Go编程语言创建损坏文件的Gif生成练习

Question

我正在做“Go编程语言”这本书中的练习。在第一章中，有一个生成gif的练习。我已经运行程序没有错误，但一直无法打开的gif。它看起来已经损坏了。

我使用的是Windows10，并尝试在浏览器、IfranView 64位版本4.53和默认的照片应用程序中打开该文件。

代码：

// 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
}

我通过调用go run {programname}.go > out.gif和编译并运行./{programname}.exe > out.gif在Powershell中运行应用程序。

如何找出gif的问题所在，以及如何正确生成gif？

Answer 1

只有当您使用Powershell时，问题才会出现。我遇到了同样的问题，并通过使用cmd执行go run命令来解决它。

Answer 2

我无法复制你的问题。

cmd.exe
Microsoft Windows [Version 10.0.18362.239]

>go version
go version devel +89d300b821 Sun Jul 14 20:15:47 2019 +0000 windows/amd64

>go run lissajous.go > lissajous.gif

Firefox 68.0 (64-bit)
Menu -> Open File -> lissajous.gif

​

​

lissajous.go (来自问题)：

// 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
}