issue 2: twm doesn't handle RandR screen size changes

	patch submitted by Preston Crow
	modified to check if xrandr development header/library is available

Signed-off-by: Thomas E. Dickey <dickey@invisible-island.net>

6 files changed, 71 insertions, 3 deletions

diff --git a/configure.ac b/configure.ac
index 7b6643b..2cb0a6e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -49,7 +49,11 @@ AC_PROG_LEX
 AC_CHECK_FUNCS([mkstemp])
 
 # Checks for pkg-config packages
-PKG_CHECK_MODULES(TWM, x11 xext xt xmu ice sm xproto >= 7.0.17)
+PKG_CHECK_MODULES([TWM], [x11 xext xt xmu ice sm xproto >= 7.0.17])
+PKG_CHECK_MODULES([XRANDR], [xrandr], [have_xrandr=yes], [have_xrandr=no])
+if test "$have_xrandr" = yes; then
+	AC_DEFINE([HAVE_XRANDR], [1], [Define to 1 if you have the xrandr headers/libraries])
+fi
 
 AC_CONFIG_FILES([Makefile
 		src/Makefile
diff --git a/src/Makefile.am b/src/Makefile.am
index 1f46e09..4bafe55 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -32,8 +32,8 @@ AM_CPPFLAGS =							\
 	-DXORG_RELEASE=\"Release\ $(VERSION)\"			\
 	-DSYSTEM_INIT_FILE=\"${rcdir}/system.twmrc\"
 
-AM_CFLAGS = $(TWM_CFLAGS)
-twm_LDADD = $(TWM_LIBS)
+AM_CFLAGS = $(TWM_CFLAGS) $(XRANDR_CFLAGS)
+twm_LDADD = $(TWM_LIBS)   $(XRANDR_LIBS)
 
 twm_SOURCES =		\
         add_window.c	\
diff --git a/src/events.c b/src/events.c
index f92014f..ce66446 100644
--- a/src/events.c
+++ b/src/events.c
@@ -73,6 +73,9 @@ in this Software without prior written authorization from The Open Group.
 #include "icons.h"
 #include "version.h"
 
+#ifdef HAVE_XRANDR
+#include <X11/extensions/Xrandr.h>
+#endif
 
 #define MAX_X_EVENT 256
 event_proc EventHandler[MAX_X_EVENT]; /* event handler jump table */
@@ -170,6 +173,18 @@ InitEvents(void)
     EventHandler[VisibilityNotify] = HandleVisibilityNotify;
     if (HasShape)
 	EventHandler[ShapeEventBase+ShapeNotify] = HandleShapeNotify;
+#ifdef HAVE_XRANDR
+    if (HasXrandr)
+    {
+	int scrnum;
+
+	EventHandler[XrandrEventBase+RRScreenChangeNotify] = HandleScreenChangeNotify;
+	for (scrnum = 0; scrnum < NumScreens; scrnum++)
+	{
+	    XRRSelectInput(dpy,ScreenList[scrnum]->Root,RRScreenChangeNotifyMask);
+	}
+    }
+#endif
 }
 
 
@@ -2399,6 +2414,31 @@ HandleShapeNotify (void)
 
 
 
+#ifdef HAVE_XRANDR
+/**
+ * xrandr screen configuration change-notification handler
+ */
+void
+HandleScreenChangeNotify (void)
+{
+    XRRScreenChangeNotifyEvent *xev = (XRRScreenChangeNotifyEvent *) &Event;
+    int scrnum;
+
+    for (scrnum = 0; scrnum < NumScreens; scrnum++)
+    {
+	if ( ScreenList[scrnum]->Root == xev->root )
+	{
+	    ScreenList[scrnum]->MyDisplayWidth = xev->width;
+	    ScreenList[scrnum]->MyDisplayHeight = xev->height;
+	}
+    }
+
+    XRRUpdateConfiguration(&Event);
+}
+#endif
+
+
+
 /**
  * unknown event handler
  */
diff --git a/src/events.h b/src/events.h
index e6bcfc9..f554642 100644
--- a/src/events.h
+++ b/src/events.h
@@ -97,6 +97,7 @@ extern void HandleEnterNotify ( void );
 extern void HandleLeaveNotify ( void );
 extern void HandleConfigureRequest ( void );
 extern void HandleShapeNotify ( void );
+extern void HandleScreenChangeNotify ( void );
 extern void HandleUnknown ( void );
 extern int Transient ( Window w, Window *propw );
 extern ScreenInfo * FindScreenInfo ( Window w );
diff --git a/src/twm.c b/src/twm.c
index a10c6ce..d05d992 100644
--- a/src/twm.c
+++ b/src/twm.c
@@ -82,10 +82,15 @@ in this Software without prior written authorization from The Open Group.
 #include <X11/Xmu/Error.h>
 #include <X11/extensions/sync.h>
 #include <X11/Xlocale.h>
+
 #ifdef XPRINT
 #include <X11/extensions/Print.h>
 #endif /* XPRINT */
 
+#ifdef HAVE_XRANDR
+#include <X11/extensions/Xrandr.h>
+#endif
+
 static void InitVariables ( void );
 
 XtAppContext appContext;	/* Xt application context */
@@ -98,6 +103,12 @@ int MultiScreen = TRUE;		/* try for more than one screen? */
 int NoPrintscreens = False;     /* ignore special handling of print screens? */
 int NumScreens;			/* number of screens in ScreenList */
 int HasShape;			/* server supports shape extension? */
+
+#ifdef HAVE_XRANDR
+int HasXrandr;			/* server supports Xrandr extension? */
+int XrandrEventBase, XrandrErrorBase;
+#endif
+
 int ShapeEventBase, ShapeErrorBase;
 int HasSync;			/* server supports SYNC extension? */
 int SyncEventBase, SyncErrorBase;
@@ -349,6 +360,9 @@ main(int argc, char *argv[])
 
     HasShape = XShapeQueryExtension (dpy, &ShapeEventBase, &ShapeErrorBase);
     HasSync = XSyncQueryExtension(dpy,  &SyncEventBase, &SyncErrorBase);
+#ifdef HAVE_XRANDR
+    HasXrandr = XRRQueryExtension(dpy, &XrandrEventBase, &XrandrErrorBase);
+#endif
     TwmContext = XUniqueContext();
     MenuContext = XUniqueContext();
     IconManagerContext = XUniqueContext();
diff --git a/src/twm.h b/src/twm.h
index 6e1e17c..dbb9980 100644
--- a/src/twm.h
+++ b/src/twm.h
@@ -355,6 +355,10 @@ extern Window ResizeWindow;	/* the window we are resizing */
 extern int HasShape;		/* this server supports Shape extension */
 extern int HasSync;		/* this server supports SYNC extension */
 
+#ifdef HAVE_XRANDR
+extern int HasXrandr;		/* this server supports Xrandr extension */
+#endif
+
 extern int PreviousScreen;
 
 extern Cursor UpperLeftCursor;
@@ -410,6 +414,11 @@ extern Bool use_fontset;
 extern int ShapeEventBase;
 extern int ShapeErrorBase;
 
+#ifdef HAVE_XRANDR
+extern int XrandrEventBase;
+extern int XrandrErrorBase;
+#endif
+
 #define _XA_MIT_PRIORITY_COLORS		TwmAtoms[0]
 #define _XA_WM_CHANGE_STATE		TwmAtoms[1]
 #define _XA_WM_STATE			TwmAtoms[2]