+LT_INIT
+gl_INIT
+
+m4_include([lib/gnulib.mk])
+
+AC_ARG_WITH([libpng],
+ [AS_HELP_STRING([--with-libpng],
+ [build support for PNG output using libpng. [default=auto]])],
+ [with_libpng=$withval], [with_libpng=auto])
+
+AS_CASE([$with_libpng],
+ [no], [have_libpng=false],
+ [yes], [DX_LIB_LIBPNG([1.5], [have_libpng=true])],
+ [DX_LIB_LIBPNG([1.5], [have_libpng=true], [have_libpng=false])])