MATLAB Object-Oriented Programming

The fcnview object stores a handle to the event.listener object in its

HLUpdateGraph property, which is used to enable/disable the listener by a context menu

(see “Enable and Disable Listeners” on page 11-63).

The fcnview object (obj) is added to the two default arguments (src, evnt) passed to

the listener callback. Keep in mind, the source of the event (src) is the fcneval object,

but the fcnview object contains the handle of the surface object that the callback

updates.

The listenUpdateGraph function is defined as follows:

function listenUpdateGraph(obj,src,evnt)

if ishandle(obj.HSurface) % If surface exists

obj.updateSurfaceData % Update surface data

end

end

The updateSurfaceData function is a class method that updates the surface data when

a different mathematical function is assigned to the fcneval object. Updating a graphics

object data is more efficient than creating a new object using the new data:

function updateSurfaceData(obj)

% Get data from fcneval object and set surface data

set(obj.HSurface,...

'XData',obj.FcnObject.Data.X,...

'YData',obj.FcnObject.Data.Y,...

'ZData',obj.FcnObject.Data.Matrix);

end

The PostSet Event Listener

All properties support the predefined PostSet event (See “Property-Set and Query

Events” on page 11-17 for more information on property events). This example uses the

PostSet event for the fcneval Lm property. This property contains a two-element vector

specifying the range over which the mathematical function is evaluated. Just after this

property is changed (by a statement like obj.Lm = [-3 5];), the fcnview objects

listening for this event update the graph to reflect the new data.

11 Events — Sending and Responding to Messages