Rendering .gif in Go

Question

I am trying to get a code example to work. It is from 'The GO Programming Language' (https://github.com/adonovan/gopl.io/blob/1ae3ec64947b7a5331b186f1b1138fc98c0f1c06/ch1/lissajous/main.go). When trying to view the animation, the gif doesn't get rendered. The gif rendering software reports the error:

Has the .gif standards changed since 2016 or is there something I'm doing wrong?

// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/

// Lissajous generates GIF animations of random Lissajous figures.
package main

import (
    "image"
    "image/color"
    "image/gif"
    "io"
    "math"
    "math/rand"
    "os"
)

var palette = []color.Color{color.White, color.Black}

const (
    whiteIndex = 0 // first color in palette
    blackIndex = 1 // next color in palette
)

func main() {
    lissajous(os.Stdout)
}

func lissajous(out io.Writer) {
    const (
        cycles  = 5     // number of complete x oscillator revolutions
        res     = 0.001 // angular resolution
        size    = 100   // image canvas covers [-size..+size]
        nframes = 64    // number of animation frames
        delay   = 8     // delay between frames in 10ms units
    )
    freq := rand.Float64() * 3.0 // relative frequency of y oscillator
    anim := gif.GIF{LoopCount: nframes}
    phase := 0.0 // phase difference
    for i := 0; i < nframes; i++ {
        rect := image.Rect(0, 0, 2*size+1, 2*size+1)
        img := image.NewPaletted(rect, palette)
        for t := 0.0; t < cycles*2*math.Pi; t += res {
            x := math.Sin(t)
            y := math.Sin(t*freq + phase)
            img.SetColorIndex(size+int(x*size+0.5), size+int(y*size+0.5),
                blackIndex)
        }
        phase += 0.1
        anim.Delay = append(anim.Delay, delay)
        anim.Image = append(anim.Image, img)
    }
    gif.EncodeAll(out, &anim) // NOTE: ignoring encoding errors
}

The build and run commands are:

go build .\main.go
.\main.exe > out.gif

Answer 1

Use bufio.NewWriter

func main() {
    fileName := "1.gif"
    f, err3 := os.Create(fileName)
    if err3 != nil {
        fmt.Println("create file fail")
    }
    w := bufio.NewWriter(f) 
    lissajous(w)
    w.Flush()
    f.Close()

}

or

func main() {
    w := bufio.NewWriter(os.Stdout)
    lissajous(w)
    w.Flush()
    os.Stdout.Close()
}