vector - svg: generate 'outline path'

Question

I have a set of coordinates that I turn into an svg path (using cubic beziers to make it smooth). When I apply a certain stroke width, I get the following result (the blue dots are my coordinates)

What I am interested in is to get a path that runs around the gray shape (like: pick any point on the gray/white border, and round around the shape until you're back at the starting point).

How would I go about computing such a path?

for reference, this is my svg info:

 <g>
  <title>number 3</title>
  <path d="m238,50c5.67569,-1.01351 11.8327,-3.8229 20.92029,-2.14724c8.68106,0.69732 14.21173,4.90255 18.07971,7.14724c6.23697,3.61945 13.47556,9.5931 15,18c1.07056,5.90372 1.17343,10.97649 -4,16c-6.76816,6.57204 -19.45392,9.57738 -25.69687,10.59046c-3.94836,0.64074 4.73492,3.29883 10.69687,5.40954c8.05417,2.85142 15,8 21,14c6,6 5.26578,10.94739 5.26578,17.03015c-2.4541,7.30975 -4.23343,11.08675 -11.26578,12.96985c-3.98279,1.0665 -11.92578,3.49756 -17,4c-8.95618,0.88684 -15.80411,2.97838 -26,0l-9.19197,-3.44464" id="svg_1" opacity="0.5" stroke-width="10" stroke-linejoin="round" stroke="#000000" fill="none"/>
 </g>

Answer 1

I created the svgContour function that is thought for scenarios similar to this,
the resulting contour offset is not related to the stroke-width value and must be set as a parameter to the function.

At the moment it will find one offset side at a time, but running it once per sides you can solve this issue.

TLDR
Actually through svgContour you can find the contour of any svg shapes, currently it doesn't support fill-modes but one of the next goals is to implement that. it relies on getPathData() to get the pathData of any SVGGeometryElement, then this data goes through three phases:

• redrawSteepCurve
  Premise: drawing a beizer-curve parallel to another isn't obtained just offsetting the points/control-points of the curve unless the curve is sufficiently flat (in this case the visual rendering will be fine); this method takes a SVGPathData and in case it finds a steep curve it splits it up until it's flat enough (return a visually equivalent SVGPathData).

• contourPathData
  In this stage the pathData is dissambled in points, points are connected in segments, each segment is offsetted, an intersection point is then found for each contiguous segment ( what we get back is a list of offsetted points).

• drawLine
  This phase places the points from step 2 in the pathData coming from step 1, and finally draws the contour.

An example:

const path = document.querySelector('path')

svgContour(path, 5)

svg {
  width: 100vw;
  height: 100vh
}

<script src="https://cdn.rawgit.com/fracalo/svg-contour/master/dist/svg-contour.js"></script>

<svg viewBox='300 0 100 200'>
  <g>
    <title>number 3</title>
    <path d="m238,50c5.67569,-1.01351 11.8327,-3.8229 20.92029,-2.14724c8.68106,0.69732 14.21173,4.90255 18.07971,7.14724c6.23697,3.61945 13.47556,9.5931 15,18c1.07056,5.90372 1.17343,10.97649 -4,16c-6.76816,6.57204 -19.45392,9.57738 -25.69687,10.59046c-3.94836,0.64074 4.73492,3.29883 10.69687,5.40954c8.05417,2.85142 15,8 21,14c6,6 5.26578,10.94739 5.26578,17.03015c-2.4541,7.30975 -4.23343,11.08675 -11.26578,12.96985c-3.98279,1.0665 -11.92578,3.49756 -17,4c-8.95618,0.88684 -15.80411,2.97838 -26,0l-9.19197,-3.44464"
    id="svg_1" opacity="0.5" stroke-width="10" stroke-linejoin="round" stroke="#000000" fill="none" />
  </g>
</svg>