This test was disabled in PR 4732, because the file was no longer available. The motivation being that there were two other files which should be good replacements. However, one of those has since been replaced with a reduced test-case (which doesn't exercise the same code-path), and in the other one the error does not appear to be entirely identical.
Hence it seems reasonable to re-add the 'aboutstacks.pdf' test, since it was possible to find it on the Internet Archive (by searching using a different URL, compared to the current one).
Issue 6854 - Update the link locations to point to the Internet Archive for tests: 20130226130259, JST2007-5, P020121130574743273239, SFAA_Japanese, TaroUTR50SortedList112
*This patch follows a similar idea as PR 5756.*
The patch is based on the nice debugging done by Brendan in the referenced issue 6782.
A better way to handle this, and similar issues, would probably be to completely ignore what the PDF file claims about font type/subtype, and just check the actual data. But until that kind of rewrite happens, this patch should help.
Fixes 6782.
When generating new references locally on Windows, after PR 6724, I get the following output:
```
WARNING: Unable to open file for reading "Error: ENOENT, open 'c:\Users\Jonas\Git\pdfjs\test\pdfs\issue_3694_reduced.pdf'".
Unable to verify the checksum for the files that are used for testing.
Please re-download the files, or adjust the MD5 checksum in the manifest for the files listed above.
```
Compared to the name of the file (`issue3694_reduced.pdf`), you see that the manifest entry has a superfluous underscore in the "file" entry.
Apparently some PDF files can have annotations with `URI` entries ending with `null` characters, thus breaking the links.
To handle this edge-case of bad PDFs, this patch moves the already existing utility function from `ui_utils.js` into `util.js`, in order to fix those URLs.
Fixes 6832.
Currently we're not applying Patterns for text, but only for graphics.
This patch is unfortunately not a complete solution, but rather a step on the way, since there are still some PDF files where the Patterns look more like a solid colour, rather than the intended gradient.
I've been unable to fix these issues completely, and I've not managed to determine if the remaining issues are caused either by the pattern code, the canvas code, or perhaps both.
However, given that even this simple patch improves the current situation quite a bit, I figured that it couldn't hurt to submit it as-is.
- Fixes 5804.
- Fixes 6130.
- Improves 3988 a lot, since the text is now visible. However, it looks like the text is *one* solid colour, instead of the correct gradient.
- Improves 5432, since the text is no longer gray. (This file also suffers from the same problem as the previous one.)
