Readd drawille-go into repo

drawille/drawille.go

@@ -0,0 +1,90 @@
+package drawille
+
+import (
+	"image"
+)
+
+const BRAILLE_OFFSET = '\u2800'
+
+var BRAILLE = [4][2]rune{
+	{'\u0001', '\u0008'},
+	{'\u0002', '\u0010'},
+	{'\u0004', '\u0020'},
+	{'\u0040', '\u0080'},
+}
+
+type Color int
+
+type Cell struct {
+	Rune  rune
+	Color Color
+}
+
+type Canvas struct {
+	CellMap map[image.Point]Cell
+}
+
+func NewCanvas() *Canvas {
+	return &Canvas{
+		CellMap: make(map[image.Point]Cell),
+	}
+}
+
+func (self *Canvas) SetPoint(p image.Point, color Color) {
+	point := image.Pt(p.X/2, p.Y/4)
+	self.CellMap[point] = Cell{
+		self.CellMap[point].Rune | BRAILLE[p.Y%4][p.X%2],
+		color,
+	}
+}
+
+func (self *Canvas) SetLine(p0, p1 image.Point, color Color) {
+	for _, p := range line(p0, p1) {
+		self.SetPoint(p, color)
+	}
+}
+
+func (self *Canvas) GetCells() map[image.Point]Cell {
+	cellMap := make(map[image.Point]Cell)
+	for point, cell := range self.CellMap {
+		cellMap[point] = Cell{cell.Rune + BRAILLE_OFFSET, cell.Color}
+	}
+	return cellMap
+}
+
+func line(p0, p1 image.Point) []image.Point {
+	points := []image.Point{}
+
+	leftPoint, rightPoint := p0, p1
+	if leftPoint.X > rightPoint.X {
+		leftPoint, rightPoint = rightPoint, leftPoint
+	}
+
+	xDistance := absInt(leftPoint.X - rightPoint.X)
+	yDistance := absInt(leftPoint.Y - rightPoint.Y)
+	slope := float64(yDistance) / float64(xDistance)
+	slopeSign := 1
+	if rightPoint.Y < leftPoint.Y {
+		slopeSign = -1
+	}
+
+	targetYCoordinate := float64(leftPoint.Y)
+	currentYCoordinate := leftPoint.Y
+	for i := leftPoint.X; i < rightPoint.X; i++ {
+		points = append(points, image.Pt(i, currentYCoordinate))
+		targetYCoordinate += (slope * float64(slopeSign))
+		for currentYCoordinate != int(targetYCoordinate) {
+			points = append(points, image.Pt(i, currentYCoordinate))
+			currentYCoordinate += slopeSign
+		}
+	}
+
+	return points
+}
+
+func absInt(x int) int {
+	if x >= 0 {
+		return x
+	}
+	return -x
+}