convert.go

// Package convert can convert a image to ascii string or matrix
package main

import (
	"bytes"
	"image"
	"image/color"

	// Support decode jpeg image
	_ "image/jpeg"
	// Support deocde the png image
	_ "image/png"
	"os"

	"github.com/pkg/errors"
	"github.com/qeesung/image2ascii/ascii"
)

// Options to convert the image to ASCII
type Options struct {
	Ratio           float64
	FixedWidth      int
	FixedHeight     int
	FitScreen       bool // only work on terminal
	StretchedScreen bool // only work on terminal
	Colored         bool // only work on terminal
	Reversed        bool
}

// DefaultOptions for convert image
var DefaultOptions = Options{
	Ratio:           1,
	FixedWidth:      -1,
	FixedHeight:     -1,
	FitScreen:       true,
	Colored:         true,
	Reversed:        false,
	StretchedScreen: false,
}

// NewImageConverter create a new image converter
func NewImageConverter() *ImageConverter {
	return &ImageConverter{
		resizeHandler:  NewResizeHandler(),
		pixelConverter: ascii.NewPixelConverter(),
	}
}

// Converter define the convert image basic operations
type Converter interface {
	Image2ASCIIMatrix(image image.Image, imageConvertOptions *Options) []string
	Image2ASCIIString(image image.Image, options *Options) string
	ImageFile2ASCIIMatrix(imageFilename string, option *Options) []string
	ImageFile2ASCIIString(imageFilename string, option *Options) string
	Image2PixelASCIIMatrix(image image.Image, imageConvertOptions *Options) [][]ascii.CharPixel
	ImageFile2PixelASCIIMatrix(image image.Image, imageConvertOptions *Options) [][]ascii.CharPixel
}

// ImageConverter implement the Convert interface, and responsible
// to image conversion
type ImageConverter struct {
	resizeHandler  ResizeHandler
	pixelConverter ascii.PixelConverter
}

// Image2CharPixelMatrix convert a image to a pixel ascii matrix
func (converter *ImageConverter) Image2CharPixelMatrix(image image.Image, imageConvertOptions *Options) ([][]ascii.CharPixel, error) {
	newImage, err := converter.resizeHandler.ScaleImage(image, imageConvertOptions)
	if err != nil {
		return nil, err
	}
	sz := newImage.Bounds()
	newWidth := sz.Max.X
	newHeight := sz.Max.Y
	pixelASCIIs := make([][]ascii.CharPixel, 0, newHeight)
	for i := 0; i < int(newHeight); i++ {
		line := make([]ascii.CharPixel, 0, newWidth)
		for j := 0; j < int(newWidth); j++ {
			pixel := color.NRGBAModel.Convert(newImage.At(j, i))
			// Convert the pixel to ascii char
			pixelConvertOptions := ascii.NewOptions()
			pixelConvertOptions.Colored = imageConvertOptions.Colored
			pixelConvertOptions.Reversed = imageConvertOptions.Reversed
			pixelASCII := converter.pixelConverter.ConvertPixelToPixelASCII(pixel, &pixelConvertOptions)
			line = append(line, pixelASCII)
		}
		pixelASCIIs = append(pixelASCIIs, line)
	}
	return pixelASCIIs, nil
}

// ImageFile2CharPixelMatrix convert a image to a pixel ascii matrix
func (converter *ImageConverter) ImageFile2CharPixelMatrix(imageFilename string, imageConvertOptions *Options) ([][]ascii.CharPixel, error) {
	img, err := OpenImageFile(imageFilename)
	if err != nil {
		return nil, errors.New("open image failed : " + err.Error())
	}
	return converter.Image2CharPixelMatrix(img, imageConvertOptions)
}

// Image2ASCIIMatrix converts a image to ASCII matrix
func (converter *ImageConverter) Image2ASCIIMatrix(image image.Image, imageConvertOptions *Options) ([]string, error) {
	// Resize the convert first
	newImage, err := converter.resizeHandler.ScaleImage(image, imageConvertOptions)
	if err != nil {
		return nil, err
	}
	sz := newImage.Bounds()
	newWidth := sz.Max.X
	newHeight := sz.Max.Y
	rawCharValues := make([]string, 0, int(newWidth*newHeight+newWidth))
	for i := 0; i < int(newHeight); i++ {
		for j := 0; j < int(newWidth); j++ {
			pixel := color.NRGBAModel.Convert(newImage.At(j, i))
			// Convert the pixel to ascii char
			pixelConvertOptions := ascii.NewOptions()
			pixelConvertOptions.Colored = imageConvertOptions.Colored
			pixelConvertOptions.Reversed = imageConvertOptions.Reversed
			rawChar := converter.pixelConverter.ConvertPixelToASCII(pixel, &pixelConvertOptions)
			rawCharValues = append(rawCharValues, rawChar)
		}
		rawCharValues = append(rawCharValues, "\n")
	}
	return rawCharValues, nil
}

// Image2ASCIIString converts a image to ascii matrix, and the join the matrix to a string
func (converter *ImageConverter) Image2ASCIIString(image image.Image, options *Options) (string, error) {
	convertedPixelASCII, err := converter.Image2ASCIIMatrix(image, options)
	if err != nil {
		return "", err
	}
	var buffer bytes.Buffer

	for i := 0; i < len(convertedPixelASCII); i++ {
		buffer.WriteString(convertedPixelASCII[i])
	}
	return buffer.String(), nil
}

// ImageFile2ASCIIMatrix converts a image file to ascii matrix
func (converter *ImageConverter) ImageFile2ASCIIMatrix(imageFilename string, option *Options) ([]string, error) {
	img, err := OpenImageFile(imageFilename)
	if err != nil {
		return nil, errors.New("open image failed : " + err.Error())
	}
	return converter.Image2ASCIIMatrix(img, option)
}

// ImageFile2ASCIIString converts a image file to ascii string
func (converter *ImageConverter) ImageFile2ASCIIString(imageFilename string, option *Options) (string, error) {
	img, err := OpenImageFile(imageFilename)
	if err != nil {
		return "", errors.New("open image failed : " + err.Error())
	}
	return converter.Image2ASCIIString(img, option)
}

// OpenImageFile open a image and return a image object
func OpenImageFile(imageFilename string) (image.Image, error) {
	f, err := os.Open(imageFilename)
	if err != nil {
		return nil, err
	}

	img, _, err := image.Decode(f)
	if err != nil {
		return nil, err
	}

	defer f.Close()
	return img, nil
}