生命不止，继续 go go go~~~~

今天做一点图片处理的东西，跟大家一起学习分享。

很久之前，介绍过golang提供的关于图片的标准库：
Go语言学习之image、image/color、image/png、image/jpeg包(the way to go)

当你search on google或百度一下的时候，你会发现很多提到了graphics-go/graphics，但是这个库不知道为何，官方好像不再提供了，很难找到了。

那也没关系，我们还有面向github编程呢！！！

温故而知新，先看一下之前的代码：
生成图片

@H_404_17@package main import "image" import "image/color" import "image/png" import "os" func main() { // Create an 100 x 50 image img := image.NewRGBA(image.Rect(0, 0, 100, 50)) // Draw a red dot at (2,3) img.Set(2, 3,color.RGBA{255, 255}) // Save to out.png f,_ := os.OpenFile("out.png",os.O_WRONLY|os.O_CREATE, 0600) defer f.Close() png.Encode(f,img) }

disintegration/imaging

github地址：
https://github.com/disintegration/imaging

Star: 1284

获取：
go get -u github.com/disintegration/imaging

生成缩略图
下面的代码，将三张图片生成一张缩略图。
出自：
https://www.socketloop.com/tutorials/golang-generate-thumbnails-from-images

@H_404_17@package main import ( "image" "image/color" "runtime" "github.com/disintegration/imaging" ) func main() { // use all cpu cores for maximum performance runtime.GOMAXPROCS(runtime.Numcpu()) // input files files := []string{"1.jpg","2.jpg","3.jpg"} // load images and make 100x100 thumbnails of them var thumbnails []image.Image for _,file := range files { img,err := imaging.Open(file) if err != nil { panic(err) } thumb := imaging.Thumbnail(img,imaging.CatmullRom) thumbnails = append(thumbnails,thumb) } // create a new blank image dst := imaging.New(100*len(thumbnails),color.NRGBA{0, 0}) // paste thumbnails into the new image side by side for i,thumb := range thumbnails { dst = imaging.Paste(dst,thumb,image.Pt(i*100, 0)) } // save the combined image to file err := imaging.Save(dst,"dst.jpg") if err != nil { panic(err) } }

生成缩略图服务
接下来，根据用户提供的url，生成不同尺寸的缩略图。

关于golang中net/http可以参考：
Go语言学习之net/http包(The way to go)

@H_404_17@package main import ( "fmt" "image" "image/color" "image/png" "net/http" "runtime" "strconv" "strings" "github.com/disintegration/imaging" ) func main() { // use all cpu cores for maximum performance runtime.GOMAXPROCS(runtime.Numcpu()) http.HandleFunc("/",doImageHandler) http.ListenAndServe("localhost:8080",nil) } func doImageHandler(w http.ResponseWriter,r *http.Request) { fmt.Printf("%q\n",strings.Split(r.URL.Path,"/")) url := strings.Split(r.URL.Path,"/") if len(url) != 3 { return } thumbnails_size := strings.Split(url[2],"_") if len(thumbnails_size) != 2 { return } thumbnails_width,_ := strconv.Atoi(thumbnails_size[0]) thumbnails_height,_ := strconv.Atoi(thumbnails_size[1]) img,err := imaging.Open(url[1]) if err != nil { panic(err) } thumb := imaging.Thumbnail(img,thumbnails_width,thumbnails_height,imaging.CatmullRom) dst := imaging.New(thumbnails_width, 0}) dst = imaging.Paste(dst,image.Pt(0, 0)) if err != nil { panic(err) } header := w.Header() header.Add("Content-Type","image/jpeg") png.Encode(w,dst) }

例如，浏览器输入：http://localhost:8080/1.jpg/80_90
就会生成一张80*90的1.jpg的缩略图

nfnt/resize

github地址:
https://github.com/nfnt/resize

Star: 1544

获取：
go get github.com/nfnt/resize

等比例放大缩小图片

@H_404_17@package main import ( "image/jpeg" "log" "os" "github.com/nfnt/resize" ) func main() { file,err := os.Open("1.jpg") if err != nil { log.Fatal(err) } img,err := jpeg.Decode(file) if err != nil { log.Fatal(err) } file.Close() // resize to width 1000 using Lanczos resampling // and preserve aspect ratio m := resize.Resize(100,img,resize.Lanczos3) out,err := os.Create("test_resized.jpg") if err != nil { log.Fatal(err) } defer out.Close() // write new image to file jpeg.Encode(out,m,nil) }