go-libwebp

Experimental translation from libwebp to Go source.
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main.go (2676B)

      1 package main
      2 
      3 import (
      4 	"flag"
      5 	"fmt"
      6 	"image"
      7 	"image/png"
      8 	"os"
      9 	"strings"
     10 
     11 	_ "image/jpeg"
     12 
     13 	_ "image/png"
     14 
     15 	"git.sr.ht/~jackmordaunt/go-libwebp/v2/webp"
     16 )
     17 
     18 func main() {
     19 	if err := run(os.Args[1:]); err != nil {
     20 		fmt.Printf("error: %v\n", err)
     21 		os.Exit(1)
     22 	}
     23 }
     24 
     25 func run(args []string) error {
     26 	if len(args) == 0 || isHelp(args[0]) {
     27 		fmt.Printf("Usage: specify command [encode, decode]\n")
     28 		return nil
     29 	}
     30 	if len(args) < 1 {
     31 		return fmt.Errorf("not enough arguments")
     32 	}
     33 	switch args[0] {
     34 	case "decode":
     35 		return decodeWebp(args[1:])
     36 	case "encode":
     37 		return encodeWebp(args[1:])
     38 	default:
     39 		return fmt.Errorf("unknown command: %q", args[0])
     40 	}
     41 }
     42 
     43 func isHelp(s string) bool {
     44 	return strings.HasPrefix(s, "-h")
     45 }
     46 
     47 func encodeWebp(args []string) error {
     48 	var (
     49 		quality  float64
     50 		lossless bool
     51 		output   string
     52 	)
     53 	cli := flag.NewFlagSet("encode", flag.ExitOnError)
     54 	cli.BoolVar(&lossless, "lossless", false, "lossless quality, ignores quality flag")
     55 	cli.Float64Var(&quality, "q", 1.0, "quality from [0,1]")
     56 	cli.StringVar(&output, "o", "out.webp", "path to output file")
     57 	if err := cli.Parse(args); err != nil {
     58 		return err
     59 	}
     60 	if len(cli.Args()) < 1 {
     61 		return fmt.Errorf("provide image to encode as webp, try megopher.png")
     62 	}
     63 	input := cli.Args()[0]
     64 	srcf, err := os.Open(input)
     65 	if err != nil {
     66 		return fmt.Errorf("opening input file: %w", err)
     67 	}
     68 	defer srcf.Close()
     69 	dstf, err := os.Create(output)
     70 	if err != nil {
     71 		return fmt.Errorf("opening output file: %w", err)
     72 	}
     73 	defer dstf.Close()
     74 	img, _, err := image.Decode(srcf)
     75 	if err != nil {
     76 		return fmt.Errorf("decoding src image: %w", err)
     77 	}
     78 	opts := []webp.EncodeOption{}
     79 	opts = append(opts, webp.Quality(float32(quality)))
     80 	if lossless {
     81 		opts = append(opts, webp.Lossless())
     82 	}
     83 	if err := webp.Encode(dstf, img, opts...); err != nil {
     84 		return fmt.Errorf("encoding webp: %w", err)
     85 	}
     86 	return nil
     87 }
     88 
     89 func decodeWebp(args []string) error {
     90 	var output string
     91 	cli := flag.NewFlagSet("decode", flag.ExitOnError)
     92 	cli.StringVar(&output, "o", "out.png", "path to output file")
     93 	if err := cli.Parse(args); err != nil {
     94 		return err
     95 	}
     96 	if len(cli.Args()) < 1 {
     97 		return fmt.Errorf("provide image to encode as webp")
     98 	}
     99 	input := cli.Args()[0]
    100 	srcf, err := os.Open(input)
    101 	if err != nil {
    102 		return fmt.Errorf("opening input file: %w", err)
    103 	}
    104 	defer srcf.Close()
    105 	dstf, err := os.Create(output)
    106 	if err != nil {
    107 		return fmt.Errorf("opening output file: %w", err)
    108 	}
    109 	defer dstf.Close()
    110 	img, err := webp.Decode(srcf)
    111 	if err != nil {
    112 		return fmt.Errorf("decoding src image: %w", err)
    113 	}
    114 	if err := png.Encode(dstf, img); err != nil {
    115 		return fmt.Errorf("encoding webp: %w", err)
    116 	}
    117 	return nil
    118 }