ui/src/vbt/Pixmap.i3

 Copyright (C) 1992, Digital Equipment Corporation                         
 All rights reserved.                                                      
 See the file COPYRIGHT for a full description.                            
                                                                           
 Last modified on Mon Feb 24 14:01:18 PST 1992 by muller                   

<*PRAGMA LL*>

 A Pixmap.T is a screen-independent specification of a pixmap.
   Many procedures interpret Pixmap.Ts as textures, by tiling the
   plane with translated copies of the pixmap. There are three
   predefined pixmaps:


   The locking level is LL.sup <= VBT.mu for all of the procedures
   in this interface. 


INTERFACE Pixmap;

TYPE T = RECORD pm: INTEGER END; Predefined = [0..2];

CONST
  Solid = T{0};
  Empty = T{1};
  Gray = T{2};

 Solid represents a pixmap of all ones.
   Empty represents a pixmap of all zeros.
   Gray represents a checkerboard of ones and zeros.


   The domains of these pixmaps may vary from screentype to
   screentype, but they will always be non-empty.


   When used on a screentype st, they will have type st.bits
   (see the PaintOp interface). 


TYPE Raw <: ROOT;

 A Pixmap.Raw represents a pixmap as a packed array of
   pixels.  The ScrnPixmap interface reveals the representation. 


PROCEDURE FromBitmap(bits: Raw): T;

 Return a pixmap that looks like bits on all screens. 
 FromBitmap causes a checked runtime error if the depth of
   bits is not one.  On a screentype st, it will have type
   st.bits. 


END Pixmap.