Xinerama: do not cut off at outer edges

This fixes the problem Mike Gabriel describes like this:

- Launch a session on a system with a single monitor. Enable Xinerama
  for this session.
- Open a desktop session in that session window (e.g. MATE or XFCE).
- Move the NX/MATE-or-XFCE session window around on that one
  monitor. Bump at the borders, so that the session window moves into
  the invisible parts around your monitor.

What you see is that the MATE-or-XFCE window manager will become
really busy with resizing the windows and panels in the NX session,
because moving the window over the physical borders of the display
will trigger resize events.

This is non-intuitive, I think.

Same with multi-monitors on the outside edges of the physical Xorg
RandR setup.

2 files changed, 77 insertions, 3 deletions

diff --git a/nx-X11/programs/Xserver/hw/nxagent/Imakefile b/nx-X11/programs/Xserver/hw/nxagent/Imakefile
index 8cae91331..160d01e60 100644
--- a/nx-X11/programs/Xserver/hw/nxagent/Imakefile
+++ b/nx-X11/programs/Xserver/hw/nxagent/Imakefile
@@ -180,7 +180,7 @@ INCLUDES = -I. -I$(XBUILDINCDIR) \
 # NXAGENT_FONTEXCLUDE              Exclude some specific font names (only "-ult1mo" at this moment).
 # NXAGENT FULLSCREEN               Fullscreen mode
 # NXAGENT_RANDR_MODE_PREFIX        Use prefixed (i.e., nx_<x>x<y>) RandR modes
-#
+# NXAGENT_RANDR_XINERAMA_CLIPPING  cut off invisible window parts in xinerama mode (you probably do not want this)
 
 #if nxVersion
 NX_DEFINES=-DNX_VERSION_CURRENT="$(NX_VERSION_CURRENT)" \
diff --git a/nx-X11/programs/Xserver/hw/nxagent/Screen.c b/nx-X11/programs/Xserver/hw/nxagent/Screen.c
index 17e749a6b..a677b7eb4 100644
--- a/nx-X11/programs/Xserver/hw/nxagent/Screen.c
+++ b/nx-X11/programs/Xserver/hw/nxagent/Screen.c
@@ -106,8 +106,8 @@ is" without express or implied warranty.
 
 #define PANIC
 #define WARNING
-#undef  TEST
-#undef  DEBUG
+#define  TEST
+#define  DEBUG
 #undef  WATCH
 #undef  DUMP
 
@@ -3640,6 +3640,36 @@ Bool intersect(int ax1, int ay1, unsigned int aw, unsigned int ah,
     return TRUE;
 }
 
+#ifndef NXAGENT_RANDR_XINERAMA_CLIPPING
+/* intersect two rectangles, return aw/ah for w/h if resulting
+   rectangle is (partly) outside of bounding box */
+Bool intersect_bb(int ax1, int ay1, unsigned int aw, unsigned int ah,
+	       int bx1, int by1, unsigned int bw, unsigned int bh,
+	       int bbx1, int bby1, int bbx2, int bby2,
+	       int *x, int *y, unsigned int *w, unsigned int *h)
+{
+  Bool result = intersect(ax1, ay1, aw, ah, bx1, by1, bw, bh, x, y, w, h);
+  if (result == TRUE) {
+    /* check if outside of bounding box */
+    if (ax1 < bbx1 || ax1 + aw > bbx2) {
+        #ifdef DEBUG
+        fprintf(stderr, "intersect: box has parts outside bounding box - width stays unchanged [%d]\n", aw);
+        #endif
+	*w = aw;
+    }
+
+    if (ay1 < bby1 || ay1 + ah > bby2) {
+        #ifdef DEBUG
+        fprintf(stderr, "intersect: box has parts outside bounding box - height stays unchanged [%d]\n", ah);
+        #endif
+	*h = ah;
+    }
+  }
+
+  return result;
+}
+#endif
+
 int nxagentChangeScreenConfig(int screen, int width, int height, int mmWidth, int mmHeight)
 {
   ScreenPtr    pScreen;
@@ -3783,6 +3813,23 @@ int nxagentAdjustRandRXinerama(ScreenPtr pScreen)
     RRGetInfo(pScreen);
 #endif
 
+#ifndef NXAGENT_RANDR_XINERAMA_CLIPPING
+    /* calculate bounding box (outer edges) */
+    int bbx2, bbx1, bby1, bby2;
+    bbx2 = bby2 = 0;
+    bbx1 = bby1 = INT_MAX;
+
+    for (i = 0; i < number; i++) {
+      bbx2 = MAX(bbx2, screeninfo[i].x_org + screeninfo[i].width);
+      bby2 = MAX(bby2, screeninfo[i].y_org + screeninfo[i].height);
+      bbx1 = MIN(bbx1, screeninfo[i].x_org);
+      bby1 = MIN(bby1, screeninfo[i].y_org);
+    }
+    #ifdef DEBUG
+    fprintf(stderr, "nxagentAdjustRandRXinerama: bounding box: left [%d] right [%d] top [%d] bottom[%d]\n", bbx1, bbx2, bby1, bby2);
+    #endif
+#endif
+
     #ifdef DEBUG
     fprintf(stderr, "nxagentAdjustRandRXinerama: numCrtcs [%d], numOutputs [%d]\n", pScrPriv->numCrtcs, pScrPriv->numOutputs);
     #endif
@@ -3873,12 +3920,37 @@ int nxagentAdjustRandRXinerama(ScreenPtr pScreen)
       int new_x, new_y;
       unsigned int new_w, new_h;
 
+      /*
+      if ((nxagentOption(X) < bbx1 || (nxagentOption(X) + width >= bbx2 )) {
+        #ifdef DEBUG
+        fprintf(stderr, "nxagentAdjustRandRXinerama: output %d: window has parts outside visible area - width stays unchanged [%d]\n", width);
+        #endif
+	new_w = width;
+      }
+
+	if ((nxagentOption(Y) < bby1 || (nxagentOption(Y) + height >= bby2 ) {
+          #ifdef DEBUG
+          fprintf(stderr, "nxagentAdjustRandRXinerama: output %d: window has parts outside visible area - height stays unchanged [%d]\n", height);
+          #endif
+	  new_h = height;
+	}
+      */
+
       /* if there's no intersection disconnect the output */
+#ifdef NXAGENT_RANDR_XINERAMA_CLIPPING
       disable_output = !intersect(nxagentOption(X), nxagentOption(Y),
                                   width, height,
                                   screeninfo[i].x_org, screeninfo[i].y_org,
                                   screeninfo[i].width, screeninfo[i].height,
                                   &new_x, &new_y, &new_w, &new_h);
+#else
+      disable_output = !intersect_bb(nxagentOption(X), nxagentOption(Y),
+                                  width, height,
+                                  screeninfo[i].x_org, screeninfo[i].y_org,
+                                  screeninfo[i].width, screeninfo[i].height,
+	                          bbx1, bby1, bbx2, bby2,
+                                  &new_x, &new_y, &new_w, &new_h);
+#endif
 
       /* save previous mode */
       prevmode = pScrPriv->crtcs[i]->mode;
@@ -3924,6 +3996,7 @@ int nxagentAdjustRandRXinerama(ScreenPtr pScreen)
         #ifdef DEBUG
         fprintf(stderr, "nxagentAdjustRandRXinerama: output %d: intersection is x [%d] y [%d] width [%d] height [%d]\n", i, new_x, new_y, new_w, new_h);
         #endif
+
         RROutputSetConnection(pScrPriv->outputs[i], RR_Connected);
 
         memset(&modeInfo, '\0', sizeof(modeInfo));
@@ -3937,6 +4010,7 @@ int nxagentAdjustRandRXinerama(ScreenPtr pScreen)
 #else
         sprintf(name, "%dx%d", new_w, new_h);
 #endif
+
         modeInfo.width  = new_w;
         modeInfo.height = new_h;
         modeInfo.hTotal = new_w;