Fixed the bug where button_states() returns None when /AP points to an indirect object.

[airgalss]

Description: Some PDF widget objects may not have their /AP(Appearance Dictionary) directly pointing to a dictionary, which is enclosed with '<< >>', but rather pointing to an indirect object, expressed by an xref number in the format 'NNN 0 R'. Therefore, the current button_states() only can correctly handle cases where /AP points to a dictionary and cannot handle cases where it points to an indirect object. Consequently, I have introduced additional logic to handle the latter scenario, ensuring that button_states() can accurately return the on/off state names for button widgets even when /AP points to an indirect object.

Test: I have tested the modified button_states() function on the mentioned type of PDF, and it now correctly returns the states instead of None.

[github-actions]

CLA Assistant Lite bot All contributors have signed the CLA ✍️ ✅

[airgalss]

I have read the CLA Document and I hereby sign the CLA

[airgalss]

recheck

[julian-smith-artifex-com]

Thanks for this. Unfortunately there are some failures in our Test quick action as you can see above, because of mixing tabs and spaces in the new python code.

It would be more useful to us if you made these changes to the rebased implementation in PyMuPDF/src/__init__.py instead of the classic implementation in PyMuPDF/fitz/ - would you be able to do that? The Python code is basically the same so it should be easy enough to port.

[JorjMcKie]

recheck

There are lines in def butten_states() method that use tab characters instead of 4 spaces.
I would simply change that and copy the method's code to the same-named method in src/__init__.py.

[airgalss]

I have addressed the issue of mixing tabs and spaces, and copied it to src/__init__.py. I hope it should be fine now.