[Qt-qml] QML and LGPL?

[Stephen Kelly]

Jason H wrote:

> In my experience LGPL only applies when you change the files in the
> library not add on to it.
> If someone adds a QML object, how does that change what was under the LGPL
> license?
> You're not modifying LGPL files are you? It sees your distinction would
> obliterate the differences between GPL and LGPL.
> 

Well your understanding doesn't match mine at all, so certainly one of us is 
misunderstanding :).

Here's my reasoning:

* The LGPL gives you certain rights to distribute the covered software.
* JavaScriptCore is covered by the LGPL.
* When you distribute JSC in source or binary form, you do so under the 
terms of the LGPL.
* When you distribute an app that uses QtQuick, either by statically or 
dynamically linking to QtScript/QtDeclarative or by distributing a 
statically or dynamically compiled qmlviewer along with some QML files, you 
distribute the JSC part along with it. Your distribution of JSC is allowed 
by the LGPL subject to the terms of the licence.
* If you modify JSC, your modifications to JSC must be made available to 
downstreams in compliance with the LGPL.
* Everything 'above' JSC you can either get a licence for (Qt, other third 
party software), or write yourself. The LGPL doesn't affect those in any 
other way.

That is, any distibution of the LGPL-covered work needs to be done under the 
terms of the LGPL. That might mean you have to include the licence text and 
a means of allowing your downstreams to download the JSC source. It might 
even mean that if you link statically to Qt, you might have to link 
dynamically to JSC somehow. I don't know if that's possible. You would have 
to ask a lawyer about what the licence really means. Obviously I am not one.

All the best,

Steve.