label-tool: make it possible to print free form text

Also commit the label subpackage that we forgot to.

label/label.go

@@ -0,0 +1,87 @@
+package label
+
+import (
+	"image"
+	"image/draw"
+	"strings"
+
+	"janouch.name/sklad/bdf"
+	"janouch.name/sklad/imgutil"
+
+	"github.com/boombuler/barcode"
+	"github.com/boombuler/barcode/qr"
+)
+
+// TODO: Rename to GenQRLabelForHeight.
+func GenLabelForHeight(font *bdf.Font,
+	text string, height, scale int) image.Image {
+	// Create a scaled bitmap of the text label.
+	textRect, _ := font.BoundString(text)
+	textImg := image.NewRGBA(textRect)
+	draw.Draw(textImg, textRect, image.White, image.ZP, draw.Src)
+	font.DrawString(textImg, image.ZP, text)
+
+	scaledTextImg := imgutil.Scale{Image: textImg, Scale: scale}
+	scaledTextRect := scaledTextImg.Bounds()
+
+	remains := height - scaledTextRect.Dy() - 20
+
+	width := scaledTextRect.Dx()
+	if remains > width {
+		width = remains
+	}
+
+	// Create a scaled bitmap of the QR code.
+	qrImg, _ := qr.Encode(text, qr.H, qr.Auto)
+	qrImg, _ = barcode.Scale(qrImg, remains, remains)
+	qrRect := qrImg.Bounds()
+
+	// Combine.
+	combinedRect := image.Rect(0, 0, width, height)
+	combinedImg := image.NewRGBA(combinedRect)
+	draw.Draw(combinedImg, combinedRect, image.White, image.ZP, draw.Src)
+	draw.Draw(combinedImg,
+		combinedRect.Add(image.Point{X: (width - qrRect.Dx()) / 2, Y: 0}),
+		qrImg, image.ZP, draw.Src)
+
+	target := image.Rect(
+		(width-scaledTextRect.Dx())/2, qrRect.Dy()+20,
+		combinedRect.Max.X, combinedRect.Max.Y)
+	draw.Draw(combinedImg, target, &scaledTextImg, scaledTextRect.Min, draw.Src)
+	return combinedImg
+}
+
+func GenLabelForWidth(font *bdf.Font,
+	text string, width, scale int) image.Image {
+	var lines []string
+	for _, line := range strings.Split(text, "\n") {
+		lines = append(lines, strings.TrimSuffix(line, "\r"))
+	}
+
+	height := 0
+	var rects []image.Rectangle
+	for _, line := range lines {
+		r, _ := font.BoundString(line)
+		rects = append(rects, r)
+		height += r.Dy() * scale
+	}
+
+	imgRect := image.Rect(0, 0, width, height)
+	img := image.NewRGBA(imgRect)
+	draw.Draw(img, imgRect, image.White, image.ZP, draw.Src)
+
+	y := 0
+	for i := 0; i < len(lines); i++ {
+		textImg := image.NewRGBA(rects[i])
+		draw.Draw(textImg, rects[i], image.White, image.ZP, draw.Src)
+		font.DrawString(textImg, image.ZP, lines[i])
+
+		scaledImg := imgutil.Scale{Image: textImg, Scale: scale}
+		scaledRect := scaledImg.Bounds()
+
+		target := image.Rect(0, y, imgRect.Max.X, imgRect.Max.Y)
+		draw.Draw(img, target, &scaledImg, scaledRect.Min, draw.Src)
+		y += scaledRect.Dy()
+	}
+	return img
+}