From de6fe4991cf30b37bdff73269384b81156b24eb3 Mon Sep 17 00:00:00 2001
From: Nicolai Ort <info@nicolai-ort.com>
Date: Thu, 12 Dec 2024 19:11:01 +0100
Subject: [PATCH] feat(barcode): Padding

---
 handlers/barcode.go   | 19 ++++++++++++++-----
 services/barcode.go   | 17 ++++++++++++++---
 services/templater.go |  2 +-
 3 files changed, 29 insertions(+), 9 deletions(-)

diff --git a/handlers/barcode.go b/handlers/barcode.go
index 5aaa4bc..0c8ae95 100644
--- a/handlers/barcode.go
+++ b/handlers/barcode.go
@@ -11,10 +11,11 @@ import (
 //	@Summary		Generate barcodes
 //	@Description	Generate barcodes based on the provided data
 //	@Tags			barcodes
-//	@Param			type	path	string	true	"Barcode type"		Enums(ean13, code128)
-//	@Param			content	path	string	true	"Barcode content"	MinLength(1)
-//	@Param			width	query	int		false	"Barcode width"		Minimum(1)	Maximum(10000) default(1000)
-//	@Param			height	query	int		false	"Barcode height"	Minimum(1)	Maximum(10000) default(1000)
+//	@Param			type	path	string	true	"Barcode type"					Enums(ean13, code128)
+//	@Param			content	path	string	true	"Barcode content"				MinLength(1)
+//	@Param			width	query	int		false	"Barcode width"					Minimum(1)	Maximum(10000)	default(1000)
+//	@Param			height	query	int		false	"Barcode height"				Minimum(1)	Maximum(10000)	default(1000)
+//	@Param			padding	query	int		false	"Padding around the barcode"	Minimum(0)	Maximum(100)	default(10)
 //	@Produce		image/png
 //	@Router			/v1/barcodes/{type}/{content} [get]
 func (h *DefaultHandler) GenerateBarcode(c *fiber.Ctx) error {
@@ -26,6 +27,7 @@ func (h *DefaultHandler) GenerateBarcode(c *fiber.Ctx) error {
 	// Get the width and height from the query parameters
 	widthStr := c.Query("width", "1000")
 	heightStr := c.Query("height", "1000")
+	paddingStr := c.Query("padding", "10")
 
 	// Convert width and height to integers
 	width, err := strconv.Atoi(widthStr)
@@ -42,8 +44,15 @@ func (h *DefaultHandler) GenerateBarcode(c *fiber.Ctx) error {
 		})
 	}
 
+	padding, err := strconv.Atoi(paddingStr)
+	if err != nil {
+		return c.Status(fiber.StatusBadRequest).JSON(fiber.Map{
+			"error": "Invalid padding parameter",
+		})
+	}
+
 	// Generate the barcode
-	barcode, err := h.BarcodeService.GenerateBarcode(barcodeType, barcodeContent, width, height)
+	barcode, err := h.BarcodeService.GenerateBarcode(barcodeType, barcodeContent, width, height, padding)
 	if err != nil {
 		return c.Status(fiber.StatusInternalServerError).JSON(fiber.Map{
 			"error": err.Error(),
diff --git a/services/barcode.go b/services/barcode.go
index 29cb5b0..59a3796 100644
--- a/services/barcode.go
+++ b/services/barcode.go
@@ -4,6 +4,9 @@ import (
 	"bytes"
 	"context"
 	"fmt"
+	"image"
+	"image/color"
+	"image/draw"
 	"image/png"
 	"log"
 	"slices"
@@ -17,7 +20,7 @@ import (
 )
 
 type BarcodeService interface {
-	GenerateBarcode(format string, content string, width int, height int) (bytes.Buffer, error)
+	GenerateBarcode(format string, content string, width int, height int, padding int) (bytes.Buffer, error)
 	IsTypeSupported(format string) bool
 }
 
@@ -25,7 +28,7 @@ type DefaultBarcodeService struct {
 	RedisClient *redis.Client
 }
 
-func (b *DefaultBarcodeService) GenerateBarcode(format string, content string, width int, height int) (bytes.Buffer, error) {
+func (b *DefaultBarcodeService) GenerateBarcode(format string, content string, width int, height int, padding int) (bytes.Buffer, error) {
 	ctx := context.Background()
 
 	if !b.IsTypeSupported(format) {
@@ -71,8 +74,16 @@ func (b *DefaultBarcodeService) GenerateBarcode(format string, content string, w
 		return bytes.Buffer{}, err
 	}
 
+	// Create a white background image
+	bg := image.NewRGBA(image.Rect(0, 0, width+2*padding, height+2*padding))
+	white := color.RGBA{255, 255, 255, 255}
+	draw.Draw(bg, bg.Bounds(), &image.Uniform{white}, image.Point{}, draw.Src)
+
+	// Draw the barcode on top of the white background with padding
+	draw.Draw(bg, scaledCode.Bounds().Add(image.Point{padding + (width-scaledCode.Bounds().Dx())/2, padding + (height-scaledCode.Bounds().Dy())/2}), scaledCode, image.Point{}, draw.Over)
+
 	var buf bytes.Buffer
-	err = png.Encode(&buf, scaledCode)
+	err = png.Encode(&buf, bg)
 	if err != nil {
 		return bytes.Buffer{}, err
 	}
diff --git a/services/templater.go b/services/templater.go
index 46cfa0d..fa644ae 100644
--- a/services/templater.go
+++ b/services/templater.go
@@ -42,7 +42,7 @@ func (t *DefaultTemplater) GenerateBarcode(code string, format string, prefix st
 		}
 	}
 
-	buf, err := t.BarcodeService.GenerateBarcode(format, code, 1000, 500)
+	buf, err := t.BarcodeService.GenerateBarcode(format, code, 1000, 500, 0)
 
 	return base64.StdEncoding.EncodeToString(buf.Bytes()), err
 }