Re: [svgwg] [circle][ellipse] SVG 2 silent on negative values for cx/cy (#1145)

Pardon me, but `cx` and `cy` as applied to `<circle>` and `<ellipse>` are only affecting the position of the element.  

So  negative values are by no means invalid or unusual – as opposed to negative `r`, `rx` and `ry` attributes – which are geometrically/logically kinda nonsensical (similar case `width` and `height`). In other words: a general rule for all circle/ellipse related presentation attributes doesn't really fit here. 

All in all  `cx` and `cy` serve a similar purpose like `x` and `y` position attributes and don't really need extra handling for negative values.  

Speaking of these negative radii "oddities". 
The current fallback handling – converting e.g `rx:-50` to `0` is slightly inconsistent with regards to the behavior in elliptic arc commands for `<path>` elements.
In pathdata negative radii are converted to positive values. This could be explained by the end-point parametrization of arc commands.  

<img width="772" height="293" alt="Image" src="https://github.com/user-attachments/assets/a5b4d367-813b-48d5-b353-16d2010d932e" />  

See also [codepen example](https://codepen.io/herrstrietzel/pen/wBgjdyR?editors=1111)

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Received on Tuesday, 14 July 2026 17:06:49 UTC