CMake: Support SDL audio back-end

Rename UNIX_SOUND_SRC_SDL to UNIX_SOUND_SDL_SRC to match the
signature of other variables (ending with _HDR or _SRC).

build/bakefiles/files.bkl

@@ -3287,7 +3287,7 @@ IMPORTANT: please read docs/tech/tn0016.txt before modifying this file!
 <!--                             Misc plugin sources:                       -->
 <!-- ====================================================================== -->
 
-<set var="UNIX_SOUND_SRC_SDL" hints="files">
+<set var="UNIX_SOUND_SDL_SRC" hints="files">
     src/unix/sound_sdl.cpp
 </set>
 
@@ -3708,7 +3708,7 @@ IMPORTANT: please read docs/tech/tn0016.txt before modifying this file!
     <!-- wxAdv sources -->
     <set var="PLUGIN_SRC">
         <if cond="FORMAT=='autoconf' and PLATFORM_UNIX=='1' and USE_PLUGINS=='0'">
-            $(UNIX_SOUND_SRC_SDL)
+            $(UNIX_SOUND_SDL_SRC)
         </if>
     </set>
 

build/bakefiles/plugins.bkl

@@ -7,7 +7,7 @@
     <!-- ================================================================ -->
     
     <wx-base-plugin id="sound_sdl" cond="WITH_PLUGIN_SDL=='1'">
-        <sources>$(UNIX_SOUND_SRC_SDL)</sources>
+        <sources>$(UNIX_SOUND_SDL_SRC)</sources>
         <ldlibs>$(EXTRALIBS_SDL)</ldlibs>
     </wx-base-plugin>
 

build/cmake/files.cmake

@@ -3057,7 +3057,7 @@ set(OPENGL_OSX_SHARED_SRC
     src/osx/glcanvas_osx.cpp
 )
 
-set(UNIX_SOUND_SRC_SDL
+set(UNIX_SOUND_SDL_SRC
     src/unix/sound_sdl.cpp
 )
 

build/cmake/init.cmake

@@ -268,4 +268,15 @@ if(wxUSE_GUI)
             wx_option_force_value(wxUSE_MEDIACTRL OFF)
         endif()
     endif()
+
+    if(UNIX AND wxUSE_LIBSDL)
+        find_package(SDL2)
+        if(NOT SDL2_FOUND)
+            find_package(SDL)
+        endif()
+        if(NOT SDL2_FOUND AND NOT SDL_FOUND)
+            message(WARNING "SDL not found, SDL Audio back-end won't be available")
+            wx_option_force_value(wxUSE_LIBSDL OFF)
+        endif()
+    endif()
 endif()

build/cmake/lib/core/CMakeLists.txt

@@ -15,6 +15,9 @@ if(WIN32)
     wx_append_sources(CORE_SRC BASE_AND_GUI_WIN32)
 elseif(UNIX)
     wx_append_sources(CORE_SRC UNIX)
+    if(wxUSE_LIBSDL)
+        wx_append_sources(CORE_SRC UNIX_SOUND_SDL)
+    endif()
 endif()
 
 if(WXMSW)
@@ -84,5 +87,14 @@ if(WXGTK AND wxUSE_PRIVATE_FONTS)
         ${FONTCONFIG_LIBRARIES}
     )
 endif()
+if(UNIX AND wxUSE_LIBSDL)
+    if(SDL2_FOUND)
+        wx_lib_include_directories(core PUBLIC ${SDL2_INCLUDE_DIR})
+        wx_lib_link_libraries(core PUBLIC ${SDL2_LIBRARY})
+    elseif(SDL_FOUND)
+        wx_lib_include_directories(core PUBLIC ${SDL_INCLUDE_DIR})
+        wx_lib_link_libraries(core PUBLIC ${SDL_LIBRARY})
+    endif()
+endif()
 
 wx_finalize_lib(core)

build/cmake/modules/FindSDL2.cmake

@@ -0,0 +1,175 @@
+
+# This module defines
+# SDL2_LIBRARY, the name of the library to link against
+# SDL2_FOUND, if false, do not try to link to SDL2
+# SDL2_INCLUDE_DIR, where to find SDL.h
+#
+# This module responds to the the flag:
+# SDL2_BUILDING_LIBRARY
+# If this is defined, then no SDL2main will be linked in because
+# only applications need main().
+# Otherwise, it is assumed you are building an application and this
+# module will attempt to locate and set the the proper link flags
+# as part of the returned SDL2_LIBRARY variable.
+#
+# Don't forget to include SDLmain.h and SDLmain.m your project for the
+# OS X framework based version. (Other versions link to -lSDL2main which
+# this module will try to find on your behalf.) Also for OS X, this
+# module will automatically add the -framework Cocoa on your behalf.
+#
+#
+# Additional Note: If you see an empty SDL2_LIBRARY_TEMP in your configuration
+# and no SDL2_LIBRARY, it means CMake did not find your SDL2 library
+# (SDL2.dll, libsdl2.so, SDL2.framework, etc).
+# Set SDL2_LIBRARY_TEMP to point to your SDL2 library, and configure again.
+# Similarly, if you see an empty SDL2MAIN_LIBRARY, you should set this value
+# as appropriate. These values are used to generate the final SDL2_LIBRARY
+# variable, but when these values are unset, SDL2_LIBRARY does not get created.
+#
+#
+# $SDL2DIR is an environment variable that would
+# correspond to the ./configure --prefix=$SDL2DIR
+# used in building SDL2.
+# l.e.galup  9-20-02
+#
+# Modified by Eric Wing.
+# Added code to assist with automated building by using environmental variables
+# and providing a more controlled/consistent search behavior.
+# Added new modifications to recognize OS X frameworks and
+# additional Unix paths (FreeBSD, etc).
+# Also corrected the header search path to follow "proper" SDL guidelines.
+# Added a search for SDL2main which is needed by some platforms.
+# Added a search for threads which is needed by some platforms.
+# Added needed compile switches for MinGW.
+#
+# On OSX, this will prefer the Framework version (if found) over others.
+# People will have to manually change the cache values of
+# SDL2_LIBRARY to override this selection or set the CMake environment
+# CMAKE_INCLUDE_PATH to modify the search paths.
+#
+# Note that the header path has changed from SDL2/SDL.h to just SDL.h
+# This needed to change because "proper" SDL convention
+# is #include "SDL.h", not <SDL2/SDL.h>. This is done for portability
+# reasons because not all systems place things in SDL2/ (see FreeBSD).
+
+#=============================================================================
+# Copyright 2003-2009 Kitware, Inc.
+#
+# Distributed under the OSI-approved BSD License (the "License");
+# see accompanying file Copyright.txt for details.
+#
+# This software is distributed WITHOUT ANY WARRANTY; without even the
+# implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+# See the License for more information.
+#=============================================================================
+# (To distribute this file outside of CMake, substitute the full
+#  License text for the above reference.)
+
+# message("<FindSDL2.cmake>")
+
+SET(SDL2_SEARCH_PATHS
+	~/Library/Frameworks
+	/Library/Frameworks
+	/usr/local
+	/usr
+	/sw # Fink
+	/opt/local # DarwinPorts
+	/opt/csw # Blastwave
+	/opt
+	${SDL2_PATH}
+)
+
+FIND_PATH(SDL2_INCLUDE_DIR SDL.h
+	HINTS
+	$ENV{SDL2DIR}
+	PATH_SUFFIXES include/SDL2 include
+	PATHS ${SDL2_SEARCH_PATHS}
+)
+
+if(CMAKE_SIZEOF_VOID_P EQUAL 8)
+	set(PATH_SUFFIXES lib64 lib/x64 lib)
+else()
+	set(PATH_SUFFIXES lib/x86 lib)
+endif()
+
+FIND_LIBRARY(SDL2_LIBRARY_TEMP
+	NAMES SDL2
+	HINTS
+	$ENV{SDL2DIR}
+	PATH_SUFFIXES ${PATH_SUFFIXES}
+	PATHS ${SDL2_SEARCH_PATHS}
+)
+
+IF(NOT SDL2_BUILDING_LIBRARY)
+	IF(NOT ${SDL2_INCLUDE_DIR} MATCHES ".framework")
+		# Non-OS X framework versions expect you to also dynamically link to
+		# SDL2main. This is mainly for Windows and OS X. Other (Unix) platforms
+		# seem to provide SDL2main for compatibility even though they don't
+		# necessarily need it.
+		FIND_LIBRARY(SDL2MAIN_LIBRARY
+			NAMES SDL2main
+			HINTS
+			$ENV{SDL2DIR}
+			PATH_SUFFIXES ${PATH_SUFFIXES}
+			PATHS ${SDL2_SEARCH_PATHS}
+		)
+	ENDIF(NOT ${SDL2_INCLUDE_DIR} MATCHES ".framework")
+ENDIF(NOT SDL2_BUILDING_LIBRARY)
+
+# SDL2 may require threads on your system.
+# The Apple build may not need an explicit flag because one of the
+# frameworks may already provide it.
+# But for non-OSX systems, I will use the CMake Threads package.
+IF(NOT APPLE)
+	FIND_PACKAGE(Threads)
+ENDIF(NOT APPLE)
+
+# MinGW needs an additional link flag, -mwindows
+# It's total link flags should look like -lmingw32 -lSDL2main -lSDL2 -mwindows
+IF(MINGW)
+	SET(MINGW32_LIBRARY mingw32 "-mwindows" CACHE STRING "mwindows for MinGW")
+ENDIF(MINGW)
+
+IF(SDL2_LIBRARY_TEMP)
+	# For SDL2main
+	IF(NOT SDL2_BUILDING_LIBRARY)
+		IF(SDL2MAIN_LIBRARY)
+			SET(SDL2_LIBRARY_TEMP ${SDL2MAIN_LIBRARY} ${SDL2_LIBRARY_TEMP})
+		ENDIF(SDL2MAIN_LIBRARY)
+	ENDIF(NOT SDL2_BUILDING_LIBRARY)
+
+	# For OS X, SDL2 uses Cocoa as a backend so it must link to Cocoa.
+	# CMake doesn't display the -framework Cocoa string in the UI even
+	# though it actually is there if I modify a pre-used variable.
+	# I think it has something to do with the CACHE STRING.
+	# So I use a temporary variable until the end so I can set the
+	# "real" variable in one-shot.
+	IF(APPLE)
+		SET(SDL2_LIBRARY_TEMP ${SDL2_LIBRARY_TEMP} "-framework Cocoa")
+	ENDIF(APPLE)
+
+	# For threads, as mentioned Apple doesn't need this.
+	# In fact, there seems to be a problem if I used the Threads package
+	# and try using this line, so I'm just skipping it entirely for OS X.
+	IF(NOT APPLE)
+		SET(SDL2_LIBRARY_TEMP ${SDL2_LIBRARY_TEMP} ${CMAKE_THREAD_LIBS_INIT})
+	ENDIF(NOT APPLE)
+
+	# For MinGW library
+	IF(MINGW)
+		SET(SDL2_LIBRARY_TEMP ${MINGW32_LIBRARY} ${SDL2_LIBRARY_TEMP})
+	ENDIF(MINGW)
+
+	# Set the final string here so the GUI reflects the final state.
+	SET(SDL2_LIBRARY ${SDL2_LIBRARY_TEMP} CACHE STRING "Where the SDL2 Library can be found")
+	# Set the temp variable to INTERNAL so it is not seen in the CMake GUI
+	SET(SDL2_LIBRARY_TEMP "${SDL2_LIBRARY_TEMP}" CACHE INTERNAL "")
+ENDIF(SDL2_LIBRARY_TEMP)
+
+# message("</FindSDL2.cmake>")
+
+INCLUDE(FindPackageHandleStandardArgs)
+
+FIND_PACKAGE_HANDLE_STANDARD_ARGS(SDL2 REQUIRED_VARS SDL2_LIBRARY SDL2_INCLUDE_DIR)
+
+MARK_AS_ADVANCED(SDL2MAIN_LIBRARY SDL2_LIBRARY SDL2_INCLUDE_DIR)

build/cmake/options.cmake

@@ -74,6 +74,7 @@ wx_option(wxUSE_LIBLZMA "use LZMA compression" OFF)
 set(wxTHIRD_PARTY_LIBRARIES ${wxTHIRD_PARTY_LIBRARIES} wxUSE_LIBLZMA "use liblzma for LZMA compression")
 
 wx_option(wxUSE_OPENGL "use OpenGL (or Mesa)")
+wx_option(wxUSE_LIBSDL "use SDL for audio on Unix")
 
 if(NOT WIN32)
     wx_option(wxUSE_LIBICONV "use libiconv (character conversion)")

build/files

@@ -2997,7 +2997,7 @@ OPENGL_OSX_SHARED_SRC =
 
 # Misc plugin sources:
 
-UNIX_SOUND_SRC_SDL =
+UNIX_SOUND_SDL_SRC =
     src/unix/sound_sdl.cpp
 
 # wxAUI