main.go

package main

import (
	"bytes"
	"image"
	"image/draw"
	"image/png"
	"log"
	"os"

	"github.com/golang/freetype"
	"github.com/mattn/go-runewidth"
	"github.com/mattn/go-sixel"
)

func main() {
	font, err := freetype.ParseFont(MustAsset("data/ipag-mona.ttf"))
	if err != nil {
		log.Fatal(err)
	}
	img, err := png.Decode(bytes.NewReader(MustAsset("data/shoei.png")))
	if err != nil {
		log.Fatal(err)
	}

	mw, mh := 0, 0
	for _, arg := range os.Args[1:] {
		w := runewidth.StringWidth(arg)
		if w > mw {
			mw = w
		}
		mh++
	}

	rgba := image.NewRGBA(image.Rect(0, 0, img.Bounds().Dx(), img.Bounds().Dy()))
	draw.Draw(rgba, rgba.Bounds(), img, image.ZP, draw.Src)
	fc := freetype.NewContext()
	fc.SetDPI(72)
	fc.SetFont(font)
	sizeh := float64(60 / mh)
	sizew := float64(580 / mw)
	size := sizeh
	if sizew < sizeh {
		size = sizew
	}
	fc.SetFontSize(size)
	fc.SetClip(rgba.Bounds())
	fc.SetDst(rgba)
	fc.SetSrc(image.Black)

	pt := freetype.Pt(80, 70-int(sizeh/2*float64(mh-1)))
	for _, arg := range os.Args[1:] {
		_, err = fc.DrawString(arg, pt)
		if err != nil {
			log.Fatal(err)
		}
		pt.Y += fc.PointToFixed(sizeh)
	}
	err = sixel.NewEncoder(os.Stdout).Encode(rgba)
	if err != nil {
		log.Fatal(err)
	}
}