#include <u.h>#include <libc.h>#include <draw.h> static int	screenid; Screen*allocscreen(Image *image, Image *fill, int public){	uchar *a;	Screen *s;	int id, try;	Display *d; 	d = image->display;	if(d != fill->display){		werrstr("allocscreen: image and fill on different displays");		return nil;	}	s = malloc(sizeof(Screen));	if(s == nil)		return nil;	_lockdisplay(d);	if(!screenid)		screenid = getpid();	_unlockdisplay(d);	for(try=0; try<25; try++){		/* loop until we find a free id */		_lockdisplay(d);		a = bufimage(d, 1+4+4+4+1);		if(a == nil){			_unlockdisplay(d);			break;		}		id = ++screenid & 0xffff;	/* old devdraw bug */		a[0] = 'A';		BPLONG(a+1, id);		BPLONG(a+5, image->id);		BPLONG(a+9, fill->id);		a[13] = public;		_unlockdisplay(d);		if(flushimage(d, 0) != -1)			goto Found;	}	free(s);	return nil;     Found:	s->display = d;	s->id = id;	s->image = image;	assert(s->image != nil && s->image->chan != 0); 	s->fill = fill;	return s;} Screen*publicscreen(Display *d, int id, ulong chan){	uchar *a;	Screen *s; 	s = malloc(sizeof(Screen));	if(s == nil)		return nil;	_lockdisplay(d);	a = bufimage(d, 1+4+4);	if(a == nil){		_unlockdisplay(d);Error:		free(s);		return nil;	}	a[0] = 'S';	BPLONG(a+1, id);	BPLONG(a+5, chan);	_unlockdisplay(d);	if(flushimage(d, 0) < 0)		goto Error; 	s->display = d;	s->id = id;	s->image = nil;	s->fill = nil;	return s;} intfreescreen(Screen *s){	uchar *a;	Display *d; 	if(s == nil)		return 0;	d = s->display;	_lockdisplay(d);	a = bufimage(d, 1+4);	if(a == nil){		_unlockdisplay(d);		free(s);		return -1;	}	a[0] = 'F';	BPLONG(a+1, s->id);	_unlockdisplay(d);	free(s);	return 1;} Image*allocwindow(Screen *s, Rectangle r, int ref, ulong col){	return _allocwindow(nil, s, r, ref, col);} Image*_allocwindow(Image *i, Screen *s, Rectangle r, int ref, ulong col){	Display *d; 	d = s->display;	i = _allocimage(i, d, r, d->screenimage->chan, 0, col, s->id, ref);	if(i == nil)		return nil;	i->screen = s;	_lockdisplay(d);	i->next = d->windows;	d->windows = i;	_unlockdisplay(d);	return i;} staticvoidtopbottom(Image **w, int n, int top){	int i;	uchar *b;	Display *d; 	if(n < 0){    Ridiculous:		fprint(2, "top/bottom: ridiculous number of windows\n");		return;	}	if(n == 0)		return;	if(n > (w[0]->display->bufsize-100)/4)		goto Ridiculous;	/*	 * this used to check that all images were on the same screen.	 * we don't know the screen associated with images we acquired	 * by name.  instead, check that all images are on the same display.	 * the display will check that they are all on the same screen.	 */	d = w[0]->display;	for(i=1; i<n; i++)		if(w[i]->display != d){			fprint(2, "top/bottom: windows not on same screen\n");			return;		} 	if(n==0)		return;	_lockdisplay(d);	b = bufimage(d, 1+1+2+4*n);	if(b == nil){		_unlockdisplay(d);		return;	}	b[0] = 't';	b[1] = top;	BPSHORT(b+2, n);	for(i=0; i<n; i++)		BPLONG(b+4+4*i, w[i]->id);	_unlockdisplay(d);} voidbottomwindow(Image *w){	if(w->screen != nil)		topbottom(&w, 1, 0);} voidtopwindow(Image *w){	if(w->screen != nil)		topbottom(&w, 1, 1);} voidbottomnwindows(Image **w, int n){	topbottom(w, n, 0);} voidtopnwindows(Image **w, int n){	topbottom(w, n, 1);} intoriginwindow(Image *w, Point log, Point scr){	uchar *b;	Point delta; 	_lockdisplay(w->display);	b = bufimage(w->display, 1+4+2*4+2*4);	if(b == nil){		_unlockdisplay(w->display);		return 0;	}	b[0] = 'o';	BPLONG(b+1, w->id);	BPLONG(b+5, log.x);	BPLONG(b+9, log.y);	BPLONG(b+13, scr.x);	BPLONG(b+17, scr.y);	_unlockdisplay(w->display);	delta = subpt(log, w->r.min);	w->r = rectaddpt(w->r, delta);	w->clipr = rectaddpt(w->clipr, delta);	return 1;}