Ellipse and line share code

artist/shapes/ellipse.go

@@ -2,8 +2,6 @@ package shapes
 
 import "math"
 import "image"
-import "image/color"
-// import "git.tebibyte.media/sashakoshka/tomo/artist"
 import "git.tebibyte.media/sashakoshka/tomo/canvas"
 
 // FillEllipse draws the content of one canvas onto another, clipped by an
@@ -57,7 +55,7 @@ func StrokeEllipse (
 	
 	bounds := source.Bounds().Inset(weight - 1)
 
-	context := ellipsePlottingContext {
+	context := plottingContext {
 		dstData:   dstData,
 		dstStride: dstStride,
 		srcData:   srcData,
@@ -88,10 +86,10 @@ func StrokeEllipse (
 
 	// draw region 1
 	for decisionX < decisionY {
-		context.plot( int(x) + center.X,  int(y) + center.Y)
+		context.plotSource(image.Pt( int(x) + center.X,  int(y) + center.Y))
-		context.plot(-int(x) + center.X,  int(y) + center.Y)
+		context.plotSource(image.Pt(-int(x) + center.X,  int(y) + center.Y))
-		context.plot( int(x) + center.X, -int(y) + center.Y)
+		context.plotSource(image.Pt( int(x) + center.X, -int(y) + center.Y))
-		context.plot(-int(x) + center.X, -int(y) + center.Y)
+		context.plotSource(image.Pt(-int(x) + center.X, -int(y) + center.Y))
 
 		if (decision1 < 0) {
 			x ++
@@ -116,10 +114,10 @@ func StrokeEllipse (
 
 	// draw region 2
 	for y >= 0 {
-		context.plot( int(x) + center.X,  int(y) + center.Y)
+		context.plotSource(image.Pt( int(x) + center.X,  int(y) + center.Y))
-		context.plot(-int(x) + center.X,  int(y) + center.Y)
+		context.plotSource(image.Pt(-int(x) + center.X,  int(y) + center.Y))
-		context.plot( int(x) + center.X, -int(y) + center.Y)
+		context.plotSource(image.Pt( int(x) + center.X, -int(y) + center.Y))
-		context.plot(-int(x) + center.X, -int(y) + center.Y)
+		context.plotSource(image.Pt(-int(x) + center.X, -int(y) + center.Y))
 
 		if decision2 > 0 {
 			y --
@@ -136,28 +134,3 @@ func StrokeEllipse (
 		}
 	}
 }
-
-type ellipsePlottingContext struct {
-	dstData   []color.RGBA
-	dstStride int
-	srcData   []color.RGBA
-	srcStride int
-	weight    int
-	offset    image.Point
-	bounds    image.Rectangle
-}
-
-func (context ellipsePlottingContext) plot (x, y int) {
-	square :=
-		image.Rect(0, 0, context.weight, context.weight).
-		Sub(image.Pt(context.weight / 2, context.weight / 2)).
-		Add(image.Pt(x, y)).
-		Intersect(context.bounds)
-	
-	for y := square.Min.Y; y < square.Min.Y; y ++ {
-	for x := square.Min.X; x < square.Min.X; x ++ {
-		context.dstData[x + y * context.dstStride] =
-			context.srcData [
-				x + y * context.dstStride]
-	}}
-}

artist/shapes/line.go

@@ -17,7 +17,6 @@ func ColorLine (
 ) (
 	updatedRegion image.Rectangle,
 ) {
-	
 	updatedRegion = image.Rectangle { Min: min, Max: max }.Canon()
 	updatedRegion.Max.X ++
 	updatedRegion.Max.Y ++
@@ -25,13 +24,15 @@ func ColorLine (
 	data, stride := destination.Buffer()
 	bounds := destination.Bounds()
 	context := linePlottingContext {
-		dstData:   data,
+		plottingContext: plottingContext {
-		dstStride: stride,
+			dstData:   data,
-		color:     color,
+			dstStride: stride,
-		weight:    weight,
+			color:     color,
-		bounds:    bounds,
+			weight:    weight,
-		min:       min,
+			bounds:    bounds,
-		max:       max,
+		},
+		min: min,
+		max: max,
 	}
 	
 	if abs(max.Y - min.Y) < abs(max.X - min.X) {
@@ -46,13 +47,9 @@ func ColorLine (
 }
 
 type linePlottingContext struct {
-	dstData   []color.RGBA
+	plottingContext
-	dstStride int
+	min image.Point
-	color     color.RGBA
+	max image.Point
-	weight    int
-	bounds    image.Rectangle
-	min       image.Point
-	max       image.Point
 }
 
 func (context *linePlottingContext) swap () {
@@ -76,7 +73,7 @@ func (context linePlottingContext) lineLow () {
 
 	for ; point.X < context.max.X; point.X ++ {
 		if !point.In(context.bounds) { break }
-		context.plot(point)
+		context.plotColor(point)
 		if D > 0 {
 			D += 2 * (deltaY - deltaX)
 			point.Y += yi
@@ -101,7 +98,7 @@ func (context linePlottingContext) lineHigh () {
 
 	for ; point.Y < context.max.Y; point.Y ++ {
 		if !point.In(context.bounds) { break }
-		context.plot(point)
+		context.plotColor(point)
 		if D > 0 {
 			point.X += xi
 			D += 2 * (deltaX - deltaY)
@@ -115,16 +112,3 @@ func abs (n int) int {
 	if n < 0 { n *= -1}
 	return n
 }
-
-func (context linePlottingContext) plot (center image.Point) {
-	square :=
-		image.Rect(0, 0, context.weight, context.weight).
-		Sub(image.Pt(context.weight / 2, context.weight / 2)).
-		Add(center).
-		Intersect(context.bounds)
-
-	for y := square.Min.Y; y < square.Min.Y; y ++ {
-	for x := square.Min.X; x < square.Min.X; x ++ {
-		context.dstData[x + y * context.dstStride] = context.color
-	}}
-}

artist/shapes/plot.go

@@ -0,0 +1,40 @@
+package shapes
+
+import "image"
+import "image/color"
+
+type plottingContext struct {
+	dstData   []color.RGBA
+	dstStride int
+	srcData   []color.RGBA
+	srcStride int
+	color     color.RGBA
+	weight    int
+	offset    image.Point
+	bounds    image.Rectangle
+}
+
+func (context plottingContext) square (center image.Point) image.Rectangle {
+	return image.Rect(0, 0, context.weight, context.weight).
+		Sub(image.Pt(context.weight / 2, context.weight / 2)).
+		Add(center).
+		Intersect(context.bounds)
+}
+
+func (context plottingContext) plotColor (center image.Point) {
+	square := context.square(center)
+	for y := square.Min.Y; y < square.Min.Y; y ++ {
+	for x := square.Min.X; x < square.Min.X; x ++ {
+		context.dstData[x + y * context.dstStride] = context.color
+	}}
+}
+
+func (context plottingContext) plotSource (center image.Point) {
+	square := context.square(center)
+	for y := square.Min.Y; y < square.Min.Y; y ++ {
+	for x := square.Min.X; x < square.Min.X; x ++ {
+		context.dstData[x + y * context.dstStride] =
+			context.srcData [
+				x + y * context.dstStride]
+	}}
+}