Added bin piping support for #28

README.md

@@ -168,6 +168,12 @@ Example:
 ascii-image-converter myImage.jpeg
 ```
 
+> **Note:** Piped binary input is also supported
+> ```
+> cat myImage.png | ascii-image-converter
+> ```
+
+
 ### Flags
 
 #### --color OR -C

aic_package/convert_gif.go

@@ -45,20 +45,26 @@ as an ascii art gif.
 
 Multi-threading has been implemented in multiple places due to long execution time
 */
-func pathIsGif(gifPath, urlImgName string, pathIsURl bool, urlImgBytes []byte, localGif *os.File) error {
+func pathIsGif(gifPath, urlImgName string, pathIsURl bool, urlImgBytes, pipedInputBytes []byte, localGif *os.File) error {
 
 	var (
 		originalGif *gif.GIF
 		err         error
 	)
 
-	if pathIsURl {
+	if isInputFromPipe() {
+		originalGif, err = gif.DecodeAll(bytes.NewReader(pipedInputBytes))
+	} else if pathIsURl {
 		originalGif, err = gif.DecodeAll(bytes.NewReader(urlImgBytes))
 	} else {
 		originalGif, err = gif.DecodeAll(localGif)
 	}
 	if err != nil {
-		return fmt.Errorf("can't decode %v: %v", gifPath, err)
+		if isInputFromPipe() {
+			return fmt.Errorf("can't decode piped input: %v", err)
+		} else {
+			return fmt.Errorf("can't decode %v: %v", gifPath, err)
+		}
 	}
 
 	var (

aic_package/convert_image.go

@@ -27,20 +27,26 @@ import (
 )
 
 // This function decodes the passed image and returns an ascii art string, optionaly saving it as a .txt and/or .png file
-func pathIsImage(imagePath, urlImgName string, pathIsURl bool, urlImgBytes []byte, localImg *os.File) (string, error) {
+func pathIsImage(imagePath, urlImgName string, pathIsURl bool, urlImgBytes, pipedInputBytes []byte, localImg *os.File) (string, error) {
 
 	var (
 		imData image.Image
 		err    error
 	)
 
-	if pathIsURl {
+	if isInputFromPipe() {
+		imData, _, err = image.Decode(bytes.NewReader(pipedInputBytes))
+	} else if pathIsURl {
 		imData, _, err = image.Decode(bytes.NewReader(urlImgBytes))
 	} else {
 		imData, _, err = image.Decode(localImg)
 	}
 	if err != nil {
-		return "", fmt.Errorf("can't decode %v: %v", imagePath, err)
+		if isInputFromPipe() {
+			return "", fmt.Errorf("can't decode piped input: %v", err)
+		} else {
+			return "", fmt.Errorf("can't decode %v: %v", imagePath, err)
+		}
 	}
 
 	imgSet, err := imgManip.ConvertToAsciiPixels(imData, dimensions, width, height, flipX, flipY, full, braille, dither)

aic_package/convert_root.go

@@ -35,6 +35,14 @@ import (
 	"github.com/golang/freetype/truetype"
 )
 
+var pipedInputTypes = []string{
+	"image/png",
+	"image/jpeg",
+	"image/webp",
+	"image/tiff",
+	"image/bmp",
+}
+
 // Return default configuration for flags.
 // Can be sent directly to ConvertImage() for default ascii art
 func DefaultFlags() Flags {
@@ -98,42 +106,78 @@ func Convert(filePath string, flags Flags) (string, error) {
 	dither = flags.Dither
 	onlySave = flags.OnlySave
 
+	inputIsGif = path.Ext(filePath) == ".gif"
+
 	// Declared at the start since some variables are initially used in conditional blocks
 	var (
-		localFile   *os.File
-		urlImgBytes []byte
-		urlImgName  string = ""
-		err         error
+		localFile       *os.File
+		urlImgBytes     []byte
+		urlImgName      string = ""
+		pipedInputBytes []byte
+		err             error
 	)
 
 	pathIsURl := isURL(filePath)
 
 	// Different modes of reading data depending upon whether or not filePath is a url
-	if pathIsURl {
-		fmt.Printf("Fetching file from url...\r")
 
-		retrievedImage, err := http.Get(filePath)
-		if err != nil {
-			return "", fmt.Errorf("can't fetch content: %v", err)
+	if !isInputFromPipe() {
+		if pathIsURl {
+			fmt.Printf("Fetching file from url...\r")
+
+			retrievedImage, err := http.Get(filePath)
+			if err != nil {
+				return "", fmt.Errorf("can't fetch content: %v", err)
+			}
+
+			urlImgBytes, err = ioutil.ReadAll(retrievedImage.Body)
+			if err != nil {
+				return "", fmt.Errorf("failed to read fetched content: %v", err)
+			}
+			defer retrievedImage.Body.Close()
+
+			urlImgName = path.Base(filePath)
+			fmt.Printf("                          \r") // To erase "Fetching image from url..." text from terminal
+
+		} else {
+
+			localFile, err = os.Open(filePath)
+			if err != nil {
+				return "", fmt.Errorf("unable to open file: %v", err)
+			}
+			defer localFile.Close()
+
 		}
 
-		urlImgBytes, err = ioutil.ReadAll(retrievedImage.Body)
+	} else {
+		// Check file/data type of piped input
+
+		pipedInputBytes, err = ioutil.ReadAll(os.Stdin)
 		if err != nil {
-			return "", fmt.Errorf("failed to read fetched content: %v", err)
+			return "", fmt.Errorf("unable to read piped input: %v", err)
 		}
-		defer retrievedImage.Body.Close()
 
-		urlImgName = path.Base(filePath)
-		fmt.Printf("                          \r") // To erase "Fetching image from url..." text from terminal
+		fileType := http.DetectContentType(pipedInputBytes)
+		invalidInput := true
 
-	} else {
+		if fileType == "image/gif" {
+			inputIsGif = true
+			invalidInput = false
 
-		localFile, err = os.Open(filePath)
-		if err != nil {
-			return "", fmt.Errorf("unable to open file: %v", err)
+		} else {
+			for _, inputType := range pipedInputTypes {
+				if fileType == inputType {
+					invalidInput = false
+					break
+				}
+			}
 		}
-		defer localFile.Close()
 
+		// Not sure if I should uncomment this.
+		// The output may be piped to another program and a warning would contaminate that
+		if invalidInput {
+			// fmt.Println("Warning: file type of piped input could not be determined, treating it as an image")
+		}
 	}
 
 	// If path to font file is provided, use it
@@ -151,9 +195,9 @@ func Convert(filePath string, flags Flags) (string, error) {
 		tempFont, _ = truetype.Parse(embeddedDejaVuObliqueFont)
 	}
 
-	if path.Ext(filePath) == ".gif" {
-		return "", pathIsGif(filePath, urlImgName, pathIsURl, urlImgBytes, localFile)
+	if inputIsGif {
+		return "", pathIsGif(filePath, urlImgName, pathIsURl, urlImgBytes, pipedInputBytes, localFile)
 	} else {
-		return pathIsImage(filePath, urlImgName, pathIsURl, urlImgBytes, localFile)
+		return pathIsImage(filePath, urlImgName, pathIsURl, urlImgBytes, pipedInputBytes, localFile)
 	}
 }

aic_package/util.go

@@ -67,6 +67,13 @@ func createSaveFileName(imagePath, urlImgName, label string) (string, error) {
 		return newName + label, nil
 	}
 
+	if isInputFromPipe() {
+		if inputIsGif {
+			return "piped-gif" + label, nil
+		}
+		return "piped-img" + label, nil
+	}
+
 	fileInfo, err := os.Stat(imagePath)
 	if err != nil {
 		return "", err
@@ -161,3 +168,8 @@ func clearScreen() {
 		os.Exit(0)
 	}
 }
+
+func isInputFromPipe() bool {
+	fileInfo, _ := os.Stdin.Stat()
+	return fileInfo.Mode()&os.ModeCharDevice == 0
+}

aic_package/vars.go

@@ -127,4 +127,5 @@ var (
 	threshold     int
 	dither        bool
 	onlySave      bool
+	inputIsGif    bool
 )

cmd/root.go

@@ -56,9 +56,9 @@ var (
 
 	// Root commands
 	rootCmd = &cobra.Command{
-		Use:     "ascii-image-converter [image paths/urls]",
+		Use:     "ascii-image-converter [image paths/urls or piped stdin]",
 		Short:   "Converts images and gifs into ascii art",
-		Version: "1.12.0",
+		Version: "1.13.0",
 		Long:    "This tool converts images into ascii art and prints them on the terminal.\nFurther configuration can be managed with flags.",
 
 		// Not RunE since help text is getting larger and seeing it for every error impacts user experience
@@ -93,28 +93,40 @@ var (
 				OnlySave:            onlySave,
 			}
 
-			for _, imagePath := range args {
+			if isInputFromPipe() {
+				printAscii("", flags)
+				return
+			}
 
-				if asciiArt, err := aic_package.Convert(imagePath, flags); err == nil {
-					fmt.Printf("%s", asciiArt)
-				} else {
-					fmt.Printf("Error: %v\n", err)
-
-					// Because this error will then be thrown for every image path/url passed
-					// if save path is invalid
-					if err.Error()[:15] == "can't save file" {
-						fmt.Println()
-						return
-					}
-				}
-				if !onlySave {
-					fmt.Println()
+			for _, imagePath := range args {
+				if err := printAscii(imagePath, flags); err != nil {
+					return
 				}
 			}
 		},
 	}
 )
 
+func printAscii(imagePath string, flags aic_package.Flags) error {
+
+	if asciiArt, err := aic_package.Convert(imagePath, flags); err == nil {
+		fmt.Printf("%s", asciiArt)
+	} else {
+		fmt.Printf("Error: %v\n", err)
+
+		// Because this error will then be thrown for every image path/url passed
+		// if save path is invalid
+		if err.Error()[:15] == "can't save file" {
+			fmt.Println()
+			return err
+		}
+	}
+	if !onlySave {
+		fmt.Println()
+	}
+	return nil
+}
+
 // Cobra configuration from here on
 
 func Execute() {

cmd/util.go

@@ -18,6 +18,7 @@ package cmd
 
 import (
 	"fmt"
+	"os"
 	"path"
 )
 
@@ -59,8 +60,8 @@ func checkInputAndFlags(args []string) bool {
 		return true
 	}
 
-	if len(args) < 1 {
-		fmt.Printf("Error: Need at least 1 input path/url\nUse the -h flag for more info\n\n")
+	if !isInputFromPipe() && len(args) < 1 {
+		fmt.Printf("Error: Need at least 1 input path/url or piped input\nUse the -h flag for more info\n\n")
 		return true
 	}
 
@@ -168,3 +169,8 @@ func checkInputAndFlags(args []string) bool {
 
 	return false
 }
+
+func isInputFromPipe() bool {
+	fileInfo, _ := os.Stdin.Stat()
+	return fileInfo.Mode()&os.ModeCharDevice == 0
+}

snapcraft.yaml

@@ -1,6 +1,6 @@
 name: ascii-image-converter
 base: core18 
-version: "1.11.0"
+version: "1.13.0"
 summary: Convert images and gifs into ascii art
 description: |
   ascii-image-converter is a command-line tool that converts images into ascii art and prints