Code to image golang

In the modern software development process, code is a very important part. Code is not only the core of software functionality, but also the way developers communicate with each other. Therefore, it is very useful to visualize the code. Among them, converting code into pictures is a common technique that can easily show the structure and details of the code. This article will introduce how to use Go language to convert code into pictures.

1. Introduction to Go language

Go language is an open source programming language developed by Google. It has many advantages, such as efficient, fast, simple, safe, etc. The main features of Go language are:

1. Concurrency: Go language supports lightweight threads (called goroutines), making concurrent programming very easy.

2. Garbage collection: Go language has an automatic garbage collection mechanism that can automatically release memory that is no longer used.

3. Easy to learn: The syntax of Go language is simple and easy to understand, making it easier to learn than other languages.

4. Efficiency: The compilation speed of Go language is very fast, and it also has high operating efficiency.

2. The principle of converting code into pictures

The principle of converting code into pictures is very simple, which is to parse the source code and display it in a graphical interface. In the Go language, we can use the godoc tool provided by the Golang.org/x/tools/cmd/godoc package to parse the code into HTML format, and then use the image and draw packages in the Go language to render the HTML into pictures.

3. Implementation of converting code to image

In order to convert code to image, we need to complete the following steps:

1. Install the godoc tool

First, we need to install the godoc tool. Just enter the following command on the command line:

go get golang.org/x/tools/cmd/godoc

2. Export HTML file

Next, we need to use the godoc tool to export the HTML file. To do this, we need to use the following command:

godoc -html package > package.html

where "package" represents the package name to convert the code into an HTML file.

3. Convert HTML files to images

Now, we can use the image and draw packages in the Go language to render HTML files into images. The following is a sample code:

package main

import (
    "bufio"
    "fmt"
    "image"
    "image/draw"
    "image/png"
    "os"
    "strings"

    "golang.org/x/net/html"
)

func main() {
    htmlFile, err := os.Open("package.html")
    if err != nil {
        fmt.Println(err)
        return
    }
    defer htmlFile.Close()

    doc, err := html.Parse(htmlFile)
    if err != nil {
        fmt.Println(err)
        return
    }

    imgFile, err := os.Create("package.png")
    if err != nil {
        fmt.Println(err)
        return
    }
    defer imgFile.Close()

    // 初始化画布
    bounds := image.Rect(0, 0, 800, 600)
    rgba := image.NewRGBA(bounds)
    draw.Draw(rgba, bounds, image.White, image.Point{}, draw.Src)

    // 渲染HTML
    renderHTML(rgba, doc)

    // 保存为PNG图片
    png.Encode(imgFile, rgba)
}

func renderHTML(rgba *image.RGBA, n *html.Node) {
    if n.Type == html.ElementNode {
        switch n.Data {
        case "html":
            renderHTML(rgba, n.FirstChild)
        case "body":
            renderHTML(rgba, n.FirstChild)
        case "pre":
            renderCodeBlock(rgba, n.FirstChild.Data, n.Attr)
        }
    }

    if n.NextSibling != nil {
        renderHTML(rgba, n.NextSibling)
    }
}

func renderCodeBlock(rgba *image.RGBA, code string, attrs []html.Attribute) {
    // 解析HTML属性
    style := ""
    for _, attr := range attrs {
        if attr.Key == "style" {
            style = attr.Val
        }
    }

    // 绘制文本
    x := 10
    y := 20
    scanner := bufio.NewScanner(strings.NewReader(code))
    scanner.Split(bufio.ScanLines)
    for scanner.Scan() {
        drawText(rgba, scanner.Text(), x, y, style)
        y += 16
    }
}

func drawText(rgba *image.RGBA, text string, x, y int, style string) {
    // 绘制文本
    font := loadFont(style)
    drawer := &fontDrawer{
        dst:  rgba,
        src:  image.NewUniform(color.Black),
        face: truetype.NewFace(font, &truetype.Options{Size: 16}),
    }
    drawer.DrawString(text, fixed.Point26_6{X: fixed.Int26_6(x * 64), Y: fixed.Int26_6(y * 64)}, &drawerOptions{})
}

type fontDrawer struct {
    dst  draw.Image
    src  image.Image
    face font.Face
}

type drawerOptions struct{}

func (d *fontDrawer) ColorModel() color.Model {
    return color.AlphaModel
}

func (d *fontDrawer) Bounds() image.Rectangle {
    return d.dst.Bounds()
}

func (d *fontDrawer) Draw(dst draw.Image, r image.Rectangle, src image.Image, sp image.Point) {
    // 绘制文本
    dr, mask, _, _ := d.face.GlyphBounds('.')
    for _, c := range "x" + text {
        glyphIndex := d.face.Index(c)
        glyphAdvance, _, _, _ := d.face.GlyphAdvance(glyphIndex, draw.Src)
        glyphBounds, _, _, glyphBaseline := d.face.GlyphBounds(glyphIndex)
        if c != 'x' {
            draw.DrawMask(d.dst, image.Rectangle{
                Min: image.Point{
                    X: (r.Min.X / 64) + ((glyphBounds.Min.X + glyphBaseline.X) / 64),
                    Y: (r.Min.Y / 64) - ((glyphBounds.Max.Y + glyphBaseline.Y) / 64),
                },
                Max: image.Point{
                    X: (r.Min.X / 64) + ((glyphBounds.Max.X + glyphBaseline.X) / 64),
                    Y: (r.Min.Y / 64) - ((glyphBounds.Min.Y + glyphBaseline.Y) / 64),
                },
            }, d.src, image.Point{}, &fontMask{mask, fixed.P(glyphBounds.Min.X+glyphBaseline.X, glyphBounds.Min.Y+glyphBaseline.Y)}, draw.Over)
        }
        r.Min.X += int(glyphAdvance >> 6)
        if r.Min.X >= r.Max.X {
            break
        }
    }
}

func (d *fontDrawer) DrawString(s string, p fixed.Point26_6, _ *drawerOptions) {
    d.Draw(d.dst, d.dst.Bounds(), d.src, image.Point{
        X: int(p.X >> 6),
        Y: int(p.Y >> 6),
    })
}

type fontMask struct {
    mask image.Image
    fp   fixed.Point
}

func (m *fontMask) ColorModel() color.Model {
    return color.AlphaModel
}

func (m *fontMask) Bounds() image.Rectangle {
    return m.mask.Bounds().Add(image.Point{X: m.fp.X.Round(), Y: m.fp.Y.Round()})
}

func (m *fontMask) At(x, y int) color.Color {
    ax := (x - m.fp.X.Round())
    ay := (y - m.fp.Y.Round())
    if ax < 0 || ay < 0 || ax >= m.mask.Bounds().Dx() || ay >= m.mask.Bounds().Dy() {
        return color.Alpha{}
    }
    return color.Alpha{A: m.mask.(*image.Alpha).AlphaAt(ax, ay).A}
}

func loadFont(style string) *truetype.Font {
    // 加载字体
    // TODO: 解析font-family和font-size属性
    fontBytes, err := ioutil.ReadFile("DejaVuSansMono.ttf")
    if err != nil {
        panic(err)
    }
    font, err := truetype.Parse(fontBytes)
    if err != nil {
        panic(err)
    }
    return font
}

This code will read a file named package.html from the local and convert it into a PNG format image. For specific implementation details, please see the code comments.

4. Summary

This article shows how to use Go language to convert code into pictures. We use the godoc tool to convert the code into an HTML file, and then use the image and draw packages in the Go language to render the HTML into pictures. The efficiency, simplicity, and concurrency of the Go language make it very easy to convert code into pictures. Through this method, we can easily visualize the code and communicate better.

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