(Mirror of a comment I wrote on a GitHub issue, responding to someone who was wondering how to parse the SVG path command a8 8 0 100-16 8 8 0 000 16, which looks at first glance like mangled data.)
This arc command is correct and standards-conformant SVG; see SVG 1.1 §8.3.9 for an exhaustive grammar, but the gist of it is that you can condense a lot.
Relevant for this particular case are the following rules:
- flags are always exactly one character (
0/1) - Whitespace can be left out wherever it's not absolutely necessary (including after flags and before negative numbers and leading decimal points)
- If a command letter is not given, it's the same as the previous command (except in the case of
M/m, where it'sL/linstead)
That is, the string a8 8 0 100-16 8 8 0 000 16 should parse as two arc commands:
| "a" | nonnegative-number | comma-wsp? | nonnegative-number | comma-wsp? | number | comma-wsp | flag | flag | coordinate-pair |
|---|---|---|---|---|---|---|---|---|---|
a |
8 |
|
8 |
|
0 |
|
1 |
0 |
0 -16 |
8 |
|
8 |
|
0 |
|
0 |
0 |
0 16 |
svg/svgo#1137 discusses this same problem, and offers some optimizations that can be turned off to work around the Illustrator bugs.