From 2f2d30b36133d5169802ad9491a772f8b6850697 Mon Sep 17 00:00:00 2001
From: wdlkmpx <wdlkmpx@gmail.com>
Date: Thu, 21 Jan 2021 14:39:58 +0800
Subject: [PATCH] configure.ac: default to GTK3, fall back to GTK2

the gtk3 port will be compiled if gtk3 is available

use --enable-gtk2 or --disable-gtk3 to compile the gtk2 port
---
 configure.ac | 59 ++++++++++++++++++++++++++++++++++++++--------------
 1 file changed, 43 insertions(+), 16 deletions(-)

diff --git a/configure.ac b/configure.ac
index 6924f64..47670a1 100644
--- a/configure.ac
+++ b/configure.ac
@@ -18,25 +18,48 @@ IT_PROG_INTLTOOL
 
 # Checks for programs.
 AC_PROG_CC
-AC_HEADER_STDC
 AC_CHECK_HEADERS([sys/param.h signal.h])
 
-AC_ARG_ENABLE(gtk3,
-AS_HELP_STRING([--enable-gtk3],[enable to use gtk-3.0 instead of gtk-2.0]),
-[case "${enableval}" in
-  yes)  enable_gtk3=yes ;;
-  no)   enable_gtk3=no ;;
-esac],[])
+#========================================================================
 
-if test "x$enable_gtk3" = "xyes" ; then
-  gtk_modules="gtk+-3.0 >= 3.0.0"
-else
-  gtk_modules="gtk+-2.0 >= 2.14.0"
-  CPPFLAGS="$CPPFLAGS -DGDK_DISABLE_DEPRECATED -DGDK_PIXBUF_DISABLE_SINGLE_INCLUDES -DGTK_DISABLE_DEPRECATED -DGTK_DISABLE_SINGLE_INCLUDES"
-fi
-PKG_CHECK_MODULES(GTK, [$gtk_modules])
-AC_SUBST(GTK_CFLAGS)
-AC_SUBST(GTK_LIBS)
+GTK3_CHECK="gtk+-3.0 >= 3.0.0"
+GTK2_CHECK="gtk+-2.0 >= 2.14.0"
+
+AC_ARG_ENABLE(gtk3,
+   AS_HELP_STRING([--disable-gtk3],[build with GTK3 (Autodetect)]),[],
+   [enable_gtk3=check])
+
+AC_ARG_ENABLE(gtk2,
+   AS_HELP_STRING([--enable-gtk2],[build with GTK2 (Autodetect)]),[],
+   [enable_gtk2=check])
+
+AS_IF([test "x$enable_gtk3" = xyes],
+   [enable_gtk2=no])
+AS_IF([test "x$enable_gtk2" = xyes],
+   [enable_gtk3=no])
+
+AS_IF([test "x$enable_gtk3" = xcheck],
+   [PKG_CHECK_MODULES([GTK],[$GTK3_CHECK],
+      [enable_gtk3=yes],[enable_gtk3=no])])
+
+AS_IF([test "x$enable_gtk3" = xyes],
+   [
+   gtk_modules="$GTK3_CHECK"
+   gtk_version="gtk+-3.0"
+   errmsg="GTK3 is not installed, use --enable-gtk2 to build with GTK2"
+   ],
+   [
+   gtk_modules="$GTK2_CHECK"
+   gtk_version="gtk+-2.0"
+   errmsg="GTK2 is not installed, use --enable-gtk3 to build with GTK3"
+   CPPFLAGS="$CPPFLAGS -DGDK_DISABLE_DEPRECATED -DGDK_PIXBUF_DISABLE_SINGLE_INCLUDES -DGTK_DISABLE_DEPRECATED -DGTK_DISABLE_SINGLE_INCLUDES"
+   ])
+
+PKG_CHECK_MODULES([GTK], [$gtk_modules], [], [AC_ERROR([$errmsg])])
+AC_SUBST([GTK_CFLAGS])
+AC_SUBST([GTK_LIBS])
+
+#========================================================================
 
 GETTEXT_PACKAGE=gtkballs
 AC_SUBST(GETTEXT_PACKAGE)
@@ -61,3 +84,7 @@ AC_CONFIG_FILES([
 	gtkballs-data/Makefile
 ])
 AC_OUTPUT
+
+echo
+echo "GTK Version: $(pkg-config --modversion $gtk_version)"
+echo