imura81gt: 課題1

kadai1/imura81gt/README.md

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+Convert Image
+================================================================================
+
+TOC
+--------------------------------------------------------------------------------
+- [Convert Image](#convert-image)
+  - [TOC](#toc)
+  - [Q. 【TRY】画像変換コマンドを作ろう](#q-try画像変換コマンドを作ろう)
+  - [Links](#links)
+    - [About filepath](#about-filepath)
+    - [About image](#about-image)
+  - [Build](#build)
+  - [Usage](#usage)
+  - [Test Data](#test-data)
+  - [Example](#example)
+    - [e.g. use no option](#eg-use-no-option)
+    - [e.g. use option](#eg-use-option)
+
+Q. 【TRY】画像変換コマンドを作ろう
+--------------------------------------------------------------------------------
+
+次の仕様を満たすコマンドを作って下さい
+
+- [x] 1. ディレクトリを指定する
+- [x] 2. 指定したディレクトリ以下のJPGファイルをPNGに変換（デフォルト）
+- [x] 3. ディレクトリ以下は再帰的に処理する
+- [x] 4. 変換前と変換後の画像形式を指定できる（オプション）
+
+以下を満たすように開発してください
+
+- [x] 5. mainパッケージと分離する
+- [x] 6. 自作パッケージと標準パッケージと準標準パッケージのみ使う
+  - 準標準パッケージ：golang.org/x以下のパッケージ
+- [x] 8. ユーザ定義型を作ってみる
+- [x] 9. GoDocを生成してみる
+
+
+Links
+--------------------------------------------------------------------------------
+
+### About filepath
+
+- https://golang.org/pkg/path/filepath/
+
+### About image
+
+- [Package image](https://golang.org/pkg/image/)
+    - [gif](https://golang.org/pkg/image/gif/)
+    - [jpeg](https://golang.org/pkg/image/jpeg/)
+    - [png](https://golang.org/pkg/image/png/)
+    - get format
+        - [DecodeConfig](https://golang.org/pkg/image/#DecodeConfig)
+- [The Go Blog](https://blog.golang.org/)
+    - [The Go image package](https://blog.golang.org/go-image-package#TOC_5.)
+
+
+Go doc
+--------------------------------------------------------------------------------
+
+```
+$ go doc github.com/gopherdojo/dojo7/kadai1/imura81gt/imgconv/img
+package img // import "github.com/gopherdojo/dojo7/kadai1/imura81gt/imgconv/img"
+
+func AllImageFiles(dirs []string) (files []string)
+func Convert(r io.Reader, w io.Writer, t string) error
+func ConvertAll(dirs []string, iType ImageType, oType ImageType) error
+func ExpectedImageFiles(files []string, iType ImageType) (f []string)
+func IsExpectedImage(path string, iType ImageType) bool
+func IsImage(path string) bool
+type ImageType struct{ ... }
+```
+
+OR
+
+```
+cd $(go env GOPATH)/src/github.com/gopherdojo/dojo7/kadai1/imura81gt/imgconv
+godoc -http=:8080
+```
+
+http://localhost:8080/pkg/github.com/gopherdojo/dojo7/kadai1/imura81gt/imgconv/img/
+
+Build
+--------------------------------------------------------------------------------
+
+```
+cd $(go env GOPATH)/src/github.com/gopherdojo/dojo7/kadai1/imura81gt/imgconv
+GO111MODULE=on go build
+```
+
+Usage
+--------------------------------------------------------------------------------
+
+```
+$ ./imgconv
+./imgconv <option> dir1 dir2 dir3
+option:
+  -G    convert to gif.
+  -J    convert to jpeg.
+  -P    convert to png.
+  -g    inpt files are gif.
+  -j    inpt files are jpeg.
+  -p    inpt files are png.
+```
+
+
+Test Data
+--------------------------------------------------------------------------------
+
+```
+$ tree testdata/
+testdata/
+├── chdir
+│   ├── gLenna.gif
+│   ├── jLenna.jpeg
+│   └── pLenna.png
+├── gLenna.gif
+├── jLenna.jpg
+├── pLenna.png
+├── this_is_not_image.gif
+├── this_is_not_image.jpg
+└── this_is_not_image.png
+
+1 directory, 9 files
+$
+```
+
+
+Example
+--------------------------------------------------------------------------------
+
+### e.g. use no option
+
+```
+$ ./imgconv testdata/
+```
+
+In stdout, the command output input files and output files.
+
+```
+["testdata/chdir/jLenna.jpeg" "testdata/jLenna.jpg"]
+["output/png/testdata/chdir/jLenna.png" "output/png/testdata/jLenna.png"]
+```
+
+```
+$ tree output/
+output/
+└── png
+    └── testdata
+        ├── chdir
+        │   └── jLenna.png
+        └── jLenna.png
+$
+```
+
+### e.g. use option
+
+- input: png, jpeg
+- output: gif
+
+```
+$ ./imgconv testdata/ -p -j -G
+```
+
+In stdout, the command output input files and output files.
+
+```
+
+["testdata/chdir/jLenna.jpeg" "testdata/chdir/pLenna.png" "testdata/jLenna.jpg" "testdata/pLenna.png"]
+["output/gif/testdata/chdir/jLenna.gif" "output/gif/testdata/chdir/pLenna.gif" "output/gif/testdata/jLenna.gif" "output/gif/testdata/pLenna.gif"]
+```
+
+```
+$ tree output/
+output/
+└── gif
+    └── testdata
+        ├── chdir
+        │   ├── jLenna.gif
+        │   └── pLenna.gif
+        ├── jLenna.gif
+        └── pLenna.gif
+$
+```

kadai1/imura81gt/imgconv/.gitignore

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+output
+imgconv

kadai1/imura81gt/imgconv/go.mod

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+module github.com/gopherdojo/dojo7/kadai1/imura81gt/imgconv
+
+go 1.12

kadai1/imura81gt/imgconv/go.sum

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+github.com/gopherdojo/dojo7 v0.0.0-20190903074013-69385d40c994 h1:UbdhtSFDdFiSYOb/TkEmlRIUFQRrBlKOzVDY3+SXaSw=

kadai1/imura81gt/imgconv/img/convert.go

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+package img
+
+import (
+	"fmt"
+	"image"
+	"image/gif"
+	"image/jpeg"
+	"image/png"
+	"io"
+	"os"
+	"path/filepath"
+)
+
+const (
+	saveDir  = "output"
+	pngType  = "png"
+	jpegType = "jpeg"
+	gifType  = "gif"
+)
+
+// ConvType is type of converted image files
+// 8. ユーザ定義型を作ってみる
+type ImageType struct {
+	Png  bool
+	Jpeg bool
+	Gif  bool
+}
+
+func (i ImageType) Enable() []string {
+	var types []string
+	if i.Png {
+		types = append(types, pngType)
+	}
+	if i.Jpeg {
+		types = append(types, jpegType)
+	}
+	if i.Gif {
+		types = append(types, gifType)
+	}
+	return types
+}
+
+// ConvertAll convert all image files in dirs
+func ConvertAll(dirs []string, iType ImageType, oType ImageType) error {
+	files := AllImageFiles(dirs)
+	files = ExpectedImageFiles(files, iType)
+	fmt.Printf("%q\n", files)
+
+	var oFiles []string
+	for _, iPath := range files {
+		for _, t := range oType.Enable() {
+			oPath := filepath.Join(saveDir, t, iPath[:len(iPath)-len(filepath.Ext(iPath))]+"."+t)
+
+			i, err := os.Open(iPath)
+			if err != nil {
+				fmt.Fprintln(os.Stderr, err)
+				os.Exit(1)
+			}
+
+			err = os.MkdirAll(filepath.Dir(oPath), 0755)
+			if err != nil {
+				fmt.Fprintln(os.Stderr, err)
+				os.Exit(1)
+			}
+
+			w, err := os.Create(oPath)
+			if err != nil {
+				fmt.Fprintln(os.Stderr, err)
+				os.Exit(1)
+			}
+
+			err = Convert(i, w, t)
+			if err != nil {
+				fmt.Fprintln(os.Stderr, err)
+				os.Exit(1)
+			}
+			oFiles = append(oFiles, oPath)
+		}
+	}
+	fmt.Printf("%q\n", oFiles)
+	return nil
+}
+
+func AllImageFiles(dirs []string) (files []string) {
+	// 3. ディレクトリ以下は再帰的に処理する
+	for _, dir := range dirs {
+		err := filepath.Walk(dir, func(path string, info os.FileInfo, err error) error {
+			if info.IsDir() {
+				return nil
+			}
+
+			if IsImage(path) {
+				files = append(files, path)
+			}
+
+			return nil
+		})
+		if err != nil {
+			fmt.Fprintln(os.Stderr, err)
+			os.Exit(1)
+		}
+	}
+	return files
+}
+
+func ExpectedImageFiles(files []string, iType ImageType) (f []string) {
+	var ret []string
+	for _, path := range files {
+		if IsExpectedImage(path, iType) {
+			ret = append(ret, path)
+		}
+	}
+	return ret
+}
+
+// IsImage return true if path is image.
+func IsImage(path string) bool {
+	r, err := os.Open(path)
+	if err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+	defer r.Close()
+
+	_, _, err = image.DecodeConfig(r)
+	if err != nil {
+		return false
+	}
+	return true
+}
+
+func IsExpectedImage(path string, iType ImageType) bool {
+	r, err := os.Open(path)
+	if err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+	defer r.Close()
+
+	_, format, err := image.DecodeConfig(r)
+	if err != nil {
+		return false
+	}
+
+	for _, t := range iType.Enable() {
+		if t == format {
+			return true
+		}
+	}
+
+	return false
+}
+
+// Convert function is image file converter
+func Convert(r io.Reader, w io.Writer, t string) error {
+	jpego := &jpeg.Options{
+		Quality: jpeg.DefaultQuality,
+	}
+
+	gifo := &gif.Options{
+		NumColors: 256,
+		Quantizer: nil,
+		Drawer:    nil,
+	}
+
+	m, _, err := image.Decode(r)
+	if err != nil {
+		return err
+	}
+
+	switch t {
+	case "png":
+		return png.Encode(w, m)
+	case "gif":
+		return gif.Encode(w, m, gifo)
+	case "jpeg", "jpg":
+		return jpeg.Encode(w, m, jpego)
+	default:
+		return png.Encode(w, m)
+	}
+
+	return nil
+
+}