curs_overlay(3X)					      curs_overlay(3X)

NAME    [Toc]    [Back]

     curs_overlay:  overlay, overwrite,	copywin	- overlap and manipulate
     overlapped	curses windows

SYNOPSIS    [Toc]    [Back]

     #include <curses.h>

     int overlay(WINDOW	*srcwin, WINDOW	*dstwin);

     int overwrite(WINDOW *srcwin, WINDOW *dstwin);
     int copywin(WINDOW	*srcwin, WINDOW	*dstwin, int sminrow,
	  int smincol, int dminrow, int	dmincol, int dmaxrow,
	  int dmaxcol, int overlay);

DESCRIPTION    [Toc]    [Back]

     The overlay and overwrite routines	overlay	srcwin on top of dstwin.
     scrwin and	dstwin are not required	to be the same size; only text where
     the two windows overlap is	copied.	 The difference	is that	overlay	is
     non-destructive (blanks are not copied) whereas overwrite is destructive.

     The copywin routine provides a finer granularity of control over the
     overlay and overwrite routines.  Like in the prefresh routine, a
     rectangle is specified in the destination window, (dminrow, dmincol) and
     (dmaxrow, dmaxcol), and the upper-left-corner coordinates of the source
     window, (sminrow, smincol).  If the argument overlay is true, then
     copying is	non-destructive, as in overlay.

RETURN VALUE    [Toc]    [Back]

     Routines that return an integer return ERR	upon failure and an integer
     value other than ERR upon successful completion.

NOTES    [Toc]    [Back]

     The header	file <curses.h>	automatically includes the header files
     <stdio.h> and <unctrl.h>.

     Note that overlay and overwrite may be macros.

SEE ALSO    [Toc]    [Back]

     curses(3X), curs_pad(3X), curs_refresh(3X)
















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overlay(3G)							   overlay(3G)

NAME    [Toc]    [Back]

     overlay - allocates bitplanes for display of overlay colors

C SPECIFICATION    [Toc]    [Back]

     void overlay(planes)
     long planes;

PARAMETERS    [Toc]    [Back]

     planes   expects the number of bitplanes to be allocated for overlay
	      colors.  Acceptable values are 0,	2, 4, and 8.

DESCRIPTION    [Toc]    [Back]

     The IRIS physical framebuffer is divided into four	separate GL
     framebuffers:  normal, popup, overlay, underlay.  Because a single
     physical framebuffer is used to implement the four	GL framebuffers,
     bitplanes must be allocated among the GL framebuffers.  overlay specifies
     the number	of bitplanes to	be allocated to	the overlay framebuffer.
     overlay does not take effect immediately.	Rather,	it is considered only
     when gconfig is called, at	which time all requests	for bitplane resources
     are resolved.

     While only	one of the four	GL framebuffers	can be drawn to	at a time (see
     drawmode),	all four are displayed simultaneously.	The decision of	which
     bitplane to display at each pixel is made based on	the contents of	the
     four framebuffers at that pixel location, using the following
     hierarchical rule:

     if		  the popup pixel contents are non-zero

     then	  display the popup bitplanes

     else if	  overlay bitplanes are	allocated AND
		  the overlay pixel contents are non-zero

     then	  display the overlay bitplanes

     else if	  the normal pixel contents are	non-zero OR
		  no underlay bitplanes	are allocated

     then	  display the normal bitplanes

     else	  display the underlay bitplanes

     Thus images drawn into the	overlay	framebuffer appear over	images in the
     normal framebuffer, and images drawn into the underlay framebuffer	appear
     under images in the normal	framebuffer.  Popup images appear over
     everything	else.

     The default configuration of the overlay framebuffer is: single buffer,
     color map mode.  To make a	change to this configuration other than	to
     change the	bitplane size, the drawing mode	must be	OVERDRAW.  For
     example, the overlay framebuffer can be configured	to be double buffered



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overlay(3G)							   overlay(3G)



     by	calling	doublebuffer while draw	mode is	OVERDRAW.

     On	models that cannot support overlay and underlay	bitplanes
     simultaneously, calling overlay with a non-zero argument forces underlay
     to	zero.  When simultaneous overlay and underlay operation	is supported,
     calling overlay may have no effect	on the number of underlay bitplanes.

SEE ALSO    [Toc]    [Back]

     doublebuffer, drawmode, gconfig, getgdesc,	singlebuffer, underlay

NOTES    [Toc]    [Back]

     This routine is available only in immediate mode.

     IRIS-4D G,	GT, and	GTX models, Personal Iris, Indy, XL, XS, XS24, XZ,
     Elan and Extreme systems support only single buffered, color map mode
     overlay bitplanes.

     The Personal Iris supports	0 or 2 overlay bitplanes.  There are no
     overlay or	underlay bitplanes in the minimum configuration	of the
     Personal Iris.

     IRIS-4D60G	and 4D70G support 2 overlay bitplanes and 2 pop-up bitplanes.

     The Indy and XL supports 0	or 8 overlay and 2 pop-up bitplanes.

     IRIS-4DG, GT, and GTX models, XS, XS24, and Elan support 0, 2, or 4
     overlay bitplanes.	 Because 4-bitplane allocation reduces the popup
     framebuffer to zero bitplanes, however, its use is	strongly discouraged.
     The window	manager	cannot operate properly	when no	popup bitplanes	are
     available.

     IRIS-4D VGX models	support	0, 2, 4, or 8 overlay bitplanes, either	single
     or	double buffered, in color map mode only.  The 4	and 8 bitplane
     allocations utilize the alpha bitplanes, which must be present, and which
     therefore are unavailable in draw mode NORMALDRAW.

     IRIS Entry	does not support overlay bitplanes.

     Use getgdesc to determine the maximum number of bitplanes supported for
     the overlay framebuffer.

     Iris Entry	does not support overlay so getgdesc returns zero for the
     number of overlay bitplanes on Iris Entry systems.

BUGS    [Toc]    [Back]

     The Personal Iris does not	support	shade model GOURAUD in the overlay
     framebuffer.


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