"

 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.

"

"{ Package: 'stx:libbasic2' }"

"{ NameSpace: Smalltalk }"

Geometric subclass:#EllipticalArc

	instanceVariableNames:'boundingBox startAngle sweepAngle'

	classVariableNames:''

	poolDictionaries:''

	category:'Graphics-Geometry-Objects'

!

!EllipticalArc 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

"

     This class implements an ellipse which is aligned to x and y axes

     given a boundingBox, a startAngle and a sweepAngle.

     Positive angles are taken clockwise, negative angles are counterclockwise.

    [author:]

        Claus Gittinger

    [see also:]

        Circle Spline Curve LineSegment Polygon Rectangle Arrow

        ArrowedSpline

        GraphicsContext

        StrokingWrapper FillingWrapper

"

!

examples

"

  ellipses; filled & unfilled:

                                                                        [exBegin]

    |v e|

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

    e := EllipticalArc 

            boundingBox:(10@10 corner:190@90)

            startAngle:0

            endAngle:360. 

    v paint:Color blue.

    e displayFilledOn:v.

    v paint:Color red.

    e displayStrokedOn: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]

  more 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) 

    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.

    ].

                                                                        [exEnd]

  more 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]

"

! !

!EllipticalArc class methodsFor:'instance creation'!

boundingBox:aRectangle

    "Return a new EllipticalArc."

    ^ self new boundingBox:aRectangle

!

boundingBox:aRectangle startAngle:startAngle endAngle:endAngle

    "Return a new EllipticalArc."

    ^ self boundingBox:aRectangle startAngle:startAngle sweepAngle:(endAngle - startAngle)

!

boundingBox:aRectangle startAngle:startAngle sweepAngle:sweepAngle

    "Return a new EllipticalArc."

    ^ self new boundingBox:aRectangle startAngle:startAngle sweepAngle:sweepAngle

!

center:centerPoint radius:radius

    "Return a new Circle."

    ^ self new center:centerPoint radius:radius

!

center:centerPoint radius:radius startAngle:startAngle endAngle:endAngle

    "Return a new (circular) Arc."

    ^ (self new center:centerPoint radius:radius)

        startAngle:startAngle; sweepAngle:(endAngle - startAngle)

    "Created: 17.5.1996 / 09:58:36 / cg"

    "Modified: 17.5.1996 / 09:59:16 / cg"

!

center:centerPoint radius:radius startAngle:startAngle sweepAngle:sweepAngle

    "Return a new (circular) Arc."

    ^ (self new center:centerPoint radius:radius)

        startAngle:startAngle; sweepAngle:sweepAngle

    "Created: 17.5.1996 / 09:59:08 / cg"

! !

!EllipticalArc methodsFor:'accessing'!

boundingBox:aRectangle

    "setup the arc, given a bounding rectangle"

    boundingBox := aRectangle.

    startAngle := 0.

    sweepAngle := 360

    "Modified: 17.5.1996 / 10:05:06 / cg"

!

boundingBox:aRectangle startAngle:start sweepAngle:sweep

    "setup the arc, given a bounding rectangle, start and endAngle"

    boundingBox := aRectangle.

    startAngle := start.

    sweepAngle := sweep

    "Modified: 17.5.1996 / 10:05:27 / cg"

!

center:centerPoint radius:radius

    "setup for a circular arc, given center and radius"

    boundingBox := Rectangle

                        left:(centerPoint x - radius)

                        top:(centerPoint y - radius)

                        width:(radius * 2)

                        height:(radius * 2).

    startAngle := 0.

    sweepAngle := 360.

    "Created: 17.5.1996 / 10:07:35 / cg"

!

endAngle

    "return the endAngle."

    ^ startAngle + sweepAngle

!

startAngle

    "return the startAngle."

    ^ startAngle

!

startAngle:angle

    "set the startAngle."

    startAngle := angle

!

sweepAngle

    "return the sweepAngle."

    ^ sweepAngle

!

sweepAngle:angle

    "set the sweepAngle."

    sweepAngle := angle

! !

!EllipticalArc methodsFor:'converting'!

asEllipticalArc

    "convert the receiver into an ellipticalArc - that's the receiver itself"

    ^ self 

! !

!EllipticalArc methodsFor:'displaying'!

displayFilledOn:aGC

    "draw the receiver as a filled arc in a graphicsContext, aGC"

    aGC fillArcX:boundingBox left

               y:boundingBox top

           width:boundingBox width

          height:boundingBox height

            from:startAngle

              to:(startAngle+sweepAngle)

!

displayStrokedOn:aGC

    "draw the receiver as a unfilled arc in a graphicsContext, aGC"

    aGC displayArcX:boundingBox left

                  y:boundingBox top

              width:boundingBox width

             height:boundingBox height

               from:startAngle

              angle:sweepAngle

! !

!EllipticalArc methodsFor:'queries'!

center

    "return the center"

    ^ boundingBox center

!

computeBounds

    "return the smallest enclosing rectangle"

    ^ boundingBox

    "Created: 12.2.1997 / 11:43:00 / cg"

! !

!EllipticalArc methodsFor:'testing'!

canBeFilled

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

     Always true here."

    ^ true

! !

!EllipticalArc class methodsFor:'documentation'!

version

    ^ '$Header$'

! !