Package edu.cnu.mdi.feedback

Class FeedbackControl

java.lang.Object

edu.cnu.mdi.feedback.FeedbackControl

public class FeedbackControl
extends Object

Controller for managing mouse-over feedback for a given IContainer.

A FeedbackControl instance coordinates a set of IFeedbackProvider listeners. Whenever the mouse moves, each provider is asked to contribute feedback strings based on the current mouse position in both screen and world coordinates. If the set of feedback strings has changed since the last update, the container's FeedbackPane (if any) is updated accordingly.

Feedback is suppressed when the Control key is held down during mouse movement.

Constructor Summary

Constructors

Constructor	Description
FeedbackControl(IContainer container)	Creates a feedback controller for the specified container.

Method Summary

Modifier and Type	Method	Description
void	addFeedbackProvider(IFeedbackProvider provider)	Adds a feedback provider to this controller.
void	removeFeedbackProvider(IFeedbackProvider provider)	Removes a feedback provider from this controller.
void	updateFeedback(MouseEvent mouseEvent, Point2D.Double wp, boolean dragging)	Updates the feedback in response to a mouse movement.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

FeedbackControl

public FeedbackControl(IContainer container)

Creates a feedback controller for the specified container.

Parameters:

container - the IContainer whose feedback is being managed; must not be null

Method Details

addFeedbackProvider

public void addFeedbackProvider(IFeedbackProvider provider)

Adds a feedback provider to this controller.

If the provider is already registered, it is first removed so that it is not stored twice.

Parameters:

provider - the feedback provider listener to add; must not be null

removeFeedbackProvider

public void removeFeedbackProvider(IFeedbackProvider provider)

Removes a feedback provider from this controller.

This method is intentionally a safe no-op in all cases where the provider cannot be present:

• If provider is null, the call is ignored.
• If no listener list has been created yet (i.e. addFeedbackProvider(edu.cnu.mdi.feedback.IFeedbackProvider) was never called on this instance), the provider cannot be registered, so there is nothing to remove and the call returns silently.

The silent no-op on a null listener list is deliberate. The primary caller for removal is AItem.prepareForRemoval(), which is invoked whenever an item is deleted from a layer. Items self-register in their constructor via addFeedbackProvider(IFeedbackProvider), but only if the container's view has called initFeedback() to create a listener list in the first place. If initFeedback() was never called — which is a normal, legitimate configuration for views that do not display a feedback pane — no listener list ever exists, and the item's removal path must not produce a spurious warning or exception.

Logging of mismatched add/remove call sites, if desired, should be performed at a higher level where the intended registration state is known.

Parameters:

provider - the feedback provider to remove; ignored if null

updateFeedback

public void updateFeedback(MouseEvent mouseEvent,
 Point2D.Double wp,
 boolean dragging)

Updates the feedback in response to a mouse movement.

The controller:

1. Skips processing entirely if the Control key is held down.
2. Requests fresh feedback strings from all providers.
3. Compares the new strings with the previous set; if unchanged, no update is performed.
4. If changed and a FeedbackPane is attached to the container, updates the pane.

Parameters:

mouseEvent - the mouse event, used for the screen location and modifier-state checks

wp - the corresponding world-space point for the mouse location

dragging - true if the mouse is currently being dragged; currently not used in the logic but reserved for possible future policy changes