Transparency support!!

box.go

@@ -3,6 +3,7 @@ package x
 import "image"
 import "image/color"
 import "git.tebibyte.media/tomo/tomo"
+import "git.tebibyte.media/tomo/x/canvas"
 import "git.tebibyte.media/tomo/tomo/data"
 import "git.tebibyte.media/tomo/tomo/input"
 import "git.tebibyte.media/tomo/tomo/event"
@@ -23,7 +24,7 @@ type box struct {
 	padding tomo.Inset
 	border  []tomo.Border
 	color   color.Color
-	texture *texture
+	texture *xcanvas.Texture
 	
 	fillTransparent bool
 
@@ -122,7 +123,7 @@ func (this *box) SetColor (c color.Color) {
 }
 
 func (this *box) SetTexture (texture tomo.Texture) {
-	this.texture = assertTexture(texture)
+	this.texture = xcanvas.AssertTexture(texture)
 	this.determineFillTransparency()
 	this.invalidateDraw()
 }

canvas/canvas.go

@@ -4,6 +4,7 @@ import "image"
 import "image/color"
 import "github.com/jezek/xgbutil"
 import "github.com/jezek/xgb/xproto"
+import "git.tebibyte.media/tomo/tomo"
 import "github.com/jezek/xgbutil/xgraphics"
 import "git.tebibyte.media/tomo/tomo/canvas"
 
@@ -73,23 +74,34 @@ type pen struct {
 	align   canvas.StrokeAlign
 	stroke  xgraphics.BGRA
 	fill    xgraphics.BGRA
+	texture *Texture
 }
 
 func (this *pen) Rectangle (bounds image.Rectangle) {
 	if this.weight == 0 {
-		this.gfx.fillRectangle(bounds)
+		if this.fill.A > 0 {
+			this.fillRectangle(this.fill, bounds)
+		}
 	} else {
-		this.gfx.strokeRectangle(bounds)
+		if this.stroke.A > 0 {
+			this.strokeRectangle(this.stroke, bounds)
+		}
 	}
 }
 
 func (this *pen) Path (points ...image.Point) {
 	if this.weight == 0 {
-		this.fillPolygon(points...)
+		if this.fill.A > 0 {
+			this.fillPolygon(this.fill, points...)
+		}
 	} else if this.closed {
-		this.strokePolygon(points...)
+		if this.stroke.A > 0 {
+			this.strokePolygon(this.stroke, points...)
+		}
 	} else {
-		this.polyLine(points...)
+		if this.stroke.A > 0 {
+			this.polyLine(this.stroke, points...)
+		}
 	}
 }
 
@@ -101,6 +113,7 @@ func (this *pen) StrokeAlign  (align canvas.StrokeAlign) { this.align  = align
 
 func (this *pen) Stroke  (stroke color.Color)   { this.stroke  = convertColor(stroke)   }
 func (this *pen) Fill    (fill color.Color)     { this.fill    = convertColor(fill)     }
+func (this *pen) Texture (texture tomo.Texture) { this.texture = AssertTexture(texture) }
 
 func convertColor (c color.Color) xgraphics.BGRA {
 	r, g, b, a := c.RGBA()

canvas/draw.go

@@ -1,5 +1,229 @@
 package xcanvas
 
-func (this *pen) fillRectangle (bounds image.Rectangle) {
+import "sort"
+import "image"
+import "github.com/jezek/xgbutil/xgraphics"
+
+func (this *pen) fillRectangle (c xgraphics.BGRA, bounds image.Rectangle) {
+	if c.A == 255 {
+		this.fillRectangleOpaque(c, bounds)
+	} else {
+		this.fillRectangleTransparent(c, bounds)
+	}
+}
+
+func (this *pen) fillRectangleOpaque (c xgraphics.BGRA, bounds image.Rectangle) {
+	bounds = bounds.Intersect(this.image.Bounds())
+	var pos image.Point
+
+	for pos.Y = bounds.Min.Y; pos.Y < bounds.Max.Y; pos.Y ++ {
+	for pos.X = bounds.Min.X; pos.X < bounds.Max.X; pos.X ++ {
+		index := this.image.PixOffset(pos.X, pos.Y)
+		this.image.Pix[index + 0] = c.B
+		this.image.Pix[index + 1] = c.G
+		this.image.Pix[index + 2] = c.R
+		this.image.Pix[index + 3] = c.A
+	}}
+}
+
+func (this *pen) fillRectangleTransparent (c xgraphics.BGRA, bounds image.Rectangle) {
+	bounds = bounds.Intersect(this.image.Bounds())
+	var pos image.Point
+
+	for pos.Y = bounds.Min.Y; pos.Y < bounds.Max.Y; pos.Y ++ {
+	for pos.X = bounds.Min.X; pos.X < bounds.Max.X; pos.X ++ {
+		index := this.image.PixOffset(pos.X, pos.Y)
+		pixel := xgraphics.BlendBGRA(xgraphics.BGRA {
+			B: this.image.Pix[index + 0],
+			G: this.image.Pix[index + 1],
+			R: this.image.Pix[index + 2],
+			A: this.image.Pix[index + 3],
+		}, c)
+		this.image.Pix[index + 0] = pixel.B
+		this.image.Pix[index + 1] = pixel.G
+		this.image.Pix[index + 2] = pixel.R
+		this.image.Pix[index + 3] = pixel.A
+	}}
+}
+
+func (this *pen) strokeRectangle (c xgraphics.BGRA, bounds image.Rectangle) {
+	if this.weight > bounds.Dx() / 2 || this.weight > bounds.Dy() / 2 {
+		this.fillRectangle(c, bounds)
+		return
+	}
+	
+	top := image.Rect (
+		bounds.Min.X,
+		bounds.Min.Y,
+		bounds.Max.X,
+		bounds.Min.Y + this.weight)
+	bottom := image.Rect (
+		bounds.Min.X,
+		bounds.Max.Y - this.weight,
+		bounds.Max.X,
+		bounds.Max.Y)
+	left := image.Rect (
+		bounds.Min.X,
+		bounds.Min.Y + this.weight,
+		bounds.Min.X + this.weight,
+		bounds.Max.Y - this.weight)
+	right := image.Rect (
+		bounds.Max.X - this.weight,
+		bounds.Min.Y + this.weight,
+		bounds.Max.X,
+		bounds.Max.Y - this.weight)
+
+	this.fillRectangle(c, top,)
+	this.fillRectangle(c, bottom,)
+	this.fillRectangle(c, left,)
+	this.fillRectangle(c, right,)
+}
+
+// the polygon filling algorithm is adapted from:
+// https://www.alienryderflex.com/polygon_fill/
+// (if you write C like that i will disassemble you)
+	
+func (this *pen) fillPolygon (c xgraphics.BGRA, points ...image.Point) {
+	if len(points) < 3 { return }
+
+	// figure out the bounds of the polygon so we don't test empty space
+	var area image.Rectangle
+	area.Min = points[0]
+	area.Max = points[0]
+	for _, point := range points[1:] {
+		if point.X < area.Min.X { area.Min.X = point.X }
+		if point.Y < area.Min.Y { area.Min.Y = point.Y }
+		if point.X > area.Max.X { area.Max.X = point.X }
+		if point.Y > area.Max.Y { area.Max.Y = point.Y }
+	}
+	area = this.image.Bounds().Intersect(area)
+	if area.Empty() { return }
+
+	context := fillingContext {
+		image:      this.image,
+		color:      this.fill,
+		min:        area.Min.X,
+		max:        area.Max.X,
+		boundaries: make([]int, len(points)),
+		points:     points,
+	}
+
+	for context.y = area.Min.Y; context.y < area.Max.Y; context.y ++ {
+		// build boundary list
+		boundaryCount := 0
+		prevPoint := points[len(points) - 1]
+		for _, point := range points {
+			fy      := float64(context.y)
+			fPointX := float64(point.X)
+			fPointY := float64(point.Y)
+			fPrevX  := float64(prevPoint.X)
+			fPrevY  := float64(prevPoint.Y)
+			addboundary :=
+				(fPointY < fy && fPrevY  >= fy) ||
+				(fPrevY  < fy && fPointY >= fy)
+			if addboundary {
+				context.boundaries[boundaryCount] = int (
+					fPointX +
+					(fy - fPointY) /
+					(fPrevY - fPointY) *
+					(fPrevX - fPointX))
+				boundaryCount ++
+			}
+			prevPoint = point
+		}
+
+		// sort boundary list
+		cutBoundaries := context.boundaries[:boundaryCount]
+		sort.Ints(cutBoundaries)
+
+		// fill pixels between boundary pairs
+		if c.A == 255 {
+			context.fillPolygonHotOpaque()
+		} else {
+			context.fillPolygonHotTransparent()
+		}
+	}
 	
 }
+
+type fillingContext struct {
+	image      *xgraphics.Image
+	color      xgraphics.BGRA
+	min, max   int
+	y          int
+	boundaries []int
+	points     []image.Point
+}
+
+func (context *fillingContext) fillPolygonHotOpaque () {
+	for index := 0; index < len(context.boundaries); index += 2 {
+		left  := context.boundaries[index]
+		right := context.boundaries[index + 1]
+
+		// stop if we have exited the polygon
+		if left >= context.max { break }
+		// begin filling if we are within the polygon
+		if right > context.min {
+			// constrain boundaries to image size
+			if left  < context.min { left  = context.min }
+			if right > context.max { right = context.max }
+			
+			// fill pixels in between
+			for x := left; x < right; x ++ {
+				index := context.image.PixOffset(x, context.y)
+				context.image.Pix[index + 0] = context.color.B
+				context.image.Pix[index + 1] = context.color.G
+				context.image.Pix[index + 2] = context.color.R
+				context.image.Pix[index + 3] = context.color.A
+			}
+		}
+	}
+}
+
+func (context *fillingContext) fillPolygonHotTransparent () {
+	for index := 0; index < len(context.boundaries); index += 2 {
+		left  := context.boundaries[index]
+		right := context.boundaries[index + 1]
+
+		// stop if we have exited the polygon
+		if left >= context.max { break }
+		// begin filling if we are within the polygon
+		if right > context.min {
+			// constrain boundaries to image size
+			if left  < context.min { left  = context.min }
+			if right > context.max { right = context.max }
+			
+			// fill pixels in between
+			for x := left; x < right; x ++ {
+				index := context.image.PixOffset(x, context.y)
+				pixel := xgraphics.BlendBGRA(xgraphics.BGRA {
+					B: context.image.Pix[index + 0],
+					G: context.image.Pix[index + 1],
+					R: context.image.Pix[index + 2],
+					A: context.image.Pix[index + 3],
+				}, context.color)
+				context.image.Pix[index + 0] = pixel.B
+				context.image.Pix[index + 1] = pixel.G
+				context.image.Pix[index + 2] = pixel.R
+				context.image.Pix[index + 3] = pixel.A
+			}
+		}
+	}
+}
+
+func (this *pen) strokePolygon (c xgraphics.BGRA, points ...image.Point) {
+	prevPoint := points[len(points) - 1]
+	for _, point := range points {
+		this.line(c, prevPoint, point)
+		prevPoint = point
+	}
+}
+
+func (this *pen) polyLine (c xgraphics.BGRA, points ...image.Point) {
+	if len(points) < 2 { return }
+	prevPoint := points[0]
+	for _, point := range points[1:] {
+		this.line(c, prevPoint, point)
+		prevPoint = point
+	}
+}

canvas/line.go

@@ -0,0 +1,94 @@
+package xcanvas
+
+import "image"
+import "github.com/jezek/xgbutil/xgraphics"
+
+func (this *pen) line  (
+	c      xgraphics.BGRA,
+	min    image.Point,
+	max    image.Point,
+) {
+	context := linePlottingContext {
+		plottingContext: plottingContext {
+			image:  this.image,
+			color:  c,
+			weight: this.weight,
+		},
+		min: min,
+		max: max,
+	}
+	
+	if abs(max.Y - min.Y) < abs(max.X - min.X) {
+		if max.X < min.X { context.swap() }
+		context.lineLow()
+		
+	} else {
+		if max.Y < min.Y { context.swap() }
+		context.lineHigh()
+	}
+}
+
+type linePlottingContext struct {
+	plottingContext
+	min image.Point
+	max image.Point
+}
+
+func (context *linePlottingContext) swap () {
+	temp := context.max
+	context.max = context.min
+	context.min = temp
+}
+
+func (context linePlottingContext) lineLow () {
+	deltaX := context.max.X - context.min.X
+	deltaY := context.max.Y - context.min.Y
+	yi     := 1
+
+	if deltaY < 0 {
+		yi      = -1
+		deltaY *= -1
+	}
+
+	D := (2 * deltaY) - deltaX
+	point := context.min
+
+	for ; point.X < context.max.X; point.X ++ {
+		context.plot(point)
+		if D > 0 {
+			D += 2 * (deltaY - deltaX)
+			point.Y += yi
+		} else {
+			D += 2 * deltaY
+		}
+	}
+}
+
+func (context linePlottingContext) lineHigh () {
+	deltaX := context.max.X - context.min.X
+	deltaY := context.max.Y - context.min.Y
+	xi     := 1
+
+	if deltaX < 0 {
+		xi      = -1
+		deltaX *= -1
+	}
+
+	D := (2 * deltaX) - deltaY
+	point := context.min
+
+	for ; point.Y < context.max.Y; point.Y ++ {
+		context.plot(point)
+		if D > 0 {
+			point.X += xi
+			D += 2 * (deltaX - deltaY)
+		} else {
+			D += 2 * deltaX
+		}
+	}
+}
+
+func abs (n int) int {
+	if n < 0 { n *= -1}
+	return n
+}

canvas/plot.go

@@ -0,0 +1,47 @@
+package xcanvas
+
+import "image"
+import "github.com/jezek/xgbutil/xgraphics"
+
+type plottingContext struct {
+	image  *xgraphics.Image
+	color  xgraphics.BGRA
+	weight int
+}
+
+func (context plottingContext) square (center image.Point) (square image.Rectangle) {
+	return image.Rect(0, 0, context.weight, context.weight).
+		Sub(image.Pt(context.weight / 2, context.weight / 2)).
+		Add(center).
+		Intersect(context.image.Bounds())
+}
+
+func (context plottingContext) plot (center image.Point) {
+	square := context.square(center)
+
+	if context.color.A == 255 {
+		for y := square.Min.Y; y < square.Max.Y; y ++ {
+		for x := square.Min.X; x < square.Max.X; x ++ {
+			index := context.image.PixOffset(x, y)
+			context.image.Pix[index + 0] = context.color.B
+			context.image.Pix[index + 1] = context.color.G
+			context.image.Pix[index + 2] = context.color.R
+			context.image.Pix[index + 3] = context.color.A
+		}}
+	} else {
+		for y := square.Min.Y; y < square.Max.Y; y ++ {
+		for x := square.Min.X; x < square.Max.X; x ++ {
+			index := context.image.PixOffset(x, y)
+			pixel := xgraphics.BlendBGRA(xgraphics.BGRA {
+				B: context.image.Pix[index + 0],
+				G: context.image.Pix[index + 1],
+				R: context.image.Pix[index + 2],
+				A: context.image.Pix[index + 3],
+			}, context.color)
+			context.image.Pix[index + 0] = pixel.B
+			context.image.Pix[index + 1] = pixel.G
+			context.image.Pix[index + 2] = pixel.R
+			context.image.Pix[index + 3] = pixel.A
+		}}
+	}
+}

canvas/texture.go

@@ -1,6 +1,7 @@
 package xcanvas
 
 import "image"
+import "git.tebibyte.media/tomo/tomo"
 
 // Texture is a read-only image texture that can be quickly written to a canvas.
 // It must be closed manually after use.
@@ -52,9 +53,17 @@ func (this *Texture) Close () error {
 }
 
 // Clip returns a subset of this texture that points to the same data.
-func (this *Texture) Clip (bounds image.Rectangle) *Texture {
+func (this *Texture) Clip (bounds image.Rectangle) tomo.Texture {
 	clipped := *this
 	clipped.rect = bounds
 	return &clipped
 }
 
+// AssertTexture checks if a given tomo.Texture is a texture from this package.
+func AssertTexture (unknown tomo.Texture) *Texture {
+	if tx, ok := unknown.(*Texture); ok {
+		return tx
+	} else {
+		panic("foregin texture implementation, i did not make this!")
+	}
+}

texture.go

@@ -4,26 +4,6 @@ import "image"
 import "git.tebibyte.media/tomo/tomo"
 import "git.tebibyte.media/tomo/x/canvas"
 
-type texture struct {
-	*xcanvas.Texture
-}
-
 func (backend Backend) NewTexture (source image.Image) tomo.Texture {
-	return texture {
+	return xcanvas.NewTextureFrom(source)
-		Texture: xcanvas.NewTextureFrom(source),
-	}
-}
-
-func (this texture) Clip (bounds image.Rectangle) tomo.Texture {
-	return texture {
-		Texture: this.Texture.Clip(bounds),
-	}
-}
-
-func assertTexture (unknown tomo.Texture) *texture {
-	if tx, ok := unknown.(*texture); ok {
-		return tx
-	} else {
-		panic("foregin texture implementation, i did not make this!")
-	}
 }