RFC: expose PDF export to command line

[joneugster]

Would it be possible to expose some commands of the Mapper to a command line tool, so that for example one could tell a Github action to create a PDF (and store as build artifact) from a .xmap file?

(btw, I might be interested to contribute something in that direction but have absolutely no overview over the relevant parts of the code.)

[dg0yt]

Basically, it should be possible and not too difficult. Our tests might help to see how it could work. (In fact, it might be an option to do this as a separate executable.) Fragments:

• Argument processing would use Qt APIs.
• Loading a map from a file name:
  https://github.com/OpenOrienteering/mapper/blob/a3cb8e4518f8d15a6938c9b1620c35703788c6ff/test/symbol_t.cpp#L258-L259
• Interactive PDF export is based on printing: https://github.com/OpenOrienteering/mapper/blob/a3cb8e4518f8d15a6938c9b1620c35703788c6ff/src/gui/print_widget.cpp#L1345-L1392

[jjojala]

As part of my "map making workflow", I usually import contours e.g. as gpkg/some other georeferenced form, then simplify, and change to curve lines. Also I import bunch of other georeferenced materials (like orto-images, etc). Would be nice if these things could be done from the command line (and from a script).

[dg0yt]

@joneugster Do you want suggest concrete arguments?

[joneugster]

For my usage, I think it would be enough to have something like mapper export ./my_map.xmap ./my_map.pdf (or mapper print [INPUT] [OUTPUT]?) which reads the <print> tag present in the .omap:

<print
    scale="15000"
    resolution="600"
    templates_visible="true"
    mode="raster">
  <page_format paper_size="A4" orientation="portrait" h_overlap="5" v_overlap="5">
    <dimensions width="210" height="297"/><page_rect left="0" top="0" width="210" height="297"/>
  </page_format
  <print_area left="7.353" top="-337.359" width="210" height="297" single_page="true"/>
</print>

[r-eddy]

It would be useful if this could also convert map format, for example from xmap to ocad. It would need an additional argument to specify the format.

I did have a go and managed to get this to work. I parsed the arguments if they existed before the window was created and ran a single shot function that did the conversion and quit. I wrote a simplified map load function will a null view. Ugly but it worked.

[joneugster]

I guess the file extension of the input/output would directly specify this:

mapper export my_map.xmap my_map.ocad
mapper export my_map.omap my_map.pdf
mapper export my_map.omap my_map.xmap
...

[r-eddy]

Ideally yes, but the various OCAD versions use the same extension.

[dg0yt]

We already have is

mapper filename.omap [filname2.omap ...]

to open files in the editor. I would like to avoid any ambiguity about the ambiguity of a free parameter like myfile. Non-filename options shall begin with -. For practial reasons, it might be useful to follow the gdal interface as in https://gdal.org/en/latest/programs/gdal_vector_convert.html#gdal-vector-convert-subcommand. I would probably start the command line mode with --cli.

mapper --cli convert -i my_map.xmap -o my_map.ocd --of OCD12
mapper --cli export -i my_map.xmap -o my_map.pdf --creation-option <KEY>=<VALUE>

Note that map formats are map formats, (geospatial) vector formats and (geospatial) raster formats are treated a little bit different internally.

The --cli might be omitted from a pure command line executable (mapper-cli) which would also remove GUI library dependencies such as X on linux.

[jjojala]

@joneugster Do you want suggest concrete arguments?

# export to some other format:
> mapper my_map.omap --cli export -o my_map.ocd --of OCD12
> mapper my_map.omap --cli export -o my_map.pdf -creation-option <KEY>=<VALUE>

# import (georeferenced) template
> mapper my_map.omap --cli import -f orto.tif
> mapper my_map.omap --cli import -f contours.gpkg

# simplify (no output file given -> modifications to my_map.omap)
> mapper my_map.omap --cli simplify -select 'SYMBOL 101'    # advanced query language (as in CRT) supported to select objects

# convert to curves (optional output file given)
> mapper my_map.omap --cli to-curves -select 'SYMBOL 102' -o my_modified_map.omap

# change scale
> mapper my_map.omap --cli change-scale -target 1:7500 -o my_map7500.omap

In general some sort of "support for scripting" -type of feature would be nice.