added implementation in GO lang

internal/ui/draw.go

@@ -0,0 +1,117 @@
+package ui
+
+import (
+	"image/color"
+	"math"
+
+	"github.com/hajimehoshi/ebiten/v2"
+	"github.com/hajimehoshi/ebiten/v2/text"
+	"github.com/hajimehoshi/ebiten/v2/vector"
+	"golang.org/x/image/font/basicfont"
+)
+
+var whitePixel = func() *ebiten.Image {
+	img := ebiten.NewImage(1, 1)
+	img.Fill(color.White)
+	return img
+}()
+
+func Rect(screen *ebiten.Image, x, y, w, h float32, clr color.Color) {
+	vector.FillRect(screen, x, y, w, h, clr, true)
+}
+
+func RectOutline(screen *ebiten.Image, x, y, w, h, stroke float32, clr color.Color) {
+	vector.StrokeRect(screen, x, y, w, h, stroke, clr, true)
+}
+
+func Line(screen *ebiten.Image, x1, y1, x2, y2, width float32, clr color.Color) {
+	vector.StrokeLine(screen, x1, y1, x2, y2, width, clr, true)
+}
+
+func Circle(screen *ebiten.Image, x, y, r float32, clr color.Color) {
+	vector.FillCircle(screen, x, y, r, clr, true)
+}
+
+func Triangle(screen *ebiten.Image, x1, y1, x2, y2, x3, y3 float32, clr color.Color) {
+	Polygon(screen, []Point{{x1, y1}, {x2, y2}, {x3, y3}}, clr)
+}
+
+func Star(screen *ebiten.Image, x, y, outer, inner float32, points int, clr color.Color) {
+	if points < 3 {
+		points = 5
+	}
+	poly := make([]Point, 0, points*2)
+	for i := 0; i < points*2; i++ {
+		r := outer
+		if i%2 == 1 {
+			r = inner
+		}
+		a := -math.Pi/2 + float64(i)*math.Pi/float64(points)
+		poly = append(poly, Point{
+			X: x + float32(math.Cos(a))*r,
+			Y: y + float32(math.Sin(a))*r,
+		})
+	}
+	for i := 0; i < len(poly); i++ {
+		next := (i + 1) % len(poly)
+		Triangle(screen, x, y, poly[i].X, poly[i].Y, poly[next].X, poly[next].Y, clr)
+	}
+}
+
+type Point struct {
+	X float32
+	Y float32
+}
+
+func Polygon(screen *ebiten.Image, points []Point, clr color.Color) {
+	if len(points) < 3 {
+		return
+	}
+	r, g, b, a := clr.RGBA()
+	vertices := make([]ebiten.Vertex, len(points))
+	for i, p := range points {
+		vertices[i] = ebiten.Vertex{
+			DstX:   p.X,
+			DstY:   p.Y,
+			SrcX:   0,
+			SrcY:   0,
+			ColorR: float32(r) / 0xffff,
+			ColorG: float32(g) / 0xffff,
+			ColorB: float32(b) / 0xffff,
+			ColorA: float32(a) / 0xffff,
+		}
+	}
+	indices := make([]uint16, 0, (len(points)-2)*3)
+	for i := 1; i < len(points)-1; i++ {
+		indices = append(indices, 0, uint16(i), uint16(i+1))
+	}
+	screen.DrawTriangles(vertices, indices, whitePixel, nil)
+}
+
+func Text(screen *ebiten.Image, s string, x, y int, clr color.Color, scale float64) {
+	drawText(screen, s, x, y, clr, scale, false)
+}
+
+func CenteredText(screen *ebiten.Image, s string, cx, cy int, clr color.Color, scale float64) {
+	drawText(screen, s, cx, cy, clr, scale, true)
+}
+
+func drawText(screen *ebiten.Image, s string, x, y int, clr color.Color, scale float64, centered bool) {
+	if scale <= 0 {
+		scale = 1
+	}
+	w := max(1, len(s)*7+4)
+	h := 17
+	img := ebiten.NewImage(w, h)
+	text.Draw(img, s, basicfont.Face7x13, 2, 13, clr)
+
+	op := &ebiten.DrawImageOptions{}
+	op.GeoM.Scale(scale, scale)
+	tx, ty := float64(x), float64(y)
+	if centered {
+		tx -= float64(w) * scale / 2
+		ty -= float64(h) * scale / 2
+	}
+	op.GeoM.Translate(tx, ty)
+	screen.DrawImage(img, op)
+}