calculated bbox is bigger than viewbox

[Esser50K]

This file when parsed with the svgelements library says that the box of the one path is 542.00.. 610.55... while the viewbox is only 512, 512

That just seems odd to me and is causing some issues as well.

raspberry-pi-4-599381.svg.zip

[tatarize]

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(93.62218501786387, 47.71372487416009, 419.0, 464.0)

Seems to give me a rather standard size well within the viewbox.

[tatarize]

Though admittedly:

list(svgelements.SVG().parse("raspberry-pi-4-599381.svg").elements())[0][1].bbox()

(124.8264592843179, 63.616709374717644, 558.6527, 618.6512)

I think the issue is that the width and height are in pt. (Points.)

1pt ≅ 1.3333px or user units (1px = 0.75pt)

This converts the size from the 512 pt to px. Which is why the values are at 4/3rds the expected size.

<svg version="1.0" xmlns="http://www.w3.org/2000/svg"
 width="512.000000pt" height="512.000000pt" viewBox="0 0 512.000000 512.000000"
 preserveAspectRatio="xMidYMid meet">

My conclusion is that this looks weird but is actually correct. The matrix and the viewbox being in px and width being in pt is what accounts for the difference there.

See: https://oreillymedia.github.io/Using_SVG/guide/units.html

[tatarize]

It seems weird but width="512.000000pt" height="512.000000pt" viewBox="0 0 512.000000 512.000000" is an automatic scale(1.3333,1.3333) appended as a transform. As 1pt == 1.3333px then 512pt == 682.6496px. The viewbox being 512 pixels wide means everything is being viewed at scale, so the scale gets appended and shapes are made bigger accordingly.

[Esser50K]

that really is weird 🤔 but I also suspected it was because of the pt I managed to work around it by checking if the bbox is greater than the viewbox and calculate how to scale it. Since it's not a bug I'll close this issue

[tatarize]

If you're just getting those values from the potrace you could just get rid of the transformations. Since potrace will just apply the modifiers itself a bit.

list(svgelements.SVG().parse("raspberry-pi-4-599381.svg", reify=False).elements())[0][1][0].d(transformed=False)

'M 3250,4634 c -25,-8 -67,-14 -95,-14 c -32,0 -62,-7 -83,-20 ...

It depends a bit on what you want. Also during the parsing it'll give you the viewbox and you can use that to check if something multiplied it weirdly. If there's some specific info you want extracted I'd be more than happy to make sure svgelements either can already do that or would do that shortly.

Also, if you want I could add some options to the pure python potrace port I wrote if something like that would make things considerably easier.

https://github.com/tatarize/potrace

I had a rough time getting the ported in C version to work really well, so I spent a few days porting it and getting permissions etc.