main.go

package main

import (
	"fmt"
	"image"
	"image/gif"
	_ "image/jpeg"
	_ "image/png"
	"net/http"
	"os"

	log "github.com/Sirupsen/logrus"
	"github.com/nfnt/resize"
)

// 64 x 48

func processImage(i image.Image) string {
	screen := [384]uint8{}
	bounds := i.Bounds()

	i = resize.Resize(64, 48, i, resize.MitchellNetravali)

	// calculate medium pixel color, as a treshold between on and off for pixels
	med := float64(0)
	for y := 0; y < 48; y++ {
		for x := 0; x < 64; x++ {
			c := i.At(bounds.Min.X+x, bounds.Min.Y+y)
			r, g, b, _ := c.RGBA()
			med += float64(r+g+b) / 3
		}
	}
	med /= 64 * 48
	med *= 0.8 // because meh.

	for y := 0; y < 48; y++ {
		for x := 0; x < 64; x++ {
			c := i.At(bounds.Min.X+x, bounds.Min.Y+y)
			r, g, b, _ := c.RGBA()
			on := float64(r+g+b)/3 > med
			if on {
				screen[x+(y/8)*64] |= 1 << uint(y%8)
			}
		}
	}
	cArray := ""
	for i, b := range screen {
		if i != 0 {
			cArray += ", "
			if i%16 == 0 {
				cArray += "\n"
			}
		}
		cArray += fmt.Sprintf("0x%02x", b)
	}
	return cArray
}

func main() {
	if len(os.Args) != 2 {
		log.Fatalf("Usage: %s image.ext", os.Args[0])
	}

	f, err := os.Open(os.Args[1])
	if err != nil {
		log.Fatal(err)
	}

	header := [512]byte{}
	if _, err := f.Read(header[:]); err != nil {
		log.Fatal(err)
	}

	t := http.DetectContentType(header[:])
	log.Info(t)

	f.Seek(0, 0)

	fmt.Print("uint8_t bender [][384] = {{\n\t")
	if t == "image/gif" {
		g, err := gif.DecodeAll(f)
		if err != nil {
			log.Fatal(err)
		}
		for n, i := range g.Image {
			if n != 0 {
				fmt.Print("},\n{")
			}
			fmt.Print(processImage(i))
		}
	} else if t != "application/octet-stream" {
		i, _, err := image.Decode(f)
		if err != nil {
			log.Fatal(err)
		}
		fmt.Print(processImage(i))
	}
	fmt.Print("}};")
}