Listeners and Callbacks

Detailed Description

Functions
Object	AddListener (int listener_type, Object listener)
	Adds an event listener to the bean. More...
void	HCallback (GlgObject viewport)
	H callback. More...
void	HierarchyCallback (GlgObject top_viewport, GlgHierarchyData hierarchy_info)
	Hierarchy callback. More...
void	InputCallback (GlgObject vp, GlgObject message_obj)
	Input callback. More...
void	ReadyCallback (GlgObject viewport)
	Ready callback. More...
void	SelectCallback (GlgObject vp, Object[] name_array, int button)
	Select callback. More...
void	Trace2Callback (GlgObject top_viewport, GlgTraceData trace_info)
	This method is invoked to handle any events in the bean's drawing and may be overridden by bean's subclasses to implement custom event handling logic. More...
void	TraceCallback (GlgObject top_viewport, GlgTraceData trace_info)
	Trace callback. More...
void	VCallback (GlgObject viewport)
	V callback. More...

Function Documentation

AddListener()

Object AddListener	(	int	listener_type,
		Object	listener
	)

Adds an event listener to the bean.

Only a single event listener for each listener type is enabled. Setting a new event listener overrides any previous settings. Hierarchy listener must be attached before loading the bean's drawing.

By default, the bean itself is used as a listener for all GLG events; adding a listener disables the corresponding event-handling callback of the bean (for example, adding the INPUT_CB listener disables the bean's InputCallback). Therefore, the application must use only one type of the event handling: either a bean's callback or a listener.

The bean's callback method is usually used for applications which subclass the bean to provide different event-handling functionality for derived classes.

Parameters

listener_type	The type of listener to add. May be one of the following: INPUT_CB SELECT_CB, TRACE_CB TRACE2_CB, HIERARCHY_CB READY_CB H_CB V_CB.
listener	The listener to be added. Must implement one of the following interfaces that match the listener_type parameter: GlgInputListener GlgSelectListener GlgTraceListener GlgHierarchyListener GlgReadyListener GlgHListener GlgVListener. A null value may be used to remove a listener for the events specified by the listener_type parameter.

Returns

Previous listener of the specified type.

HCallback()

void HCallback

(

GlgObject

viewport

)

H callback.

This method is invoked after the bean's drawing has been loaded, but before its object hierarchy has been setup.

The method can be used for setting initial parameters of the loaded drawing before its hierarchy has been setup.

Parameters

viewport

The top viewport object of the bean's drawing.

Implements GlgHListener.

HierarchyCallback()

void HierarchyCallback	(	GlgObject	top_viewport,
		GlgHierarchyData	hierarchy_info
	)

Hierarchy callback.

is used to get access to the drawing to be displayed in the SubWindow and SubDrawing objects before the drawing is displayed.

This method is invoked when a SubWindow object in the bean's drawing loads its template drawing, or when a SubDrawing loads its template. The method is invokes several times at different stages of the template setup and may used to configure the SubWindow and SubDrawing instances before they are displayed.

The method may be overridden by bean's subclasses to implement custom instance setup logic.

A Hierarchy listener can be added using AddListener as an alternative to subclassing.

Parameters

top_viewport	The top-level viewport object.
hierarchy_info	GlgHierarchyData object containing information about the subdrawing that triggered the callback. See GlgHierarchyData for more information.

The method is invoked with the same parameters as the HierarchyCallback method of GlgHierarchyListener. See HierarchyCallback for more information.

Implements GlgHierarchyListener.

InputCallback()

void InputCallback	(	GlgObject	vp,
		GlgObject	message_obj
	)

Input callback.

This method is invoked to handle user interaction with input objects, as well as to perform object selection and action processing, and may be overridden by bean's subclasses to implement custom interaction logic.

An Input listener can be added using AddListener as an alternative to subclassing.

Parameters

vp	The top-level viewport object.
message_obj	Message object containing input event information.

The method is invoked with the same parameters as the InputCallback method of GlgInputListener. See InputCallback for more information.

Implements GlgInputListener.

ReadyCallback()

void ReadyCallback

(

GlgObject

viewport

)

Ready callback.

This method is invoked when the bean has finished initializing, loading and displaying its drawing. This method may be overridden by bean's subclasses to provide a custom bean initialization logic.

The IsReady method can also be used to query the bean's readiness.

Parameters

viewport

The top viewport object of the loaded drawing.

Implements GlgReadyListener.

SelectCallback()

void SelectCallback	(	GlgObject	vp,
		Object[]	name_array,
		int	button
	)

Select callback.

This method provides a simplified name-based interface to handle object selection. It is invoked when objects are selected with the mouse and may be overridden by bean's subclasses to implement custom selection logic.

A Select listener can be added using AddListener as an alternative to subclassing.

InputCallback provides an alternative callback that provides more elaborate selection information.

Parameters

vp	The top-level viewport object.
name_array	A null-terminated list of names of all named objects selected with the mouse, or null if no objects were selected.
button	The mouse button that was pressed to select objects.

The method is invoked with the same parameters as the SelectCallback method of GlgSelectListener. See SelectCallback for more information.

Implements GlgSelectListener.

Trace2Callback()

void Trace2Callback	(	GlgObject	top_viewport,
		GlgTraceData	trace_info
	)

This method is invoked to handle any events in the bean's drawing and may be overridden by bean's subclasses to implement custom event handling logic.

The method is similar to the TraceCallback, but is invoked after the event has been processed.

A Trace2 listener can be added using AddListener as an alternative to subclassing.

Parameters

top_viewport	The top-level viewport object.
trace_info	A GlgTraceData object containing detailed event information. See GlgTraceData for more information.

The method is invoked with the same parameters as the TraceCallback method of GlgTraceListener. See TraceCallback for more information.

TraceCallback()

void TraceCallback	(	GlgObject	top_viewport,
		GlgTraceData	trace_info
	)

Trace callback.

This method is invoked to handle any events in the bean's drawing and may be overridden by bean's subclasses to implement custom event handling logic. The method is invoked before the event has been processed.

A Trace listener can be added using AddListener as an alternative to subclassing.

Parameters

top_viewport	The top-level viewport object.
trace_info	A GlgTraceData object containing detailed event information. See GlgTraceData for more information.

The method is invoked with the same parameters as the TraceCallback method of GlgTraceListener. See TraceCallback for more information.

Implements GlgTraceListener.

VCallback()

void VCallback

(

GlgObject

viewport

)

V callback.

This method is invoked after the object hierarchy of the bean's drawing has been setup.

The method can be used for setting initial parameters of the loaded drawing after its hierarchy has been setup, but before the drawing is displayed.

Parameters

viewport

The top viewport object of the bean's drawing.

Implements GlgVListener.