文字列を画像化

character2png.go

package main

import (
	"bytes"
	"fmt"
	"image"
	"image/png"
	"os"

	"github.com/golang/freetype/truetype"
	"golang.org/x/image/font"
	"golang.org/x/image/font/gofont/gobold"
	"golang.org/x/image/math/fixed"
	"golang.org/x/xerrors"
)

func main() {
	err := run("Hooooooo!")
	if err != nil {
		fmt.Fprintln(os.Stderr, err)
		os.Exit(1)
	}
}

func run(text string) error {
	// TODO: 日本語対応
	// TODO: テキストのながさを元に動的にサイズ決定ができたら嬉しい
	fontSize := 80.0
	imageWidth, imageHeight, textTopMargin := 640, 400, 220
	if len(text) > 12 {
		return xerrors.New("text length should less 12")
	}
	ft, err := truetype.Parse(gobold.TTF)
	if err != nil {
		return err
	}

	opt := truetype.Options{
		Size:              fontSize,
		DPI:               0,
		Hinting:           0,
		GlyphCacheEntries: 0,
		SubPixelsX:        0,
		SubPixelsY:        0,
	}
	img := image.NewRGBA(image.Rect(0, 0, imageWidth, imageHeight))
	face := truetype.NewFace(ft, &opt)
	dr := &font.Drawer{
		Dst:  img,
		Src:  image.White,
		Face: face,
		Dot:  fixed.Point26_6{},
	}
	dr.Dot.X = (fixed.I(imageWidth) - dr.MeasureString(text)) / 2
	dr.Dot.Y = fixed.I(textTopMargin)
	dr.DrawString(text)

	buf := &bytes.Buffer{}
	err = png.Encode(buf, img)
	if err != nil {
		return err
	}

	f, err := os.Create("./img/hoge.png")
	if err != nil {
		return err
	}
	defer f.Close()

	f.Write(buf.Bytes())
	return nil
}

// https://qiita.com/uobikiemukot/items/11dac0f1418492493226