cpolis/cmd/backend/images.go

package backend

import (
	"fmt"
	"image"
	"io"
	"os"

	"github.com/chai2010/webp"
	"github.com/disintegration/imaging"
	"github.com/google/uuid"
)

var ErrUnsupportedFormat error = image.ErrFormat // used internally by imaging

func SaveImage(c *Config, src io.Reader) (string, error) {
	img, err := imaging.Decode(src, imaging.AutoOrientation(true))
	if err != nil {
		if err == ErrUnsupportedFormat {
			return "", ErrUnsupportedFormat
		}
		return "", fmt.Errorf("error decoding image: %v", err)
	}

	if img.Bounds().Dy() > c.MaxImgHeight {
		img = imaging.Resize(img, 0, c.MaxImgHeight, imaging.Lanczos)
	}
	if img.Bounds().Dx() > c.MaxImgWidth {
		img = imaging.Resize(img, c.MaxImgWidth, 0, imaging.Lanczos)
	}

	filename := fmt.Sprint(uuid.New(), ".webp")
	file, err := os.Create(c.PicsDir + "/" + filename)
	if err != nil {
		return "", fmt.Errorf("error creating new image file: %v", err)
	}
	defer file.Close()

	if err = webp.Encode(file, img, &webp.Options{Quality: 80}); err != nil {
		return "", fmt.Errorf("error encoding image as webp: %v", err)
	}

	return filename, nil
}