Merge pull request #64 from pharo-graphics/62-Add-pathRotate-method-i…

…n-AeCanvas

AeCanvas: add pathRotateByRadians: and pathRotateByRadians:about:

src/Alexandrie-Cairo/AeCairoContext.class.st

@@ -1435,6 +1435,19 @@ AeCairoContext >> rotateByRadians: angle [
 			double angle ) )
 ]
 
+{ #category : #'API - matrix' }
+AeCairoContext >> rotateByRadians: angle aboutX: centerX y: centerY [
+	"Modifies the current transformation matrix (CTM) by rotating the user-space axes by angle radians about a center received as argument.
+	
+	See: https://www.cairographics.org/cookbook/transform_about_point/
+	See: https://www.cairographics.org/cookbook/matrix_conventions/"
+
+	self
+		translateByX: centerX y: centerY;
+		rotateByRadians: angle;
+		translateByX: centerX negated y: centerY negated
+]
+
 { #category : #'API - path' }
 AeCairoContext >> roundedRectangleLeft: l top: t right: r bottom: b tl: tlR tr: trR br: brR bl: blR [
 	"Append the path of a rounded rectangle.

src/Alexandrie-Canvas-Tests/AeCanvasTest.class.st

@@ -461,6 +461,48 @@ AeCanvasTest >> renderOpenFigure [
 	^ aeCanvas
 ]
 
+{ #category : #tests }
+AeCanvasTest >> renderWithRotation [
+
+	| aeCanvas extent |
+	extent := 40 @ 30.
+	aeCanvas := AeCanvas extent: extent.
+
+	aeCanvas pathRotateByRadians: 15 degreesToRadians.
+
+	aeCanvas pathFactory: [ :cairoContext |
+		cairoContext rectangleTo: extent / 2 ].
+
+	aeCanvas setBackgroundWith: [
+		aeCanvas setSourceColor: Color purple ].
+	aeCanvas setBorderOff.
+	aeCanvas drawFigure.
+
+	^ aeCanvas
+]
+
+{ #category : #tests }
+AeCanvasTest >> renderWithRotationAboutCenter [
+
+	| aeCanvas extent |
+	extent := 40 @ 30.
+	aeCanvas := AeCanvas extent: extent.
+
+	aeCanvas
+		pathRotateByRadians: 45 degreesToRadians
+		about: extent / 2.
+
+	aeCanvas pathFactory: [ :cairoContext |
+		cairoContext rectangleTo: extent ].
+
+	aeCanvas setBackgroundWith: [
+		aeCanvas setSourceColor: Color cyan ].
+	aeCanvas setBorderOff.
+	aeCanvas drawFigure.
+
+	^ aeCanvas
+]
+
 { #category : #tests }
 AeCanvasTest >> renderZWJEmojiWithHarfbuzz [
 

src/Alexandrie-Canvas/AeCanvas.class.st

@@ -552,6 +552,20 @@ AeCanvas >> pathFactory: aUnaryBlock [
 	borderPathBlock := nil.
 ]
 
+{ #category : #'API - transformations' }
+AeCanvas >> pathRotateByRadians: angle [
+	"Rotate by an angle, expressed in radians, about 0@0."
+
+	cairoContext rotateByRadians: angle
+]
+
+{ #category : #'API - transformations' }
+AeCanvas >> pathRotateByRadians: angle about: aPoint [
+	"Rotate by an angle, expressed in radians, about aPoint."
+
+	cairoContext rotateByRadians: angle aboutX: aPoint x y: aPoint y
+]
+
 { #category : #'API - transformations' }
 AeCanvas >> pathScale: aPoint [