Smalltalk/X Webserver

Documentation of class 'Polygon':

Class: Polygon

Inheritance
Description
Class protocol
- instance creation
Instance protocol
Examples

Inheritance:

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

Package:: stx:libbasic2

Category:: Graphics-Geometry-Objects

Version:: rev: 1.38 date: 2022/03/08 22:45:44; user: cg; file: Polygon.st directory: libbasic2; module: stx stc-classLibrary: libbasic2

Description:

Polygon - an array of points

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

copyrightCOPYRIGHT (c) 1988 by Claus Gittinger
             All Rights Reserved

This software is furnished under a license and may be used
only in accordance with the terms of that license and with the
inclusion of the above copyright notice.   This software may not
be provided or otherwise made available to, or used by, any
other person.  No title to or ownership of the software is
hereby transferred.

Class protocol:

instance creation

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]).

Usage example(s):

     |p v|

     v := View new openAndWaitUntilVisible.
     p := Polygon 
            vertices:(Array with:10@10
                            with:20@10
                            with:20@30).
     p displayOn:v

Instance protocol:

accessing

add: aPoint
vertices: return the array containing my points
vertices: anArrayOfPoints: set the array containing my points

converting

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)

Usage example(s):

     |p p2 p3 v|
     
     p := Polygon 
            vertices:{
                0 @ 0 .
                0 @ 100 .
                100 @ 100 .
                110 @ -10 .
                200 @ 150 
            }.
            
     v := (View extent:300@300) openAndWaitUntilVisible.
     v translateBy:50@250.
     v scale:(1 @ -1).
     v paint:Color blue.
     p displayStrokedOn:v.

     p2 := p asChaikinCurve:1.
     v paint:Color black.
     p2 displayStrokedOn:v.

     p3 := p asChaikinCurve:10.
     v paint:Color red.
     p3 displayStrokedOn:v.

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 ...).

displaying

displayFilledOn: aGC

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

Usage example(s):

     |v|
     v := View new openAndWaitUntilVisible.

     (Polygon vertices:(
          Array
            with:10@10
            with:60@10
            with:35@60)) displayFilledOn:v

     |v|
     v := View new openAndWaitUntilVisible.

     (Polygon vertices:(
        Array
            with:10@10
            with:60@10
            with:35@60
            with:10@10)) displayStrokedOn:v

displayStrokedOn: aGC

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

Usage example(s):

     |v|

     v := View new open.
     [v shown] whileFalse:[Processor yield].

     (Polygon vertices:(
        Array
            with:10@10
            with:60@10
            with:35@60)) displayStrokedOn:v

     |v|

     v := View new open.
     [v shown] whileFalse:[Processor yield].

     (Polygon vertices:(
        Array
            with:10@10
            with:60@10
            with:35@60
            with:10@10)) displayStrokedOn:v

enumerating

edgesDo: aTwoArgBlock

evaluate aTwoArgBlock for each pair of vertices

Usage example(s):

     |v p|

     v := View new open.
     [v shown] whileFalse:[Processor yield].

     p := Polygon vertices:(Array with:5@5 
				  with:50@5 
				  with:30@30
				  with:5@5).

     p displayOn:v.
     (Delay forSeconds:3) wait.

     p edgesDo:[:p1 :p2 | v lineWidth:3. v displayLineFrom:p1 to:p2]

verticesDo: aBlock

evaluate aBlock for each point

Usage example(s):

     |v p|

     v := View new open.
     [v shown] whileFalse:[Processor yield].

     p := Polygon vertices:(Array with:5@5 
				  with:50@5 
				  with:30@30
				  with:5@5).

     p displayOn:v.
     (Delay forSeconds:3) wait.

     p verticesDo:[:p | v displayRectangleX:p x -3  y:p y -3  width:6 height:6]

queries

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

Usage example(s):

     |p|

     p := Polygon vertices:(Array 
                             with:10@10
                             with:30@10
                             with:20@20).
     TestCase assert:(p containsPoint:14@11).     
     TestCase assert:(p containsPoint:15@15).     
     TestCase assert:(p containsPoint:5@15) not.
     TestCase assert:(p containsPoint:15@5) not.
     TestCase assert:(p containsPoint:30@15) not. 
     TestCase assert:(p containsPoint:20@15).

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

testing

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

transformations

roundedToNearestIntegerPoint: return a copy of the receiver, where all points are rounded to ly on the nearest integer coordinate
transformedBy: aMatrix: return a copy of the receiver, which is transformed using aMatrix

Examples:

simple polygon; filled & unfilled:

  |v p|

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

  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.

arbitrary polygon; filled & unfilled:

  |v p|

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

chaikin curve fitting:

   |p p2 v|

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

   v := (View extent:300@300) openAndWaitUntilVisible.
   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.

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