CRS.Simple coordinates from SVG for GeoJSON in Leaflet

Question

I am working with CRS.Simple in Leafleat. The y-coordinates from the SVG don't match what I'm supposed to use in GeoJson. I do not want to calculate them manually. How to use coordinates from SVG so that they can be easily inserted into GeoJSON Polygon from SVG:

<polygon id="001" class="fil1 str0" points="145,779 169,749 139,726 131,754 125,765"/>

GeoJSON that renders correctly on the map:

 {
    "type": "Feature",
    "properties": {"party": "Republican"},
    "geometry": {
        "type": "Polygon",
        "coordinates": [[
            [145, 421],
            [169, 451],
            [139, 474],
            [131, 446],
            [125, 435]
        ]]
    }
}

Answer 1

Y coordinate in SVG goes from top down, but in GeoJSON it goes from bottom up. If you sum up Y coordinate for specific point from SVG and GeoJSON, you'll get SVG height, which is 1200.

This means that all you have to do to get right Y coordinate in GeoJSON is to subtract SVG Y coordinate from 1200.