Playing with images
| package main | |
| import ( | |
| "bytes" | |
| "encoding/base64" | |
| "flag" | |
| "html/template" | |
| "image" | |
| "image/color" | |
| "image/draw" | |
| "image/jpeg" | |
| "log" | |
| "net/http" | |
| "strconv" | |
| ) | |
| var root = flag.String("root", ".", "file system path") | |
| func main() { | |
| http.HandleFunc("/blue/", blueHandler) | |
| http.HandleFunc("/red/", redHandler) | |
| http.Handle("/", http.FileServer(http.Dir(*root))) | |
| log.Println("Listening on 8080") | |
| err := http.ListenAndServe(":8080", nil) | |
| if err != nil { | |
| log.Fatal("ListenAndServe:", err) | |
| } | |
| } | |
| func blueHandler(w http.ResponseWriter, r *http.Request) { | |
| m := image.NewRGBA(image.Rect(0, 0, 240, 240)) | |
| blue := color.RGBA{0, 0, 255, 255} | |
| draw.Draw(m, m.Bounds(), &image.Uniform{blue}, image.ZP, draw.Src) | |
| var img image.Image = m | |
| writeImage(w, &img) | |
| } | |
| func redHandler(w http.ResponseWriter, r *http.Request) { | |
| m := image.NewRGBA(image.Rect(0, 0, 240, 240)) | |
| blue := color.RGBA{255, 0, 0, 255} | |
| draw.Draw(m, m.Bounds(), &image.Uniform{blue}, image.ZP, draw.Src) | |
| var img image.Image = m | |
| writeImageWithTemplate(w, &img) | |
| } | |
| var ImageTemplate string = `<!DOCTYPE html> | |
| <html lang="en"><head></head> | |
| <body><img src="data:image/jpg;base64,{{.Image}}"></body>` | |
| // Writeimagewithtemplate encodes an image 'img' in jpeg format and writes it into ResponseWriter using a template. | |
| func writeImageWithTemplate(w http.ResponseWriter, img *image.Image) { | |
| buffer := new(bytes.Buffer) | |
| if err := jpeg.Encode(buffer, *img, nil); err != nil { | |
| log.Fatalln("unable to encode image.") | |
| } | |
| str := base64.StdEncoding.EncodeToString(buffer.Bytes()) | |
| if tmpl, err := template.New("image").Parse(ImageTemplate); err != nil { | |
| log.Println("unable to parse image template.") | |
| } else { | |
| data := map[string]interface{}{"Image": str} | |
| if err = tmpl.Execute(w, data); err != nil { | |
| log.Println("unable to execute template.") | |
| } | |
| } | |
| } | |
| // writeImage encodes an image 'img' in jpeg format and writes it into ResponseWriter. | |
| func writeImage(w http.ResponseWriter, img *image.Image) { | |
| buffer := new(bytes.Buffer) | |
| if err := jpeg.Encode(buffer, *img, nil); err != nil { | |
| log.Println("unable to encode image.") | |
| } | |
| w.Header().Set("Content-Type", "image/jpeg") | |
| w.Header().Set("Content-Length", strconv.Itoa(len(buffer.Bytes()))) | |
| if _, err := w.Write(buffer.Bytes()); err != nil { | |
| log.Println("unable to write image.") | |
| } | |
| } |
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