Path: utzoo!attcan!uunet!cs.utexas.edu!tut.cis.ohio-state.edu!bloom-beacon!NMSU.EDU!pannaiya
From: pannaiya@NMSU.EDU
Newsgroups: comp.windows.x
Subject: Re: Scrolling in Viewport widget.
Message-ID: <8907280016.AA19316@NMSU.Edu>
Date: 28 Jul 89 00:16:38 GMT
Sender: daemon@bloom-beacon.MIT.EDU
Organization: The Internet
Lines: 51

Here are the context diffs that defines a function implementing the
software scrolling capability in the R3 Athena Viewport widget.

The name I used was XtViewportMoveChild(W, xoff, yoff).  I guess it really
ought to be XawView...   Anyway the functionality is as follows:

xoff and yoff are floating point numbers in the range 0.0 and 1.0.  The
child's new position has to be expressed as the position from the top/left.
If the ?off is > 1.0 the child will be moved to the extreme right/bottom.
if the ?off is < 0.0 the position on the axis remains unchanged.

This has worked for me(so far).  If the Xaw gods see any flaw in it please
post.

PK

-----------------------------8<----------------->8---------------------
*** vtemp.c	Thu Jul 27 17:54:51 1989
--- Viewport.c	Thu Jul 27 17:57:59 1989
***************
*** 383,388 ****
--- 383,411 ----
      RedrawThumbs(w);
  }
  
+ void XtViewportMoveChild(w,xoff,yoff)
+     ViewportWidget w;
+     float  xoff,yoff;
+ {
+     register Widget child = w->viewport.child;
+     Position x,y;
+ 
+     if(xoff > 1.0)             /* If the offset is > 1.0 scroll to   */
+        x = child->core.width;  /* extreme right                      */
+     else if (xoff < 0.0)       /* if the offset is < 0.0 no movement */ 
+        x = child->core.x;      /* in the x direction                 */
+     else
+        x = child->core.width * xoff;
+     if(yoff > 1.0) 
+        y = child->core.height;
+     else if (yoff < 0.0)
+        y = child->core.y;
+     else
+        y = child->core.height * yoff;
+ 
+     MoveChild(w,-x,-y);
+   }
+ 
  static void Resize(widget)
      Widget widget;
  {