Class: Polygon

• Inheritance
• Description
• Related information
• Class protocol
  • instance creation
• Instance protocol
  • accessing
  • converting
  • displaying
  • enumerating
  • queries
  • testing
• Examples

Inheritance:

   Object
   |
   +--Geometric
      |
      +--Polygon
         |
         +--Polyline

Package:

stx:libbasic2

Category:

Graphics-Geometry-Objects

Version:

rev: 1.32 date: 2019/03/06 21:45:49

user: cg

file: Polygon.st directory: libbasic2

module: stx stc-classLibrary: libbasic2

Author:

Claus Gittinger

Description:

Polygon - an array of points

Adds simple boundary checking methods to Array.
(needs much more - such as inside check, area computation etc.)

Related information:

    Rectangle
    EllipticalArc
    Spline
    Circle
    Point
    LineSegment
    Curve
    Arrow
    ArroedSpline
    GraphicsContext
    StrokingWrapper
    FillingWrapper

Class protocol:

 fromRectangle: aRectangle

return a new polygon, taking the rectangles vertices

usage example(s):

Polygon fromRectangle:(50@50 corner:100@100)

 vertices: anArrayOfPoints

return a new polygon, given a collection of vertices

usage example(s):

Polygon vertices:(Array with:10@10 with:20@20 with:30@30) Polygon vertices:(#(10 10 100 0 50 50) pairWiseCollect:[:x :y | x @ y]).

Instance protocol:

 add: aPoint

 vertices

return the array containing my points

 vertices: anArrayOfPoints

set the array containing my points

 asChaikinCurve

return a new polygon, which is generated by applying
the chaikin corner cutting algorithm once
(see the example on the class side)

 asChaikinCurve: level

return a new polygon, which is generated by applying
the corner cutting algorithm n-times.
(see the example on the class side)

 asPointArray

return an array containing my vertex points.
Notice, that no copy of my vertices is created - you should not
modify the returned collections points (unless you want to affect
the polygon ...).

 displayFilledOn: aGC

display a filled polygin as represented by the receiver in
the graphicsContext, aGC

 displayStrokedOn: aGC

display an unfilled polygin as represented by the receiver in
the graphicsContext, aGC

 edgesDo: aTwoArgBlock

evaluate aTwoArgBlock for each pair of vertices

 verticesDo: aBlock

evaluate aBlock for each point

 bottom

return the bottom boundary of the polygon,
that is the maximum y coordinate of all its points

usage example(s):

(Polygon vertices:( Array with:10@10 with:60@10 with:35@60)) bottom

 computeBounds

return the smallest enclosing rectangle

 containsPoint: aPoint

return true, if the argument, aPoint is contained in the receiver

 left

return the left boundary of the polygon,
that is the minimum x coordinate of all its points

usage example(s):

(Polygon vertices:( Array with:10@10 with:60@10 with:35@60)) left

 right

return the right boundary of the polygon,
that is the maximum x coordinate of all its points

usage example(s):

(Polygon vertices:( Array with:10@10 with:60@10 with:35@60)) right

 top

return the top boundary of the polygon,
that is the minimum y coordinate of all its points

usage example(s):

(Polygon vertices:( Array with:10@10 with:60@10 with:35@60)) top

 canBeFilled

return true, if the receiver can be drawn as a filled geometric.
Always true here.

Examples:

  |v p|

  v := (View extent:200@200) openAndWait.

  p := Polygon vertices:
              (Array with:(10@10)
                     with:(90@90)
                     with:(10@90)).

  v scale:2.
  v paint:Color blue.
  p displayFilledOn:v.

  v paint:Color red.
  p displayStrokedOn:v.

  v scale:1; translation:100@0.
  v paint:Color green.
  p displayFilledOn:v.

  v paint:Color black.
  p displayStrokedOn:v.

  |v p|

  v := (View extent:200@200) openAndWait.
  v scale:2.

  p := Polygon vertices:
              (Array with:(10@10)
                     with:(90@90)
                     with:(50@90)
                     with:(90@10)
                     with:(10@90)
                                 ).

  v paint:Color blue.
  p displayFilledOn:v.

  v paint:Color red.
  p displayStrokedOn:v.

   |p p2 v|

   p := Polygon 
          vertices:{
              0 @ 0 .
              0 @ 100 .
              100 @ 100 .
              110 @ -10 .
              200 @ 150 
          }.

   v := (View extent:300@300) openAndWait.
   v translateBy:50@250.
   v scale:(1 @ -1).
   v paint:Color blue.
   p displayStrokedOn:v.

   p2 := p asChaikinCurve:10.
   v paint:Color red.
   p2 displayStrokedOn:v.