artist/shapes/ellipse.go

@@ -2,6 +2,7 @@ package shapes
 
 import "math"
 import "image"
+import "image/color"
 import "git.tebibyte.media/sashakoshka/tomo/canvas"
 
 // FillEllipse draws the content of one canvas onto another, clipped by an
@@ -19,26 +20,25 @@ func FillEllipse (
 	dstData, dstStride := destination.Buffer()
 	srcData, srcStride := source.Buffer()
 	
-	bounds := source.Bounds()
-	realWidth, realHeight := bounds.Dx(), bounds.Dy()
-	bounds = bounds.Intersect(destination.Bounds()).Canon()
+	bounds     := source.Bounds().Intersect(destination.Bounds()).Canon()
+	realBounds := source.Bounds()
 	if bounds.Empty() { return }
 	updatedRegion = bounds
 
-	width, height := bounds.Dx(), bounds.Dy()
-	for y := 0; y < height; y ++ {
-	for x := 0; x < width;  x ++ {
-		xf := (float64(x) + 0.5) / float64(realWidth)  - 0.5
-		yf := (float64(y) + 0.5) / float64(realHeight) - 0.5
-		if math.Sqrt(xf * xf + yf * yf) <= 0.5 {
-			dstData[x + offset.X + (y + offset.Y) * dstStride] =
-				srcData[x + y * srcStride]
+	point := image.Point { }
+	for point.Y = bounds.Min.Y; point.Y < bounds.Max.Y; point.Y ++ {
+	for point.X = bounds.Min.X; point.X < bounds.Max.X; point.X ++ {
+		if inEllipse(point, realBounds) {
+			offsetPoint := point.Add(offset)
+			dstIndex := offsetPoint.X + (offsetPoint.Y) * dstStride
+			srcIndex := point.X + point.Y * srcStride
+			dstData[dstIndex] = srcData[srcIndex]
 		}
 	}}
 	return
 }
 
-// StrokeRectangle is similar to FillEllipse, but it draws an elliptical inset
+// StrokeEllipse is similar to FillEllipse, but it draws an elliptical inset
 // outline of the source canvas onto the destination canvas. To prevent the
 // entire source canvas's bounds from being used, it must be cut with
 // canvas.Cut().
@@ -55,82 +55,176 @@ func StrokeEllipse (
 	
 	bounds := source.Bounds().Inset(weight - 1)
 
-	context := plottingContext {
-		dstData:   dstData,
-		dstStride: dstStride,
-		srcData:   srcData,
-		srcStride: srcStride,
-		weight:    weight,
-		offset:    offset,
-		bounds:    bounds.Intersect(destination.Bounds()),
+	context := ellipsePlottingContext {
+		plottingContext: plottingContext {
+			dstData:   dstData,
+			dstStride: dstStride,
+			srcData:   srcData,
+			srcStride: srcStride,
+			weight:    weight,
+			offset:    offset,
+			bounds:    bounds.Intersect(destination.Bounds()),
+		},
+		radii:  image.Pt(bounds.Dx() / 2 - 1, bounds.Dy() / 2 - 1),
 	}
-	
-	bounds.Max.X -= 1
-	bounds.Max.Y -= 1
+	context.center = bounds.Min.Add(context.radii)
+	context.plotEllipse()
+}
 
-	radii := image.Pt (
-		bounds.Dx() / 2,
-		bounds.Dy() / 2)
-	center := bounds.Min.Add(radii)
+type ellipsePlottingContext struct {
+	plottingContext
+	radii  image.Point
+	center image.Point
+}
 
+func (context ellipsePlottingContext) plotEllipse () {
 	x := float64(0)
-	y := float64(radii.Y)
+	y := float64(context.radii.Y)
 
 	// region 1 decision parameter
 	decision1 :=
-		float64(radii.Y * radii.Y) -
-		float64(radii.X * radii.X * radii.Y) +
-		(0.25 * float64(radii.X) * float64(radii.X))
-	decisionX := float64(2 * radii.Y * radii.Y * int(x))
-	decisionY := float64(2 * radii.X * radii.X * int(y))
+		float64(context.radii.Y * context.radii.Y) -
+		float64(context.radii.X * context.radii.X * context.radii.Y) +
+		(0.25 * float64(context.radii.X) * float64(context.radii.X))
+	decisionX := float64(2 * context.radii.Y * context.radii.Y * int(x))
+	decisionY := float64(2 * context.radii.X * context.radii.X * int(y))
 
 	// draw region 1
 	for decisionX < decisionY {
-		context.plotSource(image.Pt( int(x) + center.X,  int(y) + center.Y))
-		context.plotSource(image.Pt(-int(x) + center.X,  int(y) + center.Y))
-		context.plotSource(image.Pt( int(x) + center.X, -int(y) + center.Y))
-		context.plotSource(image.Pt(-int(x) + center.X, -int(y) + center.Y))
+		points := []image.Point {
+			image.Pt(-int(x) + context.center.X, -int(y) + context.center.Y),
+			image.Pt( int(x) + context.center.X, -int(y) + context.center.Y),
+			image.Pt(-int(x) + context.center.X,  int(y) + context.center.Y),
+			image.Pt( int(x) + context.center.X,  int(y) + context.center.Y),			
+		}
+		if context.srcData == nil {
+			context.plotColor(points[0])
+			context.plotColor(points[1])
+			context.plotColor(points[2])
+			context.plotColor(points[3])
+		} else {
+			context.plotSource(points[0])
+			context.plotSource(points[1])
+			context.plotSource(points[2])
+			context.plotSource(points[3])
+		}
 
 		if (decision1 < 0) {
 			x ++
-			decisionX += float64(2 * radii.Y * radii.Y)
-			decision1 += decisionX + float64(radii.Y * radii.Y)
+			decisionX += float64(2 * context.radii.Y * context.radii.Y)
+			decision1 += decisionX + float64(context.radii.Y * context.radii.Y)
 		} else {
 			x ++
 			y --
-			decisionX += float64(2 * radii.Y * radii.Y)
-			decisionY -= float64(2 * radii.X * radii.X)
+			decisionX += float64(2 * context.radii.Y * context.radii.Y)
+			decisionY -= float64(2 * context.radii.X * context.radii.X)
 			decision1 +=
 				decisionX - decisionY +
-				float64(radii.Y * radii.Y)
+				float64(context.radii.Y * context.radii.Y)
 		}
 	}
 
 	// region 2 decision parameter
 	decision2 :=
-		float64(radii.Y * radii.Y) * (x + 0.5) * (x + 0.5) +
-		float64(radii.X * radii.X) * (y - 1)   * (y - 1) -
-		float64(radii.X * radii.X * radii.Y * radii.Y)
+		float64(context.radii.Y * context.radii.Y) * (x + 0.5) * (x + 0.5) +
+		float64(context.radii.X * context.radii.X) * (y - 1)   * (y - 1) -
+		float64(context.radii.X * context.radii.X * context.radii.Y * context.radii.Y)
 
 	// draw region 2
 	for y >= 0 {
-		context.plotSource(image.Pt( int(x) + center.X,  int(y) + center.Y))
-		context.plotSource(image.Pt(-int(x) + center.X,  int(y) + center.Y))
-		context.plotSource(image.Pt( int(x) + center.X, -int(y) + center.Y))
-		context.plotSource(image.Pt(-int(x) + center.X, -int(y) + center.Y))
+		points := []image.Point {
+			image.Pt( int(x) + context.center.X,  int(y) + context.center.Y),
+			image.Pt(-int(x) + context.center.X,  int(y) + context.center.Y),
+			image.Pt( int(x) + context.center.X, -int(y) + context.center.Y),
+			image.Pt(-int(x) + context.center.X, -int(y) + context.center.Y),
+		}
+		if context.srcData == nil {
+			context.plotColor(points[0])
+			context.plotColor(points[1])
+			context.plotColor(points[2])
+			context.plotColor(points[3])
+		} else {
+			context.plotSource(points[0])
+			context.plotSource(points[1])
+			context.plotSource(points[2])
+			context.plotSource(points[3])
+		}
 
 		if decision2 > 0 {
 			y --
-			decisionY -= float64(2 * radii.X * radii.X)
-			decision2 += float64(radii.X * radii.X) - decisionY
+			decisionY -= float64(2 * context.radii.X * context.radii.X)
+			decision2 += float64(context.radii.X * context.radii.X) - decisionY
 		} else {
 			y --
 			x ++
-			decisionX += float64(2 * radii.Y * radii.Y)
-			decisionY -= float64(2 * radii.X * radii.X)
+			decisionX += float64(2 * context.radii.Y * context.radii.Y)
+			decisionY -= float64(2 * context.radii.X * context.radii.X)
 			decision2 +=
 				decisionX - decisionY +
-				float64(radii.X * radii.X)
+				float64(context.radii.X * context.radii.X)
 		}
 	}
 }
+
+// FillColorEllipse fills an ellipse within the destination canvas with a solid
+// color.
+func FillColorEllipse (
+	destination canvas.Canvas,
+	color       color.RGBA,
+	bounds      image.Rectangle,
+) (
+	updatedRegion image.Rectangle,
+) {
+	dstData, dstStride := destination.Buffer()
+	
+	realBounds := bounds
+	bounds = bounds.Intersect(destination.Bounds()).Canon()
+	if bounds.Empty() { return }
+	updatedRegion = bounds
+
+	point := image.Point { }
+	for point.Y = bounds.Min.Y; point.Y < bounds.Max.Y; point.Y ++ {
+	for point.X = bounds.Min.X; point.X < bounds.Max.X; point.X ++ {
+		if inEllipse(point, realBounds) {
+			dstData[point.X + point.Y * dstStride] = color
+		}
+	}}
+	return
+}
+
+// StrokeColorEllipse is similar to FillColorEllipse, but it draws an inset
+// outline of an ellipse instead.
+func StrokeColorEllipse (
+	destination canvas.Canvas,
+	color       color.RGBA,
+	bounds      image.Rectangle,
+	weight      int,
+) (
+	updatedRegion image.Rectangle,
+) {
+	if weight < 1 { return }
+
+	dstData, dstStride := destination.Buffer()
+	bounds = bounds.Inset(weight - 1)
+
+	context := ellipsePlottingContext {
+		plottingContext: plottingContext {
+			dstData:   dstData,
+			dstStride: dstStride,
+			color:     color,
+			weight:    weight,
+			bounds:    bounds.Intersect(destination.Bounds()),
+		},
+		radii:  image.Pt(bounds.Dx() / 2 - 1, bounds.Dy() / 2 - 1),
+	}
+	context.center = bounds.Min.Add(context.radii)
+	context.plotEllipse()
+	return
+}
+
+func inEllipse (point image.Point, bounds image.Rectangle) bool {
+	point = point.Sub(bounds.Min)
+	x := (float64(point.X) + 0.5) / float64(bounds.Dx()) - 0.5
+	y := (float64(point.Y) + 0.5) / float64(bounds.Dy()) - 0.5
+	return math.Hypot(x, y) <= 0.5
+}

artist/shapes/line.go

@@ -4,8 +4,6 @@ import "image"
 import "image/color"
 import "git.tebibyte.media/sashakoshka/tomo/canvas"
 
-// TODO: draw thick lines more efficiently
-
 // ColorLine draws a line from one point to another with the specified weight
 // and color.
 func ColorLine (

artist/shapes/plot.go

@@ -3,6 +3,8 @@ package shapes
 import "image"
 import "image/color"
 
+// FIXME? drawing a ton of overlapping squares might be a bit wasteful.
+
 type plottingContext struct {
 	dstData   []color.RGBA
 	dstStride int
@@ -18,6 +20,7 @@ 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).
+		Add(context.offset).
 		Intersect(context.bounds)
 }
 
@@ -33,8 +36,13 @@ 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]
+		// we offset srcIndex here because we have already applied the
+		// offset to the square, and we need to reverse that to get the
+		// proper source coordinates.
+		srcIndex := 
+			x - context.offset.X +
+			(y - context.offset.Y) * context.dstStride
+		dstIndex := x + y * context.dstStride
+		context.dstData[dstIndex] = context.srcData [srcIndex]
 	}}
 }

artist/shapes/rectangle.go

@@ -1,9 +1,12 @@
 package shapes
 
 import "image"
+import "image/color"
 import "git.tebibyte.media/sashakoshka/tomo/canvas"
 import "git.tebibyte.media/sashakoshka/tomo/shatter"
 
+// TODO: return updatedRegion for all routines in this package
+
 // FillRectangle draws the content of one canvas onto another. The offset point
 // defines where the origin point of the source canvas is positioned in relation
 // to the origin point of the destination canvas. To prevent the entire source
@@ -59,8 +62,60 @@ func FillRectangleShatter (
 	offset      image.Point,
 	rocks       ...image.Rectangle,
 ) {
-	tiles := shatter.Shatter(source.Bounds(), rocks...)
+	tiles := shatter.Shatter(source.Bounds().Sub(offset), rocks...)
 	for _, tile := range tiles {
 		FillRectangle(destination, canvas.Cut(source, tile), offset)
 	}
 }
+
+// FillColorRectangle fills a rectangle within the destination canvas with a
+// solid color.
+func FillColorRectangle (
+	destination canvas.Canvas,
+	color       color.RGBA,
+	bounds      image.Rectangle,
+) (
+	updatedRegion image.Rectangle,
+) {
+	dstData, dstStride := destination.Buffer()
+	bounds = bounds.Canon().Intersect(destination.Bounds())
+	if bounds.Empty() { return }
+	
+	updatedRegion = bounds
+	for y := bounds.Min.Y; y < bounds.Max.Y; y ++ {
+	for x := bounds.Min.X; x < bounds.Max.X; x ++ {
+		dstData[x + y * dstStride] = color
+	}}
+	
+	return
+}
+
+// FillColorRectangleShatter is like FillColorRectangle, but it does not draw in
+// areas specified in "rocks".
+func FillColorRectangleShatter (
+	destination canvas.Canvas,
+	color       color.RGBA,
+	bounds      image.Rectangle,
+	rocks       ...image.Rectangle,
+) {
+	tiles := shatter.Shatter(bounds, rocks...)
+	for _, tile := range tiles {
+		FillColorRectangle(destination, color, tile)
+	}
+}
+
+// StrokeColorRectangle is similar to FillColorRectangle, but it draws an inset
+// outline of the given rectangle instead.
+func StrokeColorRectangle (
+	destination canvas.Canvas,
+	color       color.RGBA,
+	bounds      image.Rectangle,
+	weight      int,
+) {
+	insetBounds := bounds.Inset(weight)
+	if insetBounds.Empty() {
+		FillColorRectangle(destination, color, bounds)
+		return
+	}
+	FillColorRectangleShatter(destination, color, bounds, insetBounds)
+}