#include <u.h>#include <libc.h>#include <libg.h>#include <layer.h> voidbitblt(Bitmap *db, Point p, Bitmap *sb, Rectangle r, Fcode c){	Layer *dl=(Layer *)db, *sl=(Layer *)sb;	int dok;	Rectangle dr; 	if(!bitbltclip(&db))		return;	/*	 * Look for a Bitmap we use for source instead of a Layer.	 * r now fits within sl->clipr.  As long as we have	 * only Visible covering layers, we know that r will	 * therefore fit within their cliprs and no more clipping	 * is required.	 */	while(sl->cache){		if(sl->vis != Visible){			sb = sl->cache;			break;		}		sl = sl->cover->layer;		sb = sl;	}	/*	 * Do the same for the destination	 */	dok = 1;	while(dl->cache){		if(dl->vis != Visible){			db = dl->cache;			dok = 0;			break;		}		dl = dl->cover->layer;		db = dl;	} 	/*	 * sb is now directly usable.  Two cases remain: db Visible or not	 */	if(dok){		/*		 * Bitmap to bitmap, easy.		 */		_bitblt(db, p, sb, r, c);		return;	}	/*	 * Destination not Visible; use destination cache	 */	dr.min = p;	dr.max.x = p.x + Dx(r);	dr.max.y = p.y + Dy(r);	_bitblt(dl->cache, p, sb, r, c);	if(dl->vis == Obscured)		layerop(lupdate, dr, dl, (void *)0);	return;} void_bitblt(Bitmap *d, Point p, Bitmap *s, Rectangle r, Fcode f){	uchar *buf; 	buf = bneed(31);	buf[0] = 'b';	BPSHORT(buf+1, d->id);	BPLONG(buf+3, p.x);	BPLONG(buf+7, p.y);	BPSHORT(buf+11, s->id);	BPLONG(buf+13, r.min.x);	BPLONG(buf+17, r.min.y);	BPLONG(buf+21, r.max.x);	BPLONG(buf+25, r.max.y);	BPSHORT(buf+29, f);}