Don't use XRANDR 1.3 extensions if the server doesn't support them.scratch/raeburn/xrandr

* src/xterm.h (struct x_display_info): Add fields to save XRANDR
version number.
* src/xfns.c (x_get_monitor_attributes): Save the version numbers
after querying the X server.
(x_get_monitor_attributes_xrandr): Don't use XRRGetOutputPrimary or
XRRGetScreenResourcesCurrent if the server doesn't support at least
RANDR version 1.3.  Conditionalize the code blocks on compiling
against library version 1.3 or better, rather than feature tests for
each function.
* configure.ac: Stop testing for those two functions.

3 files changed, 26 insertions, 15 deletions

diff --git a/configure.ac b/configure.ac
index d42b42e0cae..afb0a7f8797 100644
--- a/configure.ac
+++ b/configure.ac
@@ -3594,14 +3594,6 @@ if test "${HAVE_X11}" = "yes"; then
     fi
   fi
   if test $HAVE_XRANDR = yes; then
-    SAVE_CFLAGS="$CFLAGS"
-    SAVE_LIBS="$LIBS"
-    CFLAGS="$XRANDR_CFLAGS $CFLAGS"
-    LIBS="$XRANDR_LIBS $LIBS"
-    AC_CHECK_FUNCS(XRRGetOutputPrimary XRRGetScreenResourcesCurrent)
-    CFLAGS="$SAVE_CFLAGS"
-    LIBS="$SAVE_LIBS"
-
     AC_DEFINE(HAVE_XRANDR, 1, [Define to 1 if you have the XRandr extension.])
   fi
 fi
diff --git a/src/xfns.c b/src/xfns.c
index 20ac6271715..07bd3e9993e 100644
--- a/src/xfns.c
+++ b/src/xfns.c
@@ -4262,8 +4262,19 @@ x_get_monitor_attributes_xrandr (struct x_display_info *dpyinfo)
   RROutput pxid = None;
   struct MonitorInfo *monitors;
 
-#ifdef HAVE_XRRGETSCREENRESOURCESCURRENT
-  resources = XRRGetScreenResourcesCurrent (dpy, dpyinfo->root_window);
+#define RANDR13_LIBRARY \
+  (RANDR_MAJOR > 1 || (RANDR_MAJOR == 1 && RANDR_MINOR >= 3))
+
+#if RANDR13_LIBRARY
+  /* Check if the display supports 1.3 too.  */
+  bool randr13_avail = (dpyinfo->xrandr_major_version > 1
+			|| (dpyinfo->xrandr_major_version == 1
+			    && dpyinfo->xrandr_minor_version >= 3));
+
+  if (randr13_avail)
+    resources = XRRGetScreenResourcesCurrent (dpy, dpyinfo->root_window);
+  else
+    resources = XRRGetScreenResources (dpy, dpyinfo->root_window);
 #else
   resources = XRRGetScreenResources (dpy, dpyinfo->root_window);
 #endif
@@ -4276,8 +4287,9 @@ x_get_monitor_attributes_xrandr (struct x_display_info *dpyinfo)
   n_monitors = resources->noutput;
   monitors = xzalloc (n_monitors * sizeof *monitors);
 
-#ifdef HAVE_XRRGETOUTPUTPRIMARY
-  pxid = XRRGetOutputPrimary (dpy, dpyinfo->root_window);
+#ifdef RANDR13_LIBRARY
+  if (randr13_avail)
+    pxid = XRRGetOutputPrimary (dpy, dpyinfo->root_window);
 #endif
 
   for (i = 0; i < n_monitors; ++i)
@@ -4360,9 +4372,11 @@ x_get_monitor_attributes (struct x_display_info *dpyinfo)
   xrr_ok = XRRQueryExtension (dpy, &xrr_event_base, &xrr_error_base);
   if (xrr_ok)
     {
-      int xrr_major, xrr_minor;
-      XRRQueryVersion (dpy, &xrr_major, &xrr_minor);
-      xrr_ok = (xrr_major == 1 && xrr_minor >= 2) || xrr_major > 1;
+      XRRQueryVersion (dpy, &dpyinfo->xrandr_major_version,
+		       &dpyinfo->xrandr_minor_version);
+      xrr_ok = ((dpyinfo->xrandr_major_version == 1
+		 && dpyinfo->xrandr_minor_version >= 2)
+		|| dpyinfo->xrandr_major_version > 1);
     }
 
   if (xrr_ok)
diff --git a/src/xterm.h b/src/xterm.h
index 3a78292907a..3211b591258 100644
--- a/src/xterm.h
+++ b/src/xterm.h
@@ -459,6 +459,11 @@ struct x_display_info
   /* SM */
   Atom Xatom_SM_CLIENT_ID;
 
+#ifdef HAVE_XRANDR
+  int xrandr_major_version;
+  int xrandr_minor_version;
+#endif
+
 #ifdef USE_CAIRO
   XExtCodes *ext_codes;
 #endif