Copyright (C) 1992, Digital Equipment Corporation                         
 All rights reserved.                                                      
 See the file COPYRIGHT for a full description.                            
 Last modified on Tue Sep 26 14:54:38 1995 by dagenais                   
      modified on Tue Mar 10 19:00:43 1992 by steveg                   
      modified on Mon Feb 24 13:52:16 PST 1992 by muller                   
An AnchorHelpVBT.T is a VBT which activates a pop up help window upon entry, after some delay. It is used for providing help bubbles.

When the position remains inside an AnchorHelpVBT for more than inDelay seconds, the help window pops up. Thereafter, help windows in any AnchorHelpVBT within the same Trestle top level window pop up directly upon entry. This behavior stops whenever the position remains outside any AnchorHelpVBT for more than outDelay seconds.

The position method may be overridden to obtain a different behavior.

Associated with each anchor VBT v is

\medskip\bulletitem v.help, the help window to be activated,

\medskip\bulletitem v.hfudge and v.vfudge, dimensions in millimeters that control where the window is popped up,

\medskip\bulletitem v.n, a count of the number of ZSplit ancestors of v to skip when looking for the ZSplit to insert the help window into.

When the help window is activated, it is inserted into the (v.n)th ZSplit ancestor of v (counting the first ZSplit ancestor as zero), or as an undecorated top-level window if v has at most v.n ZSplit ancestors. It is positioned so that its northwest corner is v.hfudge millimeters to the right and v.vfudge millimeters below the southwest corner of v.

The same help window can be associated with several anchors, provided that only one of them is active at a time.



  T <: Public;
  Public = Filter.T OBJECT
    help: VBT.T
  METHODS <* LL.sup <= VBT.mu *>
    init(ch: VBT.T;
      help: VBT.T;
      n: CARDINAL := 0;
      hfudge := 0.0;
      vfudge := 1.0): T
The call v.init(...) initializes the vbt with the given attributes. This includes a call to Filter.T.init(v, ch).

You must not change the help while the AnchorHelpVBT is active.

  ch: VBT.T;
  help: VBT.T;
  n: CARDINAL := 0;
  hfudge, vfudge := 2.0): T; <* LL.sup <= VBT.mu *>
New(...) is equivalent to NEW(T).init(...).

PROCEDURE Activate(v: T);
<* LL.sup = VBT.mu *>
Activate the help window.

PROCEDURE Deactivate(v: T);
<* LL.sup = VBT.mu *>
Deactivate the help window.

PROCEDURE Enter(v: T);
<* LL.sup = VBT.mu *>
Enter the help window. It gets activated after some delay.

PROCEDURE Leave(v: T);
<* LL.sup = VBT.mu *>
Leave the help window. It gets deactivated.

PROCEDURE Set(v: T;  n: CARDINAL; hfudge, vfudge: REAL);
<* LL.sup = VBT.mu *>
Set the attributes of v. If v is active, this is a checked runtime error.

  VAR hfudge, vfudge: REAL); <* LL.sup = VBT.mu *>
Fetch the attributes of v.

PROCEDURE IsActive(v: T): BOOLEAN; <* LL.sup = VBT.mu *>
Return TRUE if and only if v is active.

PROCEDURE GetDelay(v: VBT.T; VAR inDelay, outDelay: LONGREAL);
<* LL.sup = VBT.mu *>
Fetch the delay values for the VBT tree.

PROCEDURE SetDelay(v: VBT.T; inDelay, outDelay: LONGREAL);
<* LL.sup = VBT.mu *>
Change the delay values for the VBT tree.

END AnchorHelpVBT.