provide hints to SVG renderers to prevent antialiased edges of filled blocks causing tiled effect

.gitignore

@@ -25,4 +25,8 @@ _testmain.go
 *.DS_Store
 
 *_got
-*_expected
+*_expected
+
+**/.vscode/
+debug
+tinygraphs

draw/isogrids/gradient.go

@@ -27,7 +27,7 @@ func RandomGradientColor(w io.Writer, colors, gColors []color.RGBA, gv colors.Gr
 	}
 
 	canvas := svg.New(w)
-	canvas.Start(width, height)
+	canvas.Start(width, height, draw.DefaultSvgAttributes()...)
 	canvas.Def()
 	canvas.LinearGradient("gradientColors", gv.X1, gv.Y1, gv.X2, gv.Y2, gradientColors)
 	canvas.DefEnd()

draw/isogrids/hexa.go

@@ -11,7 +11,7 @@ import (
 // Hexa builds an image with lines x lines grids of half diagonals in the form of an hexagon
 func Hexa(w io.Writer, key string, colors []color.RGBA, size, lines int) {
 	canvas := svg.New(w)
-	canvas.Start(size, size)
+	canvas.Start(size, size, draw.DefaultSvgAttributes()...)
 
 	fringeSize := size / lines
 	distance := distanceTo3rdPoint(fringeSize)

draw/isogrids/hexa16.go

@@ -14,7 +14,7 @@ import (
 // triangle zero triangle on the center left.
 func Hexa16(w io.Writer, key string, colors []color.RGBA, size, lines int) {
 	canvas := svg.New(w)
-	canvas.Start(size, size)
+	canvas.Start(size, size, draw.DefaultSvgAttributes()...)
 
 	fringeSize := size / lines
 	distance := distanceTo3rdPoint(fringeSize)

draw/isogrids/isogrids.go

@@ -11,7 +11,7 @@ import (
 // Isogrids builds an image with 10x10 grids of half diagonals
 func Isogrids(w io.Writer, key string, colors []color.RGBA, size, lines int) {
 	canvas := svg.New(w)
-	canvas.Start(size, size)
+	canvas.Start(size, size, draw.DefaultSvgAttributes()...)
 
 	fringeSize := size / lines
 	distance := distanceTo3rdPoint(fringeSize)

draw/isogrids/labs.go

@@ -12,7 +12,7 @@ import (
 // Diagonals builds an image with 10x10 grids of diagonals.
 func Diagonals(w io.Writer, key string, color1, color2 color.RGBA, size int) {
 	canvas := svg.New(w)
-	canvas.Start(size, size)
+	canvas.Start(size, size, draw.DefaultSvgAttributes()...)
 
 	lines := 10
 	fringeSize := size / lines
@@ -50,7 +50,7 @@ func Diagonals(w io.Writer, key string, color1, color2 color.RGBA, size int) {
 // HalfDiagonals builds an image with 10x10 grids of half diagonals
 func HalfDiagonals(w io.Writer, key string, color1, color2 color.RGBA, size int) {
 	canvas := svg.New(w)
-	canvas.Start(size, size)
+	canvas.Start(size, size, draw.DefaultSvgAttributes()...)
 
 	lines := 10
 	fringeSize := size / lines
@@ -88,7 +88,7 @@ func HalfDiagonals(w io.Writer, key string, color1, color2 color.RGBA, size int)
 // Skeleton builds an image with 10x10 grids of half diagonals
 func Skeleton(w io.Writer, key string, color1, color2 color.RGBA, size int) {
 	canvas := svg.New(w)
-	canvas.Start(size, size)
+	canvas.Start(size, size, draw.DefaultSvgAttributes()...)
 
 	lines := 10
 	fringeSize := size / lines

draw/isogrids/random.go

@@ -12,7 +12,7 @@ import (
 // The image is symetric in the middle vertical axis.
 func Random(w io.Writer, colors []color.RGBA, width, height, lines int, prob float64) {
 	canvas := svg.New(w)
-	canvas.Start(width, height)
+	canvas.Start(width, height, draw.DefaultSvgAttributes()...)
 
 	fringeSize := width / lines
 	distance := distanceTo3rdPoint(fringeSize)
@@ -56,7 +56,7 @@ func Random(w io.Writer, colors []color.RGBA, width, height, lines int, prob flo
 // from left to right.
 func RandomGradient(w io.Writer, colors []color.RGBA, width, height, lines int) {
 	canvas := svg.New(w)
-	canvas.Start(width, height)
+	canvas.Start(width, height, draw.DefaultSvgAttributes()...)
 
 	fringeSize := width / lines
 	distance := distanceTo3rdPoint(fringeSize)
@@ -100,7 +100,7 @@ func RandomGradient(w io.Writer, colors []color.RGBA, width, height, lines int)
 // RandomMirror builds an image with 10x10 grids of half diagonals
 func RandomMirror(w io.Writer, colors []color.RGBA, size int, prob float64) {
 	canvas := svg.New(w)
-	canvas.Start(size, size)
+	canvas.Start(size, size, draw.DefaultSvgAttributes()...)
 
 	lines := 10
 	fringeSize := size / lines

draw/spaceinvaders/spaceinvaders.go

@@ -14,7 +14,7 @@ import (
 // argument.
 func SpaceInvaders(w io.Writer, key string, colors []color.RGBA, size int) {
 	canvas := svg.New(w)
-	canvas.Start(size, size)
+	canvas.Start(size, size, draw.DefaultSvgAttributes()...)
 	invader := newInvader(key)
 	// log.Println(fmt.Sprintf("%+v\n", invader)) // for debug
 	squares := 11

draw/squares/gradient.go

@@ -27,7 +27,7 @@ func RandomGradientColorSVG(w io.Writer, colors, gColors []color.RGBA, gv colors
 	}
 
 	canvas := svg.New(w)
-	canvas.Start(width, height)
+	canvas.Start(width, height, draw.DefaultSvgAttributes()...)
 	canvas.Def()
 	canvas.LinearGradient("gradientColors", gv.X1, gv.Y1, gv.X2, gv.Y2, gradientColors)
 	canvas.DefEnd()

draw/squares/palette.go

@@ -25,7 +25,7 @@ func Palette(m *image.RGBA, theme []color.RGBA) {
 // PaletteSVG builds an SVG image with all the colors present in the theme color array.
 func PaletteSVG(w io.Writer, theme []color.RGBA, width, height int) {
 	canvas := svg.New(w)
-	canvas.Start(width, height)
+	canvas.Start(width, height, draw.DefaultSvgAttributes()...)
 
 	numColors := len(theme)
 	quadrant := width / numColors

draw/squares/random.go

@@ -34,7 +34,7 @@ func RandomGrid(m *image.RGBA, colors []color.RGBA, xSquares int, prob float64)
 // RandomGridSVG builds a grid image with with x colors selected at random for each quadrant.
 func RandomGridSVG(w io.Writer, colors []color.RGBA, width, height, xSquares int, prob float64) {
 	canvas := svg.New(w)
-	canvas.Start(width, height)
+	canvas.Start(width, height, draw.DefaultSvgAttributes()...)
 	squares := xSquares
 	quadrantSize := width / squares
 	colorMap := make(map[int]color.RGBA)
@@ -79,7 +79,7 @@ func RandomGradientGrid(m *image.RGBA, colors []color.RGBA, xSquares int) {
 // RandomGradientGridSVG builds a grid image with with x colors selected at random for each quadrant.
 func RandomGradientGridSVG(w io.Writer, colors []color.RGBA, width, height, xSquares int) {
 	canvas := svg.New(w)
-	canvas.Start(width, height)
+	canvas.Start(width, height, draw.DefaultSvgAttributes()...)
 	squares := xSquares
 	quadrantSize := width / squares
 	colorMap := make(map[int]color.RGBA)

draw/squares/squares.go

@@ -31,7 +31,7 @@ func Grid(m *image.RGBA, color1, color2 color.RGBA) {
 // GridSVG builds an image with 6 by 6 quadrants of alternate colors.
 func GridSVG(w io.Writer, color1, color2 color.RGBA, size int) {
 	canvas := svg.New(w)
-	canvas.Start(size, size)
+	canvas.Start(size, size, draw.DefaultSvgAttributes()...)
 	squares := 6
 	quadrantSize := size / squares
 	colorMap := make(map[int]color.RGBA)
@@ -88,7 +88,7 @@ func Image(m *image.RGBA, key string, colors []color.RGBA) {
 // SVG builds an svg image with 6 by 6 quadrants of alternate colors.
 func SVG(w io.Writer, key string, colors []color.RGBA, size int) {
 	canvas := svg.New(w)
-	canvas.Start(size, size)
+	canvas.Start(size, size, draw.DefaultSvgAttributes()...)
 
 	squares := 6
 	quadrantSize := size / squares

draw/tools.go

@@ -102,3 +102,11 @@ func PickIndex(key string, n int, index int) int {
 func RGBToHex(r, g, b uint8) string {
 	return fmt.Sprintf("#%02X%02X%02X", r, g, b)
 }
+
+// DefaultSvgAttributes returns the default attributes to apply to SVG canvases
+func DefaultSvgAttributes() []string {
+	// shape-rendering provides hints to the renderer about how to render the image
+	// crispedges and optimizeSpeed prevent the edges of generated blocks from being
+	// antialiased causing a tiled effect (visible lines between each block)
+	return []string{"shape-rendering = \"optimizeSpeed\""}
+}