
3. Open and close graphics.
Call the crt_opengr function before calling of the other graphic functions
in the user application. Call the crt_closegr function after a series of
graphic drawings. The flow of the processing is as follows.
:
if ( crt_opengr() ) { /* open graphics */
/* initialize graphic screen */
_setvideomode( _98RESSCOLOR ) ;
:
}
:
: /* graphic drawings */
:
crt_closegr() ; /* close graphic */
:
The graphic drawings are not done without execution of the crt_opengr
function. ( _GRNOOUTPUT status will be returned.) The screen switching is
inhibited during opening graphics. It is enabled to switch the screen by
the execution of the crt_setswt( CRT_SWT_GREN ) function before opening
graphics, however, the graphics is closed by the screen switching during
opening graphics and graphic drawings are not done until the crt_opengr
function will be called again even if graphic functions are called.
The screen switching request during opening graphics (such as the screen
selection by MDI key) is being pending state until the graphics will be
closed, and the pending screen switching will be performed when the
crt_closegr function is called.
* Refer "36crt.man" about crt_opengr, crt_closegr and crt_setswt functions.
4. Multi-window display.
The multi-window displaying is not available for graphics. The graphic
screen is always displayed on the full screen even if the multi-windows of
character are being displayed.