Add #fitExtent: to GPolygon

Author: jecisc

src/Geometry-Tests/GPolygonTest.class.st

@@ -41,6 +41,68 @@ self
 	equals: (Rectangle left: -10  right:40  top: 10 bottom: -30)
 ]
 
+{ #category : #tests }
+GPolygonTest >> testFitInExtent [
+	| polygon |
+	polygon := GPolygon
+		newVertices:
+			{(10 @ 10).
+			(-10 @ 10).
+			(-10 @ -10)}.
+	polygon fitInExtent: 20 @ 20.
+	self
+		assert: polygon vertices
+		equals:
+			{(10 @ 10).
+			(-10 @ 10).
+			(-10 @ -10)}.
+	polygon fitInExtent: 40 @ 40.
+	self
+		assert: polygon vertices
+		equals:
+			{(20 @ 20).
+			(-20 @ 20).
+			(-20 @ -20)}.
+	polygon fitInExtent: 10 @ 10.
+	self
+		assert: polygon vertices
+		equals:
+			{(5 @ 5).
+			(-5 @ 5).
+			(-5 @ -5)}
+]
+
+{ #category : #tests }
+GPolygonTest >> testFitInExtentNonProportionnal [
+	| polygon |
+	polygon := GPolygon
+		newVertices:
+			{(10 @ 4).
+			(-4 @ 10).
+			(-10 @ -8)}.
+	polygon fitInExtent: 20 @ 20.
+	self
+		assert: polygon vertices
+		equals:
+			{(10 @ 4).
+			(-4 @ 10).
+			(-10 @ -8)}.
+	polygon fitInExtent: 40 @ 40.
+	self
+		assert: polygon vertices
+		equals:
+			{(20 @ 8).
+			(-8 @ 20).
+			(-20 @ -16)}.
+	polygon fitInExtent: 10 @ 10.
+	self
+		assert: polygon vertices
+		equals:
+			{(5 @ 2).
+			(-2 @ 5).
+			(-5 @ -4)}
+]
+
 { #category : #tests }
 GPolygonTest >> testIncludesPoint [
 self

src/Geometry/GPolygon.class.st

@@ -85,6 +85,20 @@ GPolygon >> encompasingRectangle [
 	^Rectangle left: leftMost x right: rightMost x top: top y bottom: bottom y
 ]
 
+{ #category : #converting }
+GPolygon >> fitInExtent: extent [
+	"I take as parameter a point and will fit the polygon in a rectangle whose dimensions is defined by the extent.
+	
+	To do that, I will first fit my vertices in a square of lenght of 1, then I will multiply my vertices by the extent required."
+
+	| max verticesInSquareOfSizeOne |
+	max := (self vertices collect: #x) max max: ((self vertices collect: #y )) max. "We do not take `self vertices max` because we want to preserve proportions"
+	"Fit the polygon in a square of size 1 by doing a division of it's vertices by 2 times the value of the furthest point from the center of the polygon."
+	verticesInSquareOfSizeOne := self vertices collect: [ :point | point / (max * 2) ].
+	
+	vertices := (verticesInSquareOfSizeOne collect: [ :point | point * extent ])
+]
+
 { #category : #testing }
 GPolygon >> includesPoint: point [
 
@@ -103,7 +117,7 @@ GPolygon >> intersectLineSegment: aLineSegment [
 	^ aLineSegment intersectPolygon: self
 ]
 
-{ #category : #private }
+{ #category : #converting }
 GPolygon >> moveBy: aPoint [
 	"Move a polygon by a delta defined by aPoint"