go-image.svg

Currently allows an SVG path to be rendered to a standard image.Alpha. The package is named so that it is referred to as svg following an import "github.com/sqweek/go-image.svg", much as import "image/png" gives you a package referred to as png.

example (render an SVG path to PNG)

package main

import (
    "image"
    "image/color"
    "image/draw"
    "image/png"
    "os"
    "github.com/sqweek/go-image.svg"
)

func main() {
    // Parse SVG path data into abstract representation
    path, err := svg.ParsePath("m33 33h33l-16.7 33z")
    if err != nil {
        panic(err)
    }
    // Calculate approx. bounds of the path
    bounds := svg.PathBounds(path)
    // A border can be added with bounds.Inset(-n) or bounds.Border(left, top, right, bot)
    // Note that n/left/top/right/bot are in the same coordinates as the SVG path

    // Render the path to an image.Alpha
    r := image.Rect(0, 0, 200, 200)
    mask := svg.PathMask(path, bounds, r)

    // Prepare to export a PNG
    img := image.NewRGBA(r)
    bg, fg := color.White, color.Black // background/foreground colours
    draw.Draw(img, r, &image.Uniform{bg}, image.ZP, draw.Src)
    draw.DrawMask(img, r, &image.Uniform{fg}, image.ZP, mask, image.ZP, draw.Over)

    f, err := os.Create("tmp.png")
    if err != nil {
        panic(err)
    }
    defer f.Close()
    err = png.Encode(f, img)
    if err != nil {
        panic(err)
    }
}

bugs

1. SVG Elliptical Arc segments cannot be rasterised (yet)
2. XML not supported at all (yet)
3. svg.ParsePath should probably accept a Point argument for when the first command in the path is relative (ie. not absolute)
4. There should be a way to render a path to an existing Image rather than always allocating a new one
5. It should be possible to programatically build a path without parsing a string