[Scummvm-devel] New (optional) Dependency: libjpeg

[Johannes Schickel]

Hello everybody,

as you might have noticed I merged my pull request #376GRAPHICS: 
Implement JPEGDecoder based on libjpeg 
(https://github.com/scummvm/scummvm/pull/376). This introduces a new 
optional dependency to ScummVM: libjpeg. This was done to allow us to 
load many JPEG files not supported by our previous self written JPEG 
decoder. This is mainly needed for Wintermute which now depends on libjpeg.

I want to use this mail to notify our developers and porters about the 
situation. I think all developers using Linux and not building any 
non-desktop ports can skip the remaining bits because their distribution 
should feature a libjpeg package anyway. Other port developers working 
on ports capable of supporting games which require JPEG, like Myst ME, 
Pegasus Prime demo or Wintermute games will need to build the library.


There are two alternatives you can use.

* The original libjpeg from here: http://www.ijg.org/
   This has been the default option in the past. Many platforms feature 
libjpeg v6b packages which is the most common/standard version. The v6b 
sources itself are quite old and many distros patch them a bit. But I 
managed to get it to work fine on Linux/amd64.

* libjpeg-turbo which aims to improve performance of the library and 
which can be found here: http://www.libjpeg-turbo.org/
   A more recent "fork" which split off v6b.

I am not sure whether we should prefer one over the other. If you have 
any thoughts here, please let us know.


It might be that there's already some prebuilt libraries for your port. 
I already made a quick search about that and summarized my findings 
here: https://github.com/scummvm/scummvm/pull/376#issuecomment-22834090

MSVC users can probably also use the official libjpeg-turbo prebuilt 
libraries from here 
http://sourceforge.net/projects/libjpeg-turbo/files/1.3.0/libjpeg-turbo-1.3.0-vc.exe/download 
(32bit) or from here 
http://sourceforge.net/projects/libjpeg-turbo/files/1.3.0/libjpeg-turbo-1.3.0-vc64.exe/download 
(64bit).


If you have any questions or other thoughts please let us know.

Greetings,
Johannes