From 9bdc310346077e3fd60371b3d3d0c7db54db10e3 Mon Sep 17 00:00:00 2001
From: Manolo Gouy <Manolo>
Date: Fri, 30 Sep 2011 14:46:08 +0000
Subject: Fix STR#2600 : screens configuration changes are now detected under
 all platforms. Requires the RandR X extension.

git-svn-id: file:///fltk/svn/fltk/branches/branch-1.3@9102 ea41ed52-d2ee-0310-a9c1-e6b18d33e121
---
 configh.in   |  8 ++++++++
 configure.in | 13 +++++++++++++
 src/Fl.cxx   |  2 +-
 src/Fl_x.cxx | 22 +++++++++++++++++++++-
 4 files changed, 43 insertions(+), 2 deletions(-)

diff --git a/configh.in b/configh.in
index 4a806e475..1521f46ba 100644
--- a/configh.in
+++ b/configh.in
@@ -83,6 +83,14 @@
 
 #define HAVE_XINERAMA 0
 
+/*
+ * HAVE_XRANDR
+ *
+ * Do we have the Xrandr library to support runtime update of multi-head displays?
+ */
+
+#define HAVE_XRANDR 0
+
 /*
  * USE_XFT
  *
diff --git a/configure.in b/configure.in
index 565561fef..e233d2e2a 100644
--- a/configure.in
+++ b/configure.in
@@ -997,6 +997,16 @@ case $uname_GUI in
 		LIBS="-lXext $LIBS")
 	fi
 
+	dnl Check for the XRandR extension unless disabled...
+        AC_ARG_ENABLE(xrandr, [  --enable-xrandr         turn on XRandR support [default=yes]])
+
+	if test x$enable_xrandr != xno; then
+	    AC_CHECK_HEADER(X11/extensions/Xrandr.h, AC_DEFINE(HAVE_XRANDR),,
+	        [#include <X11/Xlib.h>])
+	    AC_CHECK_LIB(Xrandr, XRRQueryExtension,
+		LIBS="-lXrandr $LIBS")
+	fi
+
 	dnl Check for overlay visuals...
 	AC_PATH_PROG(XPROP, xprop)
 	AC_CACHE_CHECK(for X overlay visuals, ac_cv_have_overlay,
@@ -1330,6 +1340,9 @@ case $uname_GUI in
 	if test x$enable_xdbe != xno; then
 	    graphics="$graphics+Xdbe"
 	fi
+	if test x$enable_xrandr != xno; then
+	    graphics="$graphics+Xrandr"
+	fi
 	if test x$enable_xinerama != xno; then
 	    graphics="$graphics+Xinerama"
 	fi
diff --git a/src/Fl.cxx b/src/Fl.cxx
index 6264c4a30..374847047 100644
--- a/src/Fl.cxx
+++ b/src/Fl.cxx
@@ -778,7 +778,7 @@ static handler_link *handlers = 0;
 
   - \ref FL_SHORTCUT events that are not recognized by any widget.
     This lets you provide global shortcut keys.
-  - \ref FL_SCREEN_CONFIGURATION_CHANGED events (not implemented on the X11 platform).
+  - \ref FL_SCREEN_CONFIGURATION_CHANGED events.
   - System events that FLTK does not recognize.  See fl_xevent.
   - \e Some other events when the widget FLTK selected returns
     zero from its handle() method.  Exactly which ones may change
diff --git a/src/Fl_x.cxx b/src/Fl_x.cxx
index bc528aa34..360981ed8 100644
--- a/src/Fl_x.cxx
+++ b/src/Fl_x.cxx
@@ -43,6 +43,10 @@
 #  include <X11/Xlocale.h>
 #  include <X11/Xlib.h>
 #  include <X11/keysym.h>
+#ifdef HAVE_XRANDR
+#include <X11/extensions/Xrandr.h>
+static int randrEventBase = -1;
+#endif
 
 static Fl_Xlib_Graphics_Driver fl_xlib_driver;
 static Fl_Display_Device fl_xlib_display(&fl_xlib_driver);
@@ -587,6 +591,7 @@ void fl_open_display() {
   fl_open_display(d);
 }
 
+
 void fl_open_display(Display* d) {
   fl_display = d;
 
@@ -637,6 +642,12 @@ void fl_open_display(Display* d) {
 #if !USE_COLORMAP
   Fl::visual(FL_RGB);
 #endif
+#ifdef HAVE_XRANDR
+  int error_base;
+  if (XRRQueryExtension(d, &randrEventBase, &error_base))
+    XRRSelectInput(d, RootWindow(d, fl_screen), RRScreenChangeNotifyMask);
+  else randrEventBase = -1;
+#endif
 }
 
 void fl_close_display() {
@@ -920,7 +931,16 @@ int fl_handle(const XEvent& thisevent)
 
   if ( XFilterEvent((XEvent *)&xevent, 0) )
       return(1);
-
+  
+#ifdef HAVE_XRANDR  
+  if( randrEventBase >= 0 && xevent.type == randrEventBase + RRScreenChangeNotify) {
+    XRRUpdateConfiguration (&xevent);
+    Fl::call_screen_init();
+    fl_init_workarea();
+    Fl::handle(FL_SCREEN_CONFIGURATION_CHANGED, NULL);
+  }
+#endif
+  
   switch (xevent.type) {
 
   case KeymapNotify:
-- 
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