Inside Macintosh: Cyberdog Programmer's Kit / Part 3 - Cyberdog Reference

Chapter 7 - Classes and Methods

CyberProgressPartExtension

Superclasses

CyberExtension --> ODExtension --> ODRefCntObject --> ODObject

Subclasses

CyberOpenerPartExtension

The CyberProgressPartExtension class defines extra behaviors for parts that display the progress and status of an asynchronous process.

Description

The CyberProgressPartExtension class is a part extension that allows a part to monitor and display the status and progress of an asynchronous operation, such as a download operation performed by a Cyberdog stream or the opening of a Cyberdog item. You use a progress part together with a progress broadcaster (page 297) and a progress receiver (page 318) to monitor and display the progress and status of an asynchronous operation.

The Cyberdog navigator and opener parts are both fully implemented progress parts. In most situations, you will use these to display progress. However, CyberProgressPartExtension is an abstract superclass that you can subclass and implement to create your own custom progress part. If you create a custom progress part, you also need to implement a corresponding CyberProgressReceiver subclass.

A progress part has two main uses in Cyberdog:

• The navigator displays status and progress information while a display part embedded in the navigator performs an asynchronous operation.
• The opener part displays status and progress information while a Cyberdog item is opened asynchronously.

When an object initiates an asynchronous operation, such as the opening of a Cyberdog stream, the object can create a corresponding CyberProgressBroadcaster object to represent that process and attach it to a progress part, such as the navigator. The progress part, in turn, attaches its progress receiver to the broadcaster. The display part calls the broadcaster's accessor methods periodically to notify it of the status and progress of the actual asynchronous operation; the broadcaster broadcasts these changes in status and progress to the progress receiver.

For example, consider an HTML display part that is embedded in the Cyberdog navigator. While the display part downloads and parses the content referenced by a Cyberdog item, the display part shows the progress of the operation using the Cyberdog navigator. This is the sequence of steps:

1. The HTML display part creates a broadcaster object.
2. The HTML display part acquires its containing navigator.
3. The HTML display part attaches the broadcaster to the navigator.
4. The navigator attaches an object of its associated progress receiver subclass to the broadcaster.
5. The HTML display part calls accessor methods on the broadcaster to update its progress attributes. The broadcaster broadcasts the changes to the progress receiver.
6. The progress receiver receives the changes and updates the navigator's progress display.

Methods

This section presents summary descriptions of the CyberProgressPartExtension methods grouped according to purpose, followed by detailed descriptions.

Initialization and Cleanup

ICyberProgressPartExtension

Initializes this ICyberProgressPartExtension object.

Attaching and Detaching Processes

AttachProgressBroadcaster

Attaches a progress broadcaster to this progress part.

DetachProgressBroadcaster

Detaches a progress broadcaster from this progress part.

Retrieving Processes

GetAttachedProgressBroadcaster

Retrieves the progress broadcaster attached to this progress part.

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Methods

AttachProgressBroadcaster

DetachProgressBroadcaster

GetAttachedProgressBroadcaster

ICyberProgressPartExtension