Improve buffer viewer display:

Buffer views no longer go off screen except when there are way too many buffers (since the min buffer frame size is now 5 pixels).
Fix a case where too many buffers being displayed results in a divide by zero.

direct/src/showbase/BufferViewer.py

@@ -343,8 +343,9 @@ class BufferViewer(DirectObject):
         # an 800x600 display.  Then, it double checks that the
         # readout will fit on the screen, and if not, it shrinks it.
 
-        if (float(self.sizex)==0.0) and (float(self.sizey)==0.0):
+        bordersize = 4.0
 
+        if (float(self.sizex)==0.0) and (float(self.sizey)==0.0):
             sizey = int(0.4266666667 * base.win.getYSize())
             sizex = (sizey * aspectx) / aspecty
             v_sizey = (base.win.getYSize() - (rows-1) - (rows*2)) / rows
@@ -352,23 +353,27 @@ class BufferViewer(DirectObject):
             if (v_sizey < sizey) or (v_sizex < sizex):
                 sizey = v_sizey
                 sizex = v_sizex
-            h_sizex = (base.win.getXSize() - (cols-1) - (cols*2)) / cols
+                
+            adjustment = 2
+            h_sizex = float (base.win.getXSize() - adjustment) / float (cols)
+            
+            h_sizex -= bordersize
+            if (h_sizex < 1.0):
+                h_sizex = 1.0
+
             h_sizey = (h_sizex * aspecty) / aspectx
             if (h_sizey < sizey) or (h_sizex < sizex):
                 sizey = h_sizey
                 sizex = h_sizex
-
         else:
-
             sizex = int(self.sizex * 0.5 * base.win.getXSize())
             sizey = int(self.sizey * 0.5 * base.win.getYSize())
             if (sizex == 0): sizex = (sizey*aspectx) / aspecty
             if (sizey == 0): sizey = (sizex*aspecty) / aspectx
 
         # Convert from pixels to render2d-units.
-
-        fsizex = (2.0*sizex) / float(base.win.getXSize())
-        fsizey = (2.0*sizey) / float(base.win.getYSize())
+        fsizex = (2.0 * sizex) / float(base.win.getXSize())        
+        fsizey = (2.0 * sizey) / float(base.win.getYSize())
         fpixelx = 2.0 / float(base.win.getXSize())
         fpixely = 2.0 / float(base.win.getYSize())
 
@@ -399,8 +404,9 @@ class BufferViewer(DirectObject):
                 index = c + r*cols
                 if (index < ncards):
                     index = (index + self.cardindex) % len(cards)
-                    posx = dirx * (1.0 - fsizex*0.5 - 3*fpixelx - (c*(fsizex+6*fpixelx)))
-                    posy = diry * (1.0 - fsizey*0.5 - 3*fpixely - (r*(fsizey+6*fpixely)))
+                    
+                    posx = dirx * (1.0 - ((c + 0.5) * (fsizex + fpixelx * bordersize))) - (fpixelx * dirx)
+                    posy = diry * (1.0 - ((r + 0.5) * (fsizey + fpixely * bordersize))) - (fpixely * diry)                    
                     placer = NodePath("card-structure")
                     placer.setPos(posx, 0, posy)
                     placer.setScale(fsizex*0.5, 1.0, fsizey*0.5)