Can fabric.js parse raster graphic to "real" svg? - fabricjs

Question

I have a question/problem with fabric.js - in my code the user can upload a picture, with filters he can convert it to a black/white image. When I export the picture with canvas.toSVG(); it exports a svg image, but it is no real vector graphic - it loses quality when scaling up.
function handleImage(e) {
var reader = new FileReader();
reader.onload = function (event) {
var img = new Image();
img.onload = function () {
var imgInstance = new fabric.Image(img, {
scaleX: 0.7,
scaleY: 0.7
})
canvas.add(imgInstance);
}
img.src = event.target.result;
} reader.readAsDataURL(e.target.files[0]);}
$('saveBtn').onclick = function() {
var filedata= canvas.toSVG(); // the SVG file is now in filedata
var locfile = new Blob([filedata], {type: "image/svg+xml;charset=utf-8"});
var locfilesrc = URL.createObjectURL(locfile);//mylocfile);
var dwn = document.getElementById('dwn');
dwn.innerHTML = "<a href=" + locfilesrc + " download='mysvg.svg'>Download</a>";}
What am I doing wrong?

Answer 1

There is no easy way to "parse" raster graphics to a vector image. Vector graphics include information for how to draw an image, while raster images only include the pixel data for how an image appears at a given size and resolution. That's enough for many purposes, but it means that while it's easy to go from vector to raster (just execute the instructions), it's not easy to go from raster to vector.
It is possible to "trace" the edges of a raster image to obtain vectors that can approximate the raster: in other words, a set of vector instructions that, for that particular resolution and depth, yields an image that is the same as the original raster (or something very like it). But there is no guarantee that these actually correspond in any way to the original vectors (if there are any original vectors at all). Usually there is no correspondence, in fact, unless your tracing algorithm is very specialized: for example, tracing images of a font to make a vector copy of that font. Because they don't correspond, there's no guarantee that the image will scale up the way you want it to: it'll scale, but things may enlarge in strange ways.
It is possible to implement tracing algorithms in JavaScript, by drawing the image into a <canvas> element, using getImageData() to grab the pixel information from that, and performing your operations on the pixel information. Doing this, though, is beyond the scope of this question.