Added "cut" layout

layouts/cut.go

@@ -0,0 +1,200 @@
+package layouts
+
+import "image"
+import "git.tebibyte.media/tomo/tomo"
+
+type Cut struct {
+	branches [2]*Cut
+	expand   [2]bool
+	vertical bool
+}
+
+func (this *Cut) Vertical () (top, bottom *Cut) {
+	this.fill()
+	this.even()
+	this.vertical = true
+	return this.Branches()
+}
+
+func (this *Cut) Top () (top, bottom *Cut) {
+	this.fill()
+	this.first()
+	this.vertical = true
+	return this.Branches()
+}
+
+func (this *Cut) Bottom () (top, bottom *Cut) {
+	this.fill()
+	this.second()
+	this.vertical = true
+	return this.Branches()
+}
+
+func (this *Cut) Horizontal () (top, bottom *Cut) {
+	this.fill()
+	this.even()
+	return this.Branches()
+}
+
+func (this *Cut) Left () (top, bottom *Cut) {
+	this.fill()
+	this.first()
+	return this.Branches()
+}
+
+func (this *Cut) Right () (top, bottom *Cut) {
+	this.fill()
+	this.second()
+	return this.Branches()
+}
+
+func (this *Cut) Branches () (first, second *Cut) {
+	return this.branches[0], this.branches[1]
+}
+
+func (this *Cut) real () bool {
+	return this != nil && this.branches[0] != nil && this.branches[1] != nil
+}
+
+func (this *Cut) fill () {
+	this.branches[0] = &Cut { }
+	this.branches[1] = &Cut { }
+}
+
+func (this *Cut) first () {
+	this.expand[0] = true
+	this.expand[1] = false
+}
+
+func (this *Cut) second () {
+	this.expand[0] = false
+	this.expand[1] = true
+}
+
+func (this *Cut) even () {
+	this.expand[0] = true
+	this.expand[1] = true
+}
+
+func (this *Cut) MinimumSize (hints tomo.LayoutHints, boxes []tomo.Box) image.Point {
+	size, _ := this.minimumSize(hints, boxes)
+	return size
+}
+
+func (this *Cut) Arrange (hints tomo.LayoutHints, boxes []tomo.Box) {
+	this.arrange(hints, boxes)
+}
+
+func (this *Cut) minimumSize (hints tomo.LayoutHints, boxes []tomo.Box) (image.Point, []tomo.Box) {
+	size := image.Point { }
+
+	for index, branch := range this.branches {
+		if len(boxes) == 0 { break }
+
+		var point image.Point
+		if branch.real() {
+			point, boxes = branch.minimumSize(hints, boxes)
+		} else {
+			point = boxes[0].MinimumSize()
+			boxes = boxes[1:]
+		}
+
+		if this.vertical {
+			if point.X > size.X { size.X  = point.X     }
+			if index   > 0      { size.Y += hints.Gap.Y }
+			size.Y += point.Y
+		} else {
+			if point.Y > size.Y { size.Y  = point.Y     }
+			if index   > 0      { size.X += hints.Gap.X }
+			size.X += point.X
+		}
+	}
+
+	return size, boxes
+}
+
+func (this *Cut) arrange (hints tomo.LayoutHints, boxes []tomo.Box) []tomo.Box {
+	// collect minimum sizes and physical endpoints
+	var minimums [2]image.Point
+	var leaves   [2]tomo.Box
+	var nBranches int
+	remaining := boxes
+	for index, branch := range this.branches {
+		if branch.real() {
+			minimums[index], remaining = branch.minimumSize(hints, remaining)
+		} else {
+			if len(remaining) == 0 { break }
+			leaves[index]   = remaining[0]
+			minimums[index] = remaining[0].MinimumSize()
+			remaining       = remaining[1:]
+		}
+		nBranches ++
+	}
+
+	// determine the amount of space to divide among expanding branches
+	gaps := nBranches - 1
+	var freeSpace float64; if this.vertical {
+		freeSpace = float64(hints.Bounds.Dy() - hints.Gap.Y * gaps)
+	} else {
+		freeSpace = float64(hints.Bounds.Dx() - hints.Gap.X * gaps)
+	}
+	var nExpanding float64
+	for index, minimum := range minimums {
+		if this.expand[index] {
+			nExpanding ++
+		} else if this.vertical {
+			freeSpace -= float64(minimum.Y)
+		} else {
+			freeSpace -= float64(minimum.X)
+		}
+	}
+	expandingSize := freeSpace / nExpanding
+
+	// calculate the size and position of branches
+	var bounds [2]image.Rectangle
+	x := float64(hints.Bounds.Min.X)
+	y := float64(hints.Bounds.Min.Y)
+	for index, minimum := range minimums {
+		// get size along significant axis
+		var size float64; if this.expand[index] {
+			size = expandingSize
+		} else if this.vertical {
+			size = float64(minimum.Y)
+		} else {
+			size = float64(minimum.X)
+		}
+
+		// figure out bounds from size
+		if this.vertical {
+			bounds[index].Max = image.Pt (
+				int(hints.Bounds.Dx()),
+				int(size))
+		} else {
+			bounds[index].Max = image.Pt (
+				int(size),
+				int(hints.Bounds.Dy()))
+		}
+		bounds[index] = bounds[index].Add(image.Pt(int(x), int(y)))
+
+		// move along
+		if this.vertical {
+			y += float64(hints.Gap.Y) + size
+		} else {
+			x += float64(hints.Gap.X) + size
+		}
+	}
+
+	// apply the size and position
+	for index, bound := range bounds {
+		if leaves[index] != nil {
+			leaves[index].SetBounds(bound)
+			boxes = boxes[1:]
+		} else if this.branches[index] != nil {
+			newHints := hints
+			newHints.Bounds = bound
+			boxes = this.branches[index].arrange(newHints, boxes)
+		}
+	}
+	
+	return boxes
+}