licence for a free scientific application

[fatecasino]

I have recently created a small application with QT which I want to release for free usage.
I just realised that my application cannot run in other Windows system unless i copy QtGui.dll, libgcc_s_dw2-1.dll, QtCore4.dll and QtGui4.dll in the same folder.
I have two quick questions on that:

1. Is it legal to distribute my application accompanied with these dlls?
2. If I want to make a commercial application should I buy a commercial licence from each of the publishers involved in these dlls?

[d_stranz]

1 - In Windows, you -must- distribute whatever DLLs are required by your application if they are not standard Windows DLLs (like kernel32.dll, etc.) regardless of the license. Follow the Qt 4.8 Windows deployment guide. (Google for it).

2 - Qt is released under LPGL, which means you can distribute the app commercially so long as you link to Qt as a shared library and provide a way for customers to get a copy of the Qt source code used to build the libraries (a link to the Qt distribution in your documentation is good enough if it is available online). I do not know how libgcc is licensed. If it has a GPL license like many GNU libraries, you cannot distribute it commercially without a commercial license.

[ars]

I do not know how libgcc is licensed. If it has a GPL license like many GNU libraries, you cannot distribute it commercially without a commercial license.

For mingw 32 bit there is the following license information on the runtime deliverables:

/*
* DISCLAIMER
* This file has no copyright assigned and is placed in the Public Domain.
* This file is a part of the mingw-runtime package.
*
* The mingw-runtime package and its code is distributed in the hope that it
* will be useful but WITHOUT ANY WARRANTY. ALL WARRANTIES, EXPRESSED OR
* IMPLIED ARE HEREBY DISCLAIMED. This includes but is not limited to
* warranties of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
*
* You are free to use this package and its code without limitation.
*/

For mingw 64 bit we get the following license information:

MinGW-w64 runtime licensing
***************************
This program or library was built using MinGW-w64 and statically
linked against the MinGW-w64 runtime. Some parts of the runtime
are under licenses which require that the copyright and license
notices are included when distributing the code in binary form.
These notices are listed below.
========================
Overall copyright notice
========================
Copyright (c) 2009, 2010 by the mingw-w64 project
This license has been certified as open source. It has also been designated
as GPL compatible by the Free Software Foundation (FSF).
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
1. Redistributions in source code must retain the accompanying copyright
notice, this list of conditions, and the following disclaimer.
2. Redistributions in binary form must reproduce the accompanying
copyright notice, this list of conditions, and the following disclaimer
in the documentation and/or other materials provided with the
distribution.
3. Names of the copyright holders must not be used to endorse or promote
products derived from this software without prior written permission
from the copyright holders.
4. The right to distribute this software or to use it for any purpose does
not give you the right to use Servicemarks (sm) or Trademarks (tm) of
the copyright holders. Use of them is covered by separate agreement
with the copyright holders.
5. If any files are modified, you must cause the modified files to carry
prominent notices stating that you changed the files and the date of
any change.
Disclaimer
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS ``AS IS'' AND ANY EXPRESSED ....

(more lines on license stuff)

So there are no problems in using it even in commercial applications.

@OP: You already have an active thread on your license questions http://www.qtcentre.org/threads/6786...ic-application. Why opening another one?

Best regards
ars

[fatecasino]

I am sorry for this duplication, I just tried to had a different focus in the other thread. Here I wanted to understand only for the dlls alone.
Thanks for your post, I have to study a bit of...law for the moment

[ars]

I have to study a bit of...law for the moment

That's some of the more or less "unpleasant" work that developers sometimes have to do in addition to the creative work of developing applications. But once you got familiar with one of the more complex licenses (like GPL/LGPL) other licenses become easier to understand.

Best regards
ars