add(Widget) to buffer rather than directly to a Smart ui parent node

[GoogleCodeExporter]

I am advocating the following strategy

    <zs:UIListGrid showResizeBar='true' width='100px'>
      <zs:UIListGridFieldArray>
        <zs:UITreeGridField>Personal Info</zs:UITreeGridField>
        <zs:UITreeGridField>Avatar</zs:UITreeGridField>
        <zs:UITreeGridField>Address</zs:UITreeGridField>
        <zs:UITreeGridField>Email</zs:UITreeGridField>
      </zs:UIListGridFieldArray>
    </zs:UIListGrid>


rather than,

    <zs:UIListGrid showResizeBar='true' width='100px'>
        <zs:UITreeGridField>Personal Info</zs:UITreeGridField>
        <zs:UITreeGridField>Avatar</zs:UITreeGridField>
        <zs:UITreeGridField>Address</zs:UITreeGridField>
        <zs:UITreeGridField>Email</zs:UITreeGridField>
    </zs:UIListGrid>


The reason being -
Smart widgets do not have add(field) methods.
Rather they have setField(Widget[] ) methods. So we have to construct an 
add(Widget) from setField(Widget[] ) method.



For example,

    public void add(Widget widget) {
        if (widget instanceof UIFormItem){

            FormItem[] fields = getFields();

            FormItem[] newFields = new FormItem[fields.length+1];

            for (int i = 0; i < fields.length; i++) {
                newFields[i] = fields[i];
            }
            newFields[fields.length] = ((UIFormItem)widget).getFormItem();
            setFields(newFields);
        }
    }


This is not optimal because if we had to add 20 widgets to a parent node, the 
array would have to be reconstructed 20 times.

However I am constructing uibinderable ArrayList buffers, on which we would 
perform the individual add(Widget) operations. So that uibinder would add the 
ArrayList buffer node to a parent node.

A uibinder buffer node would look like this:

public class UIListGridFieldArray
extends UIMasqueradedWidgetArray<UIListGridField, ListGridField>{

  @Override
  public void add(Widget widget) {
    if (widget instanceof UIListGridField){
      addMasqueradedWidget((UIListGridField)widget);
    }
  }

  @Override
  public boolean remove(Widget widget) {
    if (widget instanceof UIListGridField){
      return removeMasqueradedWidget((UIListGridField)widget);
    }
    return false;
  }

  public ListGridField[] toArray(){
    ListGridField[] a = new ListGridField[smartObjects.size()];
    smartObjects.toArray(a);
    return a;
  }
}

So that the add(Widget) of a parent node would give a choice to either add the 
ui buffer or the child widgets directly:

  public void add(Widget widget) {
    if (widget instanceof UIListGridField){
       // the usual way
    }
    else if (widget instanceof UIListGridFieldArray){
      ListGridField[] newFields = ((UIListGridFieldArray)widget).toArray();
      setFields(newFields);
    }
  }

Original issue reported on code.google.com by BlessedGeek on 12 Jul 2010 at 8:32