Marcel Taeumel uploaded a new version of ST80 to project The Trunk:
http://source.squeak.org/trunk/ST80-ct.269.mcz

==================== Summary ====================

Name: ST80-ct.269
Author: ct
Time: 17 April 2021, 10:06:28.149652 pm
UUID: 2f319f7f-9553-0d47-94ea-f3398af6f4b4
Ancestors: ST80-mt.268

Reuse new Arc >> #computeVertices: to display arcs. Complements ST80-ct.240. Also added an extension point for modifying the granularity of arcs, #numberOfVertices.

Sorry for the confusion, this patch has somehow went down in my changes file. :-)

Benchmarks: Use anArc from Arc example and do: [anArc displayOn: Display] bench.
Before: 726 microseconds per run.
After: 650 microseconds per run.

=============== Diff against ST80-mt.268 ===============

Item was changed:
  Path subclass: #Arc
+ 	instanceVariableNames: 'quadrant radius center numberOfVertices'
- 	instanceVariableNames: 'quadrant radius center'
  	classVariableNames: ''
  	poolDictionaries: ''
  	category: 'ST80-Paths'!
  
  !Arc commentStamp: '<historical>' prior: 0!
  Arcs are an unusual implementation of splines due to Ted Kaehler.  Imagine two lines that meet at a corner. Now imagine two moving points; one moves from the corner to the end on one line, the other moves from the end of the other line in to the corner.  Now imagine a series of lines drawn between those moving points at each step along the way (they form a sort of spider web pattern).  By connecting segments of the intersecting lines, a smooth curve is achieved that is tangent to both of the original lines.  Voila.!

Item was changed:
  ----- Method: Arc>>computeVertices: (in category 'displaying') -----
  computeVertices: size
  
  	| dAngle dSin dCos point |
  	dAngle := (90 / (size - 1)) degreesToRadians.
  	dSin := dAngle sin.
  	dCos := dAngle cos.
  	point := (1 to: quadrant)
  		inject: 0 @ radius
  		into: [:p :i | p leftRotated].
  	^ (OrderedCollection new: size)
  		add: (center + point) rounded;
+ 		addAll: ((2 to: size) collect: [:i |
- 		addAll: ((1 to: size - 1) collect: [:i |
  			point := point * dCos + (point * dSin) leftRotated.
  			(center + point) rounded]);
  		yourself!

Item was changed:
  ----- Method: Arc>>displayOn:at:clippingBox:rule:fillColor: (in category 'displaying') -----
  displayOn: aDisplayMedium at: aPoint clippingBox: clipRect rule: anInteger fillColor: aForm
  
+ 	| line |
- 	| nSegments line angle sin cos xn yn |
- 	nSegments := 12.0.
  	line := Line new.
  	line form: self form.
+ 	(self computeVertices: self numberOfVertices) overlappingPairsDo: [:start :dest |
+ 		line
+ 			beginPoint: start;
+ 			endPoint: dest;
+ 			displayOn: aDisplayMedium
- 	angle := (90.0 / nSegments) degreesToRadians.
- 	sin := angle sin.
- 	cos := angle cos.
- 	quadrant = 1
- 		ifTrue: 
- 			[xn := radius asFloat.
- 			yn := 0.0].
- 	quadrant = 2
- 		ifTrue: 
- 			[xn := 0.0.
- 			yn := 0.0 - radius asFloat].
- 	quadrant = 3
- 		ifTrue: 
- 			[xn := 0.0 - radius asFloat.
- 			yn := 0.0].
- 	quadrant = 4
- 		ifTrue: 
- 			[xn := 0.0.
- 			yn := radius asFloat].
- 	nSegments asInteger
- 		timesRepeat: 
- 			[ | xn1 yn1 |
- 			xn1 := xn * cos + (yn * sin).
- 			yn1 := yn * cos - (xn * sin).
- 			line beginPoint: center + (xn asInteger @ yn asInteger).
- 			line endPoint: center + (xn1 asInteger @ yn1 asInteger).
- 			line
- 				displayOn: aDisplayMedium
  				at: aPoint
  				clippingBox: clipRect
  				rule: anInteger
+ 				fillColor: aForm]!
- 				fillColor: aForm.
- 			xn := xn1.
- 			yn := yn1]!

Item was added:
+ ----- Method: Arc>>numberOfVertices (in category 'accessing') -----
+ numberOfVertices
+ 
+ 	^ numberOfVertices ifNil: [12]!

Item was added:
+ ----- Method: Arc>>numberOfVertices: (in category 'accessing') -----
+ numberOfVertices: anInteger
+ 
+ 	numberOfVertices := anInteger.!