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Page.clip_to_rect() drops 'sh' (shading) operators #5108
Description
Description of the bug
We are noticing that Page.clip_to_rect() incorrectly deletes certain graphic elements, even if they fall within the clip box. I've had this for PDFs authored in Adobe Illustrator containing certain kinds of gradients on curved lines - which are expressed in the PDF as Shading elements. I've created a minimal PDF example below.
I don't know enough about the PDF spec internals to be able to debug any further, so let me know if I'm missing anything. clip_to_rect seems to perform perfectly in all other scenarios, it's just these types of graphics.
Thanks for your help!
How to reproduce the bug
Using the minimal PDF attached below, we can see that any clip_to_rect operation that does not include the origin of the page (top left) results in the gradient shading being deleted, even if the gradient is visually in the clipped area:
import pymupdf
def clipped_content(clip):
doc = pymupdf.open("shading-repro.pdf")
doc[0].clip_to_rect(clip)
doc2 = pymupdf.open(stream=doc.tobytes(garbage=3, clean=True))
return b"".join(doc2.xref_stream(x) for x in doc2[0].get_contents())
print("pymupdf", pymupdf.version)
for label, clip in [
("whole page ", pymupdf.Rect(0, 0, 400, 400)),
("right half (holds shading) ", pymupdf.Rect(200, 0, 400, 400)),
("page inset by 1pt ", pymupdf.Rect(1, 1, 399, 399)),
("1x1 at PDF origin, no shading in it", pymupdf.Rect(0, 399, 1, 400)),
]:
content = clipped_content(clip)
print(f" {label} -> sh kept: {b'sh' in content} {content!r}")This prints:
pymupdf ('1.28.2', '1.28.2', None)
whole page -> sh kept: True
right half (holds shading) -> sh kept: False
page inset by 1pt -> sh kept: False
1x1 at PDF origin, no shading in it -> sh kept: TrueThe final test also shows that the shading graphic is not deleted when clipping to the origin where the graphic is not present.
PyMuPDF version
1.28.2
Operating system
Linux
Python version
3.14
Activity
JorjMcKie commentedon Sep 4, 2026
I am transferring this to the MuPDF team.
I am not sure whether this is even to be considered as a bug.
JorjMcKie commentedon Sep 4, 2026
MuPDF issue link: https://bugs.ghostscript.com/show_bug.cgi?id=709690
JorjMcKie commentedon Sep 4, 2026
@BenVosper I think there is no bug, specifically no MuPDF bug. The shading axis is (210, 0) → (390, 0).
The clip rectangle in your page's /Contents is (210, 10) → (390, 390).
Result:
But let's wait for the MuPDF team's response.
BenVosper commentedon Sep 4, 2026
@JorjMcKie Thanks for the quick response!
Messing with my example a little, I'm still seeing the shading get removed if the axis does lie inside the clip box. I get the same results as above with this version where the shading axis is (210, 50) → (390, 50) which has an identical visual appearance when applied to the box:
shading-repro-2.pdf
This might be a totally contrived example, but we are seeing the issue on real PDFs created in Illustrator. I'm not sure if the user can control where the shading axis itself is placed when creating gradients there.
Thanks for passing this on 👍
tests/: reproducer for #5108, `Page.clip_to_rect() drops 'sh' (shadin…
julian-smith-artifex-com commentedon Sep 22, 2026
https://bugs.ghostscript.com/show_bug.cgi?id=709690 is fixed in mupdf master.
changes.txt: mark fixed with latest mupdf-1.28.x: #5108 #5125
changes.txt: mark fixed with latest mupdf-1.28.x: #5108 #5125
julian-smith-artifex-com commentedon Oct 19, 2026
Fixed in PyMuPDF-2.0.