About "helpgen"
===============
this is a small C tool intended to simplify and make easy the process to 
tempestively update the HTML doc internally supplied by "spatialite_gui"
about SpatiaLite and Rasterlite2 SQL functions.


How it works
============
1. "helpgen" will parse and rearrange the two HTML pages supporting
   each library, merging both into a single HTML page.
2. this merged HTML page will then be compressed using the well known
   ZIP/DEFLATE algorithm (zlib).
3. then the ZIP binary payload will be transformed into many short text 
   strings encoded as hexadecimal bytes.
4. and finally a C++ source will be autogenerated; this C++ source is 
   intended to be compiled and linked within "spatialite_gui", and its
   specific scope is the one to "inject" into the executable all the
   above mentioned hexadecimal strings representing the zipped HTML doc.
5. each time that the user will request "spatialite_gui" to show the
   internal HTML doc the "MyMain::GetHelp()" function defined into the
   autogenerated C++ source, the zipped payload will be decompressed
   and the HTML page will be shown on the screen.


Using "helpgen"
===============
a. build the "helpgen" executable (see below).
b. prepare the SpatiaLite's own HTML page; this usually means copying
   "spatialite-sql-latest.html" from libspatialite's sources to
   ./spatialite-sql-latest.html
c. prepare the RasterLite2's own HTML page; this usually means
   downloading from the Fossil Wiki:
   https://www.gaia-gis.it/fossil/librasterlite2/wiki?name=sql_reference_list
   the downloaded HTML page must be saved as ./rl2-sql-latest.html
d. now you are ready to execute "helpgen" (no args):
   ./helpgen
e. the "HtmlHelp.cpp" C++ source will be autogenerated.
f. copy "HtmlHelp.cpp" into the spatialite_gui's sources and rebuild;
   the spatialite_gui executable will now contain the latest version
   of the HTML doc.
   
   
Building "helpgen"
==================
You just have to directly invoke "gcc".

on Linux and other *nix systems:
gcc helpgen.c -o helpgen -lz


on Windows using MSYS and MinGW:
gcc helpgen.c -o helpgen.exe -lz
