1 /*
2  * /dev/draw simulator -- handles the messages prepared by the draw library.
3  * Doesn't simulate the file system part, just the messages.
4  */
5 
6 #include <u.h>
7 #include <libc.h>
8 #include <draw.h>
9 #include <memdraw.h>
10 #include <memlayer.h>
11 #include "devdraw.h"
12 
13 extern void _flushmemscreen(Rectangle);
14 
15 #define NHASH (1<<5)
16 #define HASHMASK (NHASH-1)
17 
18 typedef struct Client Client;
19 typedef struct Draw Draw;
20 typedef struct DImage DImage;
21 typedef struct DScreen DScreen;
22 typedef struct CScreen CScreen;
23 typedef struct FChar FChar;
24 typedef struct Refresh Refresh;
25 typedef struct Refx Refx;
26 typedef struct DName DName;
27 
28 struct Draw
29 {
30 	QLock		lk;
31 	int		clientid;
32 	int		nclient;
33 	Client*		client[1];
34 	int		nname;
35 	DName*		name;
36 	int		vers;
37 	int		softscreen;
38 };
39 
40 struct Client
41 {
42 	/*Ref		r;*/
43 	DImage*		dimage[NHASH];
44 	CScreen*	cscreen;
45 	Refresh*	refresh;
46 	Rendez		refrend;
47 	uchar*		readdata;
48 	int		nreaddata;
49 	int		busy;
50 	int		clientid;
51 	int		slot;
52 	int		refreshme;
53 	int		infoid;
54 	int		op;
55 };
56 
57 struct Refresh
58 {
59 	DImage*		dimage;
60 	Rectangle	r;
61 	Refresh*	next;
62 };
63 
64 struct Refx
65 {
66 	Client*		client;
67 	DImage*		dimage;
68 };
69 
70 struct DName
71 {
72 	char			*name;
73 	Client	*client;
74 	DImage*		dimage;
75 	int			vers;
76 };
77 
78 struct FChar
79 {
80 	int		minx;	/* left edge of bits */
81 	int		maxx;	/* right edge of bits */
82 	uchar		miny;	/* first non-zero scan-line */
83 	uchar		maxy;	/* last non-zero scan-line + 1 */
84 	schar		left;	/* offset of baseline */
85 	uchar		width;	/* width of baseline */
86 };
87 
88 /*
89  * Reference counts in DImages:
90  *	one per open by original client
91  *	one per screen image or fill
92  * 	one per image derived from this one by name
93  */
94 struct DImage
95 {
96 	int		id;
97 	int		ref;
98 	char		*name;
99 	int		vers;
100 	Memimage*	image;
101 	int		ascent;
102 	int		nfchar;
103 	FChar*		fchar;
104 	DScreen*	dscreen;	/* 0 if not a window */
105 	DImage*	fromname;	/* image this one is derived from, by name */
106 	DImage*		next;
107 };
108 
109 struct CScreen
110 {
111 	DScreen*	dscreen;
112 	CScreen*	next;
113 };
114 
115 struct DScreen
116 {
117 	int		id;
118 	int		public;
119 	int		ref;
120 	DImage	*dimage;
121 	DImage	*dfill;
122 	Memscreen*	screen;
123 	Client*		owner;
124 	DScreen*	next;
125 };
126 
127 static	Draw		sdraw;
128 static	Client		*client0;
129 static	Memimage	*screenimage;
130 static	Rectangle	flushrect;
131 static	int		waste;
132 static	DScreen*	dscreen;
133 static	int		drawuninstall(Client*, int);
134 static	Memimage*	drawinstall(Client*, int, Memimage*, DScreen*);
135 static	void		drawfreedimage(DImage*);
136 
137 void
138 _initdisplaymemimage(Memimage *m)
139 {
140 	screenimage = m;
141 	m->screenref = 1;
142 	client0 = mallocz(sizeof(Client), 1);
143 	if(client0 == nil){
144 		fprint(2, "initdraw: allocating client0: out of memory");
145 		abort();
146 	}
147 	client0->slot = 0;
148 	client0->clientid = ++sdraw.clientid;
149 	client0->op = SoverD;
150 	sdraw.client[0] = client0;
151 	sdraw.nclient = 1;
152 	sdraw.softscreen = 1;
153 }
154 
155 void
156 _drawreplacescreenimage(Memimage *m)
157 {
158 	/*
159 	 * Replace the screen image because the screen
160 	 * was resized.
161 	 * 
162 	 * In theory there should only be one reference
163 	 * to the current screen image, and that's through
164 	 * client0's image 0, installed a few lines above.
165 	 * Once the client drops the image, the underlying backing 
166 	 * store freed properly.  The client is being notified
167 	 * about the resize through external means, so all we
168 	 * need to do is this assignment.
169 	 */
170 	Memimage *om;
171 
172 	qlock(&sdraw.lk);
173 	om = screenimage;
174 	screenimage = m;
175 	m->screenref = 1;
176 	if(om && --om->screenref == 0){
177 		_freememimage(om);
178 	}
179 	qunlock(&sdraw.lk);
180 }
181 
182 static
183 void
184 drawrefreshscreen(DImage *l, Client *client)
185 {
186 	while(l != nil && l->dscreen == nil)
187 		l = l->fromname;
188 	if(l != nil && l->dscreen->owner != client)
189 		l->dscreen->owner->refreshme = 1;
190 }
191 
192 static
193 void
194 drawrefresh(Memimage *m, Rectangle r, void *v)
195 {
196 	Refx *x;
197 	DImage *d;
198 	Client *c;
199 	Refresh *ref;
200 
201 	USED(m);
202 
203 	if(v == 0)
204 		return;
205 	x = v;
206 	c = x->client;
207 	d = x->dimage;
208 	for(ref=c->refresh; ref; ref=ref->next)
209 		if(ref->dimage == d){
210 			combinerect(&ref->r, r);
211 			return;
212 		}
213 	ref = mallocz(sizeof(Refresh), 1);
214 	if(ref){
215 		ref->dimage = d;
216 		ref->r = r;
217 		ref->next = c->refresh;
218 		c->refresh = ref;
219 	}
220 }
221 
222 static void
223 addflush(Rectangle r)
224 {
225 	int abb, ar, anbb;
226 	Rectangle nbb;
227 
228 	if(sdraw.softscreen==0 || !rectclip(&r, screenimage->r))
229 		return;
230 
231 	if(flushrect.min.x >= flushrect.max.x){
232 		flushrect = r;
233 		waste = 0;
234 		return;
235 	}
236 	nbb = flushrect;
237 	combinerect(&nbb, r);
238 	ar = Dx(r)*Dy(r);
239 	abb = Dx(flushrect)*Dy(flushrect);
240 	anbb = Dx(nbb)*Dy(nbb);
241 	/*
242 	 * Area of new waste is area of new bb minus area of old bb,
243 	 * less the area of the new segment, which we assume is not waste.
244 	 * This could be negative, but that's OK.
245 	 */
246 	waste += anbb-abb - ar;
247 	if(waste < 0)
248 		waste = 0;
249 	/*
250 	 * absorb if:
251 	 *	total area is small
252 	 *	waste is less than half total area
253 	 * 	rectangles touch
254 	 */
255 	if(anbb<=1024 || waste*2<anbb || rectXrect(flushrect, r)){
256 		flushrect = nbb;
257 		return;
258 	}
259 	/* emit current state */
260 	if(flushrect.min.x < flushrect.max.x)
261 		_flushmemscreen(flushrect);
262 	flushrect = r;
263 	waste = 0;
264 }
265 
266 static
267 void
268 dstflush(int dstid, Memimage *dst, Rectangle r)
269 {
270 	Memlayer *l;
271 
272 	if(dstid == 0){
273 		combinerect(&flushrect, r);
274 		return;
275 	}
276 	/* how can this happen? -rsc, dec 12 2002 */
277 	if(dst == 0){
278 		fprint(2, "nil dstflush\n");
279 		return;
280 	}
281 	l = dst->layer;
282 	if(l == nil)
283 		return;
284 	do{
285 		if(l->screen->image->data != screenimage->data)
286 			return;
287 		r = rectaddpt(r, l->delta);
288 		l = l->screen->image->layer;
289 	}while(l);
290 	addflush(r);
291 }
292 
293 static
294 void
295 drawflush(void)
296 {
297 	if(flushrect.min.x < flushrect.max.x)
298 		_flushmemscreen(flushrect);
299 	flushrect = Rect(10000, 10000, -10000, -10000);
300 }
301 
302 static
303 int
304 drawcmp(char *a, char *b, int n)
305 {
306 	if(strlen(a) != n)
307 		return 1;
308 	return memcmp(a, b, n);
309 }
310 
311 static
312 DName*
313 drawlookupname(int n, char *str)
314 {
315 	DName *name, *ename;
316 
317 	name = sdraw.name;
318 	ename = &name[sdraw.nname];
319 	for(; name<ename; name++)
320 		if(drawcmp(name->name, str, n) == 0)
321 			return name;
322 	return 0;
323 }
324 
325 static
326 int
327 drawgoodname(DImage *d)
328 {
329 	DName *n;
330 
331 	/* if window, validate the screen's own images */
332 	if(d->dscreen)
333 		if(drawgoodname(d->dscreen->dimage) == 0
334 		|| drawgoodname(d->dscreen->dfill) == 0)
335 			return 0;
336 	if(d->name == nil)
337 		return 1;
338 	n = drawlookupname(strlen(d->name), d->name);
339 	if(n==nil || n->vers!=d->vers)
340 		return 0;
341 	return 1;
342 }
343 
344 static
345 DImage*
346 drawlookup(Client *client, int id, int checkname)
347 {
348 	DImage *d;
349 
350 	d = client->dimage[id&HASHMASK];
351 	while(d){
352 		if(d->id == id){
353 			/*
354 			 * BUG: should error out but too hard.
355 			 * Return 0 instead.
356 			 */
357 			if(checkname && !drawgoodname(d))
358 				return 0;
359 			return d;
360 		}
361 		d = d->next;
362 	}
363 	return 0;
364 }
365 
366 static
367 DScreen*
368 drawlookupdscreen(int id)
369 {
370 	DScreen *s;
371 
372 	s = dscreen;
373 	while(s){
374 		if(s->id == id)
375 			return s;
376 		s = s->next;
377 	}
378 	return 0;
379 }
380 
381 static
382 DScreen*
383 drawlookupscreen(Client *client, int id, CScreen **cs)
384 {
385 	CScreen *s;
386 
387 	s = client->cscreen;
388 	while(s){
389 		if(s->dscreen->id == id){
390 			*cs = s;
391 			return s->dscreen;
392 		}
393 		s = s->next;
394 	}
395 	/* caller must check! */
396 	return 0;
397 }
398 
399 static
400 Memimage*
401 drawinstall(Client *client, int id, Memimage *i, DScreen *dscreen)
402 {
403 	DImage *d;
404 
405 	d = mallocz(sizeof(DImage), 1);
406 	if(d == 0)
407 		return 0;
408 	d->id = id;
409 	d->ref = 1;
410 	d->name = 0;
411 	d->vers = 0;
412 	d->image = i;
413 	if(i->screenref)
414 		++i->screenref;
415 	d->nfchar = 0;
416 	d->fchar = 0;
417 	d->fromname = 0;
418 	d->dscreen = dscreen;
419 	d->next = client->dimage[id&HASHMASK];
420 	client->dimage[id&HASHMASK] = d;
421 	return i;
422 }
423 
424 static
425 Memscreen*
426 drawinstallscreen(Client *client, DScreen *d, int id, DImage *dimage, DImage *dfill, int public)
427 {
428 	Memscreen *s;
429 	CScreen *c;
430 
431 	c = mallocz(sizeof(CScreen), 1);
432 	if(dimage && dimage->image && dimage->image->chan == 0){
433 		fprint(2, "bad image %p in drawinstallscreen", dimage->image);
434 		abort();
435 	}
436 
437 	if(c == 0)
438 		return 0;
439 	if(d == 0){
440 		d = mallocz(sizeof(DScreen), 1);
441 		if(d == 0){
442 			free(c);
443 			return 0;
444 		}
445 		s = mallocz(sizeof(Memscreen), 1);
446 		if(s == 0){
447 			free(c);
448 			free(d);
449 			return 0;
450 		}
451 		s->frontmost = 0;
452 		s->rearmost = 0;
453 		d->dimage = dimage;
454 		if(dimage){
455 			s->image = dimage->image;
456 			dimage->ref++;
457 		}
458 		d->dfill = dfill;
459 		if(dfill){
460 			s->fill = dfill->image;
461 			dfill->ref++;
462 		}
463 		d->ref = 0;
464 		d->id = id;
465 		d->screen = s;
466 		d->public = public;
467 		d->next = dscreen;
468 		d->owner = client;
469 		dscreen = d;
470 	}
471 	c->dscreen = d;
472 	d->ref++;
473 	c->next = client->cscreen;
474 	client->cscreen = c;
475 	return d->screen;
476 }
477 
478 static
479 void
480 drawdelname(DName *name)
481 {
482 	int i;
483 
484 	i = name-sdraw.name;
485 	memmove(name, name+1, (sdraw.nname-(i+1))*sizeof(DName));
486 	sdraw.nname--;
487 }
488 
489 static
490 void
491 drawfreedscreen(DScreen *this)
492 {
493 	DScreen *ds, *next;
494 
495 	this->ref--;
496 	if(this->ref < 0)
497 		fprint(2, "negative ref in drawfreedscreen\n");
498 	if(this->ref > 0)
499 		return;
500 	ds = dscreen;
501 	if(ds == this){
502 		dscreen = this->next;
503 		goto Found;
504 	}
505 	while(next = ds->next){	/* assign = */
506 		if(next == this){
507 			ds->next = this->next;
508 			goto Found;
509 		}
510 		ds = next;
511 	}
512 	/*
513 	 * Should signal Enodrawimage, but too hard.
514 	 */
515 	return;
516 
517     Found:
518 	if(this->dimage)
519 		drawfreedimage(this->dimage);
520 	if(this->dfill)
521 		drawfreedimage(this->dfill);
522 	free(this->screen);
523 	free(this);
524 }
525 
526 static
527 void
528 drawfreedimage(DImage *dimage)
529 {
530 	int i;
531 	Memimage *l;
532 	DScreen *ds;
533 
534 	dimage->ref--;
535 	if(dimage->ref < 0)
536 		fprint(2, "negative ref in drawfreedimage\n");
537 	if(dimage->ref > 0)
538 		return;
539 
540 	/* any names? */
541 	for(i=0; i<sdraw.nname; )
542 		if(sdraw.name[i].dimage == dimage)
543 			drawdelname(sdraw.name+i);
544 		else
545 			i++;
546 	if(dimage->fromname){	/* acquired by name; owned by someone else*/
547 		drawfreedimage(dimage->fromname);
548 		goto Return;
549 	}
550 	ds = dimage->dscreen;
551 	l = dimage->image;
552 	dimage->dscreen = nil;	/* paranoia */
553 	dimage->image = nil;
554 	if(ds){
555 		if(l->data == screenimage->data)
556 			addflush(l->layer->screenr);
557 		if(l->layer->refreshfn == drawrefresh)	/* else true owner will clean up */
558 			free(l->layer->refreshptr);
559 		l->layer->refreshptr = nil;
560 		if(drawgoodname(dimage))
561 			memldelete(l);
562 		else
563 			memlfree(l);
564 		drawfreedscreen(ds);
565 	}else{
566 		if(l->screenref==0)
567 			freememimage(l);
568 		else if(--l->screenref==0)
569 			_freememimage(l);
570 	}
571     Return:
572 	free(dimage->fchar);
573 	free(dimage);
574 }
575 
576 static
577 void
578 drawuninstallscreen(Client *client, CScreen *this)
579 {
580 	CScreen *cs, *next;
581 
582 	cs = client->cscreen;
583 	if(cs == this){
584 		client->cscreen = this->next;
585 		drawfreedscreen(this->dscreen);
586 		free(this);
587 		return;
588 	}
589 	while(next = cs->next){	/* assign = */
590 		if(next == this){
591 			cs->next = this->next;
592 			drawfreedscreen(this->dscreen);
593 			free(this);
594 			return;
595 		}
596 		cs = next;
597 	}
598 }
599 
600 static
601 int
602 drawuninstall(Client *client, int id)
603 {
604 	DImage *d, **l;
605 
606 	for(l=&client->dimage[id&HASHMASK]; (d=*l) != nil; l=&d->next){
607 		if(d->id == id){
608 			*l = d->next;
609 			drawfreedimage(d);
610 			return 0;
611 		}
612 	}
613 	return -1;
614 }
615 
616 static
617 int
618 drawaddname(Client *client, DImage *di, int n, char *str, char **err)
619 {
620 	DName *name, *ename, *new, *t;
621 	char *ns;
622 
623 	name = sdraw.name;
624 	ename = &name[sdraw.nname];
625 	for(; name<ename; name++)
626 		if(drawcmp(name->name, str, n) == 0){
627 			*err = "image name in use";
628 			return -1;
629 		}
630 	t = mallocz((sdraw.nname+1)*sizeof(DName), 1);
631 	ns = malloc(n+1);
632 	if(t == nil || ns == nil){
633 		free(t);
634 		free(ns);
635 		*err = "out of memory";
636 		return -1;
637 	}
638 	memmove(t, sdraw.name, sdraw.nname*sizeof(DName));
639 	free(sdraw.name);
640 	sdraw.name = t;
641 	new = &sdraw.name[sdraw.nname++];
642 	new->name = ns;
643 	memmove(new->name, str, n);
644 	new->name[n] = 0;
645 	new->dimage = di;
646 	new->client = client;
647 	new->vers = ++sdraw.vers;
648 	return 0;
649 }
650 
651 static int
652 drawclientop(Client *cl)
653 {
654 	int op;
655 
656 	op = cl->op;
657 	cl->op = SoverD;
658 	return op;
659 }
660 
661 static
662 Memimage*
663 drawimage(Client *client, uchar *a)
664 {
665 	DImage *d;
666 
667 	d = drawlookup(client, BGLONG(a), 1);
668 	if(d == nil)
669 		return nil;	/* caller must check! */
670 	return d->image;
671 }
672 
673 static
674 void
675 drawrectangle(Rectangle *r, uchar *a)
676 {
677 	r->min.x = BGLONG(a+0*4);
678 	r->min.y = BGLONG(a+1*4);
679 	r->max.x = BGLONG(a+2*4);
680 	r->max.y = BGLONG(a+3*4);
681 }
682 
683 static
684 void
685 drawpoint(Point *p, uchar *a)
686 {
687 	p->x = BGLONG(a+0*4);
688 	p->y = BGLONG(a+1*4);
689 }
690 
691 static
692 Point
693 drawchar(Memimage *dst, Point p, Memimage *src, Point *sp, DImage *font, int index, int op)
694 {
695 	FChar *fc;
696 	Rectangle r;
697 	Point sp1;
698 
699 	fc = &font->fchar[index];
700 	r.min.x = p.x+fc->left;
701 	r.min.y = p.y-(font->ascent-fc->miny);
702 	r.max.x = r.min.x+(fc->maxx-fc->minx);
703 	r.max.y = r.min.y+(fc->maxy-fc->miny);
704 	sp1.x = sp->x+fc->left;
705 	sp1.y = sp->y+fc->miny;
706 	memdraw(dst, r, src, sp1, font->image, Pt(fc->minx, fc->miny), op);
707 	p.x += fc->width;
708 	sp->x += fc->width;
709 	return p;
710 }
711 
712 static
713 uchar*
714 drawcoord(uchar *p, uchar *maxp, int oldx, int *newx)
715 {
716 	int b, x;
717 
718 	if(p >= maxp)
719 		return nil;
720 	b = *p++;
721 	x = b & 0x7F;
722 	if(b & 0x80){
723 		if(p+1 >= maxp)
724 			return nil;
725 		x |= *p++ << 7;
726 		x |= *p++ << 15;
727 		if(x & (1<<22))
728 			x |= ~0<<23;
729 	}else{
730 		if(b & 0x40)
731 			x |= ~0<<7;
732 		x += oldx;
733 	}
734 	*newx = x;
735 	return p;
736 }
737 
738 int
739 _drawmsgread(void *a, int n)
740 {
741 	Client *cl;
742 
743 	qlock(&sdraw.lk);
744 	cl = client0;
745 	if(cl->readdata == nil){
746 		werrstr("no draw data");
747 		goto err;
748 	}
749 	if(n < cl->nreaddata){
750 		werrstr("short read");
751 		goto err;
752 	}
753 	n = cl->nreaddata;
754 	memmove(a, cl->readdata, cl->nreaddata);
755 	free(cl->readdata);
756 	cl->readdata = nil;
757 	qunlock(&sdraw.lk);
758 	return n;
759 
760 err:
761 	qunlock(&sdraw.lk);
762 	return -1;
763 }
764 
765 int
766 _drawmsgwrite(void *v, int n)
767 {
768 	char cbuf[40], *err, ibuf[12*12+1], *s;
769 	int c, ci, doflush, dstid, e0, e1, esize, j, m;
770 	int ni, nw, oesize, oldn, op, ox, oy, repl, scrnid, y; 
771 	uchar *a, refresh, *u;
772 	u32int chan, value;
773 	Client *client;
774 	CScreen *cs;
775 	DImage *di, *ddst, *dsrc, *font, *ll;
776 	DName *dn;
777 	DScreen *dscrn;
778 	FChar *fc;
779 	Memimage *dst, *i, *l, **lp, *mask, *src;
780 	Memscreen *scrn;
781 	Point p, *pp, q, sp;
782 	Rectangle clipr, r;
783 	Refreshfn reffn;
784 	Refx *refx;
785 
786 	qlock(&sdraw.lk);
787 	a = v;
788 	m = 0;
789 	oldn = n;
790 	client = client0;
791 
792 	while((n-=m) > 0){
793 		a += m;
794 /*fprint(2, "msgwrite %d(%d)...", n, *a); */
795 		switch(*a){
796 		default:
797 /*fprint(2, "bad command %d\n", *a); */
798 			err = "bad draw command";
799 			goto error;
800 
801 		/* allocate: 'b' id[4] screenid[4] refresh[1] chan[4] repl[1]
802 			R[4*4] clipR[4*4] rrggbbaa[4]
803 		 */
804 		case 'b':
805 			m = 1+4+4+1+4+1+4*4+4*4+4;
806 			if(n < m)
807 				goto Eshortdraw;
808 			dstid = BGLONG(a+1);
809 			scrnid = BGSHORT(a+5);
810 			refresh = a[9];
811 			chan = BGLONG(a+10);
812 			repl = a[14];
813 			drawrectangle(&r, a+15);
814 			drawrectangle(&clipr, a+31);
815 			value = BGLONG(a+47);
816 			if(drawlookup(client, dstid, 0))
817 				goto Eimageexists;
818 			if(scrnid){
819 				dscrn = drawlookupscreen(client, scrnid, &cs);
820 				if(!dscrn)
821 					goto Enodrawscreen;
822 				scrn = dscrn->screen;
823 				if(repl || chan!=scrn->image->chan){
824 					err = "image parameters incompatibile with screen";
825 					goto error;
826 				}
827 				reffn = 0;
828 				switch(refresh){
829 				case Refbackup:
830 					break;
831 				case Refnone:
832 					reffn = memlnorefresh;
833 					break;
834 				case Refmesg:
835 					reffn = drawrefresh;
836 					break;
837 				default:
838 					err = "unknown refresh method";
839 					goto error;
840 				}
841 				l = memlalloc(scrn, r, reffn, 0, value);
842 				if(l == 0)
843 					goto Edrawmem;
844 				addflush(l->layer->screenr);
845 				l->clipr = clipr;
846 				rectclip(&l->clipr, r);
847 				if(drawinstall(client, dstid, l, dscrn) == 0){
848 					memldelete(l);
849 					goto Edrawmem;
850 				}
851 				dscrn->ref++;
852 				if(reffn){
853 					refx = nil;
854 					if(reffn == drawrefresh){
855 						refx = mallocz(sizeof(Refx), 1);
856 						if(refx == 0){
857 							if(drawuninstall(client, dstid) < 0)
858 								goto Enodrawimage;
859 							goto Edrawmem;
860 						}
861 						refx->client = client;
862 						refx->dimage = drawlookup(client, dstid, 1);
863 					}
864 					memlsetrefresh(l, reffn, refx);
865 				}
866 				continue;
867 			}
868 			i = allocmemimage(r, chan);
869 			if(i == 0)
870 				goto Edrawmem;
871 			if(repl)
872 				i->flags |= Frepl;
873 			i->clipr = clipr;
874 			if(!repl)
875 				rectclip(&i->clipr, r);
876 			if(drawinstall(client, dstid, i, 0) == 0){
877 				freememimage(i);
878 				goto Edrawmem;
879 			}
880 			memfillcolor(i, value);
881 			continue;
882 
883 		/* allocate screen: 'A' id[4] imageid[4] fillid[4] public[1] */
884 		case 'A':
885 			m = 1+4+4+4+1;
886 			if(n < m)
887 				goto Eshortdraw;
888 			dstid = BGLONG(a+1);
889 			if(dstid == 0)
890 				goto Ebadarg;
891 			if(drawlookupdscreen(dstid))
892 				goto Escreenexists;
893 			ddst = drawlookup(client, BGLONG(a+5), 1);
894 			dsrc = drawlookup(client, BGLONG(a+9), 1);
895 			if(ddst==0 || dsrc==0)
896 				goto Enodrawimage;
897 			if(drawinstallscreen(client, 0, dstid, ddst, dsrc, a[13]) == 0)
898 				goto Edrawmem;
899 			continue;
900 
901 		/* set repl and clip: 'c' dstid[4] repl[1] clipR[4*4] */
902 		case 'c':
903 			m = 1+4+1+4*4;
904 			if(n < m)
905 				goto Eshortdraw;
906 			ddst = drawlookup(client, BGLONG(a+1), 1);
907 			if(ddst == nil)
908 				goto Enodrawimage;
909 			if(ddst->name){
910 				err = "can't change repl/clipr of shared image";
911 				goto error;
912 			}
913 			dst = ddst->image;
914 			if(a[5])
915 				dst->flags |= Frepl;
916 			drawrectangle(&dst->clipr, a+6);
917 			continue;
918 
919 		/* draw: 'd' dstid[4] srcid[4] maskid[4] R[4*4] P[2*4] P[2*4] */
920 		case 'd':
921 			m = 1+4+4+4+4*4+2*4+2*4;
922 			if(n < m)
923 				goto Eshortdraw;
924 			dst = drawimage(client, a+1);
925 			dstid = BGLONG(a+1);
926 			src = drawimage(client, a+5);
927 			mask = drawimage(client, a+9);
928 			if(!dst || !src || !mask)
929 				goto Enodrawimage;
930 			drawrectangle(&r, a+13);
931 			drawpoint(&p, a+29);
932 			drawpoint(&q, a+37);
933 			op = drawclientop(client);
934 			memdraw(dst, r, src, p, mask, q, op);
935 			dstflush(dstid, dst, r);
936 			continue;
937 
938 		/* toggle debugging: 'D' val[1] */
939 		case 'D':
940 			m = 1+1;
941 			if(n < m)
942 				goto Eshortdraw;
943 			drawdebug = a[1];
944 			continue;
945 
946 		/* ellipse: 'e' dstid[4] srcid[4] center[2*4] a[4] b[4] thick[4] sp[2*4] alpha[4] phi[4]*/
947 		case 'e':
948 		case 'E':
949 			m = 1+4+4+2*4+4+4+4+2*4+2*4;
950 			if(n < m)
951 				goto Eshortdraw;
952 			dst = drawimage(client, a+1);
953 			dstid = BGLONG(a+1);
954 			src = drawimage(client, a+5);
955 			if(!dst || !src)
956 				goto Enodrawimage;
957 			drawpoint(&p, a+9);
958 			e0 = BGLONG(a+17);
959 			e1 = BGLONG(a+21);
960 			if(e0<0 || e1<0){
961 				err = "invalid ellipse semidiameter";
962 				goto error;
963 			}
964 			j = BGLONG(a+25);
965 			if(j < 0){
966 				err = "negative ellipse thickness";
967 				goto error;
968 			}
969 			
970 			drawpoint(&sp, a+29);
971 			c = j;
972 			if(*a == 'E')
973 				c = -1;
974 			ox = BGLONG(a+37);
975 			oy = BGLONG(a+41);
976 			op = drawclientop(client);
977 			/* high bit indicates arc angles are present */
978 			if(ox & ((ulong)1<<31)){
979 				if((ox & ((ulong)1<<30)) == 0)
980 					ox &= ~((ulong)1<<31);
981 				memarc(dst, p, e0, e1, c, src, sp, ox, oy, op);
982 			}else
983 				memellipse(dst, p, e0, e1, c, src, sp, op);
984 			dstflush(dstid, dst, Rect(p.x-e0-j, p.y-e1-j, p.x+e0+j+1, p.y+e1+j+1));
985 			continue;
986 
987 		/* free: 'f' id[4] */
988 		case 'f':
989 			m = 1+4;
990 			if(n < m)
991 				goto Eshortdraw;
992 			ll = drawlookup(client, BGLONG(a+1), 0);
993 			if(ll && ll->dscreen && ll->dscreen->owner != client)
994 				ll->dscreen->owner->refreshme = 1;
995 			if(drawuninstall(client, BGLONG(a+1)) < 0)
996 				goto Enodrawimage;
997 			continue;
998 
999 		/* free screen: 'F' id[4] */
1000 		case 'F':
1001 			m = 1+4;
1002 			if(n < m)
1003 				goto Eshortdraw;
1004 			if(!drawlookupscreen(client, BGLONG(a+1), &cs))
1005 				goto Enodrawscreen;
1006 			drawuninstallscreen(client, cs);
1007 			continue;
1008 
1009 		/* initialize font: 'i' fontid[4] nchars[4] ascent[1] */
1010 		case 'i':
1011 			m = 1+4+4+1;
1012 			if(n < m)
1013 				goto Eshortdraw;
1014 			dstid = BGLONG(a+1);
1015 			if(dstid == 0){
1016 				err = "can't use display as font";
1017 				goto error;
1018 			}
1019 			font = drawlookup(client, dstid, 1);
1020 			if(font == 0)
1021 				goto Enodrawimage;
1022 			if(font->image->layer){
1023 				err = "can't use window as font";
1024 				goto error;
1025 			}
1026 			ni = BGLONG(a+5);
1027 			if(ni<=0 || ni>4096){
1028 				err = "bad font size (4096 chars max)";
1029 				goto error;
1030 			}
1031 			free(font->fchar);	/* should we complain if non-zero? */
1032 			font->fchar = mallocz(ni*sizeof(FChar), 1);
1033 			if(font->fchar == 0){
1034 				err = "no memory for font";
1035 				goto error;
1036 			}
1037 			memset(font->fchar, 0, ni*sizeof(FChar));
1038 			font->nfchar = ni;
1039 			font->ascent = a[9];
1040 			continue;
1041 
1042 		/* set image 0 to screen image */
1043 		case 'J':
1044 			m = 1;
1045 			if(n < m)
1046 				goto Eshortdraw;
1047 			if(drawlookup(client, 0, 0))
1048 				goto Eimageexists;
1049 			drawinstall(client, 0, screenimage, 0);
1050 			client->infoid = 0;
1051 			continue;
1052 
1053 		/* get image info: 'I' */
1054 		case 'I':
1055 			m = 1;
1056 			if(n < m)
1057 				goto Eshortdraw;
1058 			if(client->infoid < 0)
1059 				goto Enodrawimage;
1060 			if(client->infoid == 0){
1061 				i = screenimage;
1062 				if(i == nil)
1063 					goto Enodrawimage;
1064 			}else{
1065 				di = drawlookup(client, client->infoid, 1);
1066 				if(di == nil)
1067 					goto Enodrawimage;
1068 				i = di->image;
1069 			}
1070 			ni = sprint(ibuf, "%11d %11d %11s %11d %11d %11d %11d %11d"
1071 					" %11d %11d %11d %11d ",
1072 					client->clientid,
1073 					client->infoid,	
1074 					chantostr(cbuf, i->chan),
1075 					(i->flags&Frepl)==Frepl,
1076 					i->r.min.x, i->r.min.y, i->r.max.x, i->r.max.y,
1077 					i->clipr.min.x, i->clipr.min.y, 
1078 					i->clipr.max.x, i->clipr.max.y);
1079 			free(client->readdata);
1080 			client->readdata = malloc(ni);
1081 			if(client->readdata == nil)
1082 				goto Enomem;
1083 			memmove(client->readdata, ibuf, ni);
1084 			client->nreaddata = ni;
1085 			client->infoid = -1;
1086 			continue;	
1087 
1088 		/* load character: 'l' fontid[4] srcid[4] index[2] R[4*4] P[2*4] left[1] width[1] */
1089 		case 'l':
1090 			m = 1+4+4+2+4*4+2*4+1+1;
1091 			if(n < m)
1092 				goto Eshortdraw;
1093 			font = drawlookup(client, BGLONG(a+1), 1);
1094 			if(font == 0)
1095 				goto Enodrawimage;
1096 			if(font->nfchar == 0)
1097 				goto Enotfont;
1098 			src = drawimage(client, a+5);
1099 			if(!src)
1100 				goto Enodrawimage;
1101 			ci = BGSHORT(a+9);
1102 			if(ci >= font->nfchar)
1103 				goto Eindex;
1104 			drawrectangle(&r, a+11);
1105 			drawpoint(&p, a+27);
1106 			memdraw(font->image, r, src, p, memopaque, p, S);
1107 			fc = &font->fchar[ci];
1108 			fc->minx = r.min.x;
1109 			fc->maxx = r.max.x;
1110 			fc->miny = r.min.y;
1111 			fc->maxy = r.max.y;
1112 			fc->left = a[35];
1113 			fc->width = a[36];
1114 			continue;
1115 
1116 		/* draw line: 'L' dstid[4] p0[2*4] p1[2*4] end0[4] end1[4] radius[4] srcid[4] sp[2*4] */
1117 		case 'L':
1118 			m = 1+4+2*4+2*4+4+4+4+4+2*4;
1119 			if(n < m)
1120 				goto Eshortdraw;
1121 			dst = drawimage(client, a+1);
1122 			dstid = BGLONG(a+1);
1123 			drawpoint(&p, a+5);
1124 			drawpoint(&q, a+13);
1125 			e0 = BGLONG(a+21);
1126 			e1 = BGLONG(a+25);
1127 			j = BGLONG(a+29);
1128 			if(j < 0){
1129 				err = "negative line width";
1130 				goto error;
1131 			}
1132 			src = drawimage(client, a+33);
1133 			if(!dst || !src)
1134 				goto Enodrawimage;
1135 			drawpoint(&sp, a+37);
1136 			op = drawclientop(client);
1137 			memline(dst, p, q, e0, e1, j, src, sp, op);
1138 			/* avoid memlinebbox if possible */
1139 			if(dstid==0 || dst->layer!=nil){
1140 				/* BUG: this is terribly inefficient: update maximal containing rect*/
1141 				r = memlinebbox(p, q, e0, e1, j);
1142 				dstflush(dstid, dst, insetrect(r, -(1+1+j)));
1143 			}
1144 			continue;
1145 
1146 		/* create image mask: 'm' newid[4] id[4] */
1147 /*
1148  *
1149 		case 'm':
1150 			m = 4+4;
1151 			if(n < m)
1152 				goto Eshortdraw;
1153 			break;
1154  *
1155  */
1156 
1157 		/* attach to a named image: 'n' dstid[4] j[1] name[j] */
1158 		case 'n':
1159 			m = 1+4+1;
1160 			if(n < m)
1161 				goto Eshortdraw;
1162 			j = a[5];
1163 			if(j == 0)	/* give me a non-empty name please */
1164 				goto Eshortdraw;
1165 			m += j;
1166 			if(n < m)
1167 				goto Eshortdraw;
1168 			dstid = BGLONG(a+1);
1169 			if(drawlookup(client, dstid, 0))
1170 				goto Eimageexists;
1171 			dn = drawlookupname(j, (char*)a+6);
1172 			if(dn == nil)
1173 				goto Enoname;
1174 			s = malloc(j+1);
1175 			if(s == nil)
1176 				goto Enomem;
1177 			if(drawinstall(client, dstid, dn->dimage->image, 0) == 0)
1178 				goto Edrawmem;
1179 			di = drawlookup(client, dstid, 0);
1180 			if(di == 0)
1181 				goto Eoldname;
1182 			di->vers = dn->vers;
1183 			di->name = s;
1184 			di->fromname = dn->dimage;
1185 			di->fromname->ref++;
1186 			memmove(di->name, a+6, j);
1187 			di->name[j] = 0;
1188 			client->infoid = dstid;
1189 			continue;
1190 
1191 		/* name an image: 'N' dstid[4] in[1] j[1] name[j] */
1192 		case 'N':
1193 			m = 1+4+1+1;
1194 			if(n < m)
1195 				goto Eshortdraw;
1196 			c = a[5];
1197 			j = a[6];
1198 			if(j == 0)	/* give me a non-empty name please */
1199 				goto Eshortdraw;
1200 			m += j;
1201 			if(n < m)
1202 				goto Eshortdraw;
1203 			di = drawlookup(client, BGLONG(a+1), 0);
1204 			if(di == 0)
1205 				goto Enodrawimage;
1206 			if(di->name)
1207 				goto Enamed;
1208 			if(c)
1209 				if(drawaddname(client, di, j, (char*)a+7, &err) < 0)
1210 					goto error;
1211 			else{
1212 				dn = drawlookupname(j, (char*)a+7);
1213 				if(dn == nil)
1214 					goto Enoname;
1215 				if(dn->dimage != di)
1216 					goto Ewrongname;
1217 				drawdelname(dn);
1218 			}
1219 			continue;
1220 
1221 		/* position window: 'o' id[4] r.min [2*4] screenr.min [2*4] */
1222 		case 'o':
1223 			m = 1+4+2*4+2*4;
1224 			if(n < m)
1225 				goto Eshortdraw;
1226 			dst = drawimage(client, a+1);
1227 			if(!dst)
1228 				goto Enodrawimage;
1229 			if(dst->layer){
1230 				drawpoint(&p, a+5);
1231 				drawpoint(&q, a+13);
1232 				r = dst->layer->screenr;
1233 				ni = memlorigin(dst, p, q);
1234 				if(ni < 0){
1235 					err = "image origin failed";
1236 					goto error;
1237 				}
1238 				if(ni > 0){
1239 					addflush(r);
1240 					addflush(dst->layer->screenr);
1241 					ll = drawlookup(client, BGLONG(a+1), 1);
1242 					drawrefreshscreen(ll, client);
1243 				}
1244 			}
1245 			continue;
1246 
1247 		/* set compositing operator for next draw operation: 'O' op */
1248 		case 'O':
1249 			m = 1+1;
1250 			if(n < m)
1251 				goto Eshortdraw;
1252 			client->op = a[1];
1253 			continue;
1254 
1255 		/* filled polygon: 'P' dstid[4] n[2] wind[4] ignore[2*4] srcid[4] sp[2*4] p0[2*4] dp[2*2*n] */
1256 		/* polygon: 'p' dstid[4] n[2] end0[4] end1[4] radius[4] srcid[4] sp[2*4] p0[2*4] dp[2*2*n] */
1257 		case 'p':
1258 		case 'P':
1259 			m = 1+4+2+4+4+4+4+2*4;
1260 			if(n < m)
1261 				goto Eshortdraw;
1262 			dstid = BGLONG(a+1);
1263 			dst = drawimage(client, a+1);
1264 			ni = BGSHORT(a+5);
1265 			if(ni < 0){
1266 				err = "negative cout in polygon";
1267 				goto error;
1268 			}
1269 			e0 = BGLONG(a+7);
1270 			e1 = BGLONG(a+11);
1271 			j = 0;
1272 			if(*a == 'p'){
1273 				j = BGLONG(a+15);
1274 				if(j < 0){
1275 					err = "negative polygon line width";
1276 					goto error;
1277 				}
1278 			}
1279 			src = drawimage(client, a+19);
1280 			if(!dst || !src)
1281 				goto Enodrawimage;
1282 			drawpoint(&sp, a+23);
1283 			drawpoint(&p, a+31);
1284 			ni++;
1285 			pp = mallocz(ni*sizeof(Point), 1);
1286 			if(pp == nil)
1287 				goto Enomem;
1288 			doflush = 0;
1289 			if(dstid==0 || (dst->layer && dst->layer->screen->image->data == screenimage->data))
1290 				doflush = 1;	/* simplify test in loop */
1291 			ox = oy = 0;
1292 			esize = 0;
1293 			u = a+m;
1294 			for(y=0; y<ni; y++){
1295 				q = p;
1296 				oesize = esize;
1297 				u = drawcoord(u, a+n, ox, &p.x);
1298 				if(!u)
1299 					goto Eshortdraw;
1300 				u = drawcoord(u, a+n, oy, &p.y);
1301 				if(!u)
1302 					goto Eshortdraw;
1303 				ox = p.x;
1304 				oy = p.y;
1305 				if(doflush){
1306 					esize = j;
1307 					if(*a == 'p'){
1308 						if(y == 0){
1309 							c = memlineendsize(e0);
1310 							if(c > esize)
1311 								esize = c;
1312 						}
1313 						if(y == ni-1){
1314 							c = memlineendsize(e1);
1315 							if(c > esize)
1316 								esize = c;
1317 						}
1318 					}
1319 					if(*a=='P' && e0!=1 && e0 !=~0)
1320 						r = dst->clipr;
1321 					else if(y > 0){
1322 						r = Rect(q.x-oesize, q.y-oesize, q.x+oesize+1, q.y+oesize+1);
1323 						combinerect(&r, Rect(p.x-esize, p.y-esize, p.x+esize+1, p.y+esize+1));
1324 					}
1325 					if(rectclip(&r, dst->clipr))		/* should perhaps be an arg to dstflush */
1326 						dstflush(dstid, dst, r);
1327 				}
1328 				pp[y] = p;
1329 			}
1330 			if(y == 1)
1331 				dstflush(dstid, dst, Rect(p.x-esize, p.y-esize, p.x+esize+1, p.y+esize+1));
1332 			op = drawclientop(client);
1333 			if(*a == 'p')
1334 				mempoly(dst, pp, ni, e0, e1, j, src, sp, op);
1335 			else
1336 				memfillpoly(dst, pp, ni, e0, src, sp, op);
1337 			free(pp);
1338 			m = u-a;
1339 			continue;
1340 
1341 		/* read: 'r' id[4] R[4*4] */
1342 		case 'r':
1343 			m = 1+4+4*4;
1344 			if(n < m)
1345 				goto Eshortdraw;
1346 			i = drawimage(client, a+1);
1347 			if(!i)
1348 				goto Enodrawimage;
1349 			drawrectangle(&r, a+5);
1350 			if(!rectinrect(r, i->r))
1351 				goto Ereadoutside;
1352 			c = bytesperline(r, i->depth);
1353 			c *= Dy(r);
1354 			free(client->readdata);
1355 			client->readdata = mallocz(c, 0);
1356 			if(client->readdata == nil){
1357 				err = "readimage malloc failed";
1358 				goto error;
1359 			}
1360 			client->nreaddata = memunload(i, r, client->readdata, c);
1361 			if(client->nreaddata < 0){
1362 				free(client->readdata);
1363 				client->readdata = nil;
1364 				err = "bad readimage call";
1365 				goto error;
1366 			}
1367 			continue;
1368 
1369 		/* string: 's' dstid[4] srcid[4] fontid[4] P[2*4] clipr[4*4] sp[2*4] ni[2] ni*(index[2]) */
1370 		/* stringbg: 'x' dstid[4] srcid[4] fontid[4] P[2*4] clipr[4*4] sp[2*4] ni[2] bgid[4] bgpt[2*4] ni*(index[2]) */
1371 		case 's':
1372 		case 'x':
1373 			m = 1+4+4+4+2*4+4*4+2*4+2;
1374 			if(*a == 'x')
1375 				m += 4+2*4;
1376 			if(n < m)
1377 				goto Eshortdraw;
1378 
1379 			dst = drawimage(client, a+1);
1380 			dstid = BGLONG(a+1);
1381 			src = drawimage(client, a+5);
1382 			if(!dst || !src)
1383 				goto Enodrawimage;
1384 			font = drawlookup(client, BGLONG(a+9), 1);
1385 			if(font == 0)
1386 				goto Enodrawimage;
1387 			if(font->nfchar == 0)
1388 				goto Enotfont;
1389 			drawpoint(&p, a+13);
1390 			drawrectangle(&r, a+21);
1391 			drawpoint(&sp, a+37);
1392 			ni = BGSHORT(a+45);
1393 			u = a+m;
1394 			m += ni*2;
1395 			if(n < m)
1396 				goto Eshortdraw;
1397 			clipr = dst->clipr;
1398 			dst->clipr = r;
1399 			op = drawclientop(client);
1400 			if(*a == 'x'){
1401 				/* paint background */
1402 				l = drawimage(client, a+47);
1403 				if(!l)
1404 					goto Enodrawimage;
1405 				drawpoint(&q, a+51);
1406 				r.min.x = p.x;
1407 				r.min.y = p.y-font->ascent;
1408 				r.max.x = p.x;
1409 				r.max.y = r.min.y+Dy(font->image->r);
1410 				j = ni;
1411 				while(--j >= 0){
1412 					ci = BGSHORT(u);
1413 					if(ci<0 || ci>=font->nfchar){
1414 						dst->clipr = clipr;
1415 						goto Eindex;
1416 					}
1417 					r.max.x += font->fchar[ci].width;
1418 					u += 2;
1419 				}
1420 				memdraw(dst, r, l, q, memopaque, ZP, op);
1421 				u -= 2*ni;
1422 			}
1423 			q = p;
1424 			while(--ni >= 0){
1425 				ci = BGSHORT(u);
1426 				if(ci<0 || ci>=font->nfchar){
1427 					dst->clipr = clipr;
1428 					goto Eindex;
1429 				}
1430 				q = drawchar(dst, q, src, &sp, font, ci, op);
1431 				u += 2;
1432 			}
1433 			dst->clipr = clipr;
1434 			p.y -= font->ascent;
1435 			dstflush(dstid, dst, Rect(p.x, p.y, q.x, p.y+Dy(font->image->r)));
1436 			continue;
1437 
1438 		/* use public screen: 'S' id[4] chan[4] */
1439 		case 'S':
1440 			m = 1+4+4;
1441 			if(n < m)
1442 				goto Eshortdraw;
1443 			dstid = BGLONG(a+1);
1444 			if(dstid == 0)
1445 				goto Ebadarg;
1446 			dscrn = drawlookupdscreen(dstid);
1447 			if(dscrn==0 || (dscrn->public==0 && dscrn->owner!=client))
1448 				goto Enodrawscreen;
1449 			if(dscrn->screen->image->chan != BGLONG(a+5)){
1450 				err = "inconsistent chan";
1451 				goto error;
1452 			}
1453 			if(drawinstallscreen(client, dscrn, 0, 0, 0, 0) == 0)
1454 				goto Edrawmem;
1455 			continue;
1456 
1457 		/* top or bottom windows: 't' top[1] nw[2] n*id[4] */
1458 		case 't':
1459 			m = 1+1+2;
1460 			if(n < m)
1461 				goto Eshortdraw;
1462 			nw = BGSHORT(a+2);
1463 			if(nw < 0)
1464 				goto Ebadarg;
1465 			if(nw == 0)
1466 				continue;
1467 			m += nw*4;
1468 			if(n < m)
1469 				goto Eshortdraw;
1470 			lp = mallocz(nw*sizeof(Memimage*), 1);
1471 			if(lp == 0)
1472 				goto Enomem;
1473 			for(j=0; j<nw; j++){
1474 				lp[j] = drawimage(client, a+1+1+2+j*4);
1475 				if(lp[j] == nil){
1476 					free(lp);
1477 					goto Enodrawimage;
1478 				}
1479 			}
1480 			if(lp[0]->layer == 0){
1481 				err = "images are not windows";
1482 				free(lp);
1483 				goto error;
1484 			}
1485 			for(j=1; j<nw; j++)
1486 				if(lp[j]->layer->screen != lp[0]->layer->screen){
1487 					err = "images not on same screen";
1488 					free(lp);
1489 					goto error;
1490 				}
1491 			if(a[1])
1492 				memltofrontn(lp, nw);
1493 			else
1494 				memltorearn(lp, nw);
1495 			if(lp[0]->layer->screen->image->data == screenimage->data)
1496 				for(j=0; j<nw; j++)
1497 					addflush(lp[j]->layer->screenr);
1498 			free(lp);
1499 			ll = drawlookup(client, BGLONG(a+1+1+2), 1);
1500 			drawrefreshscreen(ll, client);
1501 			continue;
1502 
1503 		/* visible: 'v' */
1504 		case 'v':
1505 			m = 1;
1506 			drawflush();
1507 			continue;
1508 
1509 		/* write: 'y' id[4] R[4*4] data[x*1] */
1510 		/* write from compressed data: 'Y' id[4] R[4*4] data[x*1] */
1511 		case 'y':
1512 		case 'Y':
1513 			m = 1+4+4*4;
1514 			if(n < m)
1515 				goto Eshortdraw;
1516 			dstid = BGLONG(a+1);
1517 			dst = drawimage(client, a+1);
1518 			if(!dst)
1519 				goto Enodrawimage;
1520 			drawrectangle(&r, a+5);
1521 			if(!rectinrect(r, dst->r))
1522 				goto Ewriteoutside;
1523 			y = memload(dst, r, a+m, n-m, *a=='Y');
1524 			if(y < 0){
1525 				err = "bad writeimage call";
1526 				goto error;
1527 			}
1528 			dstflush(dstid, dst, r);
1529 			m += y;
1530 			continue;
1531 		}
1532 	}
1533 	qunlock(&sdraw.lk);
1534 	return oldn - n;
1535 
1536 Enodrawimage:
1537 	err = "unknown id for draw image";
1538 	goto error;
1539 Enodrawscreen:
1540 	err = "unknown id for draw screen";
1541 	goto error;
1542 Eshortdraw:
1543 	err = "short draw message";
1544 	goto error;
1545 /*
1546 Eshortread:
1547 	err = "draw read too short";
1548 	goto error;
1549 */
1550 Eimageexists:
1551 	err = "image id in use";
1552 	goto error;
1553 Escreenexists:
1554 	err = "screen id in use";
1555 	goto error;
1556 Edrawmem:
1557 	err = "image memory allocation failed";
1558 	goto error;
1559 Ereadoutside:
1560 	err = "readimage outside image";
1561 	goto error;
1562 Ewriteoutside:
1563 	err = "writeimage outside image";
1564 	goto error;
1565 Enotfont:
1566 	err = "image not a font";
1567 	goto error;
1568 Eindex:
1569 	err = "character index out of range";
1570 	goto error;
1571 /*
1572 Enoclient:
1573 	err = "no such draw client";
1574 	goto error;
1575 Edepth:
1576 	err = "image has bad depth";
1577 	goto error;
1578 Enameused:
1579 	err = "image name in use";
1580 	goto error;
1581 */
1582 Enoname:
1583 	err = "no image with that name";
1584 	goto error;
1585 Eoldname:
1586 	err = "named image no longer valid";
1587 	goto error;
1588 Enamed:
1589 	err = "image already has name";
1590 	goto error;
1591 Ewrongname:
1592 	err = "wrong name for image";
1593 	goto error;
1594 Enomem:
1595 	err = "out of memory";
1596 	goto error;
1597 Ebadarg:
1598 	err = "bad argument in draw message";
1599 	goto error;
1600 
1601 error:
1602 	werrstr("%s", err);
1603 	qunlock(&sdraw.lk);
1604 	return -1;
1605 }
1606 
1607