Class: Bezier

• Inheritance
• Description
• Class protocol
  • class initialization
  • instance creation
• Instance protocol
  • accessing
  • comparing
  • converting
  • displaying
  • private
  • testing
  • transforming
• Examples

Inheritance:

   Object
   |
   +--Geometric
      |
      +--Bezier

Package:

stx:libbasic2

Category:

Graphics-Geometry-Objects

Version:

rev: 1.5 date: 2003/08/29 17:31:58

user: cg

file: Bezier.st directory: libbasic2

module: stx stc-classLibrary: libbasic2

Author:

unknown (based upon the PD path package)

Description:

Beziers represent parametric cubic curvea.

[instance variables:]
    start                   <Point>         startPoint of the curve.
    end                     <Point>         endPoint of the curve.
    controlPoint1           <Point>         control point.
    controlPoint2           <Point>         control point.

[class variables:]
    ScaledFlatness          <Integer>       curves flatness parameter

Class protocol:

 initialize

initialize class constants

usage example(s):

Bezier initialize

 start: startPoint end: endPoint controlPoint1: controlPoint1 controlPoint2: controlPoint2

create & return a new bezier curve

Instance protocol:

 controlPoint1

return the first controlPoint

 controlPoint2

return the second controlPoint

 end

return the endPoint

 start

return the startPoint

 = anObject

return true, if the receiver and the arg represent the same bezier curve

 hash

return an integer useful as hashKey;
redefined, since = is redefined

 asLine

return a line from the startPoint to the endPoint

 asPolyline

return a polygon which approximates the curve

 displayFilledOn: aGraphicsContext

report an error: cannot be filled.

 displayStrokedOn: aGraphicsContext

display the curve as an outline

 addPointsFromStartX: p1X y: p1Y control1X: p2X y: p2Y control2X: p3X y: p3Y endX: p4X y: p4Y to: aCollection

actual workHorse for point computation

 computeBounds

return the reactngle which encloses the curve.

 computePoints

compute the points along the bezier - return a collection of points

 setStart: startPoint end: endPoint controlPoint1: cp1 controlPoint2: cp2

 outlineIntersects: aRectangle

return true, if the curve intersects a rectangle

 scaledBy: scaleFactor

return a copy of the receiver, which is scaled by some amount

 translatedBy: translation

return a copy of the receiver, which is translated by some amount

Examples:

  |v s|

  v := (View extent:110@110) openAndWait.

  s := Bezier
          start:10@10
          end:100@100
          controlPoint1:50@50
          controlPoint2:10@80.

  v paint:Color red.
  s displayStrokedOn:v.

  v paint:Color black.
  v displayPoint:10@10.
  v displayPoint:100@100.
  v displayPoint:50@50.
  v displayPoint:10@80.