[Cmake] -lfltkFOO order

[Mark Foskey]

FindFLTK.cmake doesn't seem to load the FLTK libraries in the proper 
order.  I compiled a simple program with the following CMakeList.txt file:

PROJECT(choosefile)

INCLUDE (${CMAKE_ROOT}/Modules/FindFLTK.cmake)
INCLUDE (${CMAKE_ROOT}/Modules/FindJPEG.cmake)
INCLUDE (${CMAKE_ROOT}/Modules/FindPNG.cmake)

LINK_LIBRARIES(
   ${JPEG_LIBRARIES}
   ${PNG_LIBRARIES}
   ${FLTK_LIBRARIES}
)

ADD_EXECUTABLE( choosefile choosefile.cxx )

I got the following error message:

Building executable choosefile...
c++      -fPIC  choosefile.o    -o choosefile -rdynamic -L/usr/local/lib 
-L/usr/
X11R6/lib -ljpeg -lpng -lz -lfltk -lfltk_gl -lfltk_forms -lfltk_images 
-lSM -lIC
E -lX11 -lXext -lm -Wl,-rpath,/usr/local/lib:/usr/X11R6/lib
/usr/local/lib/libfltk_images.a(Fl_File_Icon2.o): In function 
`Fl_File_Icon::loa
d(char const*)':
Fl_File_Icon2.o(.text+0xe): undefined reference to `fl_filename_ext(char 
const*)
'

The problem was that -lfltk_images needed to come before -lfltk.  There 
is a utility with Unixoid versions, fltk_config, that will output the 
needed libraries:

$ fltk-config --use-gl --use-images --use-glut --use-forms --ldflags
-L/usr/local/lib -lfltk_images -lpng -ljpeg -lz -lfltk_gl -lGLU -lGL 
-lfltk_forms -lfltk -L/usr/X11R6/lib -lm -lXext -lX11 -lsupc++

I don't know if there is a way for cmake to automatically call this 
program, or if such a thing would even be desirable.  But the 
FindFLTK.cmake module should probably be fixed.

Finally, fltk_images reqires some image libraries, and fltk_gl wants GLU 
and GL.  Should the FindFLTK.cmake module find thos modules too?  What's 
the philosophy on that?

-- 
Mark Foskey    (919) 843-5436   Computer-Aided Diagnosis and Display Lab
mark_foskey at unc.edu             Department of Radiology, CB 7515, UNC
http://www.cs.unc.edu/~foskey   Chapel Hill, NC  27599-7515