shithub: purgatorio

ref: db1eb844461b07a25ca49117851fa874fd88e065
dir: /libtk/canvs.c/

#include <lib9.h>
#include <kernel.h>
#include "draw.h"
#include "tk.h"
#include "canvs.h"

/* Widget Commands (+ means implemented)
	+addtag
		except halo and start options of closest spec
	+bbox
	+bind
	+canvasx
	+canvasy
	+cget
	+configure
	+coords
	+create
	+dchars
	+delete
	+dtag
	+find
	+focus
	+gettags
	+icursor
	+index
	+insert
	+itemcget
	+itemconfigure
	+lower
	+move
	 postscript
	+raise
	+scale
	 scan
	+select
	+type
	+xview
	+yview
*/

static
TkStab tkbuffer[] = {
	"visible",	TkCbufvisible,
	"all",		TkCbufall,
	"none",	TkCbufnone,
	"auto",	TkCbufauto,

	/* backwards compatibility */
	"1",		TkCbufall,
	"yes",	TkCbufall,
	"off",		TkCbufall,
	"0",		TkCbufauto,
	"no",		TkCbufauto,
	"off",		TkCbufauto,
	nil
};
	
#define	O(t, e)		((long)(&((t*)0)->e))
#define OA(t, e)	((long)(((t*)0)->e))

static
TkOption opts[] =
{
	"closeenough",		OPTfrac,	O(TkCanvas, close),	nil,
	"confine",		OPTfrac,	O(TkCanvas, confine),	nil,
	"scrollregion",		OPTfrac,	OA(TkCanvas, scrollr),	IAUX(4),
	"xscrollincrement",	OPTfrac,	O(TkCanvas, xscrolli),	nil,
	"yscrollincrement",	OPTfrac,	O(TkCanvas, yscrolli),	nil,
	"xscrollcommand",	OPTtext,	O(TkCanvas, xscroll),	nil,
	"yscrollcommand",	OPTtext,	O(TkCanvas, yscroll),	nil,
	"width",		OPTnnfrac,	O(TkCanvas, width),	nil,
	"height",		OPTnnfrac,	O(TkCanvas, height),	nil,
	"buffer",		OPTstab,	O(TkCanvas, buffer),		tkbuffer,
	"buffered",		OPTstab,	O(TkCanvas, buffer),	tkbool,	/* backwards compatibility */
	"selectborderwidth",	OPTnndist, O(TkCanvas, sborderwidth), nil,
	nil
};

int cvslshape[] = { TKI2F(8), TKI2F(10), TKI2F(3) };
Rectangle	bbnil = { 1000000, 1000000, -1000000, -1000000 };
Rectangle	huger = { -1000000, -1000000, 1000000, 1000000 };

static void tkcvsgeom(Tk *tk);


static void
tkcvsf2i(Tk *tk, TkCanvas *tkc)
{
	Rectangle r;
	tk->req.width = TKF2I(tkc->width);
	tk->req.height = TKF2I(tkc->height);

	r.min.x = TKF2I(tkc->scrollr[0]);
	r.min.y = TKF2I(tkc->scrollr[1]);
	r.max.x = TKF2I(tkc->scrollr[2]);
	r.max.y = TKF2I(tkc->scrollr[3]);

	/*
	 * make sure that the region is big enough to hold
	 * the actually displayed area
	 */
	if (Dx(r) < tk->act.width)
		r.max.x = r.min.x + tk->act.width;
	if (Dy(r) < tk->act.height)
		r.max.y = r.min.y + tk->act.height;
	tkc->region = r;

	/*
	 * make sure that the view origin is at a valid
	 * position with respect to the scroll region.
	 */
	if (tkc->view.x + tk->act.width > r.max.x)
		tkc->view.x = r.max.x - tk->act.width;
	if (tkc->view.x < r.min.x)
		tkc->view.x = r.min.x;

	if (tkc->view.y + tk->act.height > r.max.y)
		tkc->view.y = r.max.y - tk->act.height;
	if (tkc->view.y < r.min.y)
		tkc->view.y = r.min.y;

}

char*
tkcanvas(TkTop *t, char *arg, char **ret)
{
	Tk *tk;
	char *e;
	TkCanvas *tkc;
	TkName *names;
	TkOptab tko[3];

	tk = tknewobj(t, TKcanvas, sizeof(Tk)+sizeof(TkCanvas));
	if(tk == nil)
		return TkNomem;

	tkc = TKobj(TkCanvas, tk);
	tkc->close = TKI2F(1);
	tkc->xscrolli = TKI2F(1);
	tkc->yscrolli = TKI2F(1);
	tkc->width = TKI2F(360);
	tkc->height = TKI2F(270);
	tkc->actions = 0;
	tkc->actlim = Tksweep;
	tkc->mask = nil;
	tkc->sborderwidth = 1;

	tko[0].ptr = tkc;
	tko[0].optab = opts;
	tko[1].ptr = tk;
	tko[1].optab = tkgeneric;
	tko[2].ptr = nil;

	names = nil;
	e = tkparse(t, arg, tko, &names);
	if(e != nil)
		goto err;
	if(names == nil) {
		/* tkerr(t, arg); XXX */
		e = TkBadwp;
		goto err;
	}

	tkc->current = tkmkname("current");
	if(tkc->current == nil) {
		e = TkNomem;
		goto err;
	}

	tksettransparent(tk, tkhasalpha(tk->env, TkCbackgnd));
	tkcvsf2i(tk, tkc);

	e = tkaddchild(t, tk, &names);
	tkfreename(names);
	if(e != nil) {
		tkfreename(tkc->current);
		tkc->current = nil;
		goto err;
	}
	tk->name->link = nil;

	e = tkvalue(ret, "%s", tk->name->name);
	if(e == nil)
	        return nil;
	
	tkfreename(tkc->current);
	return e;
err:
	tkfreeobj(tk);
	return e;
}

void
tkcvsdirty(Tk *sub)
{
	TkCanvas *c;
	Tk *tk, *parent;
	Rectangle r;
	Point rel;

	rel = ZP;
	for(tk = sub; tk;  tk = tk->master) {
		rel.x += tk->borderwidth + tk->act.x;
		rel.y += tk->borderwidth + tk->act.y;
		if (tk->parent != nil)
			break;
	}
	if (tk == nil)
		return;
	parent = tk->parent;
	c = TKobj(TkCanvas, parent);
	r = rectaddpt(sub->dirty, rel);
	tkbbmax(&c->update, &r);
	tkcvssetdirty(parent);
}

static void
tkcvsfocusorder(Tk *tk)
{
	TkCanvas *tkc = TKobj(TkCanvas, tk);
	TkCwind *win;
	TkCitem *it;
	TkWinfo *inf;
	int i, n;

	n = 0;
	for (it = tkc->head; it != nil; it = it->next) {
		if (it->type == TkCVwindow) {
			win = TKobj(TkCwind, it);
			if (win->sub != nil)
				n++;
		}
	}
	if (n == 0)
		return;

	inf = malloc(sizeof(*inf) * n);
	if (inf == nil)
		return;

	i = 0;
	for (it = tkc->head; it != nil; it = it->next) {
		if (it->type == TkCVwindow) {
			win = TKobj(TkCwind, it);
			if (win->sub != nil) {
				inf[i].w = win->sub;
				inf[i].r = it->p.bb;
				i++;
			}
		}
	}

	tksortfocusorder(inf, n);
	for (i = 0; i < n; i++)
		tkappendfocusorder(inf[i].w);
}

static char*
tkcvscget(Tk *tk, char *arg, char **val)
{
	TkOptab tko[3];
	TkCanvas *tkc = TKobj(TkCanvas, tk);

	tko[0].ptr = tkc;
	tko[0].optab = opts;
	tko[1].ptr = tk;
	tko[1].optab = tkgeneric;
	tko[2].ptr = nil;

	return tkgencget(tko, arg, val, tk->env->top);
}

static char*
tkcvsconf(Tk *tk, char *arg, char **val)
{
	char *e;
	int bd;
	TkGeom g;
	Rectangle r;
	TkOptab tko[3];
	TkCanvas *c = TKobj(TkCanvas, tk);

	tko[0].ptr = c;
	tko[0].optab = opts;
	tko[1].ptr = tk;
	tko[1].optab = tkgeneric;
	tko[2].ptr = nil;

	if(*arg == '\0')
		return tkconflist(tko, val);

	r.min = c->view;
	r.max.x = r.min.x+tk->act.width;
	r.max.y = r.min.y+tk->act.height;
	tkbbmax(&c->update, &r);
	tkbbmax(&c->update, &c->region);

	bd = tk->borderwidth;
	g = tk->req;
	e = tkparse(tk->env->top, arg, tko, nil);
	if(e != nil)
		return e;
	tksettransparent(tk, tkhasalpha(tk->env, TkCbackgnd));

	tkcvsf2i(tk, c);
	
	tkcvsgeom(tk);	
	tkgeomchg(tk, &g, bd);
	tkbbmax(&c->update, &c->region);
	tk->dirty = tkrect(tk, 1);
	return nil;
}

void
tkcvsfreeitem(TkCitem *i)
{
	int locked;
	Display *d;

	d = i->env->top->display;

	locked = lockdisplay(d);
	tkcimethod[i->type].free(i);
	if(locked)
		unlockdisplay(d);

	tkfreepoint(&i->p);
	tkputenv(i->env);
	free(i);
}

void
tkfreecanv(Tk *tk)
{
	Display *d;
	int j, locked;
	TkCanvas *c;
	TkName *n, *nn;
	TkCtag *t, *tt;
	TkCitem *i, *next;

	c = TKobj(TkCanvas, tk);
	for(i = c->head; i; i = next) {
		next = i->next;
		tkcvsfreeitem(i);
	}

	if(c->xscroll != nil)
		free(c->xscroll);
	if(c->yscroll != nil)
		free(c->yscroll);

	for(j = 0; j < TkChash; j++) {
		for(n = c->thash[j]; n; n = nn) {
			nn = n->link;
			for(t = n->obj; t; t = tt) {
				tt = t->taglist;
				free(t);
			}
			tkfreebind(n->prop.binds);
			free(n);
		}
	}

	free(c->current);

	if((c->ialloc && c->image != nil) || c->mask != nil) {
		if (c->ialloc && c->image != nil)
			d = c->image->display;
		else
			d = c->mask->display;
		locked = lockdisplay(d);
		if (c->image != nil && c->ialloc)
			freeimage(c->image);
		if (c->mask != nil)
			freeimage(c->mask);
		if(locked)
			unlockdisplay(d);
	}
}

char*
tkdrawcanv(Tk *tk, Point orig)
{
	Image *dst;
	TkCitem *i;
	Display *d;
	TkCanvas *c;
	Rectangle r, bufr, oclipr;
	int vis, alpha, buffer;
	Point rel, p;
	TkCimeth *imeth;

	c = TKobj(TkCanvas, tk);
	d = tk->env->top->display;
	dst = tkimageof(tk);
	/*
	 * translation from local to screen coords
	 */
	rel.x = orig.x + tk->act.x + tk->borderwidth;
	rel.y = orig.y + tk->act.y + tk->borderwidth;

	buffer = c->buffer;
	if (buffer == TkCbufauto)
		buffer = TkCbufvisible;
/*		buffer = (dst == TKobj(TkWin, tk->env->top->root)->image) ? TkCbufvisible : TkCbufnone; */

	if (buffer == TkCbufnone) {
		if(c->image != nil && c->ialloc)
			freeimage(c->image);
		c->image = dst;
		c->ialloc = 0;

		r = tkrect(tk, 0);
		bufr = r;
		rectclip(&bufr, tk->dirty);
		oclipr = dst->clipr;

		replclipr(dst, 0, rectaddpt(bufr, rel));
		draw(dst, rectaddpt(bufr, rel), tkgc(tk->env, TkCbackgnd), nil, ZP);

		p = subpt(rel, c->view);
		p.x = TKI2F(p.x);
		p.y = TKI2F(p.y);
		bufr = rectaddpt(bufr, c->view);
		for(i = c->head; i; i = i->next) {
			if(rectXrect(i->p.bb, bufr)) {
				imeth = &tkcimethod[i->type];
				imeth->coord(i, nil, p.x, p.y);
				imeth->draw(dst, i, tk->env);
				imeth->coord(i, nil, -p.x, -p.y);
			}
		}
		replclipr(dst, 0, oclipr);
	} else {
		if (c->buffer == TkCbufall)
			bufr = c->region;
		else {
			bufr.min = c->view;
			bufr.max.x = c->view.x + tk->act.width;
			bufr.max.y = c->view.y + tk->act.height;
		}
		alpha = (tk->env->colors[TkCbackgnd] & 0xff) != 0xff;
		if(c->image == nil || eqrect(bufr, c->image->r) == 0) {
			if(c->image != nil && c->ialloc)
				freeimage(c->image);
			c->image = allocimage(d, bufr, alpha?RGBA32:d->image->chan, 0, tk->env->colors[TkCbackgnd]);
			c->ialloc = 1;
			c->update = bufr;
			tkcvssetdirty(tk);		/* unnecessary? */
		}
	
		if(c->image == nil)
			return nil;
	
		r = c->update;
		if (rectclip(&r, c->image->r)) {
			if (alpha)
				drawop(c->image, c->update, nil, nil, ZP, Clear);
			draw(c->image, c->update, tkgc(tk->env, TkCbackgnd), nil, c->view);
			replclipr(c->image, 0, r);
			for(i = c->head; i; i = i->next) {
				if(rectXrect(i->p.bb, r))
					tkcimethod[i->type].draw(c->image, i, tk->env);
			}
			replclipr(c->image, 0, c->image->r);
		}
		/*
		 * if the visible area of the canvas image doesn't
		 * fit completely within the dirty rectangle,
		 * then we'll need to draw the background behind it
		 */
		r = tkrect(tk, 0);
		bufr = rectsubpt(bufr, c->view);
		vis = rectclip(&bufr, tkrect(tk, 0));
	
		if (!vis || !rectinrect(tk->dirty, bufr))
			draw(dst, rectaddpt(tk->dirty, rel), tkgc(tk->env, TkCbackgnd), nil, c->view);
	
		if (vis && rectclip(&bufr, tk->dirty))
			draw(dst, rectaddpt(bufr, rel), c->image, nil, addpt(bufr.min, c->view));
	}


	/*
	 * if the border is dirty too, then draw that
	 */
	if (!rectinrect(tk->dirty, bufr)) {
		r.min = addpt(r.min, rel);
		r.min.x -= tk->borderwidth;
		r.min.y -= tk->borderwidth;
		tkdrawrelief(dst, tk, r.min, TkCbackgnd, tk->relief);
	}
	c->update = bbnil;
	return nil;
}

void
tkcvsappend(TkCanvas *c, TkCitem *i)
{
	if(c->head == nil)
		c->head = i;
	else
		c->tail->next = i;
	c->tail = i;
}

void
tkcvssv(Tk *tk)
{
	TkCanvas *c;
	int top, bot, height;
	char val[Tkminitem], cmd[Tkmaxitem], *v, *e;

	c = TKobj(TkCanvas, tk);
	if(c->yscroll == nil)
		return;

	top = 0;
	bot = TKI2F(1);

	height = Dy(c->region);
	if(height != 0) {
		top = TKI2F(c->view.y)/height;
		bot = TKI2F(c->view.y+tk->act.height)/height;
	}

	v = tkfprint(val, top);
	*v++ = ' ';
	tkfprint(v, bot);
	snprint(cmd, sizeof(cmd), "%s %s", c->yscroll, val);
	e = tkexec(tk->env->top, cmd, nil);
	if ((e != nil) && (tk->name != nil))
		print("tk: yscrollcommand \"%s\": %s\n", tk->name->name, e);
}

void
tkcvssh(Tk *tk)
{
	int top, bot, width;
	TkCanvas *c = TKobj(TkCanvas, tk);
	char val[Tkminitem], cmd[Tkmaxitem], *v, *e;

	if(c->xscroll == nil)
		return;

	top = 0;
	bot = TKI2F(1);

	width = Dx(c->region);
	if(width != 0) {
		top = TKI2F(c->view.x)/width;
		bot = TKI2F(c->view.x+tk->act.width)/width;
	}

	v = tkfprint(val, top);
	*v++ = ' ';
	tkfprint(v, bot);
	snprint(cmd, sizeof(cmd), "%s %s", c->xscroll, val);
	e = tkexec(tk->env->top, cmd, nil);
	if ((e != nil) && (tk->name != nil))
		print("tk: xscrollcommand \"%s\": %s\n", tk->name->name, e);
}

static void
tkcvsgeom(Tk *tk)
{
	TkCanvas *c;
	c = TKobj(TkCanvas, tk);

	tkcvsf2i(tk, c);
	tk->dirty = tkrect(tk, 1);
	c->update = c->region;

	tkcvssv(tk);
	tkcvssh(tk);
}

char*
tkcvstags(Tk *tk, char *arg, char **val, int af)
{
	TkTop *o;
	int x, y;
	TkName *f;
	TkCtag *t, *tt;
	char *fmt;
	TkCpoints p;
	TkCanvas *c;
	TkCitem *i, *b;
	int d, dist, dx, dy;
	char tag[Tkmaxitem], buf[Tkmaxitem];
	char *e;

	USED(val);

	c = TKobj(TkCanvas, tk);

	o = tk->env->top;
	if(af == TkCadd) {
		arg = tkword(o, arg, tag, tag+sizeof(tag), nil);
		if(tag[0] == '\0' || (tag[0] >= '0' && tag[0] <= '9'))
			return TkBadtg;
	}

	fmt = "%d";
	arg = tkword(o, arg, buf, buf+sizeof(buf), nil);
	if(strcmp(buf, "above") == 0) {
		tkword(o, arg, buf, buf+sizeof(buf), nil);
		f = tkctaglook(tk, nil, buf);
		if(f == nil)
			return TkBadtg;

		t = tkclasttag(c->head, f->obj);
		if(t == nil)
			return TkBadtg;

		for(i = t->item->next; i; i = i->next) {
			if(af == TkCadd) {
				i->tags = tkmkname(tag);
				if(i->tags == nil)
					return TkNomem;
				tkcaddtag(tk, i, 0);
			}
			else {
				e = tkvalue(val, fmt, i->id);
				if(e != nil)
					return e;
				fmt = " %d";
			}
		}
		return nil;
	}

	if(strcmp(buf, "all") == 0) {
		for(i = c->head; i; i = i->next) {
			if(af == TkCadd) {
				i->tags = tkmkname(tag);
				if(i->tags == nil)
					return TkNomem;
				tkcaddtag(tk, i, 0);
			}
			else {
				e = tkvalue(val, fmt, i->id);
				if(e != nil)
					return e;
				fmt = " %d";
			}
		}
		return nil;
	}

	if(strcmp(buf, "below") == 0) {
		tkword(o, arg, buf, buf+sizeof(buf), nil);
		f = tkctaglook(tk, nil, buf);
		if(f == nil)
			return TkBadtg;
		tt = f->obj;
		for(b = c->head; b; b = b->next) {
			for(t = tt; t; t = t->itemlist)
				if(t->item == b)
					goto found;
		}
	found:
		for(i = c->head; i != b; i = i->next) {
			if(af == TkCadd) {
				i->tags = tkmkname(tag);
				if(i->tags == nil)
					return TkNomem;
				tkcaddtag(tk, i, 0);
			}
			else {
				e = tkvalue(val, fmt, i->id);
				if(e != nil)
					return e;
				fmt = " %d";
			}
		}
		return nil;
	}

	if(strcmp(buf, "closest") == 0) {
		e = tkfracword(o, &arg, &x, nil);
		if (e == nil)
			e = tkfracword(o, &arg, &y, nil);
		if (e != nil)
			return e;
		if(*arg != '\0')
			return "!not implemented";

		x = TKF2I(x);
		y = TKF2I(y);
		i = nil;
		dist = 0;
		for(b = c->head; b != nil; b = b->next) {
			dx = x - (b->p.bb.min.x + Dx(b->p.bb)/2);
			dy = y - (b->p.bb.min.y + Dy(b->p.bb)/2);
			d = dx*dx + dy*dy;
			if(d < dist || dist == 0) {
				i = b;
				dist = d;
			}
		}
		if(i == nil)
			return nil;

		if(af == TkCadd) {
			i->tags = tkmkname(tag);
			if(i->tags == nil)
				e = TkNomem;
			else
				tkcaddtag(tk, i, 0);
		}
		else
			e = tkvalue(val, fmt, i->id);
		return e;
	}

	if(strcmp(buf, "withtag") == 0) {
		tkword(o, arg, buf, buf+sizeof(buf), nil);
		f = tkctaglook(tk, nil, buf);
		if(f == nil)
			return TkBadtg;
		for(t = f->obj; t; t = t->taglist) {
			i = t->item;
			if(af == TkCadd) {
				i->tags = tkmkname(tag);
				if(i->tags == nil)
					return TkNomem;
				tkcaddtag(tk, i, 0);
			}
			else {
				e = tkvalue(val, fmt, i->id);
				if(e != nil)
					return e;
				fmt = " %d";
			}
		}
		return nil;
	}

	if(strcmp(buf, "enclosed") == 0) {
		e = tkparsepts(o, &p, &arg, 0);
		if(e != nil)
			goto done;
		if(p.npoint != 2) {
			e = TkFewpt;
			goto done;
		}
		for(i = c->head; i; i = i->next) {
			if(rectinrect(i->p.bb, p.bb)) {
				if(af == TkCadd) {
					i->tags = tkmkname(tag);
					if(i->tags == nil) {
						e = TkNomem;
						goto done;
					}
					tkcaddtag(tk, i, 0);
				}
				else {
					e = tkvalue(val, fmt, i->id);
					if(e != nil)
						goto done;
					fmt = " %d";
				}
			}
		}
		goto done;
	}

	if(strcmp(buf, "overlapping") == 0) {
		e = tkparsepts(o, &p, &arg, 0);
		if(e != nil)
			goto done;
		if(p.npoint != 2) {
			e = TkFewpt;
			goto done;
		}
		for(i = c->head; i; i = i->next) {
			if(rectXrect(i->p.bb, p.bb)) {
				if(af == TkCadd) {
					i->tags = tkmkname(tag);
					if(i->tags == nil) {
						e = TkNomem;
						goto done;
					}
					tkcaddtag(tk, i, 0);
				}
				else {
					e = tkvalue(val, "%d ", i->id);
					if(e != nil)
						goto done;
				}
			}
		}
		goto done;
	}

	return TkBadcm;

done: 		 /* both no error and error do the same thing */
	tkfreepoint(&p);
	return e;
}

static char*
tkcvsaddtag(Tk *tk, char *arg, char **val)
{
	return tkcvstags(tk, arg, val, TkCadd);
}

static char*
tkcvsfind(Tk *tk, char *arg, char **val)
{
	return tkcvstags(tk, arg, val, TkCfind);
}

static void
tksweepcanv(Tk *tk)
{
	int j, k;
	TkCtag *t, *tt;
	TkName **np, *n, *nn;
	TkCitem *i;
	TkCanvas *c;
	TkAction *a;

	c = TKobj(TkCanvas, tk);

	for(j = 0; j < TkChash; j++)
		for(n = c->thash[j]; n != nil; n = n->link)
			n->ref = 0;

	for(i = c->head; i != nil; i = i->next)
		for(t = i->stag; t != nil; t = t->itemlist)
			t->name->ref = 1;

	k = 0;
	for(j = 0; j < TkChash; j++) {
		np = &c->thash[j];
		for(n = *np; n != nil; n = nn) {
			nn = n->link;
			if(n->ref == 0) {
				for(t = n->obj; t != nil; t = tt) {
					tt = t->taglist;
					free(t);
				}
				tkfreebind(n->prop.binds);
				free(n);
				*np = nn;
			} else {
				np = &n->link;
				for(a = n->prop.binds; a != nil; a = a->link)
					k++;
			}
		}
	}

	c->actions = k;
	k = 3 * k / 2;
	if (k < Tksweep)
		c->actlim = Tksweep;
	else
		c->actlim = k;
}

/*
 * extension to tcl/tk:
 * grab set tag
 * grab release tag
 * grab ifunset tag
 */
static char*
tkcvsgrab(Tk *tk, char *arg, char **val)
{
	TkCtag *t;
	TkName *f;
	TkCanvas *c;
	char buf[Tkmaxitem];

	c = TKobj(TkCanvas, tk);
	arg = tkword(tk->env->top, arg, buf, buf+sizeof(buf), nil);
	if (strcmp(buf, "status") == 0) {
		if (c->grab != nil)
			return tkvalue(val, "%d", c->grab->id);
	}
	else if (strcmp(buf, "release") == 0) {
		c->grab = nil;
	}
	else if (strcmp(buf, "set") == 0 || strcmp(buf, "ifunset") == 0) {
		if (buf[0] == 'i' && c->grab != nil)
			return nil;
		tkword(tk->env->top, arg, buf, buf + sizeof(buf), nil);

		f = tkctaglook(tk, nil, buf);
		if(f == nil || f->obj == nil)
			return TkBadtg;
	
		c = TKobj(TkCanvas, tk);
		t = tkcfirsttag(c->head, f->obj);
		if(t == nil)
			return TkBadtg;
		c->grab = t->item;
	}
	else
		return TkBadvl;
	return nil;
}

static char*
tkcvsbind(Tk *tk, char *arg, char **val)
{
	Rune r;
	TkCtag *t;
	TkName *f;
	TkAction *a;
	TkCanvas *c;
	int event, mode;
	char *cmd, buf[Tkmaxitem];
	char *e;

	c = TKobj(TkCanvas, tk);
	if (c->actions >= c->actlim)
		tksweepcanv(tk);
	arg = tkword(tk->env->top, arg, buf, buf+sizeof(buf), nil);

	f = tkctaglook(tk, nil, buf);
	if(f == nil) {
		f = tkctaglook(tk, tkmkname(buf), buf);
		if(f == nil)
			return TkNomem;
	}

	arg = tkword(tk->env->top, arg, buf, buf+sizeof(buf), nil);
	if(buf[0] == '<') {
		event = tkseqparse(buf+1);
		if(event == -1)
			return TkBadsq;
	}
	else {
		chartorune(&r, buf);
		event = TkKey | r;
	}
	if(event == 0)
		return TkBadsq;

	arg = tkskip(arg, " \t");
	if(*arg == '\0') {
		for(t = f->obj; t; t = t->taglist) {
			for(a = t->name->prop.binds; a; a = a->link)
				if(event == a->event)
					return tkvalue(val, "%s", a->arg);
			for(a = t->name->prop.binds; a; a = a->link)
				if(event & a->event)
					return tkvalue(val, "%s", a->arg);
		}
		return nil;		
	}

	mode = TkArepl;
	if(*arg == '+') {
		mode = TkAadd;
		arg++;
	}
	else if(*arg == '-'){
		mode = TkAsub;
		arg++;
	}

	tkword(tk->env->top, arg, buf, buf+sizeof(buf), nil);
	cmd = strdup(buf);
	if(cmd == nil)
		return TkNomem;
	e = tkaction(&f->prop.binds, event, TkDynamic, cmd, mode);
	if(e == nil)
		c->actions++;
	return e;
}

static char*
tkcvscreate(Tk *tk, char *arg, char **val)
{
	TkCimeth *m;
	char buf[Tkmaxitem];

	arg = tkword(tk->env->top, arg, buf, buf+sizeof(buf), nil);
	for(m = tkcimethod; m->name; m++)
		if(strcmp(buf, m->name) == 0)
			return m->create(tk, arg, val);

	return TkBadit;
}

static char*
tkcvsbbox(Tk *tk, char *arg, char **val)
{
	TkName *f;
	TkCtag *t;
	Rectangle bb;
	char buf[Tkmaxitem];

	bb = bbnil;
	for(;;) {
		arg = tkword(tk->env->top, arg, buf, buf+sizeof(buf), nil);
		if(buf[0] == '\0')
			break;
		f = tkctaglook(tk, nil, buf);
		if(f == nil)
			return TkBadtg;
		for(t = f->obj; t; t = t->taglist)
			tkbbmax(&bb, &t->item->p.bb);
	}
	return tkvalue(val, "%d %d %d %d", bb.min.x, bb.min.y, bb.max.x, bb.max.y);
}

static char*
tkcvscanvx(Tk *tk, char *arg, char **val)
{
	int x, s;
	TkCanvas *c;
	Point p;
	char buf[Tkmaxitem];

	c = TKobj(TkCanvas, tk);
	arg = tkword(tk->env->top, arg, buf, buf+sizeof(buf), nil);
	if(buf[0] == '\0')
		return TkBadvl;

	p = tkposn(tk);
	x = atoi(buf) + c->view.x - (p.x + tk->borderwidth);

	if(*arg) {
		tkword(tk->env->top, arg, buf, buf+sizeof(buf), nil);
		s = atoi(buf);
		if (s) {
			if (x>=0)
				x = ((x+s/2)/s)*s;
			else
				x = ((x-s/2)/s)*s;
		}
	}
	return tkvalue(val, "%d", x);
}

static char*
tkcvscanvy(Tk *tk, char *arg, char **val)
{
	int y, s;
	TkCanvas *c;
	Point p;
	char buf[Tkmaxitem];

	c = TKobj(TkCanvas, tk);
	arg = tkword(tk->env->top, arg, buf, buf+sizeof(buf), nil);
	if(buf[0] == '\0')
		return TkBadvl;

	p = tkposn(tk);
	y = atoi(buf) + c->view.y - (p.y + tk->borderwidth);

	if(*arg) {
		tkitem(buf, arg);
		s = atoi(buf);
		if (s) {
			if (y>=0)
				y = ((y+s/2)/s)*s;
			else
				y = ((y-s/2)/s)*s;
		}
	}
	return tkvalue(val, "%d", y);
}

static char *
tkcvsscreenx(Tk *tk, char *arg, char **val)
{
	int x;
	TkCanvas *c;
	Point p;
	char buf[Tkmaxitem];

	c = TKobj(TkCanvas, tk);
	tkword(tk->env->top, arg, buf, buf+sizeof(buf), nil);
	if(buf[0] == '\0')
		return TkBadvl;
	p = tkposn(tk);
	x = atoi(buf) - c->view.x + (p.x + tk->borderwidth);
	return tkvalue(val, "%d", x);
}

static char *
tkcvsscreeny(Tk *tk, char *arg, char **val)
{
	int y;
	TkCanvas *c;
	Point p;
	char buf[Tkmaxitem];

	c = TKobj(TkCanvas, tk);
	tkword(tk->env->top, arg, buf, buf+sizeof(buf), nil);
	if(buf[0] == '\0')
		return TkBadvl;
	p = tkposn(tk);
	y = atoi(buf) - c->view.y + (p.y + tk->borderwidth);
	return tkvalue(val, "%d", y);
}

static char*
tkcvscoords(Tk *tk, char *arg, char **val)
{
	int i;
	Point *p;
	TkCtag *t;
	TkName *f;
	TkCanvas *c;
	TkCitem *item;
	char *fmt, *e, *v, buf[Tkmaxitem];

	arg = tkword(tk->env->top, arg, buf, buf+sizeof(buf), nil);
	if(buf[0] == '\0')
		return TkBadvl;

	f = tkctaglook(tk, nil, buf);
	if(f == nil || f->obj == nil)
		return TkBadtg;

	c = TKobj(TkCanvas, tk);

	t = tkcfirsttag(c->head, f->obj);
	if(t == nil)
		return TkBadtg;

	item = t->item;

	if(*arg == '\0') {
		fmt = "%s";
		p = item->p.parampt;
		for(i = 0; i < item->p.npoint; i++) {
			v = tkfprint(buf, p->x);
			*v++ = ' ';
			tkfprint(v, p->y);
			e = tkvalue(val, fmt, buf);
			if(e != nil)
				return e;
			fmt = " %s";
			p++;
		}
		return nil;
	}

	tkbbmax(&c->update, &item->p.bb);
	e = tkcimethod[item->type].coord(item, arg, 0, 0);
	tkbbmax(&c->update, &item->p.bb);
	tkcvssetdirty(tk);
	return e;
}

static char*
tkcvsscale(Tk *tk, char *arg, char **val)
{
	TkName *f;
	TkCtag *t;
	TkCanvas *c;
	TkCpoints pts;
	TkCitem *item;
	int j;
	char *e, buf[Tkmaxitem];
	Point *p, *d, origin, scalef;

	USED(val);

	c = TKobj(TkCanvas, tk);

	arg = tkword(tk->env->top, arg, buf, buf+sizeof(buf), nil);
	f = tkctaglook(tk, nil, buf);
	if(f == nil || f->obj == nil)
		return TkBadtg;

	e = tkparsepts(tk->env->top, &pts, &arg, 0);
	if(e != nil)
		return e;
	if(pts.npoint != 2) {
		tkfreepoint(&pts);
		return TkFewpt;
	}
	origin = pts.parampt[0];
	scalef = pts.parampt[1];
	tkfreepoint(&pts);
	for(t = f->obj; t; t = t->taglist) {
		item = t->item;
		p = item->p.parampt;
		d = item->p.drawpt;
		for(j = 0; j < item->p.npoint; j++) {
			p->x -= origin.x;
			p->y -= origin.y;
			p->x = TKF2I(p->x*scalef.x);
			p->y = TKF2I(p->y*scalef.y);
			p->x += origin.x;
			p->y += origin.y;
			d->x = TKF2I(p->x);
			d->y = TKF2I(p->y);
			d++;
			p++;
		}
		tkbbmax(&c->update, &item->p.bb);
		e = tkcimethod[item->type].coord(item, nil, 0, 0);
		tkbbmax(&c->update, &item->p.bb);
		if(e != nil)
			return e;

		tkcvssetdirty(tk);
	}
	return nil;
}

static char*
tkcvsdtag(Tk *tk, char *arg, char **val)
{
	TkName *f, *dt;
	char buf[Tkmaxitem];
	TkCtag **l, *t, *it, *tf;

	USED(val);

	arg = tkword(tk->env->top, arg, buf, buf+sizeof(buf), nil);
	f = tkctaglook(tk, nil, buf);
	if(f == nil || f->obj == nil)
		return TkBadtg;

/*
	XXX this code doesn't appear to work properly.
	fix it later. for the moment, it's just a somewhat more
	efficient substitute for the later code, so just use that
	instead.

	if(*arg == '\0') {
		for(t = f->obj; t; t = tf) {
			l = &t->item->stag;
			for(it = *l; it; it = it->itemlist) {
				if(it->item == t->item) {
					*l = it->itemlist;
					break;
				}
				l = &it->itemlist;
			}

			tf = t->taglist;
			free(t);
		}
		f->obj = nil;
		return nil;
	}
*/
	if (*arg == '\0')
		dt = f;
	else {
		tkword(tk->env->top, arg, buf, buf+sizeof(buf), nil);
		dt = tkctaglook(tk, nil, buf);
		if(dt == nil || dt->obj == nil)
			return TkBadtg;
	}

	for(t = f->obj; t; t = t->taglist) {
		l = (TkCtag **)&dt->obj;
		for(it = dt->obj; it; it = it->taglist) {
			if(t->item == it->item) {
				*l = it->taglist;
				l = &t->item->stag;
				for(tf = *l; tf; tf = tf->itemlist) {
					if(tf == it) {
						*l = tf->itemlist;
						break;
					}
					l = &tf->itemlist;
				}
				free(it);
				break;
			}
			l = &it->taglist;
		}
	}
	return nil;
}

static char*
tkcvsdchars(Tk *tk, char *arg, char **val)
{
	TkCtag *t;
	TkName *f;
	char *e, buf[Tkmaxitem];

	USED(val);

	arg = tkword(tk->env->top, arg, buf, buf+sizeof(buf), nil);
	f = tkctaglook(tk, nil, buf);
	if(f == nil || f->obj == nil)
		return TkBadtg;

	for(t = f->obj; t; t = t->taglist) {
		if(t->item->type == TkCVtext) {
			e = tkcvstextdchar(tk, t->item, arg);
			if(e != nil)
				return e;
		}
	}

	return nil;
}

static char*
tkcvsindex(Tk *tk, char *arg, char **val)
{
	TkCtag *t;
	TkName *f;
	char *e, buf[Tkmaxitem];

	USED(val);

	arg = tkword(tk->env->top, arg, buf, buf+sizeof(buf), nil);
	f = tkctaglook(tk, nil, buf);
	if(f == nil || f->obj == nil)
		return TkBadtg;

	for(t = f->obj; t; t = t->taglist) {
		if(t->item->type == TkCVtext) {
			e = tkcvstextindex(tk, t->item, arg, val);
			if(e != nil)
				return e;
			return nil;
		}
	}
	return nil;
}

static char*
tkcvsicursor(Tk *tk, char *arg, char **val)
{
	TkCtag *t;
	TkName *f;
	char *e, buf[Tkmaxitem];

	USED(val);

	arg = tkword(tk->env->top, arg, buf, buf+sizeof(buf), nil);
	f = tkctaglook(tk, nil, buf);
	if(f == nil || f->obj == nil)
		return TkBadtg;

	for(t = f->obj; t; t = t->taglist) {
		if(t->item->type == TkCVtext) {
			e = tkcvstexticursor(tk, t->item, arg);
			if(e != nil)
				return e;
			return nil;
		}
	}
	return nil;
}

static char*
tkcvsinsert(Tk *tk, char *arg, char **val)
{
	TkCtag *t;
	TkName *f;
	char *e, buf[Tkmaxitem];

	USED(val);

	arg = tkword(tk->env->top, arg, buf, buf+sizeof(buf), nil);
	f = tkctaglook(tk, nil, buf);
	if(f == nil || f->obj == nil)
		return TkBadtg;

	for(t = f->obj; t; t = t->taglist) {
		if(t->item->type == TkCVtext) {
			e = tkcvstextinsert(tk, t->item, arg);
			if(e != nil)
				return e;
		}
	}

	return nil;
}

static char*
tkcvsselect(Tk *tk, char *arg, char **val)
{
	int op;
	TkCtag *t;
	TkName *f;
	TkCanvas *c;
	char buf[Tkmaxitem];

	c = TKobj(TkCanvas, tk);

	arg = tkword(tk->env->top, arg, buf, buf+sizeof(buf), nil);
	if(strcmp(buf, "clear") == 0) {
		tkcvstextclr(tk);
		return nil;		
	}
	if(strcmp(buf, "item") == 0) {
		if(c->selection)
			return tkvalue(val, "%d", c->selection->id);
		return nil;		
	}

	if(strcmp(buf, "to") == 0)
		op = TkCselto;
	else
	if(strcmp(buf, "from") == 0)
		op = TkCselfrom;
	else
	if(strcmp(buf, "adjust") == 0)
		op = TkCseladjust;
	else
		return TkBadcm;

	arg = tkword(tk->env->top, arg, buf, buf+sizeof(buf), nil);
	f = tkctaglook(tk, nil, buf);
	if(f == nil)
		return TkBadtg;

	t = tkcfirsttag(c->head, f->obj);
	if(t == nil)
		return TkBadtg;

	return tkcvstextselect(tk, t->item, arg, op);
}

static char*
tkcvsitemcget(Tk *tk, char *arg, char **val)
{
	TkName *f;
	TkCtag *t;
	TkCitem *i;
	char buf[Tkmaxitem];

	arg = tkword(tk->env->top, arg, buf, buf+sizeof(buf), nil);
	f = tkctaglook(tk, nil, buf);
	if(f == nil || f->obj == nil)
		return TkBadtg;

	for(i = TKobj(TkCanvas, tk)->head; i; i = i->next) {
		for(t = f->obj; t; t = t->taglist)
			if(i == t->item)
				return tkcimethod[i->type].cget(i, arg, val);
	}
	return nil;
}

static char*
tkcvsitemconf(Tk *tk, char *arg, char **val)
{
	char *e;
	TkName *f;
	TkCtag *t;
	TkCitem *i;
	TkCanvas *c;
	char buf[Tkmaxitem];

	USED(val);
	arg = tkword(tk->env->top, arg, buf, buf+sizeof(buf), nil);
	f = tkctaglook(tk, nil, buf);
	if(f == nil || f->obj == nil)
		return TkBadtg;

	c = TKobj(TkCanvas, tk);
	for(t = f->obj; t; t = t->taglist) {
		for(i = c->head; i; i = i->next) {
			if(i == t->item) {
				tkbbmax(&c->update, &i->p.bb);
				e = tkcimethod[i->type].conf(tk, i, arg);
				tkbbmax(&c->update, &i->p.bb);
				tkcvssetdirty(tk);
				if(e != nil)
					return e;
			}
		}
	}
	return nil;
}

static void
tkcvsfreename(TkCanvas *c, TkName *n)
{
	ulong h;
	char *p, *s;
	TkName *f, **l;
	
	/* just free implicit ones for now */
	if(n == nil)
		return;
	s = n->name;
	if(s == nil || (s[0] < '0' || s[0] > '9'))
		return;
	h = 0;
	for(p = s; *p; p++)
		h += 3*h + *p;
	l = &c->thash[h%TkChash];
	for(f = *l; f; l = &f->link, f = *l)
		if(f == n){
			*l = f->link;
			tkfreebind(f->prop.binds);
			free(f);
			return;
		}
}

static char*
tkcvsdelete(Tk *tk, char *arg, char **val)
{
	TkName *f;
	TkCanvas *c;
	char buf[Tkmaxitem];
	TkCitem *item, *prev, *i;
	TkCtag *t, *inext, **l, *dit, *it;

	USED(val);

	c = TKobj(TkCanvas, tk);
	for(;;) {
		arg = tkword(tk->env->top, arg, buf, buf+sizeof(buf), nil);
		if(buf[0] == '\0')
			break;
		f = tkctaglook(tk, nil, buf);
		if(f == nil || f->obj == nil)
			return nil;
		while(f->obj) {
			t = f->obj;
			item = t->item;
			for(it = item->stag; it; it = inext) {
				inext = it->itemlist;
				l = (TkCtag **)&it->name->obj;
				for(dit = *l; dit; dit = dit->taglist) {
					if(dit->item == item) {
						*l = dit->taglist;
						if(dit != t){
							tkcvsfreename(c, dit->name);
							free(dit);
						}
						break;
					}
					l = &dit->taglist;
				}
			}
			tkbbmax(&c->update, &item->p.bb);
			tkcvssetdirty(tk);
			prev = nil;
			for(i = c->head; i; i = i->next) {
				if(i == item)
					break;
				prev = i;
			}
			if(prev == nil)
				c->head = i->next;
			else
				prev->next = i->next;
			if(c->tail == item)
				c->tail = prev;
			if(c->focus == item)
				c->focus = nil;
			if(c->mouse == item)
				c->mouse = nil;
			if(c->selection == item)
				c->selection = nil;
			if(c->curtag.item == item)
				c->current->obj = nil;
			if (c->grab == item)
				c->grab = nil;

			tkcvsfreeitem(item);
			free(t);
		}
	}
	return nil;
}

static char*
tkcvsfocus(Tk *tk, char *arg, char **val)
{
	TkName *f;
	TkCtag *t;
	TkCanvas *c;
	TkCitem *i, *focus;
	char buf[Tkmaxitem];

	c = TKobj(TkCanvas, tk);

	if(*arg == '\0') {
		if(c->focus == nil)
			return nil;
		return tkvalue(val, "%d", c->focus->id);
	}

	tkword(tk->env->top, arg, buf, buf+sizeof(buf), nil);
	if(buf[0] == '\0')
		return TkBadvl;
	f = tkctaglook(tk, nil, buf);
	if(f == nil || f->obj == nil)
		return nil;

	focus = c->focus;
	if(focus != nil && focus->type == TkCVtext)
		tkcvstextfocus(tk, focus, 0);

	for(i = c->head; i; i = i->next) {
		if(i->type == TkCVtext || i->type == TkCVwindow) {
			for(t = f->obj; t; t = t->taglist)
				if(t->item == i)
					focus = i;
		}
	}

	if(focus != nil && focus->type == TkCVtext)
		tkcvstextfocus(tk, focus, 1);

	c->focus = focus;
	return nil;
}

static char*
tkcvsgettags(Tk *tk, char *arg, char **val)
{
	TkCtag *t;
	TkName *f;
	TkCanvas *c;
	char *fmt, *e, buf[Tkmaxitem];

	tkword(tk->env->top, arg, buf, buf+sizeof(buf), nil);
	if(buf[0] == '\0')
		return TkBadvl;

	f = tkctaglook(tk, nil, buf);
	if(f == nil)
		return TkBadtg;

	c = TKobj(TkCanvas, tk);
	t = tkclasttag(c->head, f->obj);
	if(t == nil)
		return TkBadtg;
	fmt = "%s";
	t = t->item->stag;
	while(t) {
		/* XXX when might t->name be legally nil? */
		if (t->name != nil) {
			if (strcmp(t->name->name, "all")) {
				e = tkvalue(val, fmt, t->name->name);
				if(e != nil)
					return e;
				fmt = " %s";
			}
		}
		t = t->itemlist;
	}
	return nil;
}

static char*
tkcvslower(Tk *tk, char *arg, char **val)
{
	TkCtag *t;
	TkCanvas *c;
	TkName *f, *b;
	char buf[Tkmaxitem];
	TkCitem *it, **l, **below, *items, **itemtail, *prev, *iprev;

	USED(val);
	c = TKobj(TkCanvas, tk);

	arg = tkword(tk->env->top, arg, buf, buf+sizeof(buf), nil);
	f = tkctaglook(tk, nil, buf);
	if(f == nil || f->obj == nil)
		return nil;

	below = &c->head;
	tkword(tk->env->top, arg, buf, buf+sizeof(buf), nil);
	if(buf[0] != '\0') {
		b = tkctaglook(tk, nil, buf);
		if(b == nil || f->obj == nil)
			return TkBadtg;
		for(it = c->head; it; it = it->next) {
			for(t = b->obj; t; t = t->taglist)
				if(t->item == it)
					goto found;
			below = &it->next;
		}
	found:;
	}
	l = &c->head;
	prev = iprev = nil;
	itemtail = &items;;
	for (it = *l; it != nil; it = *l) {
		for (t = f->obj; t; t = t->taglist) {
			if(t->item == it) {
				if (it == *below || below == &it->next)
					below = l;
				if (it == c->tail)
					c->tail = prev;
				*l = it->next;
				*itemtail = it;
				iprev = it;
				itemtail = &it->next;
				tkbbmax(&c->update, &it->p.bb);
				goto next;
			}
		}
		prev = it;
		l = &it->next;
next:;
	}
	if (prev == nil)
		c->tail = iprev;
	*itemtail = *below;
	*below = items;
	tkcvssetdirty(tk);
	return nil;
}

static char*
tkcvsmove(Tk *tk, char *arg, char **val)
{
	TkCtag *t;
	int fx, fy;
	TkTop *top;
	TkCpoints *p;
	TkName *tag;
	Rectangle *u;
	TkCitem *item;
	char *e;
	char buf[Tkmaxitem];

	USED(val);
	top = tk->env->top;
	arg = tkword(top, arg, buf, buf+sizeof(buf), nil);
	tag = tkctaglook(tk, nil, buf);
	if(tag == nil)
		return nil;

	e = tkfracword(top, &arg, &fx, nil);
	if (e != nil)
		return e;
	e = tkfracword(top, &arg, &fy, nil);
	if(e != nil)
		return e;

	u = &TKobj(TkCanvas, tk)->update;
	for(t = tag->obj; t; t = t->taglist) {
		item = t->item;
		p = &item->p;
		tkbbmax(u, &p->bb);
		tkcimethod[item->type].coord(item, nil, fx, fy);
		tkbbmax(u, &p->bb);
	}
	tkcvssetdirty(tk);
	return nil;
}

static char*
tkcvsraise(Tk *tk, char *arg, char **val)
{
	TkCtag *t;
	TkCanvas *c;
	TkName *f, *a;
	char buf[Tkmaxitem];
	TkCitem *prev, *it, *above, *items, *itemtail, *next;

	USED(val);
	c = TKobj(TkCanvas, tk);

	arg = tkword(tk->env->top, arg, buf, buf+sizeof(buf), nil);
	f = tkctaglook(tk, nil, buf);
	if(f == nil)
		return nil;

	above = c->tail;
	tkword(tk->env->top, arg, buf, buf+sizeof(buf), nil);
	if(buf[0] != '\0') {
		a = tkctaglook(tk, nil, buf);
		if(a == nil)
			return TkBadtg;
		/*
		 * find topmost item in the display list matching the "above" tag
		 */
		for(it = c->head; it != nil; it = it->next) {
			for(t = a->obj; t; t = t->taglist)
				if(t->item == it)
					above = it;
		}
	}
	prev = nil;
	items = itemtail = nil;
	for (it = c->head; it != nil; it = next) {
		next = it->next;
		for (t = f->obj; t; t = t->taglist) {
			if(t->item == it) {
				if (it == above)
					above = next;
				if (prev)
					prev->next = next;
				else
					c->head = next;
				if (itemtail)
					itemtail->next = it;
				else
					items = it;
				itemtail = it;
				tkbbmax(&c->update, &it->p.bb);
				goto next;
			}
		}
		prev = it;
next:;
	}
	if (items != nil) {
		if (above) {
			itemtail->next = above->next;
			if (above->next == nil)
				c->tail = itemtail;
			above->next = items;
		} else {
			if (prev)
				prev->next = items;
			else
				c->head = items;
			c->tail = itemtail;
			itemtail->next = nil;
		}
	}

	tkcvssetdirty(tk);
	return nil;
}

static char*
tkcvstype(Tk *tk, char *arg, char **val)
{
	TkCtag *t;
	TkName *f;
	TkCanvas *c;
	char buf[Tkmaxitem];

	tkword(tk->env->top, arg, buf, buf+sizeof(buf), nil);
	if(buf[0] == '\0')
		return TkBadvl;

	f = tkctaglook(tk, nil, buf);
	if(f == nil || f->obj == nil)
		return nil;

	c = TKobj(TkCanvas, tk);

	t = tkcfirsttag(c->head, f->obj);
	if(t == nil)
		return nil;

	return tkvalue(val, "%s", tkcimethod[t->item->type].name);
}

static char*
tkcvsview(Tk *tk, char *arg, char **val, int nl, int *posn, int min, int max, int inc)
{
	TkTop *t;
	int top, bot, diff, amount;
	char *e;
	char buf[Tkmaxitem], *v;

	diff = max-min;
	if(*arg == '\0') {
		if ( diff == 0 ) 
			top = bot = 0;
		else {
			top = TKI2F(*posn-min)/diff;
			bot = TKI2F(*posn+nl-min)/diff;
		}
		v = tkfprint(buf, top);
		*v++ = ' ';
		tkfprint(v, bot);
		return tkvalue(val, "%s", buf);
	}

	t = tk->env->top;
	arg = tkword(t, arg, buf, buf+sizeof(buf), nil);
	if(strcmp(buf, "moveto") == 0) {
		e = tkfrac(&arg, &top, nil);
		if (e != nil)
			return e;
		*posn = min + TKF2I((top+1)*diff);
	}
	else
	if(strcmp(buf, "scroll") == 0) {
		arg = tkword(t, arg, buf, buf+sizeof(buf), nil);
		amount = atoi(buf);
		tkword(t, arg, buf, buf+sizeof(buf), nil);
		if(buf[0] == 'p')		/* Pages */
			amount = amount * nl * 9 /10;
		else if (inc > 0)
			amount *= inc;
		else
			amount = amount * nl / 10;
		*posn += amount;
	}
	else	
		return TkBadcm;

	bot = max - nl;
	if(*posn > bot)
		*posn = bot;
	if(*posn < min)
		*posn = min;

	tk->dirty = tkrect(tk, 0);
	return nil;
}

static char*
tkcvsyview(Tk *tk, char *arg, char **val)
{
	int si;
	char *e;
	TkCanvas *c = TKobj(TkCanvas, tk);

	si = TKF2I(c->yscrolli);
	e = tkcvsview(tk, arg, val, tk->act.height, &c->view.y, c->region.min.y, c->region.max.y, si); 
	tkcvssv(tk);
	return e;
}

static char*
tkcvsxview(Tk *tk, char *arg, char **val)
{
	int si;
	char *e;
	TkCanvas *c = TKobj(TkCanvas, tk);

	si = TKF2I(c->xscrolli);
	e = tkcvsview(tk, arg, val, tk->act.width, &c->view.x, c->region.min.x, c->region.max.x, si);
	tkcvssh(tk);
	return e;
}

/*
 * return in posn the new view origin such that (preferably) smin and smax
 * lie between cmin and cmax (cmin is the current view origin, and cmax the
 * other end of the visible area).
 * adjust posn (the view origin) so that (preferably) both smin and smax lie
 * inside cmin to cmax. if both smin and smax cannot fit, then
 * at least make sure that spref (smin<=spref<=smax) is visible.
 * return 0 if no adjustment is required (the interval is already visible).
 *
 * attempt to make an adjustment as small as possible that
 * fits these criteria.
 */
static int
tkadjustvis(int *posn, int c0, int c1, int s0, int s1, int spref)
{
	int d, v;

	d = c1 - c0;		/* visible width */

	/*
	 * if requested range fits inside visible range,
	 * no adjustment is necessary
	 */
	if (c0 <= s0 && s1 <= c1)
		return 0;

	/*
	 * if requested range fits, make it fully visible
	 */
	if (s1 - s0 < d) {
		if (s0 < c0)
			v = s0;
		else
			v = s1 - d;
	} else {
		/*
		 * choose upper or lower end of requested range,
		 * depending on which end of requested area is already
		 * visible (if any).
		 */
		if (c0 <= s1 && s1 < c1) {		/* overlapping left of visible */
			v = s1 - d;
			if (v > spref)
				v = spref;
		}
		else
		if (c0 <= s0 && s0 < c1) {		/* overlapping right of visible */
			v = s0;
			if (v + d <= spref)
				v = spref - d;
		}
		else
		if (s1 < c0) {				/* left of visible */
			v = spref;
			if (v + d > s1)
				v = s1 - d;
		}
		else {					/* right of visible */
			v = spref - d;
			if (v < s0)
				v = s0;
		}
	}
	*posn = v;
	return 1;
}

static void
tkcvsseerect(Tk *tk, Rectangle r, Point p)
{
	TkCanvas *c;
	int scrollh, scrollv;

	c = TKobj(TkCanvas, tk);

	scrollh = tkadjustvis(&c->view.x, c->view.x, c->view.x + tk->act.width,
			r.min.x, r.max.x, p.x);
	scrollv = tkadjustvis(&c->view.y, c->view.y, c->view.y + tk->act.height,
			r.min.y, r.max.y, p.y);
	if (scrollh)
		tkcvssh(tk);
	if (scrollv)
		tkcvssv(tk);
	if (scrollh || scrollv)
		tk->dirty = tkrect(tk, 0);
}
			
static char*
tkcvssee(Tk *tk, char *arg, char **val)
{
	Rectangle r;
	int n, coords[4];
	char *e;

	USED(val);
	n = 0;
	while (n < 4) {
		if (*arg == '\0')
			break;
		e = tkfracword(tk->env->top, &arg, &coords[n++], nil);
		if (e != nil)
			return e;
	}

	if (n != 2 && n != 4)
		return TkFewpt;

	r.min.x = TKF2I(coords[0]);
	r.min.y = TKF2I(coords[1]);
	if (n == 4) {
		r.max.x = TKF2I(coords[2]);
		r.max.y = TKF2I(coords[3]);
	} else
		r.max = r.min;
	r = canonrect(r);
	/*
	 * XXX should intersect r with scrollregion here, as you shouldn't
	 * be able to display things outside the scroll region. (??)
	 */

	tkcvsseerect(tk, r, r.min);
	return nil;
}

static void
tkcvsseesub(Tk *tk, Rectangle *rr, Point *pp)
{
	Rectangle r;
	Point p;
	TkCanvas *c;
	c = TKobj(TkCanvas, tk);

	r = rectaddpt(*rr, c->view);
	p = addpt(*pp, c->view);

	tkcvsseerect(tk, r, p);

	*rr = rectsubpt(r, c->view);
	*pp = subpt(p, c->view);
}

static void
tkcvsgetimgs(Tk* tk, Image **image, Image **mask)
{
	TkCanvas *c;
	c = TKobj(TkCanvas, tk);

	*image = c->image;
	*mask = c->mask;		/* XXX this is wrong - the mask image has nothing to do with the main image */
}

TkCimeth tkcimethod[] =
{
	"line",		tkcvslinecreat,
			tkcvslinedraw,
			tkcvslinefree,
			tkcvslinecoord,
			tkcvslinecget,
			tkcvslineconf,
			tkcvslinehit,

	"text",		tkcvstextcreat,	
			tkcvstextdraw,
			tkcvstextfree,
			tkcvstextcoord,
			tkcvstextcget,
			tkcvstextconf,
			nil,

	"rectangle",	tkcvsrectcreat,	
			tkcvsrectdraw,
			tkcvsrectfree,
			tkcvsrectcoord,
			tkcvsrectcget,
			tkcvsrectconf,
			nil,

	"oval",		tkcvsovalcreat,	
			tkcvsovaldraw,
			tkcvsovalfree,
			tkcvsovalcoord,
			tkcvsovalcget,
			tkcvsovalconf,
			tkcvsovalhit,

	"bitmap",	tkcvsbitcreat,	
			tkcvsbitdraw,
			tkcvsbitfree,
			tkcvsbitcoord,
			tkcvsbitcget,
			tkcvsbitconf,
			nil,

	"polygon",	tkcvspolycreat,	
			tkcvspolydraw,
			tkcvspolyfree,
			tkcvspolycoord,
			tkcvspolycget,
			tkcvspolyconf,
			tkcvspolyhit,

	"window",	tkcvswindcreat,	
			tkcvswinddraw,
			tkcvswindfree,
			tkcvswindcoord,
			tkcvswindcget,
			tkcvswindconf,
			nil,

	"image",	tkcvsimgcreat,	
			tkcvsimgdraw,
			tkcvsimgfree,
			tkcvsimgcoord,
			tkcvsimgcget,
			tkcvsimgconf,
			nil,

	"arc",		tkcvsarccreat,	
			tkcvsarcdraw,
			tkcvsarcfree,
			tkcvsarccoord,
			tkcvsarccget,
			tkcvsarcconf,
			nil,
	nil
};

static
TkCmdtab tkcanvcmd[] =
{
	"addtag",		tkcvsaddtag,
	"bbox",			tkcvsbbox,
	"bind",			tkcvsbind,
	"cget",			tkcvscget,
	"configure",		tkcvsconf,
	"create",		tkcvscreate,
	"canvasx",		tkcvscanvx,
	"canvasy",		tkcvscanvy,
	"coords",		tkcvscoords,
	"dchars",		tkcvsdchars,
	"delete",		tkcvsdelete,
	"dtag",			tkcvsdtag,
	"find",			tkcvsfind,
	"focus",		tkcvsfocus,
	"gettags",		tkcvsgettags,
	"grab",		tkcvsgrab,
	"icursor",		tkcvsicursor,
	"insert",		tkcvsinsert,
	"index",		tkcvsindex,
	"itemcget",		tkcvsitemcget,
	"itemconfigure",	tkcvsitemconf,
	"lower",		tkcvslower,
	"move",			tkcvsmove,
	"raise",		tkcvsraise,
	"screenx",		tkcvsscreenx,
	"screeny",		tkcvsscreeny,
	"see",		tkcvssee,
	"select",		tkcvsselect,
	"scale",		tkcvsscale,
	"type",			tkcvstype,
	"yview",		tkcvsyview,
	"xview",		tkcvsxview,
	nil
};

TkMethod canvasmethod = {
	"canvas",
	tkcanvcmd,
	tkfreecanv,
	tkdrawcanv,
	tkcvsgeom,
	tkcvsgetimgs,
	tkcvsfocusorder,
	tkcvsdirty,
	tkcvsrelpos,
	tkcvsevent,
	tkcvsseesub,
	tkcvsinwindow,
	nil,
	tkcvsforgetsub,
};