Add build option FLTK_USE_DBUS to allow build w/o dbus (PR #1252)

Thanks to @lanodan for most of the source code.

5 files changed, 17 insertions, 7 deletions

diff --git a/CMake/options.cmake b/CMake/options.cmake
index 1ef64aad4..ea265515b 100644
--- a/CMake/options.cmake
+++ b/CMake/options.cmake
@@ -320,6 +320,7 @@ if(UNIX)
     endif()
     unset(FLTK_GRAPHICS_CAIRO CACHE)
     set(FLTK_GRAPHICS_CAIRO TRUE CACHE BOOL "all drawing to X11 windows uses Cairo")
+    option(FLTK_USE_DBUS "use D-Bus - required to detect the cursor theme" ON)
     option(FLTK_USE_SYSTEM_LIBDECOR "use libdecor from the system" ON)
     set(USE_SYSTEM_LIBDECOR 1)
     unset(FLTK_USE_XRENDER CACHE)
diff --git a/CMake/variables.cmake b/CMake/variables.cmake
index b2993f032..6fcaed395 100644
--- a/CMake/variables.cmake
+++ b/CMake/variables.cmake
@@ -44,9 +44,12 @@ if(WIN32)
 elseif(APPLE AND NOT FLTK_BACKEND_X11)
   list(APPEND FLTK_LDLIBS ${FLTK_COCOA_FRAMEWORKS})
 elseif(FLTK_USE_WAYLAND)
-  foreach(_lib WLDCURSOR WLDCLIENT XKBCOMMON DBUS)
+  foreach(_lib WLDCURSOR WLDCLIENT XKBCOMMON)
     list(APPEND FLTK_LDLIBS "${${_lib}_LDFLAGS}")
   endforeach()
+  if(FLTK_USE_DBUS AND DBUS_FOUND)
+    list(APPEND FLTK_LDLIBS "${DBUS_LDFLAGS}")
+  endif()
   if(USE_SYSTEM_LIBDECOR)
     list(APPEND FLTK_LDLIBS ${SYSTEM_LIBDECOR_LDFLAGS})
   endif(USE_SYSTEM_LIBDECOR)
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 4a45b5cc1..b846da477 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -411,6 +411,7 @@ if(FLTK_USE_WAYLAND)
   else()
     fl_summary("" "Libdecor = Bundled")
   endif()
+  fl_summary_yn("Use DBUS" DBUS_FOUND)
 endif(FLTK_USE_WAYLAND)
 
 message("")
diff --git a/README.CMake.txt b/README.CMake.txt
index 6f1e5147c..c774a59cb 100644
--- a/README.CMake.txt
+++ b/README.CMake.txt
@@ -288,6 +288,9 @@ FLTK_OPTION_SVG - default ON
     FLTK has a built-in SVG library and can create (write) SVG image files.
     Turning this option off disables SVG (read and write) support.
 
+FLTK_USE_DBUS - default ON (Wayland only).
+    Meaningful only under Wayland. Allows FLTK to detect the current cursor theme.
+
 FLTK_USE_LIBDECOR_GTK - default ON (Wayland only).
     Meaningful only under Wayland and if FLTK_USE_SYSTEM_LIBDECOR is 'OFF'.
     Allows to use libdecor's GTK plugin to draw window titlebars. Otherwise
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index ed1cfc276..b43794804 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -532,14 +532,16 @@ if(FLTK_USE_X11)
 endif(FLTK_USE_X11)
 
 if(FLTK_USE_WAYLAND)
-  pkg_check_modules(DBUS IMPORTED_TARGET dbus-1)
   set(IDIRS "${CMAKE_CURRENT_BINARY_DIR}")
   set(CDEFS "_GNU_SOURCE;HAVE_MEMFD_CREATE;HAVE_MKOSTEMP;HAVE_POSIX_FALLOCATE")
   set(COPTS "-fPIC")
-  if(DBUS_FOUND)
-    set(CDEFS "${CDEFS};HAS_DBUS")
-    set(IDIRS "${IDIRS};${DBUS_INCLUDE_DIRS}")
-  endif(DBUS_FOUND)
+  if(FLTK_USE_DBUS)
+    pkg_check_modules(DBUS IMPORTED_TARGET dbus-1)
+    if(DBUS_FOUND)
+      set(CDEFS "${CDEFS};HAS_DBUS")
+      set(IDIRS "${IDIRS};${DBUS_INCLUDE_DIRS}")
+    endif(DBUS_FOUND)
+  endif(FLTK_USE_DBUS)
   if(USE_SYSTEM_LIBDECOR)
     set(CDEFS "${CDEFS};USE_SYSTEM_LIBDECOR;LIBDECOR_PLUGIN_DIR=${LIBDECOR_PLUGIN_DIR}")
     if(GTK_FOUND)
@@ -809,7 +811,7 @@ if(UNIX AND FLTK_USE_WAYLAND)
 
   append_optional_libs("PkgConfig::WLDCURSOR;PkgConfig::WLDCLIENT;PkgConfig::XKBCOMMON")
 
-  if(DBUS_FOUND)
+  if(FLTK_USE_DBUS AND DBUS_FOUND)
     append_optional_libs(PkgConfig::DBUS)
   endif()