Replaced EventListener with signals based on libsigc++

This replaces the rather hard to understand event dispatcher with a
probably even harder to understand templated library, but fortunately
we can rely on the available documentation.

Hopefully it will also help with the readability of our code and with
adding additional signals to other classes.

Added libsigc++ to README and Travis CI configuration.

Reviewed-by: Erik Schilling

2 files changed, 133 insertions, 0 deletions

diff --git a/CMake/Modules/FindSigC++.cmake b/CMake/Modules/FindSigC++.cmake
new file mode 100644
index 0000000..35687d5
--- /dev/null
+++ b/CMake/Modules/FindSigC++.cmake
@@ -0,0 +1,34 @@
+# - Try to find SigC++-2.0
+# Once done, this will define
+#
+#  SigC++_FOUND - system has SigC++
+#  SigC++_INCLUDE_DIRS - the SigC++ include directories
+#  SigC++_LIBRARIES - link these to use SigC++
+
+include(LibFindMacros)
+
+# Use pkg-config to get hints about paths
+libfind_pkg_check_modules(SigC++_PKGCONF sigc++-2.0)
+
+# Main include dir
+find_path(SigC++_INCLUDE_DIR
+  NAMES sigc++/sigc++.h
+  PATHS ${SigC++_PKGCONF_INCLUDE_DIRS}
+  PATH_SUFFIXES sigc++-2.0
+)
+
+# Glib-related libraries also use a separate config header, which is in lib dir
+find_path(SigC++Config_INCLUDE_DIR
+  NAMES sigc++config.h
+  PATHS ${SigC++_PKGCONF_INCLUDE_DIRS} /usr
+  PATH_SUFFIXES lib/sigc++-2.0/include
+)
+
+libfind_library(SigC++ sigc 2.0)
+
+# Set the include dir variables and the libraries and let libfind_process do
+# the rest.  NOTE: Singular variables for this library, plural for libraries
+# this this lib depends on.
+set(SigC++_PROCESS_INCLUDES SigC++_INCLUDE_DIR SigC++Config_INCLUDE_DIR)
+set(SigC++_PROCESS_LIBS SigC++_LIBRARY)
+libfind_process(SigC++)
diff --git a/CMake/Modules/LibFindMacros.cmake b/CMake/Modules/LibFindMacros.cmake
new file mode 100644
index 0000000..69975c5
--- /dev/null
+++ b/CMake/Modules/LibFindMacros.cmake
@@ -0,0 +1,99 @@
+# Works the same as find_package, but forwards the "REQUIRED" and "QUIET" arguments
+# used for the current package. For this to work, the first parameter must be the
+# prefix of the current package, then the prefix of the new package etc, which are
+# passed to find_package.
+macro (libfind_package PREFIX)
+  set (LIBFIND_PACKAGE_ARGS ${ARGN})
+  if (${PREFIX}_FIND_QUIETLY)
+    set (LIBFIND_PACKAGE_ARGS ${LIBFIND_PACKAGE_ARGS} QUIET)
+  endif (${PREFIX}_FIND_QUIETLY)
+  if (${PREFIX}_FIND_REQUIRED)
+    set (LIBFIND_PACKAGE_ARGS ${LIBFIND_PACKAGE_ARGS} REQUIRED)
+  endif (${PREFIX}_FIND_REQUIRED)
+  find_package(${LIBFIND_PACKAGE_ARGS})
+endmacro (libfind_package)
+
+# CMake developers made the UsePkgConfig system deprecated in the same release (2.6)
+# where they added pkg_check_modules. Consequently I need to support both in my scripts
+# to avoid those deprecated warnings. Here's a helper that does just that.
+# Works identically to pkg_check_modules, except that no checks are needed prior to use.
+macro (libfind_pkg_check_modules PREFIX PKGNAME)
+  if (${CMAKE_MAJOR_VERSION} EQUAL 2 AND ${CMAKE_MINOR_VERSION} EQUAL 4)
+    include(UsePkgConfig)
+    pkgconfig(${PKGNAME} ${PREFIX}_INCLUDE_DIRS ${PREFIX}_LIBRARY_DIRS ${PREFIX}_LDFLAGS ${PREFIX}_CFLAGS)
+  else (${CMAKE_MAJOR_VERSION} EQUAL 2 AND ${CMAKE_MINOR_VERSION} EQUAL 4)
+    find_package(PkgConfig)
+    if (PKG_CONFIG_FOUND)
+      pkg_check_modules(${PREFIX} ${PKGNAME})
+    endif (PKG_CONFIG_FOUND)
+  endif (${CMAKE_MAJOR_VERSION} EQUAL 2 AND ${CMAKE_MINOR_VERSION} EQUAL 4)
+endmacro (libfind_pkg_check_modules)
+
+# Do the final processing once the paths have been detected.
+# If include dirs are needed, ${PREFIX}_PROCESS_INCLUDES should be set to contain
+# all the variables, each of which contain one include directory.
+# Ditto for ${PREFIX}_PROCESS_LIBS and library files.
+# Will set ${PREFIX}_FOUND, ${PREFIX}_INCLUDE_DIRS and ${PREFIX}_LIBRARIES.
+# Also handles errors in case library detection was required, etc.
+macro (libfind_process PREFIX)
+  # Skip processing if already processed during this run
+  if (NOT ${PREFIX}_FOUND)
+    # Start with the assumption that the library was found
+    set (${PREFIX}_FOUND TRUE)
+
+    # Process all includes and set _FOUND to false if any are missing
+    foreach (i ${${PREFIX}_PROCESS_INCLUDES})
+      if (${i})
+        set (${PREFIX}_INCLUDE_DIRS ${${PREFIX}_INCLUDE_DIRS} ${${i}})
+        mark_as_advanced(${i})
+      else (${i})
+        set (${PREFIX}_FOUND FALSE)
+      endif (${i})
+    endforeach (i)
+
+    # Process all libraries and set _FOUND to false if any are missing
+    foreach (i ${${PREFIX}_PROCESS_LIBS})
+      if (${i})
+        set (${PREFIX}_LIBRARIES ${${PREFIX}_LIBRARIES} ${${i}})
+        mark_as_advanced(${i})
+      else (${i})
+        set (${PREFIX}_FOUND FALSE)
+      endif (${i})
+    endforeach (i)
+
+    # Print message and/or exit on fatal error
+    if (${PREFIX}_FOUND)
+      if (NOT ${PREFIX}_FIND_QUIETLY)
+        message (STATUS "Found ${PREFIX} ${${PREFIX}_VERSION}")
+      endif (NOT ${PREFIX}_FIND_QUIETLY)
+    else (${PREFIX}_FOUND)
+      if (${PREFIX}_FIND_REQUIRED)
+        foreach (i ${${PREFIX}_PROCESS_INCLUDES} ${${PREFIX}_PROCESS_LIBS})
+          message("${i}=${${i}}")
+        endforeach (i)
+        message (FATAL_ERROR "Required library ${PREFIX} NOT FOUND.\nInstall the library (dev version) and try again. If the library is already installed, use ccmake to set the missing variables manually.")
+      endif (${PREFIX}_FIND_REQUIRED)
+    endif (${PREFIX}_FOUND)
+  endif (NOT ${PREFIX}_FOUND)
+endmacro (libfind_process)
+
+macro(libfind_library PREFIX basename)
+  set(TMP "")
+  if(MSVC80)
+    set(TMP -vc80)
+  endif(MSVC80)
+  if(MSVC90)
+    set(TMP -vc90)
+  endif(MSVC90)
+  set(${PREFIX}_LIBNAMES ${basename}${TMP})
+  if(${ARGC} GREATER 2)
+    set(${PREFIX}_LIBNAMES ${basename}${TMP}-${ARGV2})
+    string(REGEX REPLACE "\\." "_" TMP ${${PREFIX}_LIBNAMES})
+    set(${PREFIX}_LIBNAMES ${${PREFIX}_LIBNAMES} ${TMP})
+  endif(${ARGC} GREATER 2)
+  find_library(${PREFIX}_LIBRARY
+    NAMES ${${PREFIX}_LIBNAMES}
+    PATHS ${${PREFIX}_PKGCONF_LIBRARY_DIRS}
+  )
+endmacro(libfind_library)
+