metarare_api-main/util/media.go

package util

import (
	"bytes"
	"fmt"
	"image"
	"image/gif"
	"image/jpeg"
	"image/png"
	"io"

	imaging "github.com/disintegration/imaging"
	"github.com/nfnt/resize"
	exif "github.com/rwcarlsen/goexif/exif"
	"golang.org/x/image/bmp"
)

type ContentsCenter struct {
	TargetWidth int
}
type rectangle struct {
	Width  int
	Hegith int
}

// Support image format list -> "png", "jpeg", "gif", "jpg",
func (mc *ContentsCenter) setting() {
	image.RegisterFormat("jpeg", "jpeg", jpeg.Decode, jpeg.DecodeConfig)
	image.RegisterFormat("png", "png", png.Decode, png.DecodeConfig)
	image.RegisterFormat("gif", "gif", gif.Decode, gif.DecodeConfig)
	image.RegisterFormat("bmp", "bmp", bmp.Decode, bmp.DecodeConfig)
	mc.TargetWidth = 1440
}
func (mc *ContentsCenter) analyzeImage(reader io.Reader) (bool, string, image.Config) { // protected function
	config, format, err := image.DecodeConfig(reader)
	if err == nil {
		return true, format, config
	}
	return false, "", image.Config{}
}
func (mc *ContentsCenter) analyzeVideo() bool { // protected function
	return false
}

func (mc *ContentsCenter) Resize(fileData []byte) ([]byte, error) {
	mc.setting()
	var c image.Config
	res := false
	format := ""
	axisSwap := false
	r := bytes.NewReader(fileData)
	if res, format, c = mc.analyzeImage(io.Reader(r)); !res && !mc.analyzeVideo() {
		return nil, fmt.Errorf("Unsupported file format")
	}
	r = bytes.NewReader(fileData)
	img, _, err := image.Decode(r)
	if err != nil {
	}
	// rotate if exif's orient value.
	r = bytes.NewReader(fileData)
	if _exif, err := exif.Decode(r); err == nil {
		if exifInfo, err := _exif.Get(exif.Orientation); err != nil {
			fmt.Errorf(err.Error())
		} else {
			_v := exifInfo.Val[0]
			if _v == 0 {
				_v = exifInfo.Val[1]
			}

			// fmt.Printf("exifInfo: %d, %d", _v, exifInfo.Val[1])
			if _v == 6 {
				img = imaging.Rotate270(img)
				axisSwap = true
			} else if _v == 1 {

			} else if _v == 8 {
				img = imaging.Rotate90(img)
				axisSwap = true
			} else if _v == 3 {
				img = imaging.Rotate180(img)
			}
		}
	} else {
		fmt.Print("Occurred error when decoding!")
		fmt.Print(err.Error())
	}
	//calculate image ratio

	var modImg image.Image
	rY := float32(c.Height) / float32(c.Width)
	if axisSwap {
		modImg = resize.Resize(
			(uint)((float32)(mc.TargetWidth)*rY), (uint)(float32(mc.TargetWidth)),
			img, resize.Lanczos3)
	} else {

		modImg = resize.Resize(
			(uint)(mc.TargetWidth), (uint)(float32(mc.TargetWidth)*rY),
			img, resize.Lanczos3)
	}
	var buff bytes.Buffer
	if format == "png" {
		png.Encode(&buff, modImg)
	} else if format == "jpeg" || format == "jpg" {
		jpeg.Encode(&buff, modImg, &jpeg.Options{70})
	} else if format == "gif" {
		gif.Encode(&buff, modImg, &gif.Options{NumColors: 256})
	} else if format == "bmp" {
		png.Encode(&buff, modImg)
	}
	return buff.Bytes(), nil
}