clipPath ignored with PNG rendering

[victorbnl]

The SVG I have

svg source

The PNG it produces

Additionnal context

OS: Windows 10 / Arch Linux (this happens on both) svglib: 1.1.0 reportlab: 3.6.1

[claudep]

@replabrobin, can you confirm that ReportLab only support Path-like clip paths? Is there anything that would prevent using a circle as a clip path, like in this example image?

[victorbnl]

Even using a path it doesn't work

[claudep]

Are you really sure? It worked for me.

[victorbnl]

I tested again and yep, I still get the image of the first post, without masks

[victorbnl]

Maybe you have a dev version or anything?

[claudep]

No, even when reverting code to 1.1.0, it still works. I have no Windows to test, but I don't see this would make a difference.

[victorbnl]

I'll test on Linux

[victorbnl]

The issues is still there for me on Linux

[victorbnl]

Here are the debug logs

DEBUG:svglib.svglib:Exception during applyStyleOnShape
DEBUG:svglib.svglib:Exception during applyStyleOnShape
DEBUG:svglib.svglib:Exception during applyStyleOnShape
DEBUG:svglib.svglib:Unused attrs: path ['class']
DEBUG:svglib.svglib:Exception during applyStyleOnShape
DEBUG:svglib.svglib:Exception during applyStyleOnShape
DEBUG:svglib.svglib:Exception during applyStyleOnShape
DEBUG:svglib.svglib:Unused attrs: path ['class']
DEBUG:svglib.svglib:Exception during applyStyleOnShape
DEBUG:svglib.svglib:Exception during applyStyleOnShape
DEBUG:svglib.svglib:Exception during applyStyleOnShape
DEBUG:svglib.svglib:Exception during applyStyleOnShape
DEBUG:svglib.svglib:Exception during applyStyleOnShape
DEBUG:svglib.svglib:Exception during applyStyleOnShape
DEBUG:svglib.svglib:Unused attrs: image ['__rules_applied', '{http://www.w3.org/1999/xlink}href']
DEBUG:svglib.svglib:Unused attrs: g ['__rules_applied']
DEBUG:svglib.svglib:Exception during applyStyleOnShape
DEBUG:svglib.svglib:Exception during applyStyleOnShape
DEBUG:svglib.svglib:Exception during applyStyleOnShape
DEBUG:svglib.svglib:Exception during applyStyleOnShape
DEBUG:svglib.svglib:Exception during applyStyleOnShape
DEBUG:svglib.svglib:Exception during applyStyleOnShape
DEBUG:svglib.svglib:Unused attrs: image ['__rules_applied', '{http://www.w3.org/1999/xlink}href']
DEBUG:svglib.svglib:Unused attrs: g ['__rules_applied']
DEBUG:PIL.PngImagePlugin:STREAM b'IHDR' 16 13
DEBUG:PIL.PngImagePlugin:STREAM b'IDAT' 41 41578
DEBUG:PIL.PngImagePlugin:STREAM b'IHDR' 16 13
DEBUG:PIL.PngImagePlugin:STREAM b'IDAT' 41 65536

[replabrobin]

Claude, so far as I can tell PDF supports clipping with paths and in canvas.py we use a path to create ellipse/circle So at least in principle it ought to be possible to mask using a circle. Unfortunately the canvas api doesn't make this terribly easy as the canvas circle/ellipse methods don't return the created path and don't have a render mode to allow easier specification of the rendering. On the other hand one can create the path with path.ellipse(....) and then just use canvas.clipPath on the result

[victorbnl]

With PDF, path clips work, but circle ones don't. And for PNG both don't work. So what we need to figure out is why path clips don't work in PNG

[claudep]

Ah sorry, indeed I only tested PDF rendering. I admit I don't care so much for PNG (not in my use cases).

[claudep]

On the other hand one can create the path with path.ellipse(....) and then just use canvas.clipPath on the result

Thanks for this tip. I think we should able to support at least Circles with that trick.

[victorbnl]

Ah sorry, indeed I only tested PDF rendering. I admit I don't care so much for PNG (not in my use cases).

So, with PNG, does the issue also happen on your device?

[replabrobin]

Hi Victor, unfortunately the renderPM/PDF/PS/SVG csnvasses sre all slightly different.from the original pdfgen/canvas.py code. The shapes.path class does allow isClipPath to be set so if png is not obeying the setting then presumably we will have to mess with the renderPM canvas/renderer classes to amke it work.