ui/src/vbt/BatchUtil.i3

 Copyright (C) 1992, Digital Equipment Corporation 
 All rights reserved. 
 See the file COPYRIGHT for a full description. 
 
 BatchUtil.def, by Greg Nelson and Mark Manasse. 
 Last modified on Mon Oct  4 11:36:04 PDT 1993 by sfreeman 
 modified on Mon Feb 24 13:56:41 PST 1992 by muller 
 modified on Thu Dec 12 0:02:43 PST 1991 by gnelson 

<*PRAGMA LL*>

 This interface provides operations to clip and translate a batch of
   painting commands.  It is useful to those who are implementing window
   classes with customized painting behavior.


   Don't apply these procedures to a batch whose contents are concurrently
   being read or written. 


INTERFACE BatchUtil;

IMPORT Batch, Rect, Point, PaintPrivate;

PROCEDURE GetLength (ba: Batch.T): CARDINAL;

 Return the number of Word.Ts in use in ba. 

PROCEDURE Copy (ba: Batch.T): Batch.T;

 Allocate and return a new batch initialized with a copy of ba. 
 Every entry in a batch has a clipping rectangle; there is also a
   clipping rectangle for the batch as a whole.  The effective clipping
   rectangle for a painting operation is the intersection of its clipping
   rectangle with its batch's clipping rectangle. 


PROCEDURE GetClip (ba: Batch.T): Rect.T;

 Return ba's clipping rectangle. 

TYPE ClipState = {Unclipped, Clipped, Tight};

PROCEDURE GetClipState (ba: Batch.T): ClipState;

 Return ba's clipping state. 
 If GetClipState(ba) is Clipped then the clipping rectangle of every
   painting operation in ba is a subset of GetClip(ba).  If
   GetClipState(ba) is Tight then GetClip(ba) is equal to the join of
   the clipping rectangles of the painting operations in ba.  If
   GetClipState(ba) is Unclipped, there is no particular relationship
   between ba's clipping rectangle and the clipping rectangles of the
   entries in ba. 


PROCEDURE Meet (ba: Batch.T; READONLY clip: Rect.T);

 Set ba's clipping rectangle to Rect.Meet(GetClip(ba), clip). 
 If the assignment is non-trivial, this will change the clip state of
   ba to be Unclipped. 


PROCEDURE Clip (ba: Batch.T);

 Apply ba's clipping rectangle to each operation. 
 That is, if GetClipState(ba) is Unclipped, then for each painting
   operation in ba, Clip replaces the clipping rectangle of the
   operation with the meet of the rectangle and GetClip(ba), and sets the
   clipstate of ba to Clipped. 


PROCEDURE Tighten (ba: Batch.T);

 Achieve ba.clipped = Tight without changing the effect of ba. 
 That is, Tighten(ba) is equivalent to Clip(ba) followed by assigning
   to ba's clipping rectangle the join of the resulting clipping
   rectangles of the entries in ba. 


PROCEDURE Translate (ba: Batch.T; READONLY delta: Point.T);

 Translate ba by delta. 
 That is, for each painting operation in ba, translate the target of
   the painting operation by delta.  This always involves translating the
   clipping rectangle of the operation by delta.  It also adds delta to
   the delta components of all textures and to the reference point of
   TextComs.  It adjusts the p1, p2, vlo, and vhi fields of
   TrapComs.  The relative displacement of a scrolling command is not
   affected; that is, both the source and target of the scroll are
   translated by delta.  The clipping rectangle of the batch is also
   translated. 


PROCEDURE ByteSwap (ba: Batch.T);

 Convert all text painting operations in ba to have the same byteorder
   as PaintPrivate.HostByteOrder. 

PROCEDURE Succ (ba: Batch.T; cptr: PaintPrivate.CommandPtr):
  PaintPrivate.CommandPtr;

 Return the pointer to the entry in ba that follows the one pointed to
   by cptr. 
 Succ(ba, NIL) returns the first entry in ba; Succ(ba, cptr) = NIL
   when cptr is the last entry in ba.  To visit each entry in the batch
   ba, use a loop like this:



      cptr := BatchUtil.Succ(ba, NIL);
      WHILE cptr # NIL DO
        CASE cptr.command OF ... END;
        cptr := BatchUtil.Succ(ba, cptr)
      END


   The PaintPrivate interface explains the format of the entries. 


PROCEDURE SetPicture (ba: Batch.T);

 mark the batch as containing pictures 

END BatchUtil.