pen-list% : class?

superclass: object%

A pen-list% object maintains a list of pen% objects to avoid repeatedly creating pen objects. A pen% object in a pen list cannot be mutated.

A global pen list the-pen-list is created automatically.

(make-object pen-list%) → (is-a?/c pen-list%)

Creates an empty pen list.

(send a-pen-list find-or-create-pen   color             width             style)   →   (is-a?/c pen%)

color : (is-a?/c color%)

width : (real-in 0 255)

style   :   (one-of/c 'transparent 'solid 'xor 'hilite           'dot 'long-dash 'short-dash 'dot-dash           'xor-dot 'xor-long-dash 'xor-short-dash           'xor-dot-dash)

(send a-pen-list find-or-create-pen   color-name       width       style)

→ (or/c (is-a?/c pen%) false/c)

color-name : string?

width : (real-in 0 255)

style   :   (one-of/c 'transparent 'solid 'xor 'hilite           'dot 'long-dash 'short-dash 'dot-dash           'xor-dot 'xor-long-dash 'xor-short-dash           'xor-dot-dash)

Finds a pen of the given specification, or creates one and adds it to the list. The arguments are the same as for creating a pen% instance. When color-name is provided, however, the return value is #f when no color matching color-name can be found in the-color-database.