Python API for GSAPI

Overview

All functions have the same name as the C function that they wrap.

Functions raise a GSError exception if the underlying function returned a negative error code.

Functions that don't have out-parameters return None. Out-parameters are returned directly (using tuples if there are more than one).

See demos/python/examples.py for sample usage.

Usage

make sodebug
LD_LIBRARY_PATH=sodebugbin ./demos/python/gsapi.py

Limitations as of 2020-12-19:

Only very limited testing has been done.

Tested on Linux, Windows and OpenBSD with python-2.7 and 3.7.

We don't provide gsapi_add_fs() or gsapi_remove_fs().

We only provide display_callback V2, without V3's display_adjust_band_height() and display_rectangle_request().

Please send any questions, comments or suggestions about this page to: julian.smith@artifex.com

• Use python ctypes. This works pretty well. See ghostpdl:demos/python/gsapi.py, a self-contained python module that, as of 2020-Jun-29, provides all of the ghostpdl:psi/iapi.h API except for gsapi_add_fs() or gsapi_remove_fs(). The drawback here is that it is specific to python - equivalent code would have to be written for each front-end language that is required.

Python version of the gsapi API in ghostpdl:psi/iapi.h.

• Use SWIG to wrap the functions declared in ghostpdl:psi/iapi.h. This done by ghostpdl:toolbin/gsapiwrap.py. This hasn't been entirely succesfull - SWIG is surprisingly limited at dealing with APIs that use (argc, argv) parameters, out-parameters and function pointers. So we end up with lots of manipulation in the SWIG .i file, plus custom front end (e.g. Python or C#) code to make things work.

• Use python ctypes. This works pretty well. See ghostpdl:toolbin/gsapi.py, a self-contained python module that, as of 2020-Jun-29, provides all of the ghostpdl:psi/iapi.h API except for gsapi_add_fs() or gsapi_remove_fs(). The drawback here is that it is specific to python - equivalent code would have to be written for each front-end language that is required.

Python version of the gsapi API.

There are two approaches that have been tried here:

• Use SWIG to wrap the functions declared in ghostpdl:psi/iapi.h. This done by ghostpdl:toolbin/gsapiwrap.py. This hasn't been entirely succesfull - SWIG is surprisingly limited at dealing with APIs that use (argc, argv)-style parameters, out-parameters and function pointers. So we end up with lots of manipulation in the SWIG .i file, plus custom front end (e.g. python or c#) code to make things work.

• Use python ctypes. This works pretty well. See ghostpdl:toolbin/gsapi.py which is a python module that, as of 2020-Jun-29, provides all of the ghostpdl:psi/iapi.h API except for gsapi_add_fs() or gsapi_remove_fs(). The drawback here is that it is specific to python - equivalent code would have to be written for each front-end language that is required.

-- Julian Smith - 2020-06-29

Comments

<--/commentPlugin-->