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>

(cherry picked from commit 8a43aa7167b56784f7b50c557391b990861d594f)

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

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 &&

configure.ac

@@ -612,7 +612,7 @@ 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)],
@@ -625,6 +625,15 @@ 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])
@@ -632,6 +641,7 @@ 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],
@@ -1234,6 +1244,9 @@ echo "Cogl - $COGL_1_VERSION/$COGL_VERSION (${COGL_RELEASE_STATUS})"
 echo ""
 echo " • Global:"
 echo "        Prefix: ${prefix}"
+if test "x$COGL_DEFAULT_DRIVER" != "x"; then
+echo "        Default driver: ${COGL_DEFAULT_DRIVER}"
+fi
 
 echo ""
 # Features