libqjpeg troubles

**jacek** · 25th August 2006, 14:17

Originally Posted by TheRonin

I have qjpeg1.dll and qjpegd1.dll in my Qt/plugins/imageformats/ folder though. Aren't those the right ones?

Yes, but for linking you need libqjpeg.a or libqjpegd.a. Do you have these files somewhere?

Anyway, if you want to use QJPEG plugin on a system where Qt isn't installed, just create a imageformats subdirectory in the directory where your executable is and place qjpeg1.dll there.

**TheRonin** · 25th August 2006, 14:44

Well i have libqjpeg1.a and libqjpegd1.a in the same imageformats directory as the dlls.

Thanks for the tip with the dll's in the executable directory. Works devinely. If and when i get the compilation to work with libqjpeg, will i still need to distribute the dll's with my app? if so, what do i gain from using the qjpeg plugin?

**jacek** · 25th August 2006, 15:36

Originally Posted by TheRonin

Well i have libqjpeg1.a and libqjpegd1.a in the same imageformats directory as the dlls.

I guess that the problem is in that "1" at the end.

Originally Posted by TheRonin

If and when i get the compilation to work with libqjpeg, will i still need to distribute the dll's with my app? if so, what do i gain from using the qjpeg plugin?

"static plugins" mechanism was intended for use with static linking.

With dynamic linking, you will have to distribute DLLs and your application won't start without them. If you were using plugins, it would start --- just missing plugins wouldn't be available.

Also it might be useful for troubleshooting "plugin not loaded" problems, since you link against the plugin, instead of loading it at runtime.

**TheRonin** · 25th August 2006, 15:48

Ok thanks!

As far as the 1 at the end of the filename is concerned, that's Qt's doing! When i try to remove it the compiler whines about methods and functions in the plugin.

But if i understand you correctly then the solution is that i haven't built qt for static linking so the plugins aren't either. If i were to configure qt for static linking i'm confident the plugin dll's will get the proper names and my troubles will go away. I'm thinking that the error was caused by me loading a plugin for static linking when i was linking dynamically.

That's my theory at this point, but please let me know if i'm wrong