src/swipl-devel/packages/xpce/man/refmanual/md/pen.md

In rswipl: Embed 'SWI'-'Prolog'

class pen {#class-pen}

A pen holds the stroke parameters used by graphicals when drawing lines and borders: line thickness, dash pattern (texture) and stroke colour. Pens are normally manipulated indirectly through the graphical->pen, graphical->texture and graphical->colour slots rather than created as explicit objects, but they may be constructed and passed where a pen-valued argument is expected.

@see class graphical @see class colour @see graphical->pen

Instance variables {#class-pen-instvars}

• pen<->thickness: 0.. Line thickness in pixels. 0 selects the thinnest device line.

• pen<->texture: texture_name Dash pattern. One of none, dotted, dashed, dashdot, dashdotted or longdash.

• pen<->colour: [colour] Stroke colour, or @default to use the graphical's foreground.

Send methods {#class-pen-send}

• pen->initialise: thickness=[0..], texture=[texture_name], colour=[colour|pixmap] Create a pen from a thickness, texture and stroke colour. Omitted arguments default to 1, none and @default respectively.

Get methods {#class-pen-get}

• pen<-convert: 0.. -> pen Convert an integer to a pen of the indicated thickness with default texture and colour. Used by the type-checker to coerce integer pen-valued arguments.

rswipl documentation built on June 16, 2026, 5:07 p.m.