ui/src/vbt/Cursor.i3

 Copyright (C) 1992, Digital Equipment Corporation                         
 All rights reserved.                                                      
 See the file COPYRIGHT for a full description.                            
                                                                           
 Last modified on Mon Feb 24 14:01:20 PST 1992 by muller                   

<*PRAGMA LL*>

 A Cursor.T is a screen-independent specification of a cursor shape.
   The call VBT.SetCursor(v, cs) sets the cursor of v to
   be cs.


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


INTERFACE Cursor;

IMPORT Pixmap, Point;

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

CONST
  DontCare = T{0};
  TextPointer = T{1};
  NotReady = T{2};

 You should set Cursor.DontCare when you don't care about the cursor
   shape; Cursor.TextPointer when the cursor is to be used for editing
   text, and Cursor.NotReady to indicate that the application is not
   receptive to user input.  


TYPE Raw = RECORD
    plane1, plane2: Pixmap.Raw;
    hotspot: Point.T;
    color1, color2, color3: RGB;
  END;
  BW = {UseBg, UseFg, UseIntensity};
  RGB = RECORD
    r, g, b: REAL;
    gray := -1.0;
    bw := BW.UseIntensity
  END;

 A Raw represents a cursor with explicit offset,
   bitmaps, and colors.


   The plane1 and plane2 are depth-1 pixmaps.  They must
   have the same bounding rectangle, and the hotspot must lie
   within the bounding rectangle or on its east or south edge.
   If the hotspot is illegal, it will be moved to the closest
   legal position.


   The cursor's hotspot is kept on top of the mouse's location on the
   screen.  The cursor's image tracks the mouse relative to the hotspot.
   For example, if the hotspot is (0, 0), the (0, 0) bit of the cursor's
   image will be located over the mouse's location.  The remainder of
   the cursor will appear to the south and east.


   The color of each pixel in the cursor's image is determined from the
   corresponding bits in plane1 and plane2 (p1 and p2):



      p1 = 0, p2 = 0  => transparent
      p1 = 0, p2 = 1  => color1
      p1 = 1, p2 = 0  => color2
      p1 = 1, p2 = 1  => color3


   The colors for the cursor are matched as closely as possible to the
   selection of cursor colors that the screentype supports.  If the
   screentype allows only two colors for the cursor, then the pixels that
   would have been color3 will be color1.  The gray and bw
   values control the color on gray-scale and monochrome displays,
   according to the same rule used in PaintOp.FromRGB.  


PROCEDURE FromRaw(READONLY r: Raw): T;

 Return a cursor that looks like r on all screens. 
 If the screentype does not support r's colors or size, FromRaw
   will clip or convert colors as necessary.  On a screentype that does
   not allow user-defined cursors, the cursor returned by FromRaw
   will behave like DontCare.  


PROCEDURE FromName(READONLY names: ARRAY OF TEXT): T;

 Return the first available cursor of those named in the array names. 
 The entries of names are cursor names as specified in the
   ScrnCursor interface, possibly containing wild card characters.
   On any particular screentype, FromName(names) iterates through
   names in order and returns an arbitrary match from the first name
   that matches anything.  If no name has any matches, it returns
   DontCare.


   Standard X screentypes support the cursors named in {\it X Window
   System} by Scheifler et.  al. \cite{XSpec} Appendix B. Therefore, for
   example,



      FromName(ARRAY OF TEXT{"XC_arrow"})


   returns a cursor that behaves like the X arrow cursor on
   X screentypes, and like DontCare on screentypes
   that have no cursor named XC_arrow.  


END Cursor.