private Iterator sortedChildren(final NodeItem n) {
double base = 0;
// update base angle for node ordering
NodeItem p = (NodeItem) n.getParent();
if (p != null) {
base = normalize(Math.atan2(p.getY() - n.getY(), p.getX() - n.getX()));
}
int cc = n.getChildCount();
if (cc == 0) return null;
NodeItem c = (NodeItem) n.getFirstChild();
if (!c.isStartVisible()) {
// use natural ordering for previously invisible nodes
return n.children();
}
double angle[] = new double[cc];
final int idx[] = new int[cc];
for (int i = 0; i < cc; ++i, c = (NodeItem) c.getNextSibling()) {
idx[i] = i;
angle[i] = normalize(-base + Math.atan2(c.getY() - n.getY(), c.getX() - n.getX()));
}
ArrayLib.sort(angle, idx);
// return iterator over sorted children
return new Iterator() {
int cur = 0;
public Object next() {
return n.getChild(idx[cur++]);
}
public boolean hasNext() {
return cur < idx.length;
}
public void remove() {
throw new UnsupportedOperationException();
}
};
}
/**
* Calculates the angular bounds of the layout, attempting to preserve the angular orientation of
* the display across transitions.
*/
private void calcAngularBounds(NodeItem r) {
if (m_prevRoot == null || !m_prevRoot.isValid() || r == m_prevRoot) {
m_prevRoot = r;
return;
}
// try to find previous parent of root
NodeItem p = m_prevRoot;
while (true) {
NodeItem pp = (NodeItem) p.getParent();
if (pp == r) {
break;
} else if (pp == null) {
m_prevRoot = r;
return;
}
p = pp;
}
// compute offset due to children's angular width
double dt = 0;
Iterator iter = sortedChildren(r);
while (iter.hasNext()) {
Node n = (Node) iter.next();
if (n == p) break;
dt += ((Params) n.get(PARAMS)).width;
}
double rw = ((Params) r.get(PARAMS)).width;
double pw = ((Params) p.get(PARAMS)).width;
dt = -MathLib.TWO_PI * (dt + pw / 2) / rw;
// set angular bounds
m_theta1 = dt + Math.atan2(p.getY() - r.getY(), p.getX() - r.getX());
m_theta2 = m_theta1 + MathLib.TWO_PI;
m_prevRoot = r;
}