	(	bool &	scrollX ,
		bool &	scrollY
		)

Is the ClickableContainer scrollable in either direction? Takes the width of the contained elements into account and also checks to see if horizontal or vertical scrolling is allowed.

Parameters:

scrollX	True if the container is able to scroll horizontally.
scrollY	True if the container is able to scroll vertically.

See also:

enableHorizontalScroll, enableVerticalScroll

moveChildrenRelative

virtual void moveChildrenRelative	(	int16_t	deltaX ,
		int16_t	deltaY
		)

Calls moveRelative on all children.

Parameters:

deltaX	Horizontal displacement.
deltaY	Vertical displacement.

Note

Takes care not to move the scrollbars, which are also children.

Reimplements: touchgfx::Container::moveChildrenRelative

reset

void reset	(			)

Resets the ScrollableContainer to its original state, before the user started dragging the contents.

This reset the x/y coordinates of children to the position they were in before the first drag event was received.

ScrollableContainer

ScrollableContainer	(			)

setMaxVelocity

void setMaxVelocity	(	uint16_t	max	)

Sets the maximum velocity of a scroll due to a swipe.

This can be used to force smooth scrolling by limiting the speed of any swipe gesture.

Parameters:

max	The maximum velocity of the scroll.

See also:

GestureEvent::getVelocity

setScrollbarPadding

void setScrollbarPadding	(	uint8_t	padding	)

Sets the amount of space between the scrollbar and the edge of the ScrollableContainer.

Parameters:

padding	The padding.

setScrollbarsAlpha

void setScrollbarsAlpha	(	uint8_t	alpha	)

Sets the alpha value (transparency) of the scrollbars.

Parameters:

alpha	The alpha value. 255 being completely solid, 0 being completely invisible.

setScrollbarsColor

void setScrollbarsColor	(	colortype	color	)

Sets the color of the scrollbars.

Parameters:

color	The color of the box.

setScrollbarsPermanentlyVisible

void setScrollbarsPermanentlyVisible	(	bool	permanentlyVisible =true	)

Make scrollbars permanently visible regardless of the size and position of the children of the ScrollableContainer.

Normally the scrollbars are hidden and only shown when dragging the contents of the ScrollableContainer (unless prohibited using setScrollbarsVisible()).

Parameters:

permanentlyVisible	(Optional) True to show the scrollbars permanently, false for default behavior.

See also:

setScrollbarsVisible

setScrollbarsVisible

void setScrollbarsVisible	(	bool	newVisible	)

Sets the visibility of the scrollbars, when the scrollable area is pressed.

By default the scrollbars are hidden, but shown when the contents of the ScrollableContainer is being dragged around. Using setScrollbarsVisible, it is possible to hide the scrollbars when dragging the contents.

Parameters:

newVisible	If true (default), the scrollbars are visible when scrollable area is pressed. If false, scrollbars are always hidden.

See also:

setScrollbarsPermanentlyVisible

setScrollbarWidth

void setScrollbarWidth	(	uint8_t	width	)

Sets the width of the scrollbar measured in pixels.

Parameters:

width	The width of the scrollbar.

setScrollDurationSlowdown

void setScrollDurationSlowdown	(	uint16_t	slowdown	)

Sets scroll duration speedup divisor.

Default value is 1.

Parameters:

slowdown	The scroll duration speedup divisor.

See also:

setScrollDurationSpeedup, getScrollDurationSlowdown

setScrollDurationSpeedup

void setScrollDurationSpeedup	(	uint16_t	speedup	)

Sets scroll duration speedup multiplier.

Default value is 7 which gives a nice speedup on gestures.

Parameters:

speedup	The scroll duration speedup multiplier.

See also:

getScrollDurationSpeedup, setScrollDurationSlowdown

setScrollThreshold

void setScrollThreshold	(	int16_t	t	)

Change the threshold which the first drag event received must exceed before initiating a scroll.

This can be used to avoid touching the screen and moving the finger only a few pixels resulting in the contents being scrolled.

Parameters:

t	The new threshold value.

Note

All subsequent scrolls will be processed regardless of threshold value until a ClickEvent::RELEASED is received.

Protected Functions Documentation

doScroll

virtual bool doScroll	(	int16_t	deltaX ,
		int16_t	deltaY
		)

Method to actually scroll the container.

Passing negative values will scroll the items in the ScrollableContainer up / left, whereas positive values will scroll items down / right.

If the distance is larger than allowed, the deltas are adjusted down to make sure the contained items stay inside view.

Parameters:

deltaX	The horizontal amount to scroll.
deltaY	The vertical amount to scroll.

Returns:

did the container actually scroll. The call doScroll(0,0) will always return false.

getXBorder

Rect getXBorder	(	const Rect &	xBar ,		const
		const Rect &	yBar		const
		)	const

Gets the area where the horizontal scrollbar can move.

Parameters:

xBar	The current horizontal scrollbar, supplied for caching reasons.
yBar	The current vertical scrollbar, supplied for caching reasons.

Returns:

The area.

getXScrollbar

Rect getXScrollbar	(			)	const

Gets x coordinate of the scrollbar.

Returns:

The horizontal scrollbar area.

getYBorder

Rect getYBorder	(	const Rect &	xBar ,		const
		const Rect &	yBar		const
		)	const

Gets the area where the vertical scrollbar can move.

Parameters:

xBar	The current horizontal scrollbar, supplied for caching reasons.
yBar	The current vertical scrollbar, supplied for caching reasons.

Returns:

The area.

getYScrollbar

Rect getYScrollbar	(			)	const

Gets y coordinate of the scrollbar.

Returns:

The vertical scrollbar area.

invalidateScrollbars

void invalidateScrollbars	(			)

Invalidate the scrollbars.

Protected Attributes Documentation

accelDirection

GestureEvent::GestureEventType accelDirection

The current direction (horizontal or vertical) of scroll.

animate

bool animate

Is scroll animation currently active.

animationCounter

uint16_t animationCounter

Current step/tick in scroll animation.

beginningValue

int16_t beginningValue

Initial X or Y for calculated values in scroll animation.

fingerAdjustmentX

int16_t fingerAdjustmentX

How much should the finger be adjusted horizontally.

fingerAdjustmentY

int16_t fingerAdjustmentY

and how much vertically

hasIssuedCancelEvent

bool hasIssuedCancelEvent

true if the pressed drawable has received cancel event

isPressed

bool isPressed

Is the container currently pressed (maybe show scrollbars)

isScrolling

bool isScrolling

Is the container scrolling (i.e. has overcome the initial larger drag that is required to initiate a scroll).

lastDraggableChild

Drawable * lastDraggableChild

The drawable child of this container which should receive drag events. Note that only drag events in directions which cannot be scrolled by this ScrollableContainer will be forwarded to children.

maxVelocity

uint16_t maxVelocity

The maximum velocity of a scroll (due to a swipe)

pressedDrawable

Drawable * pressedDrawable

The drawable child of this container which received the last ClickEvent::PRESSED notification. When scrolling, send this drawable a CANCEL event if the new x/y coords no longer matches this drawable.

pressedX

int16_t pressedX

The x coordinate where the last ClickEvent::PRESSED was received.

pressedY

int16_t pressedY

The y coordinate where the last ClickEvent::PRESSED was received.

scrollableX

bool scrollableX

Is the container scrollable in the horizontal direction.

scrollableY

bool scrollableY

Is the container scrollable in the vertical direction.

scrollbarAlpha

uint8_t scrollbarAlpha

The scrollbar is semitransparent.

scrollbarColor

colortype scrollbarColor

The color of the scrollbar.

scrollbarPadding

uint8_t scrollbarPadding

The amount of padding. The scrollbar will have a bit of space to the borders of the container.

scrollbarsPermanentlyVisible

bool scrollbarsPermanentlyVisible

Are scrollbars always visible.

scrollbarsVisible

bool scrollbarsVisible

Are scrollbars visible.

scrollbarWidth

uint8_t scrollbarWidth

The width of the scrollbar.

scrollDuration

uint16_t scrollDuration

Number of ticks the scroll animation should use.

scrollDurationSlowdown

uint16_t scrollDurationSlowdown

The scroll durations is divided by this number.

scrollDurationSpeedup

uint16_t scrollDurationSpeedup

The scroll durations is multipled by this number.

scrolledXDistance

int16_t scrolledXDistance

The scrolled horizontal distance.

scrolledYDistance

int16_t scrolledYDistance

The scrolled vertical distance.

scrollThreshold

int16_t scrollThreshold

The threshold which the first drag event received must exceed before scrolling. Default is 5.

targetValue

int16_t targetValue

Target X or Y value for scroll animation.

xSlider

Box xSlider

The horizontal scrollbar drawable.

ySlider

Box ySlider

The vertical scrollbar drawable.

SCROLLBAR_LINE

const uint8_t SCROLLBAR_LINE = 0

The scrollbar line.

SCROLLBAR_MAX_VELOCITY

const uint16_t SCROLLBAR_MAX_VELOCITY = 17

The (default) maximum velocity of a scroll due to a swipe.

SCROLLBAR_MIN_VELOCITY

const uint16_t SCROLLBAR_MIN_VELOCITY = 5

The minimum velocity of a scroll due to a swipe.