glenda.party
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BITBLT(9.3)                                                        BITBLT(9.3)



NAME
       Code,  addr, bitblt, point, rectf, screenswap, segment, texture - basic
       jerq graphics functions

SYNOPSIS
       #include <jerq.h>

       typedef int Code;
       Code F_STORE, F_XOR, F_OR, F_CLR;

       Word *addr(b, p) Bitmap *b; Point p;

       void bitblt(sb, r, db, p, f) Bitmap *sb, *db;  Rectangle  r;  Point  p;
       Code f;

       void point(b, p, f) Bitmap *b; Point p; Code f;

       void rectf(b, r, f) Bitmap *b; Rectangle r; Code f;

       void screenswap(b, r, s) Bitmap *b; Rectangle r, s;

       void segment(b, p, q, f) Bitmap *b; Point p, q; Code f;

       void texture(b, r, t, f) Bitmap *b; Rectangle r; Texture *t; Code f;

DESCRIPTION
       The  type  Code defines the constants passed to the graphics primitives
       to indicate the Boolean operation to be performed  on  the  source  and
       destination.  The meanings of a Code are:

              F_STORE        target =  source
              F_OR           target |= source
              F_XOR               target ^= source
              F_CLR               target &= ~source

       In  other  words,  if  a Rectangle is copied to another place with Code
       F_OR, the result will be the bitwise OR of the contents of  the  source
       Rectangle and the target area.  For operations with no explicit source,
       such as line drawing, the source is taken to be an infinite bitmap with
       zeroes everywhere except on the object (e.g. line) generated by the op‐
       erator, with coordinates aligned with the destination bitmap.   F_STORE
       is the same as F_OR for non-rectangular operations.

       Addr  returns  the address of the Word containing the bit at Point p in
       the Bitmap b.

       Bitblt (bit-block transfer) copies the data in Rectangle r in Bitmap sb
       to  the  congruent Rectangle with origin p in Bitmap db.  The nature of
       the copy is specified by the Code f.

       Point draws the pixel at location p in the Bitmap b according  to  Code
       f.

       Screenswap  does  an in-place exchange of the on-screen Rectangle s and
       the Rectangle r within the Bitmap b.  Its action is undefined if r  and
       s  are  not congruent.  The Rectangle s is not clipped to the Bitmap b,
       only to the screen.

       Segment draws a line segment in Bitmap b from Point p to q,  with  Code
       f.  The segment is half-open: p is the first point of the segment and q
       is the first point beyond the segment,  so  adjacent  segments  sharing
       endpoints  abut.  Like all the other graphics operations, segment clips
       the line so that only the portion of the line intersecting  the  bitmap
       is displayed.

       Texture  draws  with function specified by f in the Rectangle r, in the
       Bitmap b, the Texture specified by t.  The  texture  is  replicated  to
       cover r.  Rectf is equivalent to texture with *t set to all one's.

       In  the  above  definitions, the type Bitmap may be replaced with Layer
       anywhere; see newlayer(9.2).

SEE ALSO
       types(9.5)



                                                                   BITBLT(9.3)