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 	_flushmemscreen(flushrect);
298 	flushrect = Rect(10000, 10000, -10000, -10000);
299 }
300 
301 void
302 xdrawflush(void)
303 {
304 	qlock(&sdraw.lk);
305 	drawflush();
306 	qunlock(&sdraw.lk);
307 }
308 
309 static
310 int
311 drawcmp(char *a, char *b, int n)
312 {
313 	if(strlen(a) != n)
314 		return 1;
315 	return memcmp(a, b, n);
316 }
317 
318 static
319 DName*
320 drawlookupname(int n, char *str)
321 {
322 	DName *name, *ename;
323 
324 	name = sdraw.name;
325 	ename = &name[sdraw.nname];
326 	for(; name<ename; name++)
327 		if(drawcmp(name->name, str, n) == 0)
328 			return name;
329 	return 0;
330 }
331 
332 static
333 int
334 drawgoodname(DImage *d)
335 {
336 	DName *n;
337 
338 	/* if window, validate the screen's own images */
339 	if(d->dscreen)
340 		if(drawgoodname(d->dscreen->dimage) == 0
341 		|| drawgoodname(d->dscreen->dfill) == 0)
342 			return 0;
343 	if(d->name == nil)
344 		return 1;
345 	n = drawlookupname(strlen(d->name), d->name);
346 	if(n==nil || n->vers!=d->vers)
347 		return 0;
348 	return 1;
349 }
350 
351 static
352 DImage*
353 drawlookup(Client *client, int id, int checkname)
354 {
355 	DImage *d;
356 
357 	d = client->dimage[id&HASHMASK];
358 	while(d){
359 		if(d->id == id){
360 			/*
361 			 * BUG: should error out but too hard.
362 			 * Return 0 instead.
363 			 */
364 			if(checkname && !drawgoodname(d))
365 				return 0;
366 			return d;
367 		}
368 		d = d->next;
369 	}
370 	return 0;
371 }
372 
373 static
374 DScreen*
375 drawlookupdscreen(int id)
376 {
377 	DScreen *s;
378 
379 	s = dscreen;
380 	while(s){
381 		if(s->id == id)
382 			return s;
383 		s = s->next;
384 	}
385 	return 0;
386 }
387 
388 static
389 DScreen*
390 drawlookupscreen(Client *client, int id, CScreen **cs)
391 {
392 	CScreen *s;
393 
394 	s = client->cscreen;
395 	while(s){
396 		if(s->dscreen->id == id){
397 			*cs = s;
398 			return s->dscreen;
399 		}
400 		s = s->next;
401 	}
402 	/* caller must check! */
403 	return 0;
404 }
405 
406 static
407 Memimage*
408 drawinstall(Client *client, int id, Memimage *i, DScreen *dscreen)
409 {
410 	DImage *d;
411 
412 	d = mallocz(sizeof(DImage), 1);
413 	if(d == 0)
414 		return 0;
415 	d->id = id;
416 	d->ref = 1;
417 	d->name = 0;
418 	d->vers = 0;
419 	d->image = i;
420 	if(i->screenref)
421 		++i->screenref;
422 	d->nfchar = 0;
423 	d->fchar = 0;
424 	d->fromname = 0;
425 	d->dscreen = dscreen;
426 	d->next = client->dimage[id&HASHMASK];
427 	client->dimage[id&HASHMASK] = d;
428 	return i;
429 }
430 
431 static
432 Memscreen*
433 drawinstallscreen(Client *client, DScreen *d, int id, DImage *dimage, DImage *dfill, int public)
434 {
435 	Memscreen *s;
436 	CScreen *c;
437 
438 	c = mallocz(sizeof(CScreen), 1);
439 	if(dimage && dimage->image && dimage->image->chan == 0){
440 		fprint(2, "bad image %p in drawinstallscreen", dimage->image);
441 		abort();
442 	}
443 
444 	if(c == 0)
445 		return 0;
446 	if(d == 0){
447 		d = mallocz(sizeof(DScreen), 1);
448 		if(d == 0){
449 			free(c);
450 			return 0;
451 		}
452 		s = mallocz(sizeof(Memscreen), 1);
453 		if(s == 0){
454 			free(c);
455 			free(d);
456 			return 0;
457 		}
458 		s->frontmost = 0;
459 		s->rearmost = 0;
460 		d->dimage = dimage;
461 		if(dimage){
462 			s->image = dimage->image;
463 			dimage->ref++;
464 		}
465 		d->dfill = dfill;
466 		if(dfill){
467 			s->fill = dfill->image;
468 			dfill->ref++;
469 		}
470 		d->ref = 0;
471 		d->id = id;
472 		d->screen = s;
473 		d->public = public;
474 		d->next = dscreen;
475 		d->owner = client;
476 		dscreen = d;
477 	}
478 	c->dscreen = d;
479 	d->ref++;
480 	c->next = client->cscreen;
481 	client->cscreen = c;
482 	return d->screen;
483 }
484 
485 static
486 void
487 drawdelname(DName *name)
488 {
489 	int i;
490 
491 	i = name-sdraw.name;
492 	memmove(name, name+1, (sdraw.nname-(i+1))*sizeof(DName));
493 	sdraw.nname--;
494 }
495 
496 static
497 void
498 drawfreedscreen(DScreen *this)
499 {
500 	DScreen *ds, *next;
501 
502 	this->ref--;
503 	if(this->ref < 0)
504 		fprint(2, "negative ref in drawfreedscreen\n");
505 	if(this->ref > 0)
506 		return;
507 	ds = dscreen;
508 	if(ds == this){
509 		dscreen = this->next;
510 		goto Found;
511 	}
512 	while(next = ds->next){	/* assign = */
513 		if(next == this){
514 			ds->next = this->next;
515 			goto Found;
516 		}
517 		ds = next;
518 	}
519 	/*
520 	 * Should signal Enodrawimage, but too hard.
521 	 */
522 	return;
523 
524     Found:
525 	if(this->dimage)
526 		drawfreedimage(this->dimage);
527 	if(this->dfill)
528 		drawfreedimage(this->dfill);
529 	free(this->screen);
530 	free(this);
531 }
532 
533 static
534 void
535 drawfreedimage(DImage *dimage)
536 {
537 	int i;
538 	Memimage *l;
539 	DScreen *ds;
540 
541 	dimage->ref--;
542 	if(dimage->ref < 0)
543 		fprint(2, "negative ref in drawfreedimage\n");
544 	if(dimage->ref > 0)
545 		return;
546 
547 	/* any names? */
548 	for(i=0; i<sdraw.nname; )
549 		if(sdraw.name[i].dimage == dimage)
550 			drawdelname(sdraw.name+i);
551 		else
552 			i++;
553 	if(dimage->fromname){	/* acquired by name; owned by someone else*/
554 		drawfreedimage(dimage->fromname);
555 		goto Return;
556 	}
557 	ds = dimage->dscreen;
558 	l = dimage->image;
559 	dimage->dscreen = nil;	/* paranoia */
560 	dimage->image = nil;
561 	if(ds){
562 		if(l->data == screenimage->data)
563 			addflush(l->layer->screenr);
564 		if(l->layer->refreshfn == drawrefresh)	/* else true owner will clean up */
565 			free(l->layer->refreshptr);
566 		l->layer->refreshptr = nil;
567 		if(drawgoodname(dimage))
568 			memldelete(l);
569 		else
570 			memlfree(l);
571 		drawfreedscreen(ds);
572 	}else{
573 		if(l->screenref==0)
574 			freememimage(l);
575 		else if(--l->screenref==0)
576 			_freememimage(l);
577 	}
578     Return:
579 	free(dimage->fchar);
580 	free(dimage);
581 }
582 
583 static
584 void
585 drawuninstallscreen(Client *client, CScreen *this)
586 {
587 	CScreen *cs, *next;
588 
589 	cs = client->cscreen;
590 	if(cs == this){
591 		client->cscreen = this->next;
592 		drawfreedscreen(this->dscreen);
593 		free(this);
594 		return;
595 	}
596 	while(next = cs->next){	/* assign = */
597 		if(next == this){
598 			cs->next = this->next;
599 			drawfreedscreen(this->dscreen);
600 			free(this);
601 			return;
602 		}
603 		cs = next;
604 	}
605 }
606 
607 static
608 int
609 drawuninstall(Client *client, int id)
610 {
611 	DImage *d, **l;
612 
613 	for(l=&client->dimage[id&HASHMASK]; (d=*l) != nil; l=&d->next){
614 		if(d->id == id){
615 			*l = d->next;
616 			drawfreedimage(d);
617 			return 0;
618 		}
619 	}
620 	return -1;
621 }
622 
623 static
624 int
625 drawaddname(Client *client, DImage *di, int n, char *str, char **err)
626 {
627 	DName *name, *ename, *new, *t;
628 	char *ns;
629 
630 	name = sdraw.name;
631 	ename = &name[sdraw.nname];
632 	for(; name<ename; name++)
633 		if(drawcmp(name->name, str, n) == 0){
634 			*err = "image name in use";
635 			return -1;
636 		}
637 	t = mallocz((sdraw.nname+1)*sizeof(DName), 1);
638 	ns = malloc(n+1);
639 	if(t == nil || ns == nil){
640 		free(t);
641 		free(ns);
642 		*err = "out of memory";
643 		return -1;
644 	}
645 	memmove(t, sdraw.name, sdraw.nname*sizeof(DName));
646 	free(sdraw.name);
647 	sdraw.name = t;
648 	new = &sdraw.name[sdraw.nname++];
649 	new->name = ns;
650 	memmove(new->name, str, n);
651 	new->name[n] = 0;
652 	new->dimage = di;
653 	new->client = client;
654 	new->vers = ++sdraw.vers;
655 	return 0;
656 }
657 
658 static int
659 drawclientop(Client *cl)
660 {
661 	int op;
662 
663 	op = cl->op;
664 	cl->op = SoverD;
665 	return op;
666 }
667 
668 static
669 Memimage*
670 drawimage(Client *client, uchar *a)
671 {
672 	DImage *d;
673 
674 	d = drawlookup(client, BGLONG(a), 1);
675 	if(d == nil)
676 		return nil;	/* caller must check! */
677 	return d->image;
678 }
679 
680 static
681 void
682 drawrectangle(Rectangle *r, uchar *a)
683 {
684 	r->min.x = BGLONG(a+0*4);
685 	r->min.y = BGLONG(a+1*4);
686 	r->max.x = BGLONG(a+2*4);
687 	r->max.y = BGLONG(a+3*4);
688 }
689 
690 static
691 void
692 drawpoint(Point *p, uchar *a)
693 {
694 	p->x = BGLONG(a+0*4);
695 	p->y = BGLONG(a+1*4);
696 }
697 
698 static
699 Point
700 drawchar(Memimage *dst, Point p, Memimage *src, Point *sp, DImage *font, int index, int op)
701 {
702 	FChar *fc;
703 	Rectangle r;
704 	Point sp1;
705 
706 	fc = &font->fchar[index];
707 	r.min.x = p.x+fc->left;
708 	r.min.y = p.y-(font->ascent-fc->miny);
709 	r.max.x = r.min.x+(fc->maxx-fc->minx);
710 	r.max.y = r.min.y+(fc->maxy-fc->miny);
711 	sp1.x = sp->x+fc->left;
712 	sp1.y = sp->y+fc->miny;
713 	memdraw(dst, r, src, sp1, font->image, Pt(fc->minx, fc->miny), op);
714 	p.x += fc->width;
715 	sp->x += fc->width;
716 	return p;
717 }
718 
719 static
720 uchar*
721 drawcoord(uchar *p, uchar *maxp, int oldx, int *newx)
722 {
723 	int b, x;
724 
725 	if(p >= maxp)
726 		return nil;
727 	b = *p++;
728 	x = b & 0x7F;
729 	if(b & 0x80){
730 		if(p+1 >= maxp)
731 			return nil;
732 		x |= *p++ << 7;
733 		x |= *p++ << 15;
734 		if(x & (1<<22))
735 			x |= ~0<<23;
736 	}else{
737 		if(b & 0x40)
738 			x |= ~0<<7;
739 		x += oldx;
740 	}
741 	*newx = x;
742 	return p;
743 }
744 
745 int
746 _drawmsgread(void *a, int n)
747 {
748 	Client *cl;
749 
750 	qlock(&sdraw.lk);
751 	cl = client0;
752 	if(cl->readdata == nil){
753 		werrstr("no draw data");
754 		goto err;
755 	}
756 	if(n < cl->nreaddata){
757 		werrstr("short read");
758 		goto err;
759 	}
760 	n = cl->nreaddata;
761 	memmove(a, cl->readdata, cl->nreaddata);
762 	free(cl->readdata);
763 	cl->readdata = nil;
764 	qunlock(&sdraw.lk);
765 	return n;
766 
767 err:
768 	qunlock(&sdraw.lk);
769 	return -1;
770 }
771 
772 int
773 _drawmsgwrite(void *v, int n)
774 {
775 	char cbuf[40], *err, ibuf[12*12+1], *s;
776 	int c, ci, doflush, dstid, e0, e1, esize, j, m;
777 	int ni, nw, oesize, oldn, op, ox, oy, repl, scrnid, y; 
778 	uchar *a, refresh, *u;
779 	u32int chan, value;
780 	Client *client;
781 	CScreen *cs;
782 	DImage *di, *ddst, *dsrc, *font, *ll;
783 	DName *dn;
784 	DScreen *dscrn;
785 	FChar *fc;
786 	Memimage *dst, *i, *l, **lp, *mask, *src;
787 	Memscreen *scrn;
788 	Point p, *pp, q, sp;
789 	Rectangle clipr, r;
790 	Refreshfn reffn;
791 	Refx *refx;
792 
793 	qlock(&sdraw.lk);
794 	a = v;
795 	m = 0;
796 	oldn = n;
797 	client = client0;
798 
799 	while((n-=m) > 0){
800 		a += m;
801 /* print("msgwrite %d(%c)...", n, *a); */
802 		switch(*a){
803 		default:
804 /*fprint(2, "bad command %d\n", *a); */
805 			err = "bad draw command";
806 			goto error;
807 
808 		/* allocate: 'b' id[4] screenid[4] refresh[1] chan[4] repl[1]
809 			R[4*4] clipR[4*4] rrggbbaa[4]
810 		 */
811 		case 'b':
812 			m = 1+4+4+1+4+1+4*4+4*4+4;
813 			if(n < m)
814 				goto Eshortdraw;
815 			dstid = BGLONG(a+1);
816 			scrnid = BGSHORT(a+5);
817 			refresh = a[9];
818 			chan = BGLONG(a+10);
819 			repl = a[14];
820 			drawrectangle(&r, a+15);
821 			drawrectangle(&clipr, a+31);
822 			value = BGLONG(a+47);
823 			if(drawlookup(client, dstid, 0))
824 				goto Eimageexists;
825 			if(scrnid){
826 				dscrn = drawlookupscreen(client, scrnid, &cs);
827 				if(!dscrn)
828 					goto Enodrawscreen;
829 				scrn = dscrn->screen;
830 				if(repl || chan!=scrn->image->chan){
831 					err = "image parameters incompatibile with screen";
832 					goto error;
833 				}
834 				reffn = 0;
835 				switch(refresh){
836 				case Refbackup:
837 					break;
838 				case Refnone:
839 					reffn = memlnorefresh;
840 					break;
841 				case Refmesg:
842 					reffn = drawrefresh;
843 					break;
844 				default:
845 					err = "unknown refresh method";
846 					goto error;
847 				}
848 				l = memlalloc(scrn, r, reffn, 0, value);
849 				if(l == 0)
850 					goto Edrawmem;
851 				addflush(l->layer->screenr);
852 				l->clipr = clipr;
853 				rectclip(&l->clipr, r);
854 				if(drawinstall(client, dstid, l, dscrn) == 0){
855 					memldelete(l);
856 					goto Edrawmem;
857 				}
858 				dscrn->ref++;
859 				if(reffn){
860 					refx = nil;
861 					if(reffn == drawrefresh){
862 						refx = mallocz(sizeof(Refx), 1);
863 						if(refx == 0){
864 							if(drawuninstall(client, dstid) < 0)
865 								goto Enodrawimage;
866 							goto Edrawmem;
867 						}
868 						refx->client = client;
869 						refx->dimage = drawlookup(client, dstid, 1);
870 					}
871 					memlsetrefresh(l, reffn, refx);
872 				}
873 				continue;
874 			}
875 			i = allocmemimage(r, chan);
876 			if(i == 0)
877 				goto Edrawmem;
878 			if(repl)
879 				i->flags |= Frepl;
880 			i->clipr = clipr;
881 			if(!repl)
882 				rectclip(&i->clipr, r);
883 			if(drawinstall(client, dstid, i, 0) == 0){
884 				freememimage(i);
885 				goto Edrawmem;
886 			}
887 			memfillcolor(i, value);
888 			continue;
889 
890 		/* allocate screen: 'A' id[4] imageid[4] fillid[4] public[1] */
891 		case 'A':
892 			m = 1+4+4+4+1;
893 			if(n < m)
894 				goto Eshortdraw;
895 			dstid = BGLONG(a+1);
896 			if(dstid == 0)
897 				goto Ebadarg;
898 			if(drawlookupdscreen(dstid))
899 				goto Escreenexists;
900 			ddst = drawlookup(client, BGLONG(a+5), 1);
901 			dsrc = drawlookup(client, BGLONG(a+9), 1);
902 			if(ddst==0 || dsrc==0)
903 				goto Enodrawimage;
904 			if(drawinstallscreen(client, 0, dstid, ddst, dsrc, a[13]) == 0)
905 				goto Edrawmem;
906 			continue;
907 
908 		/* set repl and clip: 'c' dstid[4] repl[1] clipR[4*4] */
909 		case 'c':
910 			m = 1+4+1+4*4;
911 			if(n < m)
912 				goto Eshortdraw;
913 			ddst = drawlookup(client, BGLONG(a+1), 1);
914 			if(ddst == nil)
915 				goto Enodrawimage;
916 			if(ddst->name){
917 				err = "can't change repl/clipr of shared image";
918 				goto error;
919 			}
920 			dst = ddst->image;
921 			if(a[5])
922 				dst->flags |= Frepl;
923 			drawrectangle(&dst->clipr, a+6);
924 			continue;
925 
926 		/* draw: 'd' dstid[4] srcid[4] maskid[4] R[4*4] P[2*4] P[2*4] */
927 		case 'd':
928 			m = 1+4+4+4+4*4+2*4+2*4;
929 			if(n < m)
930 				goto Eshortdraw;
931 			dst = drawimage(client, a+1);
932 			dstid = BGLONG(a+1);
933 			src = drawimage(client, a+5);
934 			mask = drawimage(client, a+9);
935 			if(!dst || !src || !mask)
936 				goto Enodrawimage;
937 			drawrectangle(&r, a+13);
938 			drawpoint(&p, a+29);
939 			drawpoint(&q, a+37);
940 			op = drawclientop(client);
941 			memdraw(dst, r, src, p, mask, q, op);
942 			dstflush(dstid, dst, r);
943 			continue;
944 
945 		/* toggle debugging: 'D' val[1] */
946 		case 'D':
947 			m = 1+1;
948 			if(n < m)
949 				goto Eshortdraw;
950 			drawdebug = a[1];
951 			continue;
952 
953 		/* ellipse: 'e' dstid[4] srcid[4] center[2*4] a[4] b[4] thick[4] sp[2*4] alpha[4] phi[4]*/
954 		case 'e':
955 		case 'E':
956 			m = 1+4+4+2*4+4+4+4+2*4+2*4;
957 			if(n < m)
958 				goto Eshortdraw;
959 			dst = drawimage(client, a+1);
960 			dstid = BGLONG(a+1);
961 			src = drawimage(client, a+5);
962 			if(!dst || !src)
963 				goto Enodrawimage;
964 			drawpoint(&p, a+9);
965 			e0 = BGLONG(a+17);
966 			e1 = BGLONG(a+21);
967 			if(e0<0 || e1<0){
968 				err = "invalid ellipse semidiameter";
969 				goto error;
970 			}
971 			j = BGLONG(a+25);
972 			if(j < 0){
973 				err = "negative ellipse thickness";
974 				goto error;
975 			}
976 			
977 			drawpoint(&sp, a+29);
978 			c = j;
979 			if(*a == 'E')
980 				c = -1;
981 			ox = BGLONG(a+37);
982 			oy = BGLONG(a+41);
983 			op = drawclientop(client);
984 			/* high bit indicates arc angles are present */
985 			if(ox & ((ulong)1<<31)){
986 				if((ox & ((ulong)1<<30)) == 0)
987 					ox &= ~((ulong)1<<31);
988 				memarc(dst, p, e0, e1, c, src, sp, ox, oy, op);
989 			}else
990 				memellipse(dst, p, e0, e1, c, src, sp, op);
991 			dstflush(dstid, dst, Rect(p.x-e0-j, p.y-e1-j, p.x+e0+j+1, p.y+e1+j+1));
992 			continue;
993 
994 		/* free: 'f' id[4] */
995 		case 'f':
996 			m = 1+4;
997 			if(n < m)
998 				goto Eshortdraw;
999 			ll = drawlookup(client, BGLONG(a+1), 0);
1000 			if(ll && ll->dscreen && ll->dscreen->owner != client)
1001 				ll->dscreen->owner->refreshme = 1;
1002 			if(drawuninstall(client, BGLONG(a+1)) < 0)
1003 				goto Enodrawimage;
1004 			continue;
1005 
1006 		/* free screen: 'F' id[4] */
1007 		case 'F':
1008 			m = 1+4;
1009 			if(n < m)
1010 				goto Eshortdraw;
1011 			if(!drawlookupscreen(client, BGLONG(a+1), &cs))
1012 				goto Enodrawscreen;
1013 			drawuninstallscreen(client, cs);
1014 			continue;
1015 
1016 		/* initialize font: 'i' fontid[4] nchars[4] ascent[1] */
1017 		case 'i':
1018 			m = 1+4+4+1;
1019 			if(n < m)
1020 				goto Eshortdraw;
1021 			dstid = BGLONG(a+1);
1022 			if(dstid == 0){
1023 				err = "can't use display as font";
1024 				goto error;
1025 			}
1026 			font = drawlookup(client, dstid, 1);
1027 			if(font == 0)
1028 				goto Enodrawimage;
1029 			if(font->image->layer){
1030 				err = "can't use window as font";
1031 				goto error;
1032 			}
1033 			ni = BGLONG(a+5);
1034 			if(ni<=0 || ni>4096){
1035 				err = "bad font size (4096 chars max)";
1036 				goto error;
1037 			}
1038 			free(font->fchar);	/* should we complain if non-zero? */
1039 			font->fchar = mallocz(ni*sizeof(FChar), 1);
1040 			if(font->fchar == 0){
1041 				err = "no memory for font";
1042 				goto error;
1043 			}
1044 			memset(font->fchar, 0, ni*sizeof(FChar));
1045 			font->nfchar = ni;
1046 			font->ascent = a[9];
1047 			continue;
1048 
1049 		/* set image 0 to screen image */
1050 		case 'J':
1051 			m = 1;
1052 			if(n < m)
1053 				goto Eshortdraw;
1054 			if(drawlookup(client, 0, 0))
1055 				goto Eimageexists;
1056 			drawinstall(client, 0, screenimage, 0);
1057 			client->infoid = 0;
1058 			continue;
1059 
1060 		/* get image info: 'I' */
1061 		case 'I':
1062 			m = 1;
1063 			if(n < m)
1064 				goto Eshortdraw;
1065 			if(client->infoid < 0)
1066 				goto Enodrawimage;
1067 			if(client->infoid == 0){
1068 				i = screenimage;
1069 				if(i == nil)
1070 					goto Enodrawimage;
1071 			}else{
1072 				di = drawlookup(client, client->infoid, 1);
1073 				if(di == nil)
1074 					goto Enodrawimage;
1075 				i = di->image;
1076 			}
1077 			ni = sprint(ibuf, "%11d %11d %11s %11d %11d %11d %11d %11d"
1078 					" %11d %11d %11d %11d ",
1079 					client->clientid,
1080 					client->infoid,	
1081 					chantostr(cbuf, i->chan),
1082 					(i->flags&Frepl)==Frepl,
1083 					i->r.min.x, i->r.min.y, i->r.max.x, i->r.max.y,
1084 					i->clipr.min.x, i->clipr.min.y, 
1085 					i->clipr.max.x, i->clipr.max.y);
1086 			free(client->readdata);
1087 			client->readdata = malloc(ni);
1088 			if(client->readdata == nil)
1089 				goto Enomem;
1090 			memmove(client->readdata, ibuf, ni);
1091 			client->nreaddata = ni;
1092 			client->infoid = -1;
1093 			continue;	
1094 
1095 		/* load character: 'l' fontid[4] srcid[4] index[2] R[4*4] P[2*4] left[1] width[1] */
1096 		case 'l':
1097 			m = 1+4+4+2+4*4+2*4+1+1;
1098 			if(n < m)
1099 				goto Eshortdraw;
1100 			font = drawlookup(client, BGLONG(a+1), 1);
1101 			if(font == 0)
1102 				goto Enodrawimage;
1103 			if(font->nfchar == 0)
1104 				goto Enotfont;
1105 			src = drawimage(client, a+5);
1106 			if(!src)
1107 				goto Enodrawimage;
1108 			ci = BGSHORT(a+9);
1109 			if(ci >= font->nfchar)
1110 				goto Eindex;
1111 			drawrectangle(&r, a+11);
1112 			drawpoint(&p, a+27);
1113 			memdraw(font->image, r, src, p, memopaque, p, S);
1114 			fc = &font->fchar[ci];
1115 			fc->minx = r.min.x;
1116 			fc->maxx = r.max.x;
1117 			fc->miny = r.min.y;
1118 			fc->maxy = r.max.y;
1119 			fc->left = a[35];
1120 			fc->width = a[36];
1121 			continue;
1122 
1123 		/* draw line: 'L' dstid[4] p0[2*4] p1[2*4] end0[4] end1[4] radius[4] srcid[4] sp[2*4] */
1124 		case 'L':
1125 			m = 1+4+2*4+2*4+4+4+4+4+2*4;
1126 			if(n < m)
1127 				goto Eshortdraw;
1128 			dst = drawimage(client, a+1);
1129 			dstid = BGLONG(a+1);
1130 			drawpoint(&p, a+5);
1131 			drawpoint(&q, a+13);
1132 			e0 = BGLONG(a+21);
1133 			e1 = BGLONG(a+25);
1134 			j = BGLONG(a+29);
1135 			if(j < 0){
1136 				err = "negative line width";
1137 				goto error;
1138 			}
1139 			src = drawimage(client, a+33);
1140 			if(!dst || !src)
1141 				goto Enodrawimage;
1142 			drawpoint(&sp, a+37);
1143 			op = drawclientop(client);
1144 			memline(dst, p, q, e0, e1, j, src, sp, op);
1145 			/* avoid memlinebbox if possible */
1146 			if(dstid==0 || dst->layer!=nil){
1147 				/* BUG: this is terribly inefficient: update maximal containing rect*/
1148 				r = memlinebbox(p, q, e0, e1, j);
1149 				dstflush(dstid, dst, insetrect(r, -(1+1+j)));
1150 			}
1151 			continue;
1152 
1153 		/* create image mask: 'm' newid[4] id[4] */
1154 /*
1155  *
1156 		case 'm':
1157 			m = 4+4;
1158 			if(n < m)
1159 				goto Eshortdraw;
1160 			break;
1161  *
1162  */
1163 
1164 		/* attach to a named image: 'n' dstid[4] j[1] name[j] */
1165 		case 'n':
1166 			m = 1+4+1;
1167 			if(n < m)
1168 				goto Eshortdraw;
1169 			j = a[5];
1170 			if(j == 0)	/* give me a non-empty name please */
1171 				goto Eshortdraw;
1172 			m += j;
1173 			if(n < m)
1174 				goto Eshortdraw;
1175 			dstid = BGLONG(a+1);
1176 			if(drawlookup(client, dstid, 0))
1177 				goto Eimageexists;
1178 			dn = drawlookupname(j, (char*)a+6);
1179 			if(dn == nil)
1180 				goto Enoname;
1181 			s = malloc(j+1);
1182 			if(s == nil)
1183 				goto Enomem;
1184 			if(drawinstall(client, dstid, dn->dimage->image, 0) == 0)
1185 				goto Edrawmem;
1186 			di = drawlookup(client, dstid, 0);
1187 			if(di == 0)
1188 				goto Eoldname;
1189 			di->vers = dn->vers;
1190 			di->name = s;
1191 			di->fromname = dn->dimage;
1192 			di->fromname->ref++;
1193 			memmove(di->name, a+6, j);
1194 			di->name[j] = 0;
1195 			client->infoid = dstid;
1196 			continue;
1197 
1198 		/* name an image: 'N' dstid[4] in[1] j[1] name[j] */
1199 		case 'N':
1200 			m = 1+4+1+1;
1201 			if(n < m)
1202 				goto Eshortdraw;
1203 			c = a[5];
1204 			j = a[6];
1205 			if(j == 0)	/* give me a non-empty name please */
1206 				goto Eshortdraw;
1207 			m += j;
1208 			if(n < m)
1209 				goto Eshortdraw;
1210 			di = drawlookup(client, BGLONG(a+1), 0);
1211 			if(di == 0)
1212 				goto Enodrawimage;
1213 			if(di->name)
1214 				goto Enamed;
1215 			if(c)
1216 				if(drawaddname(client, di, j, (char*)a+7, &err) < 0)
1217 					goto error;
1218 			else{
1219 				dn = drawlookupname(j, (char*)a+7);
1220 				if(dn == nil)
1221 					goto Enoname;
1222 				if(dn->dimage != di)
1223 					goto Ewrongname;
1224 				drawdelname(dn);
1225 			}
1226 			continue;
1227 
1228 		/* position window: 'o' id[4] r.min [2*4] screenr.min [2*4] */
1229 		case 'o':
1230 			m = 1+4+2*4+2*4;
1231 			if(n < m)
1232 				goto Eshortdraw;
1233 			dst = drawimage(client, a+1);
1234 			if(!dst)
1235 				goto Enodrawimage;
1236 			if(dst->layer){
1237 				drawpoint(&p, a+5);
1238 				drawpoint(&q, a+13);
1239 				r = dst->layer->screenr;
1240 				ni = memlorigin(dst, p, q);
1241 				if(ni < 0){
1242 					err = "image origin failed";
1243 					goto error;
1244 				}
1245 				if(ni > 0){
1246 					addflush(r);
1247 					addflush(dst->layer->screenr);
1248 					ll = drawlookup(client, BGLONG(a+1), 1);
1249 					drawrefreshscreen(ll, client);
1250 				}
1251 			}
1252 			continue;
1253 
1254 		/* set compositing operator for next draw operation: 'O' op */
1255 		case 'O':
1256 			m = 1+1;
1257 			if(n < m)
1258 				goto Eshortdraw;
1259 			client->op = a[1];
1260 			continue;
1261 
1262 		/* filled polygon: 'P' dstid[4] n[2] wind[4] ignore[2*4] srcid[4] sp[2*4] p0[2*4] dp[2*2*n] */
1263 		/* polygon: 'p' dstid[4] n[2] end0[4] end1[4] radius[4] srcid[4] sp[2*4] p0[2*4] dp[2*2*n] */
1264 		case 'p':
1265 		case 'P':
1266 			m = 1+4+2+4+4+4+4+2*4;
1267 			if(n < m)
1268 				goto Eshortdraw;
1269 			dstid = BGLONG(a+1);
1270 			dst = drawimage(client, a+1);
1271 			ni = BGSHORT(a+5);
1272 			if(ni < 0){
1273 				err = "negative cout in polygon";
1274 				goto error;
1275 			}
1276 			e0 = BGLONG(a+7);
1277 			e1 = BGLONG(a+11);
1278 			j = 0;
1279 			if(*a == 'p'){
1280 				j = BGLONG(a+15);
1281 				if(j < 0){
1282 					err = "negative polygon line width";
1283 					goto error;
1284 				}
1285 			}
1286 			src = drawimage(client, a+19);
1287 			if(!dst || !src)
1288 				goto Enodrawimage;
1289 			drawpoint(&sp, a+23);
1290 			drawpoint(&p, a+31);
1291 			ni++;
1292 			pp = mallocz(ni*sizeof(Point), 1);
1293 			if(pp == nil)
1294 				goto Enomem;
1295 			doflush = 0;
1296 			if(dstid==0 || (dst->layer && dst->layer->screen->image->data == screenimage->data))
1297 				doflush = 1;	/* simplify test in loop */
1298 			ox = oy = 0;
1299 			esize = 0;
1300 			u = a+m;
1301 			for(y=0; y<ni; y++){
1302 				q = p;
1303 				oesize = esize;
1304 				u = drawcoord(u, a+n, ox, &p.x);
1305 				if(!u)
1306 					goto Eshortdraw;
1307 				u = drawcoord(u, a+n, oy, &p.y);
1308 				if(!u)
1309 					goto Eshortdraw;
1310 				ox = p.x;
1311 				oy = p.y;
1312 				if(doflush){
1313 					esize = j;
1314 					if(*a == 'p'){
1315 						if(y == 0){
1316 							c = memlineendsize(e0);
1317 							if(c > esize)
1318 								esize = c;
1319 						}
1320 						if(y == ni-1){
1321 							c = memlineendsize(e1);
1322 							if(c > esize)
1323 								esize = c;
1324 						}
1325 					}
1326 					if(*a=='P' && e0!=1 && e0 !=~0)
1327 						r = dst->clipr;
1328 					else if(y > 0){
1329 						r = Rect(q.x-oesize, q.y-oesize, q.x+oesize+1, q.y+oesize+1);
1330 						combinerect(&r, Rect(p.x-esize, p.y-esize, p.x+esize+1, p.y+esize+1));
1331 					}
1332 					if(rectclip(&r, dst->clipr))		/* should perhaps be an arg to dstflush */
1333 						dstflush(dstid, dst, r);
1334 				}
1335 				pp[y] = p;
1336 			}
1337 			if(y == 1)
1338 				dstflush(dstid, dst, Rect(p.x-esize, p.y-esize, p.x+esize+1, p.y+esize+1));
1339 			op = drawclientop(client);
1340 			if(*a == 'p')
1341 				mempoly(dst, pp, ni, e0, e1, j, src, sp, op);
1342 			else
1343 				memfillpoly(dst, pp, ni, e0, src, sp, op);
1344 			free(pp);
1345 			m = u-a;
1346 			continue;
1347 
1348 		/* read: 'r' id[4] R[4*4] */
1349 		case 'r':
1350 			m = 1+4+4*4;
1351 			if(n < m)
1352 				goto Eshortdraw;
1353 			i = drawimage(client, a+1);
1354 			if(!i)
1355 				goto Enodrawimage;
1356 			drawrectangle(&r, a+5);
1357 			if(!rectinrect(r, i->r))
1358 				goto Ereadoutside;
1359 			c = bytesperline(r, i->depth);
1360 			c *= Dy(r);
1361 			free(client->readdata);
1362 			client->readdata = mallocz(c, 0);
1363 			if(client->readdata == nil){
1364 				err = "readimage malloc failed";
1365 				goto error;
1366 			}
1367 			client->nreaddata = memunload(i, r, client->readdata, c);
1368 			if(client->nreaddata < 0){
1369 				free(client->readdata);
1370 				client->readdata = nil;
1371 				err = "bad readimage call";
1372 				goto error;
1373 			}
1374 			continue;
1375 
1376 		/* string: 's' dstid[4] srcid[4] fontid[4] P[2*4] clipr[4*4] sp[2*4] ni[2] ni*(index[2]) */
1377 		/* 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]) */
1378 		case 's':
1379 		case 'x':
1380 			m = 1+4+4+4+2*4+4*4+2*4+2;
1381 			if(*a == 'x')
1382 				m += 4+2*4;
1383 			if(n < m)
1384 				goto Eshortdraw;
1385 
1386 			dst = drawimage(client, a+1);
1387 			dstid = BGLONG(a+1);
1388 			src = drawimage(client, a+5);
1389 			if(!dst || !src)
1390 				goto Enodrawimage;
1391 			font = drawlookup(client, BGLONG(a+9), 1);
1392 			if(font == 0)
1393 				goto Enodrawimage;
1394 			if(font->nfchar == 0)
1395 				goto Enotfont;
1396 			drawpoint(&p, a+13);
1397 			drawrectangle(&r, a+21);
1398 			drawpoint(&sp, a+37);
1399 			ni = BGSHORT(a+45);
1400 			u = a+m;
1401 			m += ni*2;
1402 			if(n < m)
1403 				goto Eshortdraw;
1404 			clipr = dst->clipr;
1405 			dst->clipr = r;
1406 			op = drawclientop(client);
1407 			if(*a == 'x'){
1408 				/* paint background */
1409 				l = drawimage(client, a+47);
1410 				if(!l)
1411 					goto Enodrawimage;
1412 				drawpoint(&q, a+51);
1413 				r.min.x = p.x;
1414 				r.min.y = p.y-font->ascent;
1415 				r.max.x = p.x;
1416 				r.max.y = r.min.y+Dy(font->image->r);
1417 				j = ni;
1418 				while(--j >= 0){
1419 					ci = BGSHORT(u);
1420 					if(ci<0 || ci>=font->nfchar){
1421 						dst->clipr = clipr;
1422 						goto Eindex;
1423 					}
1424 					r.max.x += font->fchar[ci].width;
1425 					u += 2;
1426 				}
1427 				memdraw(dst, r, l, q, memopaque, ZP, op);
1428 				u -= 2*ni;
1429 			}
1430 			q = p;
1431 			while(--ni >= 0){
1432 				ci = BGSHORT(u);
1433 				if(ci<0 || ci>=font->nfchar){
1434 					dst->clipr = clipr;
1435 					goto Eindex;
1436 				}
1437 				q = drawchar(dst, q, src, &sp, font, ci, op);
1438 				u += 2;
1439 			}
1440 			dst->clipr = clipr;
1441 			p.y -= font->ascent;
1442 			dstflush(dstid, dst, Rect(p.x, p.y, q.x, p.y+Dy(font->image->r)));
1443 			continue;
1444 
1445 		/* use public screen: 'S' id[4] chan[4] */
1446 		case 'S':
1447 			m = 1+4+4;
1448 			if(n < m)
1449 				goto Eshortdraw;
1450 			dstid = BGLONG(a+1);
1451 			if(dstid == 0)
1452 				goto Ebadarg;
1453 			dscrn = drawlookupdscreen(dstid);
1454 			if(dscrn==0 || (dscrn->public==0 && dscrn->owner!=client))
1455 				goto Enodrawscreen;
1456 			if(dscrn->screen->image->chan != BGLONG(a+5)){
1457 				err = "inconsistent chan";
1458 				goto error;
1459 			}
1460 			if(drawinstallscreen(client, dscrn, 0, 0, 0, 0) == 0)
1461 				goto Edrawmem;
1462 			continue;
1463 
1464 		/* top or bottom windows: 't' top[1] nw[2] n*id[4] */
1465 		case 't':
1466 			m = 1+1+2;
1467 			if(n < m)
1468 				goto Eshortdraw;
1469 			nw = BGSHORT(a+2);
1470 			if(nw < 0)
1471 				goto Ebadarg;
1472 			if(nw == 0)
1473 				continue;
1474 			m += nw*4;
1475 			if(n < m)
1476 				goto Eshortdraw;
1477 			lp = mallocz(nw*sizeof(Memimage*), 1);
1478 			if(lp == 0)
1479 				goto Enomem;
1480 			for(j=0; j<nw; j++){
1481 				lp[j] = drawimage(client, a+1+1+2+j*4);
1482 				if(lp[j] == nil){
1483 					free(lp);
1484 					goto Enodrawimage;
1485 				}
1486 			}
1487 			if(lp[0]->layer == 0){
1488 				err = "images are not windows";
1489 				free(lp);
1490 				goto error;
1491 			}
1492 			for(j=1; j<nw; j++)
1493 				if(lp[j]->layer->screen != lp[0]->layer->screen){
1494 					err = "images not on same screen";
1495 					free(lp);
1496 					goto error;
1497 				}
1498 			if(a[1])
1499 				memltofrontn(lp, nw);
1500 			else
1501 				memltorearn(lp, nw);
1502 			if(lp[0]->layer->screen->image->data == screenimage->data)
1503 				for(j=0; j<nw; j++)
1504 					addflush(lp[j]->layer->screenr);
1505 			free(lp);
1506 			ll = drawlookup(client, BGLONG(a+1+1+2), 1);
1507 			drawrefreshscreen(ll, client);
1508 			continue;
1509 
1510 		/* visible: 'v' */
1511 		case 'v':
1512 			m = 1;
1513 			drawflush();
1514 			continue;
1515 
1516 		/* write: 'y' id[4] R[4*4] data[x*1] */
1517 		/* write from compressed data: 'Y' id[4] R[4*4] data[x*1] */
1518 		case 'y':
1519 		case 'Y':
1520 			m = 1+4+4*4;
1521 			if(n < m)
1522 				goto Eshortdraw;
1523 			dstid = BGLONG(a+1);
1524 			dst = drawimage(client, a+1);
1525 			if(!dst)
1526 				goto Enodrawimage;
1527 			drawrectangle(&r, a+5);
1528 			if(!rectinrect(r, dst->r))
1529 				goto Ewriteoutside;
1530 			y = memload(dst, r, a+m, n-m, *a=='Y');
1531 			if(y < 0){
1532 				err = "bad writeimage call";
1533 				goto error;
1534 			}
1535 			dstflush(dstid, dst, r);
1536 			m += y;
1537 			continue;
1538 		}
1539 	}
1540 	qunlock(&sdraw.lk);
1541 	return oldn - n;
1542 
1543 Enodrawimage:
1544 	err = "unknown id for draw image";
1545 	goto error;
1546 Enodrawscreen:
1547 	err = "unknown id for draw screen";
1548 	goto error;
1549 Eshortdraw:
1550 	err = "short draw message";
1551 	goto error;
1552 /*
1553 Eshortread:
1554 	err = "draw read too short";
1555 	goto error;
1556 */
1557 Eimageexists:
1558 	err = "image id in use";
1559 	goto error;
1560 Escreenexists:
1561 	err = "screen id in use";
1562 	goto error;
1563 Edrawmem:
1564 	err = "image memory allocation failed";
1565 	goto error;
1566 Ereadoutside:
1567 	err = "readimage outside image";
1568 	goto error;
1569 Ewriteoutside:
1570 	err = "writeimage outside image";
1571 	goto error;
1572 Enotfont:
1573 	err = "image not a font";
1574 	goto error;
1575 Eindex:
1576 	err = "character index out of range";
1577 	goto error;
1578 /*
1579 Enoclient:
1580 	err = "no such draw client";
1581 	goto error;
1582 Edepth:
1583 	err = "image has bad depth";
1584 	goto error;
1585 Enameused:
1586 	err = "image name in use";
1587 	goto error;
1588 */
1589 Enoname:
1590 	err = "no image with that name";
1591 	goto error;
1592 Eoldname:
1593 	err = "named image no longer valid";
1594 	goto error;
1595 Enamed:
1596 	err = "image already has name";
1597 	goto error;
1598 Ewrongname:
1599 	err = "wrong name for image";
1600 	goto error;
1601 Enomem:
1602 	err = "out of memory";
1603 	goto error;
1604 Ebadarg:
1605 	err = "bad argument in draw message";
1606 	goto error;
1607 
1608 error:
1609 	werrstr("%s", err);
1610 	qunlock(&sdraw.lk);
1611 	return -1;
1612 }
1613 
1614