Redirect stderr->stdout to hopefully make GS output easier to work with
overall, since the previous code didn’t seem to account for mixed used
properly.
As of 3.1.1, our minimum version, these codecs are now required by
default for a successful installation, effectively solving the problem
of Pillow installed without libjpeg/libpng.
Never really investigated the reason why ruffus returns a mutex to go
along with its logger. It seems that the mutex is only needed if one
wanted to make multiple successive calls to a log function and have
them appear appear atomically. It is not needed to protect the logger
proxy because accessing the proxy triggers IPC in the child process
that handles the multiprocessing.Manager() object.
The logging wrapper only logs one line at a time, so the mutex does not
actually protect logging sequence. Cut it.
Also manager.Lock() returns a threading.Lock object so the purpose of it
is actually to help processes share a thread-level lock. It would be
more appropriate to use a semaphore based multiprocessing.Lock.
I experimented with the idea of using asyncio-based processing but
realized that that does not solve the import time binding problem
that is the real issue. Therefore the simpler refactoring is to convert
to ruffus-oo syntax and get things working again.
build_pipeline() is really ugly at the moment. The old syntax had its
advantages.
This test reproduces the complete pipeline graph but does not work
otherwise.
It looks like GS 9.19 can incorrectly set overprinting for the text layer
even though this makes no sense in PDF/A, or at least someone produced
PDFs that have this after a Tesseract PDF -> GS PDF/A conversion. GS 9.20
complains about this. Instead of aborting, elide the feature.
See
http://git.ghostscript.com/?p=ghostpdl.git;a=commitdiff;h=094d5a1880f1cb9ed320ca9353eb69436e09b594
and
issue #107.
It looks like it is better to elide features and warn about elision rather
than abort with an error.
Turns out this occurred in any case where pdf-renderer hocr was used
and a tesseract timeout or error occurred. We created a replacement
page based on the unrotated page dimensions instead of the input image’s
dimensions.
Some PDFs omit the traditional q/Q wrapper and alter ctm with a stack
depth of zero, so make our test for stack depth specifically test for
the case where the PDF calls for rendering to an uninitialized ctm.
Probably related to #97.
James R. Barlow