add subtitle feature

README.md

@@ -38,12 +38,15 @@ func main() {
 	// Scale the barcode to 200x200 pixels
 	qrCode, _ = barcode.Scale(qrCode, 200, 200)
 
+	// Optional: Add text to the bottom of the code
+	img := barcode.WithSubtitle(qrCode)
+
 	// create the output file
 	file, _ := os.Create("qrcode.png")
 	defer file.Close()
 
 	// encode the barcode as png
-	png.Encode(file, qrCode)
+	png.Encode(file, img)
 }
 ```
 

subtitle.go

@@ -0,0 +1,56 @@
+package barcode
+
+import (
+	"image"
+	"image/color"
+	"image/draw"
+
+	"github.com/boombuler/barcode"
+	"golang.org/x/image/font"
+	"golang.org/x/image/font/basicfont"
+	"golang.org/x/image/math/fixed"
+)
+
+// WithSubtitle will add the content to the bottom of the image
+func WithSubtitle(bc barcode.Barcode) image.Image {
+	fontFace := basicfont.Face7x13
+	fontColor := color.RGBA{0, 0, 0, 255}
+	margin := 5 // Space between barcode and text
+
+	// Get the bounds of the string
+	bounds, _ := font.BoundString(fontFace, bc.Content())
+
+	widthTxt := int((bounds.Max.X - bounds.Min.X) / 64)
+	heightTxt := int((bounds.Max.Y - bounds.Min.Y) / 64)
+
+	// calc width and height
+	width := widthTxt
+	if bc.Bounds().Dx() > width {
+		width = bc.Bounds().Dx()
+	}
+	height := heightTxt + bc.Bounds().Dy() + margin
+
+	// create result img
+	img := image.NewRGBA(image.Rect(0, 0, width, height))
+	// draw the barcode
+	draw.Draw(img, image.Rect(0, 0, bc.Bounds().Dx(), bc.Bounds().Dy()), bc, bc.Bounds().Min, draw.Over)
+
+	// TextPt
+	offsetY := bc.Bounds().Dy() + margin - int(bounds.Min.Y/64)
+	offsetX := (width - widthTxt) / 2
+
+	point := fixed.Point26_6{
+		X: fixed.Int26_6(offsetX * 64),
+		Y: fixed.Int26_6(offsetY * 64),
+	}
+
+	d := &font.Drawer{
+		Dst:  img,
+		Src:  image.NewUniform(fontColor),
+		Face: fontFace,
+		Dot:  point,
+	}
+	d.DrawString(bc.Content())
+
+	return img
+}