Implement loonycyborg's more capable SDL check.

SConstruct

@@ -83,15 +83,71 @@ def CheckPKG(context, name):
      context.Result( ret )
      return ret
 
+# vi: syntax=python:et:ts=4
+from os.path import join
+from SCons.Script import *
+
+def CheckSDL(context, sdl_lib = "SDL", require_version = None):
+    if require_version:
+        version = require_version.split(".", 2)
+        major_version = int(version[0])
+        minor_version = int(version[1])
+        try:
+            patchlevel    = int(version[2])
+        except (ValueError, IndexError):
+            patch_level = 0
+
+    sdldir = context.env.get("SDLDIR", context.env["prefix"])
+    if sdl_lib == "SDL": 
+        if require_version:
+            context.Message("Checking for Simple DirectMedia Layer library version >= %d.%d.%d... " % (major_version, minor_version, patchlevel))
+        else:
+            context.Message("Checking for Simple DirectMedia Layer library... ")
+        env = context.env
+        env.AppendUnique(CPPPATH = [os.path.join(sdldir, "include/SDL")], LIBPATH = [os.path.join(sdldir, "lib")])
+        if env["PLATFORM"] == "posix" or env["PLATFORM"] == "darwin":
+            env.ParseConfig("sdl-config --cflags --libs")
+        if env["PLATFORM"] == "win32":
+            env.AppendUnique(CCFLAGS = ["-D_GNU_SOURCE"])
+            env.AppendUnique(LIBS = Split("mingw32 SDLmain SDL SDL_image SDL_ttf"))
+            env.AppendUnique(LINKFLAGS = ["-mwindows"])
+    else:
+        if require_version:
+            context.Message("Checking for %s library version >= %d.%d.%d... " % (sdl_lib, major_version, minor_version, patchlevel))
+        else:
+            context.Message("Checking for %s library... " % sdl_lib)
+        context.env.AppendUnique(LIBS = [sdl_lib])
+    test_program = """
+        #include <%s.h> 
+        \n""" % sdl_lib
+    if require_version:
+        test_program += "#if SDL_VERSIONNUM(%s, %s, %s) < SDL_VERSIONNUM(%d, %d, %d)\n#error Library is too old!\n#endif\n" % \
+            (sdl_lib.upper() + "_MAJOR_VERSION", \
+             sdl_lib.upper() + "_MINOR_VERSION", \
+             sdl_lib.upper() + "_PATCHLEVEL", \
+             major_version, minor_version, patchlevel)
+    test_program += """
+        int main(int argc, char** argv)
+        {
+        }
+        \n"""
+    if context.TryLink(test_program, ".c"):
+        context.Result("yes")
+        return True
+    else:
+        context.Result("no")
+        return False
+
 conf = Configure(env, custom_tests = { 'CheckPKGConfig' : CheckPKGConfig,
-                                       'CheckPKG' : CheckPKG })
+                                       'CheckPKG' : CheckPKG,
+                                       'CheckSDL' : CheckSDL,})
 
 if not conf.CheckPKGConfig('0.15.0'):
      print 'pkg-config >= 0.15.0 not found.'
      Exit(1)
 
 # FIXME: It would be good to check for SDL_ttf >= 2.0.8 here
-if not conf.CheckPKG('SDL >= 1.2.7'):
+if not conf.CheckSDL(require_version = '1.2.7'):
      print 'SDL >= 1.2.7 not found.'
      Exit(1)