/**
* Adds a widget to the specified edge of the dock. If the widget is already a child of this
* panel, this method behaves as though {@link #remove(Widget)} had already been called.
*
* @param widget the widget to be added
* @param direction the widget's direction in the dock
* @param before the widget before which to insert the new child, or <code>null</code> to append
*/
protected void insert(Widget widget, Direction direction, double size, Widget before) {
assertIsChild(before);
// Validation.
if (before == null) {
assert center == null : "No widget may be added after the CENTER widget";
} else {
assert direction != Direction.CENTER : "A CENTER widget must always be added last";
}
// Detach new child.
widget.removeFromParent();
// Logical attach.
WidgetCollection children = getChildren();
if (before == null) {
children.add(widget);
} else {
int index = children.indexOf(before);
children.insert(widget, index);
}
if (direction == Direction.CENTER) {
center = widget;
}
// Physical attach.
Layer layer =
layout.attachChild(
widget.getElement(), (before != null) ? before.getElement() : null, widget);
LayoutData data = new LayoutData(direction, size, layer);
widget.setLayoutData(data);
// Adopt.
adopt(widget);
// Update the layout.
animate(0);
}