Class: Circle

• Inheritance
• Description
• Class protocol
  • instance creation
• Instance protocol
  • accessing
  • converting
  • displaying
  • queries
  • testing
  • transformations
• Examples

Inheritance:

   Object
   |
   +--Geometric
      |
      +--Circle

Package:

stx:libbasic2

Category:

Graphics-Geometry-Objects

Version:

rev: 1.23 date: 2022/02/17 10:25:36

user: cg

file: Circle.st directory: libbasic2

module: stx stc-classLibrary: libbasic2

Description:

This class implements a circles which are defined by a radius and
a centerpoint.

copyright
COPYRIGHT (c) 1995 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:

 boundingBox: aRectangle

Return a new Circle centered in aRectangle.

 center: centerPoint radius: radius

Return a new Circle.

Instance protocol:

 center

return the center.

 center: aPoint

set the center point.

 center: centerPoint radius: radiusNumber

set the center and radius

 radius

return the radius.

 radius: aNumber

set the radius.

 asEllipticalArc

convert the receiver into an ellipticalArc

 displayFilledOn: aGC

draw the receiver as a filled circle in a graphicsContext, aGC

 displayStrokedOn: aGC

draw the receiver as a unfilled circle in a graphicsContext, aGC

 area

return the area of the receiver.

 computeBounds

return the smallest enclosing rectangle

 diameter

return the diameter of the receiver.

 startAngle

return the startAngle.
Provided for protocol compatibility with arcs and ellipese;
for circles, this is an arbitrary angle.

 sweepAngle

return the sweepAngle.
Provided for protocol compatibility with arcs and ellipese;
for circles, this is always 360 degrees.

 canBeFilled

return true, if the receiver can be drawn filled; always true here

 rotatedBy: angle about: centerPoint

return a copy of the receiver, which is rotated around rotationCenter
by an angle (radians) around rotationCenter (which may be located outside);
the angle is interpreted as counter-clockwise (same as in Point >> rotatedBy:)

 roundedToNearestIntegerPoint

return a copy of the receiver, where all points are rounded to ly on the nearest integer coordinate

 scaledBy: amount

return a new circle which is scaled (i.e. moved)
by amount, aPoint or Number

Usage example(s):

(Circle center:10@10 radius:50) scaledBy:2

 translatedBy: amount

return a copy of the receiver which is translated (i.e. moved)
by amount, aPoint or Number

Usage example(s):

(Circle center:10@10 radius:50) translatedBy:10 (Circle center:10@10 radius:50) translatedBy:(10@20)

Examples:

  |v c|

  v := (View extent:200@100) openAndWaitUntilVisible.

  c := Circle boundingBox:(10@10 corner:90@90). 

  v paint:Color blue.
  c displayFilledOn:v.

  c center:150@50.
  v paint:Color red.
  c displayStrokedOn:v.

  |v c|

  v := (View extent:100@100) openAndWaitUntilVisible.

  c := Circle center:50@50 radius:40. 

  v paint:Color red.
  c asRectangle displayFilledOn:v.

  v paint:Color blue.
  c displayFilledOn:v.

  |v c|

  v := View new openAndWaitUntilVisible.

  c := Circle center:50@50 radius:40.

  v paint:Color red.
  c displayFilledOn:v.
  50 to:1 by:-1 do:[:r |
      c radius:r.
      v paint:(Color grey:(r * 2)).
      c displayStrokedOn:v.
  ].
  1 to:50 do:[:r |
      c radius:r.
      v paint:(Color grey:100-(r * 2)).
      c displayStrokedOn:v.
  ]

  |v ell|

  v := View new openAndWaitUntilVisible.

  ell := EllipticalArc
              boundingBox:(10@10 corner:90@90) 
              startAngle:0
              sweepAngle:0.

  #(45 90 135 180 225 270 315 360) 
  keysAndValuesReverseDo:[:index :angle |
      index odd ifTrue:[
          v paint:Color white
      ] ifFalse:[
          v paint:Color black
      ].
      ell sweepAngle:angle.
      ell displayFilledOn:v.
      Delay waitForSeconds:0.1.
  ].

  |v ell|

  v := View new openAndWaitUntilVisible.

  ell := EllipticalArc
              boundingBox:(10@10 corner:90@90) 
              startAngle:0
              sweepAngle:45.

  #(45 90 135 180 225 270 315 360) 
  with:#( 0.125 0.25 0.375 0.5 0.625 0.75 0.875 1)
  do:[:angle :grey |
      ell startAngle:angle-45.
      v paint:(ColorValue red:grey green:0 blue:0).
      ell displayFilledOn:v.
  ].