[Qgis-developer] RE: [Qgis-user] QGIS and ECW and MrSid formats

Kolberg Sjur A Sjur.A.Kolberg at sintef.no
Mon Nov 10 03:33:38 EST 2008

Marco, or just in case someone really needs it;

Windows indeed allows plugin dlls, using the LoadLibrary() and GetProcAddress() functions, the former taking a file name as input. Combined with a FileOpen dialog, the user can direct the program to her separately downloaded (or built) dll. 

I don't know if these port to linux/Mac. Or if they are at all necessary (or elegant) in Qgis. I've used them to load dlls implementing a subclass, and with an object factory as the only dll export. The application grabs the object factory by GetProcAddress(), and must know the base class which defines the interface. Then the dll subclass can perform any task as long as the base class interface suffice.

Best regards,

Sjur Kolberg
SINTEF Energiforskning A/S
Sem Sælands vei 11
7465 Trondheim
tlf. 73 59 72 78
fax  73 59 72 50 

> -----Original Message-----
> From: qgis-user-bounces at lists.osgeo.org 
> [mailto:qgis-user-bounces at lists.osgeo.org] On Behalf Of Marco Pasetti
> Sent: 10 november 2008 08:40

> -----

> That because in MS-Windows we can't build applications with 
> some dependencies/libraries enabled and then redistribute the 
> application binaries without those libraries bundled (that is 
> consider them as optional features, to be separately 
> downloaded and installed by users): if built with that 
> libraries enabled, the application binaries will never work 
> if some DLL (the optional features) is missing.

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