Feature: Support generating SVG images

[tinacious]

Great library!

I was wondering if it's possible to generate an SVG image. I saw there was support for bitmaps with gozxing.NewBinaryBitmapFromImage(img), and for PNG with png.Encode(file, img) (which is what I'm currently using). Is it possible to generate an SVG file?

Thank you! 🙏

[makiuchi-d]

Hi @tinacious,

*gozxing.BitMatrix implements the standard image.Image interface.
Please use an existing library that converts image.Image to SVG.

[tinacious]

Thanks for that suggestion. Based on this suggestion, I did go looking for a library and I found xyproto/png2svg which works, it's just pretty slow. It appears to be slow because it draws a <rect x="1" width="1" height="1"/> for every pixel. The resulting output for a 200x200 QR code with data hello world is 608 bytes as PNG and 1.7 MB as SVG with the above-mentioned library. I noticed the SVG generation with the above-mentioned png2svg library is significantly slower and produces a significantly larger file than the PNG generation with png.Encode().

Are you familiar with any other SVG libraries that can work with the image.Image interface that might perform the SVG generation faster and use less disk space?

I'm using the *gozxing.BitMatrix output from your library and passing it to the following methods in the png2svg library:

func createSvg(img image.Image, fileName string) {
	var verbose bool = false
	pi := png2svg.NewPixelImage(img, verbose)
	pi.CoverAllPixels()
	pi.WriteSVG(fileName)
}

Example implementation

Thank you!

Update: Just an update on this ask, I was able to dig into the source code of that library and find a more efficient algorithm (ref) but I would still be happy to hear about any library suggestions so I can remove some of the copy/pasted code.

[makiuchi-d]

I’m not too familiar with SVG generation, and it’s out of scope for this library.
Converting a bitmap image to a vector-based SVG is generally inefficient, and that’s probably unavoidable.