Files
rgb2rgb8/rgb2rgb8.go
2025-08-05 12:14:20 -04:00

219 lines
4.7 KiB
Go

/* SPDX-License-Identifier: MIT */
package main
import (
"bufio"
"encoding/hex"
"fmt"
"github.com/spf13/pflag"
"github.com/wayneashleyberry/truecolor/pkg/color"
"math"
"os"
)
var output *os.File
var (
outputFile string
verbose bool
version bool
colors bool
print bool
help bool
)
func init() {
pflag.StringVarP(
&outputFile,
"output",
"o",
"out.hex",
"output file",
)
pflag.BoolVarP(
&print,
"print",
"p",
false,
"print to stdout instead of output file. -o will have no effect",
)
pflag.BoolVarP(
&colors,
"colors",
"c",
false,
"print colors to terminal (needs 24 bit color support)",
)
pflag.BoolVarP(
&verbose,
"verbose",
"v",
false,
"verbose output",
)
pflag.BoolVar(
&version,
"version",
false,
"version info",
)
pflag.BoolVarP(
&help,
"help",
"h",
false,
"displays help",
)
}
// converts different size bytes to float64 to compare
// high and low and return the one thats closer
func compareChannels(base, high, low byte) byte {
absHigh := math.Abs(float64(high - base))
absLow := math.Abs(float64(low - base))
if absHigh < absLow {
return high
}
return low
}
func printDefaults() {
fmt.Fprintf(os.Stderr, "Usage: %s [options] [-o outfile] infile\n", os.Args[0])
fmt.Fprintf(os.Stderr, "Options:\n")
pflag.PrintDefaults()
}
func main() {
pflag.Usage = printDefaults
pflag.Parse()
if version {
fmt.Fprintf(os.Stderr, "%s is a utility that converts RGB24 hex palette files to 8bit 3-3-2 RGB.\n", os.Args[0])
fmt.Println("rgb2rgb8 v0.1.0")
fmt.Println("(c) 2025 Amber Zeller")
fmt.Println("Distributed under the MIT license")
os.Exit(0)
}
if help {
printDefaults()
os.Exit(0)
}
if len(pflag.Args()) == 0 {
fmt.Println("Error: No file specified.")
printDefaults()
os.Exit(1)
}
var inputFile = pflag.Args()[0]
if verbose {
fmt.Println("outputFile:", outputFile)
fmt.Println("inputFile:", inputFile)
}
//read input file
input, err := os.Open(inputFile)
if err != nil {
fmt.Println("Error: Cannot read input file", err)
os.Exit(2)
}
defer input.Close()
//create output file
if !print {
output, err = os.Create(outputFile)
if err != nil {
fmt.Println("Error: Cannot create output file.", err)
os.Exit(3)
}
}
//scan through input
scanner := bufio.NewScanner(input)
var data string
counter := 1
for scanner.Scan() {
line := scanner.Text()
if verbose {
fmt.Println()
fmt.Println("Parsing line:", line)
}
lineHex, err := hex.DecodeString(line)
if err != nil || len(lineHex) != 3 {
fmt.Println("Error: Failed to parse line as hex.", err)
} else {
//separate rgb components
red := byte(lineHex[0])
green := byte(lineHex[1])
blue := byte(lineHex[2])
//and with 11100000
red3bitLow := red & 224
green3bitLow := green & 224
//and with 11000000
blue2bitLow := blue & 192
//and with 11100000 and add 00011111
red3bitHigh := (red & 224) + 31
green3bitHigh := (green & 224) + 31
//and with 11000000 and add 00111111
blue2bitHigh := (blue & 192) + 63
//combine color channels into bytes again
rgb8High := []byte{red3bitHigh, green3bitHigh, blue2bitHigh}
rgb8Low := []byte{red3bitLow, green3bitLow, blue2bitLow}
//compare channels to find closer one to original
redFinal := compareChannels(red, red3bitHigh, red3bitLow)
greenFinal := compareChannels(green, green3bitHigh, green3bitLow)
blueFinal := compareChannels(blue, blue2bitHigh, blue2bitLow)
//combine final color channels
rgb8Final := []byte{redFinal, greenFinal, blueFinal}
if verbose {
fmt.Println("Raw RGB values:", red, green, blue)
fmt.Println("High values:", red3bitHigh, green3bitHigh, blue2bitHigh)
fmt.Println("Low values:", red3bitLow, green3bitLow, blue2bitLow)
fmt.Println("Final values:", redFinal, greenFinal, blueFinal)
fmt.Println("Hex high value:", hex.EncodeToString(rgb8High))
fmt.Println("Hex high value:", hex.EncodeToString(rgb8Low))
fmt.Println("Hex final value:", hex.EncodeToString(rgb8Final))
}
//generate pretty color patterns
if colors {
fmt.Println("Raw High Low Final")
color.Background(red, green, blue).Print(" ")
color.Background(red3bitHigh, green3bitHigh, blue2bitHigh).Print(" ")
color.Background(red3bitLow, green3bitLow, blue2bitLow).Print(" ")
color.Background(redFinal, greenFinal, blueFinal).Println(" ")
}
data += hex.EncodeToString(rgb8Final) + "\n"
}
counter++
}
if scanner.Err() != nil {
fmt.Println(scanner.Err())
}
if print {
fmt.Fprintf(os.Stderr, "%s", data)
} else {
_, err = output.WriteString(data)
if err != nil {
fmt.Println("Error: Failed to write output file.", err)
os.Exit(4)
}
output.Close()
}
}