itemview

Shared vertical item viewport helpers for List and Dropdown.

Types

ItemViewScrollbarMode

ItemViewScrollbarMode = "auto"|"always"|"hidden"

ItemViewGeometry

Field	Type	Description
show	boolean	Whether the scrollbar is visible
rows	integer	Visible row count
maximum	integer	Greatest valid item offset
offset	integer	Clamped current item offset
thumbSize	integer	Scrollbar thumb size
thumbPos	integer	Zero-based scrollbar thumb position

Methods

itemview.maxOffset(count, rows)

Returns the greatest valid item offset for a viewport.

• count (integer) Item count

• rows (integer) Visible row count

• returns offset (integer)

itemview.clampOffset(offset, count, rows)

Clamps an item offset to the visible collection range.

• offset (number, optional) Requested offset

• count (integer) Item count

• rows (integer) Visible row count

• returns offset (integer)

itemview.ensureVisible(offset, index, count, rows)

Adjusts an offset until the requested item is visible.

• offset (number) Current offset

• index (integer, optional) Item index

• count (integer) Item count

• rows (integer) Visible row count

• returns offset (integer)

itemview.geometry(count, rows, offset, mode)

Calculates scrollbar geometry for an item viewport.

• count (integer) Item count

• rows (integer) Visible row count

• offset (number, optional) Current item offset

• mode (ItemViewScrollbarMode) Scrollbar mode

• returns geometry (ItemViewGeometry)

itemview.draw(buf, x, y, geometry, foreground, track, thumb)

Draws the scrollbar(s) into the buffer.

• buf (Render) Render buffer
• x (integer) Scrollbar x position
• y (integer) Scrollbar y position
• geometry (ItemViewGeometry) Viewport geometry
• foreground (number) Foreground color
• track (number) Track color
• thumb (number) Thumb color

itemview.pointerDown(coordinate, geometry)

Resolves a scrollbar press into a new offset or drag grab position.

• coordinate (integer) Coordinate along the scrollbar

• geometry (ItemViewGeometry) Geometry returned by itemview.geometry

• returns offset (integer|nil)

• returns grab (integer|nil)

itemview.drag(coordinate, grab, geometry)

Converts a scrollbar drag position into an item offset.

• coordinate (integer) Coordinate along the scrollbar

• grab (integer) Thumb grab offset

• geometry (ItemViewGeometry) Geometry returned by itemview.geometry

• returns offset (integer)