filestash/server/plugin/plg_image_golang/index.go

package plg_image_golang

import (
	"bytes"
	. "github.com/mickael-kerjean/filestash/server/common"
	"golang.org/x/image/draw"
	"image"
	_ "image/gif"
	_ "image/jpeg"
	"image/png"

	"io"
	"net/http"
)

const THUMB_SIZE int = 150

func init() {
	Hooks.Register.ProcessFileContentBeforeSend(func(reader io.ReadCloser, ctx *App, res *http.ResponseWriter, req *http.Request) (io.ReadCloser, error) {
		query := req.URL.Query()
		mType := GetMimeType(query.Get("path"))

		if query.Get("thumbnail") != "true" {
			return reader, nil
		} else if mType != "image/jpeg" && mType != "image/png" && mType != "image/gif" {
			return reader, nil
		}

		src, _, err := image.Decode(reader)
		if err != nil {
			return reader, nil
		}
		ratio := func(i image.Image) int {
			b := src.Bounds()
			max := b.Max.X
			if b.Max.X < b.Max.Y {
				max = b.Max.Y
			}
			r := max / THUMB_SIZE
			if r <= 1 {
				return 1
			}
			return r
		}(src)

		dst := image.NewRGBA(image.Rect(0, 0, src.Bounds().Max.X/ratio, src.Bounds().Max.Y/ratio))
		draw.ApproxBiLinear.Scale(dst, dst.Rect, src, src.Bounds(), draw.Over, nil)
		output := bytes.NewBuffer([]byte(""))
		if err = png.Encode(output, dst); err != nil {
			return reader, err
		}
		return NewReadCloserFromBytes(output.Bytes()), nil
	})
}