[cogl] Make the default driver selectable at configure time

[Robert Bragg <rbragg src gnome org>]

commit 8a43aa7167b56784f7b50c557391b990861d594f
Author: Sjoerd Simons <sjoerd simons collabora co uk>
Date:   Wed Jun 20 09:47:41 2012 +0200

    Make the default driver selectable at configure time
    
    When building COGL with multiple backends it can be useful to force a
    default driver to be selected. For example while for Debian we do want to
    build the GL renderer on ARM, GLESv2 is much more suitable as the
    default renderer on that platform.
    
    Reviewed-by: Robert Bragg <robert linux intel com>

 cogl/Makefile.am     |    6 ++++++
 cogl/cogl-renderer.c |    5 +++++
 configure.ac         |   15 ++++++++++++++-
 3 files changed, 25 insertions(+), 1 deletions(-)
---
diff --git a/cogl/Makefile.am b/cogl/Makefile.am
index 853c296..f8e6e18 100644
--- a/cogl/Makefile.am
+++ b/cogl/Makefile.am
@@ -32,6 +32,12 @@ AM_CPPFLAGS = \
 	-DCOGL_LOCALEDIR=\""$(localedir)"\" \
 	$(NULL)
 
+if HAVE_COGL_DEFAULT_DRIVER
+AM_CPPFLAGS += \
+	-DCOGL_DEFAULT_DRIVER=\"$(COGL_DEFAULT_DRIVER)\"
+endif
+
+
 AM_CFLAGS = $(COGL_DEP_CFLAGS) $(COGL_EXTRA_CFLAGS) $(MAINTAINER_CFLAGS)
 
 BUILT_SOURCES += cogl-defines.h cogl-egl-defines.h cogl-gl-header.h
diff --git a/cogl/cogl-renderer.c b/cogl/cogl-renderer.c
index 82e45b6..d47e972 100644
--- a/cogl/cogl-renderer.c
+++ b/cogl/cogl-renderer.c
@@ -260,6 +260,11 @@ _cogl_renderer_choose_driver (CoglRenderer *renderer,
         }
     }
 
+#ifdef COGL_DEFAULT_DRIVER
+  if (!driver_name)
+    driver_name = COGL_DEFAULT_DRIVER;
+#endif
+
 #ifdef HAVE_COGL_GL
   if (renderer->driver_override == COGL_DRIVER_GL ||
       (renderer->driver_override == COGL_DRIVER_ANY &&
diff --git a/configure.ac b/configure.ac
index d3dc826..ca61b03 100644
--- a/configure.ac
+++ b/configure.ac
@@ -603,7 +603,7 @@ AM_CONDITIONAL([COGL_DRIVER_GL_SUPPORTED], [test "x$enable_gl" = "xyes"])
 AM_CONDITIONAL([COGL_DRIVER_GLES_SUPPORTED],
                [test "x$enable_gles1" = "xyes" || test "x$enable_gles2" = "xyes"])
 
-dnl Allow the GL library names to be overridden with configure options
+dnl Allow the GL library names and default driver to be overridden with configure options
 AC_ARG_WITH([gl-libname],
             [AS_HELP_STRING([--with-gl-libname],
                             override the name of the GL library to dlopen)],
@@ -616,6 +616,15 @@ AC_ARG_WITH([gles2-libname],
             [AS_HELP_STRING([--with-gles2-libname],
                             override the name of the GLESv2 library to dlopen)],
             [COGL_GLES2_LIBNAME="$withval"])
+AC_ARG_WITH([default-driver],
+            [AS_HELP_STRING([--with-default-driver],
+                            specify a default cogl driver)],
+            [COGL_DEFAULT_DRIVER="${withval}"],
+            [COGL_DEFAULT_DRIVER="" ])
+
+AM_CONDITIONAL(HAVE_COGL_DEFAULT_DRIVER,
+  [ test "x$COGL_DEFAULT_DRIVER" != "x" ])
+
 
 AC_SUBST([COGL_GL_LIBNAME])
 AC_SUBST([HAVE_GL])
@@ -623,6 +632,7 @@ AC_SUBST([COGL_GLES1_LIBNAME])
 AC_SUBST([HAVE_GLES1])
 AC_SUBST([COGL_GLES2_LIBNAME])
 AC_SUBST([HAVE_GLES2])
+AC_SUBST([COGL_DEFAULT_DRIVER])
 
 if test "x$GL_LIBRARY_DIRECTLY_LINKED" = "xyes"; then
    AC_DEFINE([HAVE_DIRECTLY_LINKED_GL_LIBRARY], [1],
@@ -1221,6 +1231,9 @@ echo "Cogl - $COGL_VERSION (${COGL_RELEASE_STATUS})"
 echo ""
 echo " â Global:"
 echo "        Prefix: ${prefix}"
+if test "x$COGL_DEFAULT_DRIVER" != "x"; then
+echo "        Default driver: ${COGL_DEFAULT_DRIVER}"
+fi
 
 echo ""
 # Features