g_scalar.c

        sprintf(tagbuf, "scalar%lxgobj", (long unsigned int)x->sc_vec);
        sprintf(groupbuf, "dgroup%lx.%lx", (long unsigned int)templatecanvas,
            (long unsigned int)x->sc_vec);
        gui_vmess("gui_create_scalar_group", "xss",
            glist_getcanvas(owner), groupbuf, tagbuf);
    }

    /* warning: don't need--- have recursive func. */
    for (y = templatecanvas->gl_list; y; y = y->g_next)
    {
        t_parentwidgetbehavior *wb = pd_getparentwidget(&y->g_pd);
        if (!wb)
        {
            /* check subpatches for more drawing commands.
               (Optimized to only search [group] subpatches) */
            if (pd_class(&y->g_pd) == canvas_class &&
                ((t_glist *)y)->gl_svg)
            {
                scalar_groupvis(x, owner, template,
                    (t_glist *)y, templatecanvas, vis);
            }
            continue;
        }
        (*wb->w_parentvisfn)(y, owner, 0, x, x->sc_vec, template,
            basex, basey, vis);
    }
    if (!vis)
    {
        //sys_vgui(".x%lx.c delete .scalar%lx\n", glist_getcanvas(owner),
        //    x->sc_vec);
        char tagbuf[MAXPDSTRING];
        sprintf(tagbuf, "scalar%lx", (long unsigned int)x->sc_vec);
        gui_vmess("gui_scalar_erase", "xs",
            glist_getcanvas(owner), tagbuf);
    }

    sys_unqueuegui(x);
    if (glist_isselected(owner, &x->sc_gobj))
    {
        // we removed this because it caused infinite recursion
        // in the scalar-help.pd example
        //scalar_select(z, owner, 1);
        post("here we are in scalar vis, selected...");
        scalar_drawselectrect(x, owner, 0);
        scalar_drawselectrect(x, owner, 1);
    }
}

static void scalar_doredraw(t_gobj *client, t_glist *glist)
{
    scalar_vis(client, glist, 0);
    scalar_vis(client, glist, 1);
    if (glist_isselected(glist_getcanvas(glist), (t_gobj *)glist))
    {
        //fprintf(stderr,"yes\n");
        sys_vgui("pdtk_select_all_gop_widgets .x%lx %lx %d\n",
            glist_getcanvas(glist), glist, 1);
    }
    canvas_getscroll(glist_getcanvas(glist));
}

void scalar_redraw(t_scalar *x, t_glist *glist)
{
    if (glist_isvisible(glist))
        scalar_doredraw((t_gobj *)x, glist);
        //sys_queuegui(x, glist, scalar_doredraw);
}

/* here we call the parentclickfns for drawing commands.
   We recurse all the way to the end of the glist (and, for the
   groups, as deep as they go) and then call the functions from the bottom up.
   This way the clicks can "bubble" up from the bottom.  This has the effect
   that the shape visually closest to the front gets called first.

   This is called "event bubbling" in the HTML5 DOM.  You can also call
   events in top down order in HTML5/SVG as well (called "capturing" or
   "trickling"). But because some old version of Internet Explorer only did
   bubbling, that is the most widely used model today, and the only one
   I decided to implement here.

   However, [group] doesn't yet have an outlet to report events. Only a
   single [draw] should report a click here atm.
*/
int scalar_groupclick(struct _glist *groupcanvas,
    t_word *data, t_template *template, t_scalar *sc,
    t_array *ap, struct _glist *owner,
    t_float xloc, t_float yloc, int xpix, int ypix,
    int shift, int alt, int dbl, int doit, t_float basex, t_float basey,
    t_gobj *obj)
{
    int hit = 0;
    t_gobj *nextobj = obj->g_next;
    /* let's skip over any objects that aren't drawing instructions
       or groups */
    while (nextobj &&
           !class_isdrawcommand(pd_class((t_pd *)nextobj)) &&
           !(pd_class(&nextobj->g_pd) == canvas_class &&
               ((t_glist *)nextobj)->gl_svg))
        nextobj = nextobj->g_next;
    /* If there's another link in the list go ahead and recurse with it */
    if (nextobj)
    {
        hit = (scalar_groupclick(groupcanvas, data, template, sc, ap,
            owner, xloc, yloc, xpix, ypix,
            shift, alt, dbl, doit, basex, basey, nextobj));
        if (hit) return hit;
    }
    /* recurse inside a [group] object to look for more objects */
    if (pd_class(&obj->g_pd) == canvas_class && ((t_glist *)obj)->gl_svg)
    {
            t_canvas *cnv = (t_canvas *)obj;
            obj = cnv->gl_list;
            if (obj)
                return (scalar_groupclick(cnv, data, template, sc, ap,
                owner, xloc, yloc, xpix, ypix,
                shift, alt, dbl, doit, basex, basey, obj));
    }
    else /* finally, try to call the parent click function ... */
    {
        t_parentwidgetbehavior *wb = pd_getparentwidget(&obj->g_pd);
        if (!wb) return hit;
        if ((*wb->w_parentclickfn)(obj, owner,
            data, template, sc, ap, basex + xloc, basey + yloc,
            xpix, ypix, shift, alt, dbl, doit))
                hit = 1;
    }
    return (hit);
}

/*
int scalar_groupclick(struct _glist *groupcanvas,
    t_word *data, t_template *template, t_scalar *sc,
    t_array *ap, struct _glist *owner,
    t_float xloc, t_float yloc, int xpix, int ypix,
    int shift, int alt, int dbl, int doit, t_float basex, t_float basey)
{
    int hit = 0;
    t_gobj *y;
    for (y = groupcanvas->gl_list; y; y = y->g_next)
    {
        if (pd_class(&y->g_pd) == canvas_class &&
            ((t_glist *)y)->gl_svg)
        {
            if (hit = scalar_groupclick((t_glist *)y, data, template, sc, ap,
                owner, xloc, yloc, xpix, ypix,
                shift, alt, dbl, doit, basex, basey))
            {
                return (hit);
            }
        }
        t_parentwidgetbehavior *wb = pd_getparentwidget(&y->g_pd);
        if (!wb) continue;
        if (hit = (*wb->w_parentclickfn)(y, owner,
            data, template, sc, ap, basex + xloc, basey + yloc,
            xpix, ypix, shift, alt, dbl, doit))
        {
            return (hit);
        }
    }
    return 0;
}
*/

int scalar_doclick(t_word *data, t_template *template, t_scalar *sc,
    t_array *ap, struct _glist *owner,
    t_float xloc, t_float yloc, int xpix, int ypix,
    int shift, int alt, int dbl, int doit)
{
    int hit = 0;
    t_canvas *templatecanvas = template_findcanvas(template);
    t_atom at[2];
    t_gobj *obj;
    t_float basex = template_getfloat(template, gensym("x"), data, 0);
    t_float basey = template_getfloat(template, gensym("y"), data, 0);
    //fprintf(stderr,"=================scalar_doclick %f %f %f %f %d\n",
    //    basex, basey, xloc, yloc, doit);

    SETFLOAT(at, basex + xloc);
    SETFLOAT(at+1, basey + yloc);
    if (doit)
    {
        //fprintf(stderr,"    doit\n");
        template_notifyforscalar(template, owner, 
            sc, gensym("click"), 2, at);
    }

    // if we are nested ignore xloc and yloc, otherwise
    // nested objects get their hitbox miscalculated
    if (xloc != 0.0 || yloc != 0.0)
    {
        //fprintf(stderr,"ignoring\n");
        //basex = 0.0;
        //basey = 0.0;
    }

    if (templatecanvas)
    {
        if (!(obj = templatecanvas->gl_list)) return 0;
        hit = scalar_groupclick(templatecanvas, data, template, sc, ap,
                    owner, xloc, yloc, xpix, ypix,
                    shift, alt, dbl, doit, basex, basey, obj);
    }
    return hit;
}

/* Unfortunately, nested gops don't yet handle scalar clicks correctly. The
   nested scalar seems not to receive the click.  However, the enter/leave
   messages happen just fine since most of their logic is in tcl/tk. */
static int scalar_click(t_gobj *z, struct _glist *owner,
    int xpix, int ypix, int shift, int alt, int dbl, int doit)
{
    //fprintf(stderr,"scalar_click %d %d\n", xpix, ypix);
    t_scalar *x = (t_scalar *)z;

    x->sc_bboxcache = 0;

    t_template *template = template_findbyname(x->sc_template);

    return (scalar_doclick(x->sc_vec, template, x, 0,
        owner, 0, 0, xpix, ypix, shift, alt, dbl, doit));
}

void canvas_writescalar(t_symbol *templatesym, t_word *w, t_binbuf *b,
    int amarrayelement);

static void scalar_save(t_gobj *z, t_binbuf *b)
{
    t_scalar *x = (t_scalar *)z;
    t_binbuf *b2 = binbuf_new();
    canvas_writescalar(x->sc_template, x->sc_vec, b2, 0);
    binbuf_addv(b, "ss", &s__X, gensym("scalar"));
    binbuf_addbinbuf(b, b2);
    binbuf_addsemi(b);
    binbuf_free(b2);
}

static void scalar_menuopen(t_scalar *x)
{
    t_canvas *c = scalar_getcanvasfield(x);
    canvas_vis(c, 1);
}

static void scalar_properties(t_gobj *z, struct _glist *owner)
{
    t_scalar *x = (t_scalar *)z;
    char *buf, buf2[80];
    int bufsize;
    t_binbuf *b;
    glist_noselect(owner);
    glist_select(owner, z);
    b = glist_writetobinbuf(owner, 0);
    binbuf_gettext(b, &buf, &bufsize);
    binbuf_free(b);
    buf = t_resizebytes(buf, bufsize, bufsize+1);
    buf[bufsize] = 0;
    sprintf(buf2, "pdtk_data_dialog %%s {");
    gfxstub_new((t_pd *)owner, x, buf2);
    sys_gui(buf);
    sys_gui("}\n");
    t_freebytes(buf, bufsize+1);
}

static t_widgetbehavior scalar_widgetbehavior =
{
    scalar_getrect,
    scalar_displace,
    scalar_select,
    scalar_activate,
    scalar_delete,
    scalar_vis,
    scalar_click,
    scalar_displace_withtag,
};

static void scalar_free(t_scalar *x)
{
    t_symbol *templatesym = x->sc_template;
    t_template *template = template_findbyname(templatesym);
    if (!template)
    {
        error("scalar: couldn't find template %s", templatesym->s_name);
        return;
    }
    word_free(x->sc_vec, template);
    char buf[50];
    sprintf(buf, "x%lx", (long unsigned int)x);
    pd_unbind(&x->sc_gobj.g_pd, gensym(buf));
    gfxstub_deleteforkey(x);
        /* the "size" field in the class is zero, so Pd doesn't try to free
        us automatically (see pd_free()) */
    freebytes(x, sizeof(t_scalar) + (template->t_n - 1) * sizeof(*x->sc_vec));
}

/* ----------------- setup function ------------------- */

void g_scalar_setup(void)
{
    scalar_class = class_new(gensym("scalar"), 0, (t_method)scalar_free, 0,
        CLASS_GOBJ, 0);
    class_addmethod(scalar_class, (t_method)scalar_menuopen,
        gensym("menu-open"), 0);
    class_setwidget(scalar_class, &scalar_widgetbehavior);
    class_setsavefn(scalar_class, scalar_save);
    class_setpropertiesfn(scalar_class, scalar_properties);
}