kadai1_gashiura

kadai1/gashiura/.gitignore

@@ -0,0 +1,14 @@
+# Binaries for programs and plugins
+*.exe
+*.exe~
+*.dll
+*.so
+*.dylib
+
+# Test binary, build with `go test -c`
+*.test
+
+# Output of the go coverage tool, specifically when used with LiteIDE
+*.out
+
+.DS_Store

kadai1/gashiura/docker-compose.yml

@@ -0,0 +1,11 @@
+version: '3'
+services:
+  app:
+    container_name: golang
+    image: golang:latest
+    volumes:
+      - ./src:/go/src
+    ports:
+      - "8080:8080"
+      - "6060:6060"
+    tty: true

kadai1/gashiura/src/imgconv/imgconv.go

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+// Package imgconv is a lib to convert image formats.
+package imgconv
+
+import (
+	"errors"
+	"image"
+	"image/jpeg"
+	"image/png"
+	"image/gif"
+	"io"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+type Converter struct {
+	// image extension before conversion
+	SrcExt string
+	// image extension after conversion
+	DstExt string
+}
+
+const (
+	extJpeg = "jpeg"
+	extPng = "png"
+	extGif = "gif"
+)
+
+/*
+Convert converts the image format file specified as the conversion source under the specified directory
+into the image format of the conversion destination
+*/
+func (conv Converter) Convert(rootDir string) error {
+	err := filepath.Walk(rootDir, func(path string, info os.FileInfo, err error) error {
+		if filepath.Ext(path) == "." + conv.SrcExt {
+			file, err := os.Open(path)
+			if err != nil { return err }
+			defer file.Close()
+
+			img, err := conv.decodeImage(file)
+			if err != nil { return err }
+
+			outPath := strings.Replace(path, conv.SrcExt, conv.DstExt, -1)
+
+			out, err := os.Create(outPath)
+			if err != nil { return err }
+			defer out.Close()
+
+			err = conv.encodeImage(out, img)
+			if err != nil { return err }
+		}
+		return nil
+	})
+
+	return err
+}
+
+func (conv Converter) decodeImage(file io.Reader) (img image.Image, err error) {
+	switch conv.SrcExt {
+	case extJpeg:
+		img, err = jpeg.Decode(file)
+	case extPng:
+		img, err = png.Decode(file)
+	case extGif:
+		img, err = gif.Decode(file)
+	default:
+		img, err = image.Image(nil), errors.New("extension is incorrect.")
+	}
+	return
+}
+
+func (conv Converter) encodeImage(file io.Writer, image image.Image) (err error) {
+	switch conv.DstExt {
+	case extJpeg:
+		opt := &jpeg.Options{Quality: 100}
+		err = jpeg.Encode(file, image, opt)
+	case extPng:
+		err = png.Encode(file, image)
+	case extGif:
+		err = gif.Encode(file, image, nil)
+	default:
+		err = errors.New("extension is incorrect.")
+	}
+	return
+}

kadai1/gashiura/src/main.go

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+package main
+
+import (
+	"flag"
+	"fmt"
+
+	"imgconv"
+	"option"
+)
+
+var (
+	s = flag.String("s", "jpeg", "source image format. support:[jpeg, png, gif]")
+	d = flag.String("d", "png", "destination image format. support:[jpeg, png, gif]")
+)
+
+func main() {
+	flag.Parse()
+	args := flag.Args()
+	if len(args) != 1 {
+		fmt.Println("set the directory path in the argument.")
+		return
+	}
+
+	err := option.Valid(*s, *d)
+	if err != nil {
+		fmt.Println(err)
+		return
+	}
+
+	conv := imgconv.Converter{SrcExt: *s, DstExt: *d}
+	err = conv.Convert(args[0])
+
+	if err != nil {
+		fmt.Println(err)
+		return
+	}
+
+	fmt.Println("complete!")
+}

kadai1/gashiura/src/option/option.go

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+package option
+
+import (
+	"errors"
+	"regexp"
+)
+
+func Valid(s, d string) error {
+	r := regexp.MustCompile("^(jpeg|png|gif)$")
+	if !r.MatchString(s) || !r.MatchString(d) {
+		return errors.New("please set \"jpeg\" or \"png\" or \"gif\" as an option.")
+	}
+	return nil
+}