I am fine to start with something that works and fine-tuned that later.

To 3: We cannot reconstruct the correct height, width if we only have the information from Google Cloud Vision OCR and therefore any estimation is probable semantically wrong (also it may work on a technical level). However, I suggest to drop these parameters as hard requirements and thereby also simplifying the integration here, see dinosauria123/gcv2hocr#2.

To 4: This also belongs to the upstream repo.

We should check further the travis problems here and also the Docker image has some build errors on this branch: https://hub.docker.com/r/ubma/ocr-fileformat/builds/

I resolved the merge conflict here, this triggered new travis checks which are now passing, but the docker builds still fails:

make -C gcv2hocr

make[2]: Entering directory '/ocr-fileformat/vendor/gcv2hocr'
gcc -std=c99 -o gcv2hocr main.c
make[2]: Leaving directory '/ocr-fileformat/vendor/gcv2hocr'
make[1]: Leaving directory '/ocr-fileformat/vendor'

[91mmake[2]: gcc: Command not found
make[2]: *** [Makefile:9: gcv2hocr] Error 127
make[1]: *** [Makefile:112: gcv2hocr] Error 2
make: *** [Makefile:27: vendor] Error 2 
[0m
Removing intermediate container 417d39381b83

Must add gcc to the apk add line and probably uninstall it afterwards since that's a pretty big package.

Okay, I tried to add this package but there is now a new error in the docker build:

make -C gcv2hocr
make[2]: Entering directory '/ocr-fileformat/vendor/gcv2hocr' 
gcc -std=c99 -o gcv2hocr main.c 
[91mmain.c:1:19: fatal error: stdio.h: No such file or directory 
 #include <stdio.h> 
                   ^ 
compilation terminated.

Any hint how to fix this?

Okay, adding libc-dev as well did the trick...

Okay, this looks now ready to merge from my side.

I merged it finally. Thank you, @kba and @zuphilip.

@stweil Cool! Do you also want to do a new release v0.2.2 now?

What about the remaining pull requests? Yes, it's time for a new release, but before tagging, I'd like to look after a problem report which I got for https://digi.bib.uni-mannheim.de/ocr-fileformat/ (download button not working as expected).

I don't know the status of the other PR which are just making some branches by @kba visible. Thus, these could take more time to understand and have a plan how to proceed. Fixing an error before releasing sounds certainly like a good idea.