[Emacs-diffs] emacs-25 8b8a6ad: Don't use XRANDR 1.3 extensions if the server doesn't support them.

[Ken Raeburn]

branch: emacs-25
commit 8b8a6ad3e3239eb2cff325e72e29dc30fdaa58c5
Author: Ken Raeburn <address@hidden>
Commit: Ken Raeburn <address@hidden>

    Don't use XRANDR 1.3 extensions if the server doesn't support them.
    
    * 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.
---
 configure.ac |    8 --------
 src/xfns.c   |   28 +++++++++++++++++++++-------
 src/xterm.h  |    5 +++++
 3 files changed, 26 insertions(+), 15 deletions(-)

diff --git a/configure.ac b/configure.ac
index 370cb54..075f611 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 9ef7cb9..0a4a09e 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 06cd2e7..8e1fc78 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