►GUI: Racket Graphics Toolkit
►2 Reference
▼2.3 Drawing Classes
2.3.1 bitmap%
2.3.2 bitmap-dc%
2.3.3 brush%
2.3.4 brush-list%
2.3.5 color%
2.3.6 color-database<%>
2.3.7 dc<%>
2.3.8 dc-path%
2.3.9 font%
2.3.10 font-list%
2.3.11 font-name-directory<%>
2.3.12 gl-config%
2.3.13 gl-context<%>
2.3.14 pen%
2.3.15 pen-list%
2.3.16 point%
2.3.17 post-script-dc%
2.3.18 printer-dc%
2.3.19 ps-setup%
2.3.20 region%
On this page:
find-or-create-pen
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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.

(new pen-list%) → (is-a?/c pen-list%)
Creates an empty pen list.

(send a-pen-list find-or-create-pen color    
  width    
  style    
  [cap    
  join]) → (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)
  cap : (one-of/c 'round 'projecting 'butt) = 'round
  join : (one-of/c 'round 'bevel 'miter) = 'round
(send a-pen-list find-or-create-pen color-name 
  width 
  style 
  [cap 
  join]) 
 → (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)
  cap : (one-of/c 'round 'projecting 'butt) = 'round
  join : (one-of/c 'round 'bevel 'miter) = 'round
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 plus a cap and join style as for set-cap and set-join. When color-name is provided, however, the return value is #f when no color matching color-name can be found in the-color-database.

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