Initial commit

internal/watermark/watermark.go

@@ -0,0 +1,67 @@
+package watermark
+
+import (
+	"errors"
+	"github.com/nfnt/resize"
+	"image"
+	"image/draw"
+	"image/jpeg"
+	"image/png"
+	"os"
+	"sync"
+)
+
+func AddWatermark(origImage string, watermarkImage string) (image.Image, error) {
+	wg := sync.WaitGroup{}
+
+	var img image.Image
+	var watermark image.Image
+
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		var err error
+		file, err := os.Open(origImage)
+		if err != nil {
+			return
+		}
+		defer file.Close()
+
+		img, err = jpeg.Decode(file)
+		if err != nil {
+			return
+		}
+	}()
+
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		var err error
+		watermarkFile, err := os.Open(watermarkImage)
+		if err != nil {
+			return
+		}
+		defer watermarkFile.Close()
+
+		watermark, err = png.Decode(watermarkFile)
+		if err != nil {
+			return
+		}
+	}()
+	wg.Wait()
+
+	if img == nil || watermark == nil {
+		return nil, errors.New("failed to decode image")
+	}
+
+	offset := image.Pt(10, 10)
+	b := img.Bounds()
+	m := image.NewRGBA(b)
+	draw.Draw(m, b, img, image.Point{}, draw.Src)
+	draw.Draw(m, watermark.Bounds().Add(offset), watermark, image.Point{}, draw.Over)
+	return m, nil
+}
+
+func Resize(img image.Image, width int) image.Image {
+	return resize.Resize(uint(width), 0, img, resize.Lanczos3)
+}