The Show Object in a a2dCanvasView
The part of the a2dCanvasDocument that is shown in a a2dCanvasView start at the ShowObject. Each view can have a different ShowObject, which can be any a2dCanvasObject in the hierarchy of object in the document. Event on the view are redirected to the ShowObject, rendering also start here. Updates as a result of changes in the document, are reported as areas relative to the ShowObject. The size of the drawing when zoomed out is the boundingbox of the show object. In a view the position of the ShowObject as defined by its matrix is ignored. This matrix is only used when the object is drawn as a child of some other level in the document. In the view first the inverse matrix is applied. So the show object is always placed at vertex (0,0). Often the root object in a document is used as a start setting for the ShowObject, and the children of this root object is what is displayed.