Allow enabling and disabling GLX support

Since X11 can be used on multiple platforms, or disabled in special
environments, we should provide a way to control whether or not Epoxy is
built with GLX support.

Fixes anholt/libepoxy#52
Fixes anholt/libepoxy#63
Closes anholt/libepoxy#80
Closes anholt/libepoxy#81

configure.ac

@@ -58,13 +58,42 @@ AC_CHECK_HEADER([KHR/khrplatform.h],
 # uintptr_t to a void *") by default.  Kill that.
 XORG_TESTSET_CFLAG(CWARNFLAGS, [-Wno-int-conversion])
 
-has_znow=yes
+AC_ARG_ENABLE([glx],
+              [AC_HELP_STRING([--enable-glx=@<:@auto,yes,no@:>@], [Enable GLX support @<:@default=auto@:>@])],
+              [enable_glx=$enableval],
+              [enable_glx=auto])
+
+# GLX can be used on different platforms, so we expose a
+# configure time switch to enable or disable it; in case
+# the "auto" default value is set, we only enable GLX
+# support on Linux and Unix
+AS_CASE([$enable_glx],
+  [auto], [
+    AS_CASE([$host_os],
+            [mingw*], [build_glx=no],
+            [darwin*], [build_glx=no],
+            [android*], [build_glx=no],
+            [build_glx=yes])
+  ],
 
-case $host_os in
-    mingw*)
-        build_egl=no
+  [yes], [
+    build_glx=yes
+  ],
+
+  [no], [
     build_glx=no
+  ],
+
+  [AC_MSG_ERROR([Invalid value "$enable_glx" for option "--enable-glx"])]
+])
+
+# The remaining platform specific API for GL/GLES are enabled
+# depending on the platform we're building for
+AS_CASE([$host_os],
+  [mingw*], [
+    build_egl=no
     build_wgl=yes
+    has_znow=yes
     # On windows, the DLL has to have all of its functions
     # resolved at link time, so we have to link directly aginst
     # opengl32.dll.  But that's the only GL provider, anyway.
@@ -75,24 +104,25 @@ case $host_os in
     # there's lots of missing autodetection for the testsuite
     # (like checking for EGL and GLX libs in non-windows.).
     AC_SUBST([LOG_COMPILER], [wine])
-        ;;
-    darwin*)
+  ],
+
+  [darwin*], [
     build_egl=no
-        build_glx=no
     build_wgl=no
     build_apple=yes
     has_znow=no
     EPOXY_LINK_LIBS=""
-        ;;
-    *)
+  ],
+
+  [
     build_egl=yes
-        build_glx=yes
     build_wgl=no
+    has_znow=yes
     # On platforms with dlopen, we load everything dynamically and
     # don't link against a specific window system or GL implementation.
     EPOXY_LINK_LIBS=""
-        ;;
-esac
+   ]
+)
 
 AC_SUBST(EPOXY_LINK_LIBS)
 
@@ -161,15 +191,29 @@ AS_CASE(["$host"],
 
 AC_SUBST([VISIBILITY_CFLAGS])
 
-PKG_CHECK_MODULES(X11, [x11], [x11=yes], [x11=no])
-if test x$x11 = xno -a x$build_glx = xyes; then
+if test x$build_glx = xyes; then
+  PKG_CHECK_MODULES(X11, [x11], [x11=yes], [x11=no])
+  if test x$x11 = xno -a x$build_glx = xyes; then
       AC_MSG_ERROR([libX11 headers (libx11-dev) required to build with GLX support])
+  fi
+  AC_DEFINE(ENABLE_GLX, [1], [Whether GLX support is enabled])
+else
+  x11=no
 fi
 
 AM_CONDITIONAL(HAVE_X11, test x$x11 = xyes)
 
 PKG_CHECK_MODULES(GL, [gl], [gl=yes], [gl=no])
 
+# Variables for the pkg-config file; AC_SUBST does not do `test` substitutions,
+# so we need to specify the boolean values here
+AS_IF([test x$build_glx = xyes], [epoxy_has_glx=1], [epoxy_has_glx=0])
+AS_IF([test x$build_egl = xyes], [epoxy_has_egl=1], [epoxy_has_egl=0])
+AS_IF([test x$build_wgl = xyes], [epoxy_has_wgl=1], [epoxy_has_wgl=0])
+AC_SUBST(epoxy_has_glx)
+AC_SUBST(epoxy_has_egl)
+AC_SUBST(epoxy_has_wgl)
+
 AC_CONFIG_FILES([
                 epoxy.pc
                 Makefile

epoxy.pc.in

@@ -3,6 +3,10 @@ exec_prefix=@exec_prefix@
 libdir=@libdir@
 includedir=@includedir@
 
+epoxy_has_glx=@epoxy_has_glx@
+epoxy_has_egl=@epoxy_has_egl@
+epoxy_has_wgl=@epoxy_has_wgl@
+
 Name: epoxy
 Description: epoxy GL dispatch Library
 Version: @PACKAGE_VERSION@

meson.build

@@ -30,26 +30,48 @@ conf.set_quoted('PACKAGE_LOCALEDIR', join_paths(get_option('prefix'), get_option
 conf.set_quoted('PACKAGE_LIBEXECDIR', join_paths(get_option('prefix'), get_option('libexecdir')))
 conf.set('HAVE_KHRPLATFORM_H', cc.has_header('KHR/khrplatform.h', required: false))
 
-if host_system == 'windows'
+# GLX can be used on different platforms, so we expose a
+# configure time switch to enable or disable it; in case
+# the "auto" default value is set, we only enable GLX
+# support on Linux and Unix
+enable_glx = get_option('enable-glx')
+if enable_glx == 'auto'
+  if host_system == 'windows'
+    build_glx = false
+  elif host_system == 'darwin'
+    build_glx = false
+  elif host_system == 'android'
     build_glx = false
+  else
+    build_glx = true
+  endif
+elif enable_glx == 'yes'
+  build_glx = true
+elif enable_glx == 'no'
+  build_glx = false
+endif
+
+# The remaining platform specific API for GL/GLES are enabled
+# depending on the platform we're building for
+if host_system == 'windows'
   build_egl = false
   build_apple = false
   build_wgl = true
   has_znow = true
 elif host_system == 'darwin'
-  build_glx = false
   build_egl = false
   build_apple = true
   build_wgl = false
   has_znow = false
 else
-  build_glx = true
   build_egl = true
   build_apple = false
   build_wgl = false
   has_znow = true
 endif
 
+conf.set10('ENABLE_GLX', build_glx)
+
 # Compiler flags, taken from the Xorg macros
 test_cflags = [
   '-Wpointer-arith',
@@ -138,6 +160,9 @@ pkgconf.set('prefix', epoxy_prefix)
 pkgconf.set('exec_prefix', epoxy_prefix)
 pkgconf.set('libdir', epoxy_libdir)
 pkgconf.set('includedir', epoxy_includedir)
+pkgconf.set10('epoxy_has_glx', build_glx)
+pkgconf.set10('epoxy_has_egl', build_egl)
+pkgconf.set10('epoxy_has_wgl', build_wgl)
 pkgconf.set('PACKAGE_VERSION', meson.project_version())
 if dl_dep.found()
   pkgconf.set('DLOPEN_LIBS', '-ldl')

meson_options.txt

@@ -1,3 +1,8 @@
 option('enable-docs',
        type: 'boolean', value: false,
        description: 'Enable generating the Epoxy API reference (depends on Doxygen)')
+option('enable-glx',
+       type: 'combo',
+       choices: [ 'auto', 'yes', 'no' ],
+       value: 'auto',
+       description: 'Enable GLX support')

src/dispatch_common.h

@@ -25,11 +25,11 @@
 
 #ifdef _WIN32
 #define PLATFORM_HAS_EGL 0
-#define PLATFORM_HAS_GLX 0
+#define PLATFORM_HAS_GLX ENABLE_GLX
 #define PLATFORM_HAS_WGL 1
 #elif defined(__APPLE__)
 #define PLATFORM_HAS_EGL 0
-#define PLATFORM_HAS_GLX 0
+#define PLATFORM_HAS_GLX ENABLE_GLX
 #define PLATFORM_HAS_WGL 0
 #elif defined(ANDROID)
 #define PLATFORM_HAS_EGL 1
@@ -37,7 +37,7 @@
 #define PLATFORM_HAS_WGL 0
 #else
 #define PLATFORM_HAS_EGL 1
-#define PLATFORM_HAS_GLX 1
+#define PLATFORM_HAS_GLX ENABLE_GLX
 #define PLATFORM_HAS_WGL 0
 #endif
 

test/Makefile.am

@@ -72,8 +72,11 @@ check_PROGRAMS = $(TESTS)
 
 if BUILD_EGL
 EGL_TESTS = \
+	$()
+
+if HAVE_X11
+EGL_TESTS += \
 	egl_has_extension_nocontext \
-	egl_gl \
 	egl_gles2_without_glx \
 	$()
 
@@ -83,6 +86,7 @@ endif
 
 EGL_UTIL_LIB = libegl_common.la
 endif
+endif
 
 if BUILD_GLX
 if HAS_ZNOW
@@ -93,6 +97,7 @@ if BUILD_EGL
 if BUILD_GLX
 if !BUILD_APPLE
 EGL_AND_GLX_TESTS = \
+	egl_gl \
 	egl_and_glx_different_pointers_egl_glx \
 	egl_and_glx_different_pointers_egl \
 	egl_and_glx_different_pointers_glx \

test/meson.build

@@ -1,6 +1,6 @@
 has_gles1 = gles1_dep.found()
 has_gles2 = gles2_dep.found()
-build_x11_tests = x11_dep.found()
+build_x11_tests = build_glx and x11_dep.found()
 
 test_cflags = common_cflags + [
   '-D_XOPEN_SOURCE',