Convert a text file with R G B values [0-255] separated by whitespace or commas, one triplet per line, to Photoshop's ACT format.

act-out.go

package main

import (
	"fmt"
	"io/ioutil"
	"os"
	"strconv"
	"strings"
)

func usage() {
	fmt.Println("Convert a text file with up to 256 RGB values to Photoshop's ACT format")
	fmt.Println()
	fmt.Println("Usage: <infile> <outfile>")
	fmt.Println("	<infile> is a text file with R G B values [0-255] separated by")
	fmt.Println("   	whitespace or commas, one per line")
	fmt.Println("<outfile> will be written in Photoshop's .ACT color format")
}

func exists(filename string) bool {
	_, err := os.Stat(filename)
	return err == nil
}

func toByte(s string) uint8 {
	if v, err := strconv.ParseUint(s, 10, 8); err == nil {
		return uint8(v)
	} else {
		fmt.Println(err)
		os.Exit(1)
	}
	return 0
}

func main() {
	if len(os.Args) != 3 {
		usage()
		os.Exit(1)
	}
	infile, outfile := os.Args[1], os.Args[2]

	if exists(outfile) {
		fmt.Println("Cowardly refusing to overwrite " + outfile)
		os.Exit(1)
	}

	transparencyColorIndex := 0

	act := make([]byte, 772)

	colormap, err := ioutil.ReadFile(infile)
	if err != nil {
		fmt.Println("Could not open " + infile + " for reading")
		os.Exit(1)
	}

	text := strings.ReplaceAll(string(colormap), "\r\n", "\n")
	text := strings.ReplaceAll(string(colormap), ",", " ")
	lines := strings.Split(text, "\n")
	if len(lines) > 256 {
		lines = lines[0:256]
	}
	colorCount := len(lines)

	for i := range lines {
		components := strings.Fields(lines[i])
		if len(components) != 3 {
			fmt.Printf("File malformed. Expected 3, found %d color components on line: %s\n",
				len(components), lines[i])
			os.Exit(1)
		}
		act[i*3+0] = toByte(components[0]) // R
		act[i*3+1] = toByte(components[1]) // G
		act[i*3+2] = toByte(components[2]) // B
	}

	act[768] = uint8(colorCount >> 8)
	act[769] = uint8(colorCount & 0xff)
	act[770] = uint8(transparencyColorIndex >> 8)
	act[771] = uint8(transparencyColorIndex & 0xff)

	err = ioutil.WriteFile(outfile, act, 0644)
	if err != nil {
		fmt.Println("Could not write output file: ", err)
	}
}