If in the Author mode, an element is fully selected, I would like to perform an action on it. If not, I would like to perform an action on the node which is located at the cursor position. Is this possible via the API?
When an element is fully selected by the user the selection start and end offsets are actually outside of the node's offset bounds. So using AuthorDocumentController.getNodeAtOffset will actually return the parent of the selected node. We have some special API which makes it easier for you to determine this situation: WSAuthorEditorPageBase.getFullySelectedNode().
AuthorDocumentController controller = authorPageAccess.getDocumentController();
AuthorAccess authorAccess = authorPageAccess.getAuthorAccess();
int caretOffset = authorAccess.getEditorAccess().getCaretOffset();
AuthorElement nodeAtCaret = (AuthorElement) authorAccess.getEditorAccess().getFullySelectedNode();
if (nodeAtCaret == null) {
//We have no fully selected node. We can look at the cursor offset.
nodeAtCaret = (AuthorElement) authorAccess.getDocumentController().getNodeAtOffset(caretOffset);
//Or we could look at the selection start and end, see which node is the parent of each offset and get the closest common ancestor.
}