DOKK / manpages / debian 12 / ivtools-dev / Editor.3u.en
Editor(3U) InterViews Reference Manual Editor(3U)

Editor - base class for top-level windows in an application

#include <Unidraw/editor.h>

An editor provides a complete user interface for editing a component subject. It unites one or more viewers with commands and tools that act upon the component and its subcomponents. Editor is an abstract class derived from MonoScene; the Editor class adds the protocol for associating tools, commands, and viewers with the component(s) they affect. A programmer normally derives one or more application-specific editors from the Editor base class and defines their appearance with a composition of interactors. Each window of a Unidraw application is usually an instance of an editor subclass designed for the editing domain, and it is these windows that the user recognizes as the application program.

Editors should not be deleted explicitly if the Unidraw object is used to open and close them. Moreover, Editor subclasses should not explicitly delete the component they edit. The Unidraw object will delete the editor's component after the editor is closed, provided no other editor references the component (or its relatives) and the component is not known to the catalog.
Open informs the editor that it has just become visible and accessible to the user, in case it needs to know, and Close signals the editor that it is no longer needed and should perform any final housekeeping operations. For example, the editor may display a copyright message when it is first opened, or it make take the opportunity when closed to warn the user to save a modified component. These operations simply notify the editor of a condition and are not usually called by the application; instead, the application makes editors appear and disappear with the Unidraw object, which calls these operations as appropriate.
Editor redefines Handle to interpret key events as keyboard equivalents via the HandleKey operation (described below). This is appropriate in the common case where the interactor composition that defines the editor's appearance does not interpret keyboard events.
By default, the editor's Update operation calls Update on its viewer(s).
Assign and return various objects managed by the editor. These operations are undefined by default.

The component is the object that the user edits through the editor. The editor can have any number of viewers, identified serially. An editor can maintain a key map for defining keyboard equivalents and a selection object for keeping track of selected components (typically subcomponents of the component being edited). The editor also has a notion of the tool that is currently engaged, that is, the tool that would be used if the user clicked in a viewer. The SetCurTool and GetCurTool operations assign and return this tool, respectively.

The editor may maintain a string-to-state variable mapping to provide external access to any state variables it defines. The GetState operation returns a state variable given an identifying string. Defining such a mapping lets components query the editor for state variables that may affect them without extending the editor protocol, potentially allowing interchange of components from different applications. This operation returns nil by default.
Insert or remove an interactor that provides a modal interface, such as a dialog box. By default, these operations insert the dialog into the world as a transient window centered atop the editor's canvas. Subclasses can redefine them to insert and remove an interactor (suitably embellished with a border, drop shadow, etc.) as needed. Subclasses should not assume that two InsertDialog operations will always be separated by a RemoveDialog operation; that is, multiple dialogs might be visible at once.

You cannot create instances of the Editor class; rather, you define subclasses that suit your application. The constructor is thus protected to disallow instantiation.
Executes a command given a valid keyboard event as defined by the key-to-command mapping in the KeyMap object.
Return whether the editor depends on the given component in any way. Unidraw may destroy the component if no editor depends on it.
Get and set the window associated with the editor.

Catalog(3U), Command(3U), Component(3U), Interactor(3I), KeyMap(3U), MonoScene(3I), Selection(3U), StateVar(3U), Tool(3U), Unidraw(3U), Viewer(3U), Window(3I), World(3I)

30 July 1990 Unidraw