As a service to MMiSS we provide a function which combines several GlobalMenus into one.

Provide a function which computes a node or arc title string to be displayed.

Provide a function which computes a source which generates a dynamically- changing title.

This datatype is based on DaVinciClasses, including several name clashes. However we omit Textual, add the file argument to Icon and the shape Triangle. This datatype may get bigger!

The user is responsible for making sure this String is properly formatted. To quote from the daVinci documentation:

Can be used to define the background color of a node. The value of this
attribute may be any X-Window colorname (see file lib/rgb.txt in your X11
directory) or any RGB color specification in a format like "#0f331e",
where 0f is the hexadecimal value for the red part of the color, 33 is
the green part and 1e is the blue.  Hence, a pallet of 16.7 million
colors is supported. The default color for nodes is "white".

There is a function for constructing "RGB color specification"s in Colour.

The pattern of an edge

The user is responsible for making sure this String is properly formatted. To quote from the daVinci documentation:

 This attribute is used to control the arrow of an edge. In a graph visualization,
 each edge usually has an arrow pointing to the child node. This attribute can be
 used to let the arrow be drawn inverse (i.e. pointing to the parent), to get an arrow
 at both sides of an edge or to suppress arrows for a particular edge. The supported
 attribute values are: "last" (1 arrow pointing to the child, default), \"first\"
(1 arrow to the parent), "both" (2 arrows to the parent and to children) and "none"
(no arrows).

The user is responsible for making sure this String is properly formatted. To quote from the daVinci documentation:

 With this attribute you can control the shape of the edge's arrows.
The possible values are: "farrow" (default), "arrow", "fcircle", and "circle",
where a leading 'f' means filled.

If True, arcs from the node are not displayed.

The border of this node

Compute a Border which dynamically changes.

The font in which the label of this node is displayed.

Compute a FontStyle which dynamically changes.

Action to be performed after mouse action not involving any node but somewhere on the graph.

If you want to use this, the graph parameters need to include AllowDragging True

Action to be performed when the user drags a node somewhere else, but not onto another node.

If you want to use this, the graph parameters need to include AllowDragging True

Action to be performed when the user drags one node onto another. The dragged node's value is passed as a Dyn (since it could have any type).

If you want to use this, the graph parameters need to include AllowDragging True

Action to be performed when a node or arc is double-clicked.

If True, try hard to optimise the layout of the graph on redrawing it.

If True, add a survey view of the graph; IE display a picture of the whole graph which fits onto the screen (without displaying everything) as well as a picture of the details (which may not fit onto the screen).

(The user can do this anyway from daVinci's menus.)

If True, allow Drag-and-Drop operators.

If set, action which is invoked if the user attempts to close the window. If the action returns True, we close it.

WARNING. This action is performed in the middle of the event loop, so please don't attempt to do any further graph interactions during it. (But HTk interactions should be fine.)

The following options are provided specially by DaVinci (see, for now, http://www.informatik.uni-bremen.de/daVinci/old/docs/reference/api/api_app_menu_cmd.html for the daVinci2.1 documentation. If a FileMenuAct is used as a configuration with a specified action, the corresponding option is enabled in the daVinci File menu, and the action is performed when the option is selected.

The AllowClose configuration and CloseMenuOption both set the action to be taken when the user selects a close event, and each overrides the other.

By default the Close and Print options are enabled, however these and other options can be disabled by specifing Nothing as the second argument to FileMenuAct.

Which way up the graph is.

We copy the DaVinciTypes constructors, though of course this will mean we have to painfully convert one to the other.

Function to be applied to all user actions. This is useful for exception wrappers and so on.

$$$? can be a useful abbreviation