/// <summary>
/// Return a copied object for an object (first pass only).
/// </summary>
/// <param name="obj"></param>
/// <returns></returns>
/// <remarks>
/// <para>
/// First this method looks up <paramref name="obj" /> in its mapping
/// table--if it finds an object, it returns it, because presumably it
/// has already been copied.
/// Otherwise it calls <see cref="T:Northwoods.Go.GoObject" />.<see cref="M:Northwoods.Go.GoObject.CopyObject(Northwoods.Go.GoCopyDictionary)" /> in order to
/// make a copy of <paramref name="obj" />.
/// If <paramref name="obj" /> is null, this returns null.
/// </para>
/// <para>
/// The primary use of this method is to be called by <see cref="T:Northwoods.Go.GoDocument" />'s
/// <c>GoDocument.CopyFromCollection(IGoCollection, bool, bool, SizeF, GoCopyDictionary)</c> method.
/// This is also typically called within a <see cref="M:Northwoods.Go.GoObject.CopyObject(Northwoods.Go.GoCopyDictionary)" />
/// override method to make a copy of a referenced object that is not
/// a child of the copied object.
/// </para>
/// <para>
/// If you don't call this in the context of a
/// <c>GoDocument.CopyFromCollection(IGoCollection, bool, bool, SizeF, GoCopyDictionary)</c> method,
/// be sure to call <see cref="M:Northwoods.Go.GoCopyDictionary.FinishDelayedCopies" /> afterwards to perform the
/// second copying pass, which resolves references and can do other copying work
/// as implemented by <see cref="T:Northwoods.Go.GoObject" />.<see cref="M:Northwoods.Go.GoObject.CopyObjectDelayed(Northwoods.Go.GoCopyDictionary,Northwoods.Go.GoObject)" />.
/// </para>
/// <para>
/// The easiest way to make a full copy of an object in a document is to call
/// <see cref="T:Northwoods.Go.GoDocument" />.<see cref="M:Northwoods.Go.GoDocument.AddCopy(Northwoods.Go.GoObject,System.Drawing.PointF)" />, which calls <c>CopyFromCollection</c>.
/// However, if you want to create a copy of an object without adding it to a document,
/// you can call <see cref="M:Northwoods.Go.GoCopyDictionary.CopyComplete(Northwoods.Go.GoObject)" />, which performs both copying passes.
/// </para>
/// </remarks>
public virtual GoObject Copy(GoObject obj)
{
if (obj == null)
{
return(null);
}
GoObject goObject = this[obj] as GoObject;
if (goObject == null)
{
goObject = obj.CopyObject(this);
}
return(goObject);
}