From: Vladimir Pshenkin <PSHENKIN AT main DOT econ DOT msu DOT su>
Organization: MSU Faculty of Economics
To: djgpp AT sun DOT soe DOT clarkson DOT edu
Date: Thu, 25 May 1995 19:21:30 +0300
Subject: LibGrx BitBlit corrections

Hi, all!

I found an error while using GrBitBlt() function from LibGrx, mouse
cursor began to blink too often.
Next version of GrBitBlt() is more correct.

---------------------- cut here --------------------------
/**
 ** BITBLT.C
 **
 **  Copyright (C) 1992, Csaba Biegl
 **    820 Stirrup Dr, Nashville, TN, 37221
 **    csaba AT vuse DOT vanderbilt DOT edu
 **
 **  This file is distributed under the terms listed in the document
 **  "copying.cb", available from the author at the address above.
 **  A copy of "copying.cb" should accompany this file; if not, a copy
 **  should be available from where this file was obtained.  This file
 **  may not be distributed without a verbatim copy of "copying.cb".
 **  You should also have received a copy of the GNU General Public
 **  License along with this program (it is in the file "copying");
 **  if not, write to the Free Software Foundation, Inc., 675 Mass
Ave,
 **  Cambridge, MA 02139, USA.
 **
 **  This program is distributed in the hope that it will be useful,
 **  but WITHOUT ANY WARRANTY; without even the implied warranty of
 **  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 **  GNU General Public License for more details.
 **/

#include "grx.h"
#include "libgrx.h"
#include "clipping.h"

void GrBitBlt(GrContext *dst,int x,int y,
          GrContext *src,int x1,int y1,int x2,int y2,int oper)
{
    int oldx,oldy;
    int msflag = FALSE;

    if(dst == NULL) dst = CURC;
    if(src == NULL) src = CURC;
    SORT2(x1,x2);
    SORT2(y1,y2);
    oldx = x1;
    oldy = y1;
    CLIPBOXTOCONTEXT(src,x1,y1,x2,y2);
    x += (x1 - oldx);
    y += (y1 - oldy);
    x2 += ((oldx = x) - x1);
    y2 += ((oldy = y) - y1);
    CLIPBOX(dst,x,y,x2,y2);
    x1 += (x - oldx);
    y1 += (y - oldy);
    if(_GrMouseDrawn) {
        GrContext *cxt = NULL;
        int mx1,my1,mx2,my2;
/*
// Begin of modyfied part ( by PV@ )
*/
        if(src->gc_onscreen) {
        cxt = src->gc_root ? src->gc_root : src;
        mx1 = x1  + src->gc_xoffset;
        my1 = y1  + src->gc_yoffset;
        mx2 = mx1 + x2 - x;
        my2 = my1 + y2 - y;
        if(dst->gc_onscreen) {
            cxt = dst->gc_root ? dst->gc_root : dst;
            mx1 = MIN(mx1,x  + dst->gc_xoffset);
            my1 = MIN(my1,y  + dst->gc_yoffset);
            mx2 = MAX(mx2,x2 + dst->gc_xoffset);
            my2 = MAX(my2,y2 + dst->gc_yoffset);
        }
        }else{
            if(dst->gc_onscreen) {
            cxt = dst->gc_root ? dst->gc_root : dst;
            mx1 = x  + dst->gc_xoffset;
            my1 = y  + dst->gc_yoffset;
            mx2 = x2 + dst->gc_xoffset;
            my2 = y2 + dst->gc_yoffset;
            }
        }
/*
// End of modyfied part ( by PV@ )
*/
        if(cxt) msflag = (*_GrMouseBlock)(cxt,mx1,my1,mx2,my2);
    }
    _GrPixCopy(dst,PIX_ADDR(dst,x,y),
        src,PIX_ADDR(src,x1,y1),
        (x2 - x + 1),
        (y2 - y + 1),
        oper
    );
    if(msflag) (*_GrMouseUnBlock)(msflag);
}
---------------------- cut here --------------------------

Enjoy!

With best regards,
                   Vladimir A. Pshenkin

Moscow State University, Moscow, Russia.

Tel:     (095) 939-5726
E-mail:  pshenkin AT dei DOT econ DOT msu DOT su
         root AT pva DOT econ DOT msu DOT su
FIDO:    2:5020/169.2