I've tried to explore a python library for SVG parsing named svgelements. And there is an unusual concept I can't find in any SVG docs, also nor dolphin file browser nor firefox nor gimp can't render svg files using this. There is a z in pathd parsed as a coordinate and passed to Path to create the curve or line with z_point (the end of last move operation). So z used with LQTCS operations to replace a coordinate. Is it something standard for SVG? And why many other apps can't process this?

I've explored this code for path d parsing https://github.com/meerk40t/svgelements/blob/master/svgelements/svgelements.py#L408

There's a part with z as number processing

CodePudding user response：

The library is implementing something that is actually part of the SVG 2 specification: Segment-completing close path operation. There is a (apparently failing) test in the Chromium test suite that exemplifies what is meant. It gives the test path element:

 <path d="M 10 10 z m 20 70 h 10 v 10 h -10 l z M 70 30 q 20 0 20 20 t -20 20 t -20 -20 T z" />

To make it clear: since SVG 1.0 the z command closes any path in a straight line. This variant makes it possible to define the closing segment as a curved line.

Unfortunately, that part of the specification looks a bit like a dead end. This issue of the W3C SVG working group from August says:

The spec for the Segment-completing close path operation command was added 4 years ago and hasn't been implemented by any browser yet. (https://svgwg.org/svg2-draft/paths.html#PathDataClosePathCommand). Currently it only exists in the spec, and as a failing wpt test.

consider removing it from the spec?

So far, there has been no further discussion as it seems.