[poppler] Generating lovely pen plotter output from Poppler: Pull request

[jonh.poppler at jonh.net]

Hi Oliver,

I've done so, and gone on a journey of discovery, deepening my 
relationship with the CI infrastructure. :v) That cleaned up a number of 
minor issues.

Thanks for your reply. The PR is in.

     --Jon


On 2020-12-17 02:51, Oliver Sander wrote:
> Hi Jon,
> 
> thanks for reaching out---what you have sounds like an interesting 
> project.
> 
> In order to get your code reviewed for inclusion into poppler you need 
> to get
> an account for the freedesktop/poppler GitLab instance:
> 
>   https://gitlab.freedesktop.org/poppler/poppler
> 
> Afterwards please open a merge request with your proposed changes.
> 
> Best regards,
> Oliver
> 
> On 17.12.20 08:58, jonh.poppler at jonh.net wrote:
>> Howdy team Poppler,
>> 
>> I've been on a decades-long quest for the best way to get cool output 
>> onto my 1985 HP 7585B pen plotter. There are dozens of tools for 
>> generating HPGL from various formats around the Internet, and they all 
>> stink. This tool is the HPGL conversion tool to end all HPGL 
>> conversion tools -- a motto that rolls off the tongue!
>> 
>> I'd greatly appreciate it if someone on the team could *guide me 
>> through getting these changes into Poppler*. Below i give a brief 
>> description of the changes, quick-start instructions to try it out, 
>> and specific requests for feedback and guidance.
>> 
>> Thank you!
>> 
>> 
>> What's in the tin
>> 
>> Please find my branch here:
>> 
>> https://github.com/jonhnet/plotler 
>> <https://github.com/jonhnet/plotler>
>> 
>> It consists of:
>> 
>> * A first commit that refactors SplashOutputDev to put a part of its 
>> functionality into a weaker superclass VectorOutputDev. This is to 
>> prepare for code sharing without "subclass-by-deletion". This commit 
>> also exposes a couple of methods in SplashPath as public.  It also 
>> moves some supporting code that used to be in SplashOutputDev into a 
>> pair of new files VectorFonts and VectorDynamicPatters; just an 
>> overdue cleanup. (4dec008eddea2329c0e8277398803cb9022b15cc)
>> 
>> * Then the rest of plotler as new files: A new StrokeOutputDev that 
>> inherits from VectorOutputDev to capture stroke and drawChar commands 
>> and flatten them down to simple strokes. A new utils/plotler.cc CLI 
>> that invokes it. It relies on:
>> 
>> - Plot, PlotClip, and PlotEmit for manipulating pen paths.
>> 
>> - HersheyFont, HersheyDirectory, and HersheyUnicodeSubstitutions for 
>> manipulating Hershey fonts.
>> 
>> 
>> Try it out
>> 
>> # standard poppler build
>> git clone https://github.com/jonhnet/plotler 
>> <https://github.com/jonhnet/plotler>
>> mkdir poppler-install
>> cd plotler
>> mkdir build; cd build;
>> INSTALLDIR=`(cd ../../poppler-install; pwd)`
>> cmake .. -DCMAKE_INSTALL_PREFIX=$INSTALLDIR 
>> -DCMAKE_BUILD_TYPE=debugfull
>> make -j4
>> make install
>> 
>> # and now try plotler
>> ./utils/plotler -i ../test/plotler/brake-diagram.pdf -o proof.svg && 
>> eog proof.svg
>> ./utils/plotler -i ../test/plotler/verikv-osdi2020-final.pdf -n 9 -o 
>> proof2.svg && eog proof2.svg
>> 
>> 
>> Feedback requested
>> 
>> - Community code standards. Guidance welcome.
>> 
>> - I have written zero tests. Guidance on meeting appropriate standards 
>> would be helpful.
>> 
>> - My commit includes a bunch of PDF test files I used to guide 
>> development. Should these be removed or included in the proposed 
>> change?
>> 
>> - Utility name. Plotler maybe is too clever? I considered "pdftohpgl", 
>> but the thing can already emit SVG, and I could imagine growth to 
>> support more formats.
>> 
>> 
>> Background
>> 
>> After finding other tools wanting, I wrote my own Python SVG->HPGL 
>> extension a decade ago. It sucked, because it required me to interpret 
>> so much of SVG. Then I thought, hey, I/nkscape/ knows how to interpret 
>> SVG! So I hacked a converter into inkscape 0.42 -- and it served me 
>> well for years, long after modern distros couldn't build that version 
>> of Inkscape. But it wasn't super flexible, and there was no reasonable 
>> way to share it. A couple years ago I thought, maybe it's time to try 
>> again with a general vector graphics engine designed for library 
>> access, so I sat down with Ghostscript. I aged three years that 
>> weekend.
>> 
>> It finally struck me that I should find a /modern/ vector graphics 
>> toolkit. And if I start with PDF, I'm basically building a printer 
>> driver. Poppler was the perfect fit -- nicely organized & modularized 
>> code, and already set up to build a set of conversion utilities, so 
>> plotler fits right in.
>> 
>> I think it would be fun to write a CUPS backend based on Plotler, so I 
>> can just click "Print" in any application and have it pop out on a pen 
>> plotter.
>> 
>> 
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