V10/man/man9/newlayer.9

.TH NEWLAYER 9.2
.CT 2 comm_term
.SH NAME
newlayer, dellayer, downback, lbitblt, lpoint, lrectf, lsegment, ltexture, upfront \- layer control and graphics
.SH SYNOPSIS
.B #include <jerq.h>
.PP
.B Layer *newlayer(r);
.B Rectangle r;
.PP
.B void dellayer(l)
.B Layer *l;
.PP
.B void lbitblt(sl, r, dl, p, f)
.B "Layer *sl, *dl; Rectangle r; Point p; Code f;
.PP
.B void lpoint(l, p, f)
.B "Layer *l; Point p; Code f;
.PP
.B void lrectf(l, r, f)
.B "Layer *l; Rectangle r; Code f;
.PP
.B void segment(l, p, q, f)
.B "Layer *l; Point p, q; Code f;
.PP
.B void ltexture(l, r, t, f)
.B "Layer *l; Rectangle r; Texture *t; Code f;
.PP
.B void upfront(l)
.B "Layer *l;
.PP
.B void downback(l)
.B "Layer *l;
.SH DESCRIPTION
.I Newlayer
creates a layer in Rectangle
.I r
in the physical display bitmap, and returns its address,
or 0 on failure.
.IR Newproc (9.2)
explains how to attach a process to a layer.
.PP
.I Dellayer
de-allocates a layer; the associated process must also
be freed (see
.IR newproc (9.2)).
.PP
.I Upfront
and
.I downback
are the subroutines corresponding to the
.IR mux (9.1)
menu items
.B Top
and
.BR Bottom .
.PP
The routines
.IR lbitblt ,
.IR lpoint ,
.I lsegment
and
.IR ltexture
are equivalent to their
.IR bitblt (9.3)
counterparts
except that they never inhibit the mouse cursor,
so they are mainly useful only for implementation
of efficient composite graphics operations such
as circle-drawing.
Because of the duality of Bitmaps and Layers,
arguments of either type may be passed freely
to any of the graphics primitives.
.SH SEE ALSO
.IR bitblt (9.3), 
.IR newproc (9.2)
.br
Rob Pike,
.I
Graphics in Overlapping Bitmap Layers,
ACM Trans. on Graphics, April 1983.