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, 24 insertions, 11 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 19d7b09c3..f00237a35 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -102,7 +102,17 @@ endif (debug_build)
 unset (debug_build)
 
 #######################################################################
-# build the FLTK libraries
+# Build a dummy ("empty") Cairo library for backwards compatibility.
+# This should be removed some time after 1.4.0 was released, maybe
+# in FLTK 1.4.1, 1.4.2, 1.5.0, or whatever the next minor release is.
+#######################################################################
+
+if (FLTK_HAVE_CAIRO)
+  add_subdirectory (cairo)
+endif ()
+
+#######################################################################
+# build the standard FLTK libraries
 #######################################################################
 
 add_subdirectory(src)
@@ -129,11 +139,13 @@ endif (FLTK_BUILD_FLTK_OPTIONS)
 # install.cmake creates these files for an installed FLTK
 # these two would only differ in paths, so common variables are set here
 #######################################################################
+
 include (CMake/variables.cmake)
 
 #######################################################################
 # final config and export
 #######################################################################
+
 include (CMake/export.cmake)
 
 configure_file (
@@ -157,6 +169,7 @@ endif (FLTK_BUILD_EXAMPLES)
 #######################################################################
 # installation
 #######################################################################
+
 include (CMake/install.cmake)
 
 #######################################################################
@@ -221,15 +234,15 @@ else ()
 endif ()
 
 if (FLTK_BUILD_FLUID)
-   message (STATUS "FLUID will be built in ${CMAKE_CURRENT_BINARY_DIR}/bin/fluid")
+  message (STATUS "FLUID            will be built in ${CMAKE_CURRENT_BINARY_DIR}/bin/fluid")
 else ()
-   message (STATUS "FLUID will not be built (set FLTK_BUILD_FLUID=ON to build)")
+  message (STATUS "FLUID            will not be built (set FLTK_BUILD_FLUID=ON to build)")
 endif ()
 
 if (FLTK_BUILD_FLTK_OPTIONS)
-   message (STATUS "fltk-options will be built in ${CMAKE_CURRENT_BINARY_DIR}/bin/fltk-options")
+  message (STATUS "fltk-options     will be built in ${CMAKE_CURRENT_BINARY_DIR}/bin/fltk-options")
 else ()
-   message (STATUS "fltk-options will not be built (set FLTK_BUILD_FLTK_OPTIONS=ON to build)")
+  message (STATUS "fltk-options     will not be built (set FLTK_BUILD_FLTK_OPTIONS=ON to build)")
 endif ()
 
 if (FLTK_BUILD_TEST)
@@ -243,21 +256,21 @@ else ()
 endif ()
 
 if (FLTK_USE_BUILTIN_JPEG)
-  message (STATUS "Image Libraries: JPEG = Builtin")
+  message (STATUS "Image Libraries:         JPEG = Builtin")
 else ()
-  message (STATUS "Image Libraries: JPEG = System")
+  message (STATUS "Image Libraries:         JPEG = System")
 endif ()
 
 if (FLTK_USE_BUILTIN_PNG)
-  message (STATUS "                 PNG  = Builtin")
+  message (STATUS "                         PNG  = Builtin")
 else ()
-  message (STATUS "                 PNG  = System")
+  message (STATUS "                         PNG  = System")
 endif ()
 
 if (FLTK_USE_BUILTIN_ZLIB)
-  message (STATUS "                 ZLIB = Builtin")
+  message (STATUS "                         ZLIB = Builtin")
 else ()
-  message (STATUS "                 ZLIB = System")
+  message (STATUS "                         ZLIB = System")
 endif ()
 
 if (UNIX AND NOT (APPLE AND NOT OPTION_APPLE_X11))