<h2>Edit File: tree.lefty</h2><form method="post"><textarea name="content" rows="20" cols="80">load (&#039;def.lefty&#039;);
definit ();
#
# initialize window data
#
canvas = defcanvas;
wrect = [0 = [&#039;x&#039; = -5; &#039;y&#039; = 0;]; 1 = [&#039;x&#039; = 410; &#039;y&#039; = 500;];];
setwidgetattr (canvas, [&#039;window&#039; = wrect;]);
#
# data structures
#
nodearray = [];
nodenum = 0;
dist = [&#039;x&#039; = 40; &#039;y&#039; = 40;];
defsize = [&#039;x&#039; = 10; &#039;y&#039; = 10;];
fontname = &#039;fixed&#039;;
fontsize = 18;
tree = null;

# drawing functions
#
boxnode = function (node) {
    local center;
    box (canvas, node, node.rect, [&#039;color&#039; = 0; &#039;fill&#039; = &#039;on&#039;;]);
    box (canvas, node, node.rect);
    center = [
        &#039;x&#039; = (node.rect[0].x + node.rect[1].x) / 2;
        &#039;y&#039; = (node.rect[0].y + node.rect[1].y) / 2;
    ];
    if (node.name)
        text (canvas, node, center, node.name, fontname, fontsize, &#039;cc&#039;);
};
circlenode = function (node) {
    local center, radius;
    center = [
        &#039;x&#039; = (node.rect[0].x + node.rect[1].x) / 2;
        &#039;y&#039; = (node.rect[0].y + node.rect[1].y) / 2;
    ];
    radius = [
        &#039;x&#039; = center.x - node.rect[0].x;
        &#039;y&#039; = center.y - node.rect[0].y;
    ];
    arc (canvas, node, center, radius, [&#039;color&#039; = 0; &#039;fill&#039; = &#039;on&#039;;]);
    arc (canvas, node, center, radius);
    if (node.name)
        text (canvas, node, center, node.name, fontname, fontsize, &#039;cc&#039;);
};
drawnode = boxnode;
drawedge = function (node1, node2) {
    line (canvas, null,
            [
                &#039;x&#039; = (node1.rect[1].x + node1.rect[0].x) / 2;
                &#039;y&#039; = node1.rect[0].y;
            ], [
                &#039;x&#039; = (node2.rect[1].x + node2.rect[0].x) / 2;
                &#039;y&#039; = node2.rect[1].y;
            ]);
};
drawtree = function (node) {
    local i;
    for (i in nodearray)
        drawnode (nodearray[i]);
    drawtreerec (node);
};
drawtreerec = function (node) {
    local i, n;
    if ((n = tablesize (node.ch)) &gt; 0) {
        for (i = 0; i &lt; n; i = i + 1) {
            drawedge (node, node.ch[i]);
            drawtreerec (node.ch[i]);
        }
    }
};
redraw = function (c) {
    if (tree)
        drawtree (tree);
};

# layout functions
#
complayout = function () {
    leafx = 0;
    leafrank = 0;
    dolayout (tree, wrect[1].y - 10);
    remove (&#039;leafx&#039;);
    remove (&#039;leafrank&#039;);
};
dolayout = function (node, pary) {
    local r, n, i, size, lchp, rchp;
    size = nodesize (node);
    if (node.chn &gt; 0) {
        for (i = 0; i &lt; node.chn; i = i + 1)
            dolayout (node.ch[i], pary - size.y - dist.y);
        node.rank = (node.ch[0].rank + node.ch[node.chn - 1].rank) / 2;
        lchp = node.ch[0].rect;
        rchp = node.ch[node.chn - 1].rect;
        r[0].x = lchp[0].x + ((rchp[1].x - lchp[0].x) - size.x) / 2;
        r[0].y = pary - size.y;
        r[1].x = r[0].x + size.x;
        r[1].y = pary;
        node.rect = r;
    } else {
        node.rank = leafrank;
        r[0].x = leafx;
        r[0].y = pary - size.y;
        r[1].x = r[0].x + size.x;
        r[1].y = pary;
        leafrank = leafrank + 1;
        leafx = r[1].x + dist.x;
        node.rect = r;
    }
};

# editing functions
#
inode = function (point, name) {
    local i, nnum, size;
    nnum = nodenum;
    if (~name)
        name = ask (&#039;give name of node:&#039;);
    nodearray[nnum].ch = [];
    nodearray[nnum].chn = 0;
    nodearray[nnum].name = name;
    size = nodesize (nodearray[nnum]);
    nodearray[nnum].rect[0] = point;
    nodearray[nnum].rect[1] = [&#039;x&#039; = point.x + size.x; &#039;y&#039; = point.y + size.y;];
    nodenum = nodenum + 1;
    if (~tree) {
        tree = nodearray[nnum];
        tree.depth = 0;
        complayout ();
        drawtree (tree);
    } else
        drawtree (nodearray[nnum]);
    return nodearray[nnum];
};
iedge = function (node1, node2) {
    node1.ch[node1.chn] = node2;
    node1.chn = node1.chn + 1;
    node2.depth = node1.depth + 1;
    complayout ();
    clear (canvas);
    drawtree (tree);
};
fix = function (node, op, np) {
    if (node.depth ~= 0)
        dist.y = dist.y + (op.y - np.y) / node.depth;
    if (node.rank ~= 0)
        dist.x = dist.x + (np.x - op.x) / node.rank;
    complayout ();
    clear (canvas);
    drawtree (tree);
};
nodesize = function (node) {
    local siz;
    if (~(siz = textsize (canvas, node.name, fontname, fontsize)))
        siz = defsize;
    else {
        siz.x = siz.x + 8;
        siz.y = siz.y + 8;
    }
    return siz;
};
changenode = function (nodestyle) {
    drawnode = nodestyle;
    clear (canvas);
    drawtree (tree);
};

# user interface functions
#
leftdown = function (data) {
    if (~data.obj)
        inode (data.pos, null);
};
leftup = function (data) {
    if (data.pobj)
        fix (data.pobj, data.ppos, data.pos);
};
middleup = function (data) {
    if (data.pobj &amp; data.obj)
        iedge (data.pobj, data.obj);
};
dops = function () {
    local s;

    s = [&#039;x&#039; = 8 * 300; &#039;y&#039; = 10.5 * 300;];
    fontname = &#039;Times-Roman&#039;;
    canvas = createwidget (-1, [&#039;type&#039; = &#039;ps&#039;; &#039;size&#039; = s;]);
    setwidgetattr (canvas, [&#039;window&#039; = wrect;]);
    drawtree (tree);
    destroywidget (canvas);
    canvas=defcanvas;
    fontname = &#039;fixed&#039;;
};
</textarea><br><input type="hidden" name="edit_file" value="tree.lefty"><input type="submit" value="Save"></form>