compute num of steps more intelligently

demos/anim.script

@@ -5,10 +5,10 @@ all = GetValue("Animate one view at a time or all views together?
 0: one at a time, 1: all together", 1) ;
 
 oldw = General.GraphicsWidth;
-General.GraphicsWidth = GetValue("Width of animation?", 640); 
+neww = GetValue("Width of animation? (enter 0 to keep current width)", 640); 
 
 oldh = General.GraphicsHeight;
-General.GraphicsHeight = GetValue("Height of animation?", 640) ;
+newh = GetValue("Height of animation? (enter 0 to keep current height)", 640) ;
 
 method = GetValue("Animation method?
 
@@ -17,14 +17,27 @@ MPEG_ENCODE = 0;
 MENCODER = 1;
 WHIRLGIF = 2;
 
+If(neww)
+  General.GraphicsWidth = neww;
+EndIf
+If(newh)
+  General.GraphicsHeight = newh;
+EndIf
+
 Print.JpegQuality = 100;
 
 If(all)
+  maxstep = 1;
   For i In {1:PostProcessing.NbViews}
     View[i-1].TimeStep = 0;
+    // compute max num of steps
+    If(View[i-1].Visible)
+      If(View[i-1].NbTimeStep > maxstep)
+        maxstep = View[i-1].NbTimeStep;
+      EndIf
+    EndIf
   EndFor
-  // Use the first view as the reference
-  For index In {1:View[0].NbTimeStep}
+  For index In {1:maxstep}
     Draw;
     If(method == WHIRLGIF)
       Print Sprintf("/tmp/tmp%03g.gif", index);