"
 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.
"

Object subclass:#Geometric
	instanceVariableNames:''
	classVariableNames:''
	poolDictionaries:''
	category:'Graphics-Geometry'
!

!Geometric class methodsFor:'documentation'!

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.
"
!

documentation
"
    Abstract superclass for geometric figures.
    Concrete classes are (currently) Rectangle, Polygon and the classes
    found in goodies/shape.

    These are not graphical objects, but pure mathematical ones.
    I.e. instances do not carry graphics attributes such as color, lineWidth etc.
    However, they ``know'' how to display themself as stroked or possibly
    filled picture on a graphicsContext (although, the GC's current
    paint and lineStyles are used).

    Use instances of (subclasses) of DisplayObject or 
    of the GeometricWrapper classes for objects which keep the color 
    and lineStyle information with them.

    Notice: 
        ST/X does not use Geometric instances for drawing (yet).
        Except for Rectangle, Geometry and its subclasses exists mainly 
        for ST-80 compatibility and to provide a home when other (PD) 
        geometry classes are to be filed in.

    [author:]
        Claus Gittinger

    [see also:]
        Rectangle Polygon EllipticalArc Circle Spline Point
        LineSegment Curve Arrow ArrowedSpline
        GraphicsContext
        StrokingWrapper FillingWrapper
"
!

examples
"
  line segment:
                                                                        [exBegin]
    |v l|

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

    l := LineSegment from:10@10 to:90@90. 

    v paint:Color red.
    l displayStrokedOn:v.

    l start:90@10 end:10@90.
    v paint:Color blue.
    l displayStrokedOn:v.
                                                                        [exEnd]

  rectangle, unfilled:
                                                                        [exBegin]
    |v r|

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

    r := Rectangle origin:10@10 corner:90@90. 

    v paint:Color red.
    r displayStrokedOn:v.
                                                                        [exEnd]

  circle; filled and unfilled:
                                                                        [exBegin]
    |v c|

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

    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.

                                                                        [exEnd]
  circle & rectangle; both filled:
                                                                        [exBegin]
    |v c|

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

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

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

    v paint:Color blue.
    c displayFilledOn:v.

                                                                        [exEnd]
  elliptical arcs; filled & unfilled:
                                                                        [exBegin]
    |v e|

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

    e := EllipticalArc 
            boundingBox:(10@10 corner:190@90)
            startAngle:0
            endAngle:270. 

    v paint:Color blue.
    e displayFilledOn:v.

    v paint:Color red.
    e displayStrokedOn:v.

                                                                        [exEnd]
  polygon; filled & unfilled:
                                                                        [exBegin]
    |v p|

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

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

    v paint:Color blue.
    p displayFilledOn:v.

    v paint:Color red.
    p displayStrokedOn:v.
                                                                        [exEnd]

  circles; filled & unfilled:
                                                                        [exBegin]
    |v c|

    v := View new openAndWait.

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

    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.
    ]

                                                                        [exEnd]
  arcs; filled:
                                                                        [exBegin]
    |v ell|

    v := View new openAndWait.

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

    #(45 90 135 180 225 270 315 360) keysAndValuesDo:[:index :angle |
        index odd ifTrue:[
            v paint:Color white
        ] ifFalse:[
            v paint:Color black
        ].
        ell sweepAngle:angle.
        ell displayFilledOn:v.
        Delay waitForSeconds:0.5.
    ].

                                                                        [exEnd]
  arcs; filled:
                                                                        [exBegin]
    |v ell|

    v := View new openAndWait.

    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.
    ].

                                                                        [exEnd]
  spline; filled & unfilled:
                                                                        [exBegin]
    |v p|

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

    p := Spline controlPoints:
                (Array with:(20@20)
                       with:(80@80)
                       with:(20@80)).

    v paint:Color blue.
    p displayFilledOn:v.

    v paint:Color red.
    p displayStrokedOn:v.
                                                                        [exEnd]

  closed spline; filled & unfilled:
                                                                        [exBegin]
    |v p|

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

    p := Spline controlPoints:
                (Array with:(20@20)
                       with:(80@80)
                       with:(20@80)
                       with:(20@20)).

    v paint:Color blue.
    p displayFilledOn:v.

    v paint:Color red.
    p displayStrokedOn:v.
                                                                        [exEnd]
"
! !

!Geometric methodsFor:'converting'!

asFiller
    "return a wrapper which displays the receiver in its filled form"

    ^ FillingWrapper on:self

    "Created: 8.5.1996 / 14:38:59 / cg"
    "Modified: 8.5.1996 / 18:22:56 / cg"
!

asRectangle
    "return the enclosing rectangle; same as #bounds"

    ^ self bounds

    "Created: 8.5.1996 / 14:36:35 / cg"
!

asStroker
    "return a wrapper which displays the receiver as stroked outline"

    ^ StrokingWrapper on:self

    "Created: 8.5.1996 / 14:38:09 / cg"
    "Modified: 8.5.1996 / 18:23:00 / cg"
! !

!Geometric methodsFor:'displaying'!

displayFilledOn:aGC
    "display myself filled on a graphicsContext; the current graphics
     attributes are used. Since we do not know how to do it, nothing is
     drawn here."

    ^ self subclassResponsibility

    "Modified: 8.5.1996 / 09:07:02 / cg"
!

displayOn:aGC
    "display myself on a graphicsContext; the current graphics
     attributes are used. The default here is to display the outline."

    ^ self displayStrokedOn:aGC
!

displayStrokedOn:aGC
    "display my outline on a graphicsContext; the current graphics
     attributes are used. Since we do not know how to do it, nothing is
     drawn here."

    ^ self subclassResponsibility

    "Modified: 8.5.1996 / 21:20:19 / cg"
! !

!Geometric methodsFor:'queries'!

bounds
    "return the smallest enclosing rectangle"

    ^ self subclassResponsibility

    "Created: 8.5.1996 / 13:56:08 / cg"
    "Modified: 8.5.1996 / 14:06:31 / cg"
!

canBeFilled
    "return true, if the receiver can be drawn as a filled geometric.
     Return false here, since we dont know."

    ^ false

    "Created: 1.6.1996 / 11:28:58 / cg"
! !

!Geometric class methodsFor:'documentation'!

version
    ^ '$Header: /cvs/stx/stx/libbasic/Geometric.st,v 1.20 1996-06-01 09:29:59 cg Exp $'
! !