LingDong- / svg2pl

convert svg to polylines

svg2pl

a tiny library to convert (reasonable subset of) svg to polylines

• uses very little memory, 0 dynamic allocations
• single file, no dependencies other than C
• extremely fast
• no error checking -- assumes svg is perfectly valid, otherwise UB
• intended for compact projects or embeded systems

supported svg features:

• transform attribute on all elements
• all path d= commands (beziers, arcs...)
• elements: g, path, line, polyline, polygon, circle, ellipse, rect, svg
• you can register custom parser functions for other tags (see usage)

limitations:

• curves and ellipses are discretized
• fills and other styles are ignored, you can choose whether to skip all elements without "stoke" attribute
• viewBox and nested svg are supported, but preserveAspectRatio can only be "xMidYMid meet"(default) or "none"
• percentage(%) and physical units are not supported
• JS, CSS and other crazy stuff are obviously not supported

usage:

1. first define macros S2P_MOVETO(x,y) and S2P_LINETO(x,y)
   • these define what to do when the library has extracted polyline vertices
   • you can write to your own data structure, print, or control a machine, etc.
   • when not overwritten, these macros by default print the vertices to stdout.
2. (optional) define macro S2P_SETDIM(w,h)
   • this define what to do when the width/height of the svg are extracted
   • e.g. you might scale all subsequent vertices
3. #include "svg2pl.c"
4. (optional) call s2p_def_tag to register parsers for custom tags (e.g. <text)
5. call s2p_parse_from_file OR s2p_parse_from_str OR s2p_parse (FILE*)

notes:

• I use this library to control an axidraw plotter from a microcontroller, which reads svg files from an SD card -- a project I'll soon publish.
• examples/hershey_text.c is a demo for adding custom parsers for text tags using hershey font. It is simplistic and only supports x, y, font-size, and an ascii string as content -- leaving out font styles, tspans, and all the other crazy stuff you can do in svg text -- it's just intended for showing how easily you can extend or customize svg2pl to support the features you need.
• see the Makefile for more examples / usage hints