holly molly

imageutils/concat.go

@@ -0,0 +1,126 @@
+package imageutils
+
+import (
+	"image"
+	"image/color"
+	"image/draw"
+)
+
+type Side int
+
+const (
+	Left Side = iota
+	Right
+	Up
+	Down
+)
+
+type pair struct {
+	first, second image.Image
+	side          Side
+}
+
+// Takes color.Model of the first Image.
+func (p pair) ColorModel() color.Model { return p.first.ColorModel() }
+
+func (p pair) Bounds() image.Rectangle {
+	var (
+		b1 = p.first.Bounds()
+		b2 = p.second.Bounds()
+	)
+
+	point := image.Point{}
+	switch p.side {
+	case Left:
+		fallthrough
+	case Right:
+		point = image.Point{
+			X: b1.Dx() + b2.Dx(),
+			Y: max(b1.Dy(), b2.Dy()),
+		}
+	case Up:
+		fallthrough
+	case Down:
+		point = image.Point{
+			X: max(b1.Dx(), b2.Dx()),
+			Y: b1.Dy() + b2.Dy(),
+		}
+	}
+	return image.Rectangle{
+		image.ZP,
+		point,
+	}
+}
+
+func (p pair) At(x, y int) color.Color {
+	img := image.NewRGBA(p.Bounds())
+
+	point := image.Point{}
+	switch p.side {
+	case Left:
+		p.first, p.second = p.second, p.first
+		fallthrough
+	case Right:
+		point = image.Point{-p.first.Bounds().Dx(), 0}
+	case Up:
+		p.first, p.second = p.second, p.first
+		fallthrough
+	case Down:
+		point = image.Point{0, -p.first.Bounds().Dy()}
+	}
+	// draw main
+	draw.Draw(
+		img, img.Bounds(),
+		p.first,
+		image.ZP, draw.Src,
+	)
+
+	// draw second
+	draw.Draw(
+		img, p.Bounds(),
+		p.second,
+		point,
+		draw.Src,
+	)
+
+	return img.At(x, y)
+}
+
+func render(p pair) image.Image {
+	img := image.NewRGBA(p.Bounds())
+
+	point := image.Point{}
+	switch p.side {
+	case Left:
+		p.first, p.second = p.second, p.first
+		fallthrough
+	case Right:
+		point = image.Point{-p.first.Bounds().Dx(), 0}
+	case Up:
+		p.first, p.second = p.second, p.first
+		fallthrough
+	case Down:
+		point = image.Point{0, -p.first.Bounds().Dy()}
+	}
+	// draw main
+	draw.Draw(
+		img, img.Bounds(),
+		p.first,
+		image.ZP, draw.Src,
+	)
+
+	// draw second
+	draw.Draw(
+		img, p.Bounds(),
+		p.second,
+		point,
+		draw.Src,
+	)
+
+	return img
+}
+
+// Concat concatenates second image on a given side.
+func Concat(i1, i2 image.Image, s Side) image.Image {
+	return render(pair{i1, i2, s})
+}