Class: Curve

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

Inheritance:

   Object
   |
   +--Geometric
      |
      +--Curve

Package:

stx:libbasic2

Category:

Graphics-Geometry-Objects

Version:

rev: 1.12 date: 2022/02/17 10:25:29

user: cg

file: Curve.st directory: libbasic2

module: stx stc-classLibrary: libbasic2

Description:

A Curve is a conic section determined by three points
that interpolates the first and the third and is tangent to the angle formed
by the three points at the first and third points.

copyright
COPYRIGHT (c) 1996 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:

 from: startPoint to: endPoint through: middlePoint

return a new curve, passing through the three given points

 start: startPoint middle: middlePoint end: endPoint

return a new curve, passing through the three given points

 with: startPoint with: middlePoint with: endPoint

return a new curve, passing through the three given points

Instance protocol:

 end

return the endPoint

 start

return the startPoint

 start: p1 middle: p2 end: p3

set the startPoint, middlePoint and the endPoint

 asPointArray

return an array containing my points.

 asPolygon

return a polygon, approximating the spline

 displayFilledOn: aGC

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

 displayStrokedOn: aGC

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

 computeLineSegments

compute the lines which approxiamte this curve

 computeBounds

return the smallest enclosing rectangle

 canBeFilled

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

Examples:

  |v c|

  v := (View extent:200@200) openAndWaitUntilVisible.
  v transformation:(WindowingTransformation 
                      scale:1 
                      translation:(100@100)).
   
  v paint:Color black.
  v displayLineFrom:(-90@0) to:(90@0).
  v displayLineFrom:(0@-90) to:(0@90).

  c := Curve start:(20@20) middle:(80@80) end:(20@80).

  v paint:Color blue.
  c displayFilledOn:v.

  v paint:Color red.
  c displayStrokedOn:v.

  |v c|

  v := (View extent:200@200) openAndWaitUntilVisible.
  v transformation:(WindowingTransformation 
                      scale:1 
                      translation:(100@100)).

  v paint:Color black.
  v displayLineFrom:(-90@0) to:(90@0).
  v displayLineFrom:(0@-90) to:(0@90).

  c := Curve start:(0@20) middle:(40@60) end:(0@80).

  v paint:Color blue.
  c displayFilledOn:v.

  v paint:Color red.
  c displayStrokedOn:v.

  |v c|

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

  v lineStyle:#dashed.
  v displayLineFrom:(20@0) to:(20@200).
  v displayLineFrom:(180@0) to:(180@200).

  v displayLineFrom:(0@20) to:(200@20).
  v displayLineFrom:(0@80) to:(200@80).

  v lineStyle:#solid.
  c := Curve start:(20@20) middle:(180@80) end:(20@80).

  v paint:Color blue.
  c displayFilledOn:v.

  v paint:Color red.
  c displayStrokedOn:v.

  v paint:(Color black).
  v displayLineFrom:(20@20) to:(180@80).
  v displayLineFrom:(20@80) to:(180@80).