vbtkit/src/lego/ShadowedFeedbackVBT.i3

 Copyright (C) 1992, Digital Equipment Corporation                         
 All rights reserved.                                                      
 See the file COPYRIGHT for a full description.                            
                                                                           
 Last modified on Thu Jun 10 14:03:49 PDT 1993 by meehan 
      modified on Thu Feb  4 15:02:29 PST 1993 by mhb    
      modified on Tue Jun 16 13:08:16 PDT 1992 by muller 

<* PRAGMA LL *>
<* PRAGMA SUBTYPE *>

 A ShadowedFeedbackVBT is a multi-filter feedback that displays a
   3-D border as visual feedback to another VBT. 


INTERFACE ShadowedFeedbackVBT;

IMPORT FeedbackVBT, Shadow, VBT;

TYPE
  <* SUBTYPE T <: MultiFilter.T *>
  T <: Public;
  Public =
    FeedbackVBT.T OBJECT
    METHODS
      <* LL <= VBT.mu *>
      init (ch            : VBT.T;
            shadow        : Shadow.T := NIL;
            onStyle                  := Shadow.Style.Lowered;
            onExcitedStyle           := Shadow.Style.Raised;
            offStyle                 := Shadow.Style.Raised;
            offExcitedStyle          := Shadow.Style.Lowered): T
    END;

 The call v.init(ch, shadow, ...) initializes v as a
   ShadowedFeedbackVBT.  The internal structure of v includes a
   ShadowedVBT for displaying the shadow shadow around ch.  The
   default normal and excited methods change the style of the
   shadow, taking into account the state of v.  For example, when
   FeedbackVBT.GetState(v) returns FALSE, the excited method
   uses the value of offExcitedStyle.


   On a monochrome screen (whenever Shadow.IsSupport(v, shadow) is
   false), ch is inverted by the default normal method when the
   state is ``on'' and by the excited method when the state is
   ``off.''


   The default parameters to the init method generate a feedback
   that is appropriate for buttons.  The following procedure generates
   a feedback that is appropriate for use by menu buttons: 


PROCEDURE NewMenu (ch: VBT.T; shadow: Shadow.T := NIL): T;
<* LL <= VBT.mu *>

 Return a ShadowedFeedbackVBT appropriate for menu buttons.  The
   normal method always uses Shadow.Style.Flat; the excited
   method always uses Shadow.Style.Lowered. 

END ShadowedFeedbackVBT.