Maybe I should open with the good news, that all
the libraries which are used and available in this 
toolset, allow you also commercial usage (without
opening up your Application under one of the 
OpenSource-licenses, since VB-Classic does not offer
any static linking) - but that is of course not 
saying, that "we" (as the VB-community) should
not "give back" something under one of these 
licenses too - your choice of course... :-)


So, I will go this route in the next months at least -
by opening up the sources of the two ActiveX- (COM-)
Dlls dhRichClient3.dll and dhCairo.dll to the community
under LGPL, to offer a "larger security", for those
who make use of these wrapper-libs already in their projects - 
(since "closed source One-Man-shows" are always considered 
as a little bit risky in the long run) - but also to 
"give something back" into the general OpenSource-community, 
since without their generousity and efforts something like 
this "free usable package" here would not be possible at all.


Ok, what now follows is a short description of the
contents of the two OpenSource-library-builds and the
different licenses, all the sub-parts come under: 

sqlite36_engine.dll
and
cairo2_engine.dll

which do the underlying "main-work" here in this small 
framework ... the two ActiveX-Dlls:
dhRichClient3.dll 
and
dhCairo.dll

are comfortable COM-wrappers "on top", which allow to deal 
with the functionality of the OpenSource-libs in an (VB-)
objectoriented and secure way (secure here means, that you
will not need to take care with regards to handle- and/or 
memory-freeing yourself.

But I digress...

Both opensource-libs were build from C-Source with VS-2008,
with statically linked-in MS-runtime-libs + any suitable 
speed-optimization was applied, therefore their somewhat
larger size, compared with MingW-builds:

sqlite36_engine.dll and its statically linked "Sub-Parts":
   the main-sources herein are public domain due to the
   generous D.R. Hipp (www.sqlite.org)- but the lib also 
   contains some sub-parts as are:
   
   - FastLZ (compression-algos, included as Source-Modules)
     http://www.fastlz.org/
	 MIT-license
	 
   - ZLib (higher compression, well-balanced compr./decomp. Speed)
     http://www.gzip.org/zlib/zlib_license.html
	 ZLib-license (very liberal too)
	 
   - LZMA (highest compression, decomp. fast, compr. slow)
     http://www.7-zip.org/sdk.html
	 Public Domain license
	 
All of the different compression-algos are available within
cCrypt of the dhRichClient3.dll.


Somewhat more Sub-Libs are included in the cairo2_engine compile:

cairo2_engine.dll and its statically linked "Sub-Parts":
   the "main-sources" come of course from the cairo-project,
   which is licensed under LGPL/MPL: (http://cairographics.org/)

   - libpixman (fast, optimized pixel-surface-routines)
	 BSD-like license, e.g. mentioned here: 
	 http://wiki.mozilla.org/License_Policy

   - libPng 
     http://www.libpng.org/pub/png/src/libpng-LICENSE.txt
	 PNG-license
	 
   - ZLib (again, but used here mainly by libPng in CDecl-fashion)
	 http://www.gzip.org/zlib/zlib_license.html
	 ZLib-license
	 
   - chipmunk (2D-physics engine)
     http://howlingmoonsoftware.com/chipmunk.php
	 MIT-license
   
   - libjpeg-turbo (superfast JPG De- and Encoding)
     http://www.wxwidgets.org/about/licence3.txt
	 wxWindows-license (resembling and in many parts identical to LGPL)
	 

I hope this new text-file here, now offers more clarity on 
"what's in there - in the package" - and it is also a necessitiy 
now, to provide these Infos along with any package, which is using 
not only the "older" dhRichClient-stuff alone - since now with cairo, 
coming under LGPL, we need to provide such a license-info-file in 
either way along with our binary-packages that make use of these
new toolset-parts.

So, please make sure, you include at least this file here along
with the cairo-related binaries (dhCairo.dll and cairo2_engine.dll)
when you plan to deploy your solutions, based on that in the future.


And maybe an additional note about using the wrappers new
SVG-functionality, which is implemented directly in dhCairo.dll
in plain VB6-code, so - the usual (and somewhat large with all
its additional dependencies) librsvg was not needed and linked 
in the cairo-C-build).
The new cairo-tutorial "VB-cairoTutorial.zip", downloadable under
the toolset-page as well:
www.thecommon.net/3.html

...now contains a few Demo-Icons from the modern (and huge) Oxygen-
Iconset - I've already placed a License-Info for these Images in 
the Demo-Zip-package, but at this occassion let me write something
here too, since we are at it.

The Oxygen-IconTheme is now under LGPL too:
http://www.oxygen-icons.org/?page_id=4

Which means, that you can use these nice art also commercially
in your VB-Apps now (rendered over the wrapper) - but take
care, that you do *not* link any Oxygen-Icon-resources (no 
matter if as *.svg, *.svgz or as a "derived" *.png) as 
resource-file-content directly into your VB-Apps binaries. 
You may link them as resource into a dll-binary - but *only* 
if you open up the sources for these "resource-lib" under
LGPL too.
Background is, that the LGPL forbids any static linking - 
any part which comes under LGPL (be it a C-compiled library,
or an icon), may not be "hidden" within your own (non-LGPL)
Binaries. 
For Binaries under LGPL, this usually means dynamic linking 
against them (which e.g. dhCairo.dll does per Declare-Statements) - 
and for LGPL-icons that means "dynamic linking" (or better 
"dynamic loading") too ... either from a Sub-ResourcePath 
under your Apps path - or over a Resource-Dll which comes 
under LGPL itself.

Ok, I hope all these "license-issues" are now somewhat more
clear for all you "new potential dhCairo-users out there" -
and I didn't "scared you away" with all that... ;-)

But I think (aside from the necessitiy of this file), that
the infos within here are useful for our community, which
maybe somewhat inexperienced yet with regards to opensource-
licenses.

Maybe as a "final upshot" again (in simple words), and to 
avoid any confusion:
Commercial usage of "all the cairo-stuff" in this toolset
is allowed, as well as the usage of the huge reservoir of  
the Oxygen-IconTheme - just don't try to "hide" where all
these things came from - "play fair", so to say.


Olaf Schmidt

(in May 2010)


