get information of image without download all image

image

package main

import (
	_ "image/png"
	_ "image/gif"
	_ "image/jpeg"
	"time"
	"net/http"
	"log"
	"io"
	"fmt"
	"image"
	"bytes"
	"path"
	"io/ioutil"
)

const BYTES_64K = 64 * 1 << 10

func main() {
	//imageSize("http://localhost:8080/hh-us-lc-gopher-facts-habitat.png")
	//imageSize("http://localhost:8080/8k-image.jpg")
	//imageSize("http://localhost:8080/logo-vikings.png")
	//imageSize("http://localhost:8080/image8k.jpg")
	//imageSize("http://localhost:8080/image8k.jpg")
	//imageSize("http://localhost:8080/gopher-open-graph-f175d940694bad1bc4e5fe3da49b6ac6.jpg")
	imageSize("http://www.andrealeixo.com/images/home/andrealeixo.png")
}

func imageSize(imageURL string) {
	start := time.Now()
	res, err := http.Get(imageURL)
	end := time.Since(start)

	if err != nil {
		log.Fatal(err)
	}

	fmt.Printf("\n\n %#v \n\n", res)

	buf := make([]byte, BYTES_64K)
	io.ReadAtLeast(res.Body, buf, BYTES_64K)
	res.Body.Close()

	config, format, err := image.DecodeConfig(bytes.NewReader(buf))
	if err != nil {
		log.Fatal(err)
	}

	fmt.Println("./" + path.Base(imageURL))

	err = ioutil.WriteFile("./"+path.Base(imageURL), buf, 0644)
	if err != nil {
		log.Fatal(err)
	}


	fmt.Printf("Format: %s, Dimensions: %d x %d with time [%v] \n", format, config.Width, config.Height, end)
}