CMake: build shared libs with OPTION_CAIROEXT (issue #250)

- remove separate libfltk_cairo to avoid cyclic dependencies, but
- keep a dummy libfltk_cairo in 1.4.0 for backwards compatibility
- move cairo/Fl_Cairo.cxx to src/Fl_Cairo.cxx
- add preliminary Cairo support for Visual Studio (MSVC)

Static linking is not affected by this change, but users building
with hand-made Makefiles will have to remove libfltk_cairo starting
with FLTK 1.4.0. The dummy library can be linked for backwards
compatibility but it will be removed later (in 1.4.x or 1.5.0).

The shared FLTK library libfltk.{so|dylib|dll|..} depends on libcairo
if and only if FLTK is built with one of the Cairo options. This has
always been the case for OPTION_CAIROEXT but is now also true if only
OPTION_CAIRO is selected, i.e. FLTK programs linked with a Cairo
enabled shared FLTK library will also be linked with libcairo. The same
is true for configure options --enable-cairo and --enable-cairoext,
respectively.

Preliminary Cairo support for MSVC now detects a Cairo installation
using the CMake variable FLTK_CAIRO_DIR which must be set by the user.
Note that this feature is temporary and may be changed in the future
for a better and more comfortable version.

1 files changed, 3 insertions, 3 deletions

diff --git a/configure.ac b/configure.ac
index 292829ceb..41b054ab5 100644
--- a/configure.ac
+++ b/configure.ac
@@ -86,7 +86,7 @@ AC_SUBST(OPTIM)
 
 dnl Other options
 AC_ARG_ENABLE([cairo], AS_HELP_STRING([--enable-cairo], [add support for Fl_Cairo_Window]))
-AC_ARG_ENABLE([cairoext], AS_HELP_STRING([--enable-cairoext], [use FLTK code instrumentation for cairo extended use]))
+AC_ARG_ENABLE([cairoext], AS_HELP_STRING([--enable-cairoext], [use FLTK code instrumentation for Cairo extended use]))
 
 AC_ARG_ENABLE([cp936], AS_HELP_STRING([--enable-cp936], [turn on CP936]))
 AS_IF([test x$enable_cp936 = xyes], [
@@ -235,7 +235,7 @@ AS_IF([test x$enable_cairoext = xyes], [
         LIBS="$CAIROLIBS $LIBS"
         LINKFLTK="$LINKFLTK $LINKFLTKCAIRO"
     ], [
-        AC_MSG_ERROR([Cairo requested but not available.])
+        AC_MSG_ERROR([Cairo requested but not found.])
     ])
 ], [test x$enable_cairo = xyes], [
     AS_IF([$PKGCONFIG --exists cairo], [
@@ -247,7 +247,7 @@ AS_IF([test x$enable_cairoext = xyes], [
         LINKFLTKCAIRO="../lib/libfltk_cairo.a"
         FLTKCAIROOPTION="-L ../cairo -lfltk_cairo$SHAREDSUFFIX"
     ], [
-        AC_MSG_ERROR([Cairo requested but not available.])
+        AC_MSG_ERROR([Cairo requested but not found.])
     ])
 ])