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

Chapter 7 - Classes and Methods

CyberPartExtension

Superclasses

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

Subclasses

none

CyberPartExtension defines extra behaviors for Cyberdog display parts, parts that display content referenced by a Cyberdog item.

Description

The CyberPartExtension class is a part extension that allows an OpenDoc part to be a Cyberdog display part, a part that displays content referenced by a Cyberdog item. CyberPartExtension is an abstract superclass that you must subclass and implement to create a Cyberdog display part. Any part that displays content referenced by a Cyberdog item must be composed of an object of class ODPart (or one of its subclasses) paired with an object of a class derived from the CyberPartExtension class.

The CyberPartExtension object is the public interface for a Cyberdog display part. External entities that want to communicate with a Cyberdog display part obtain the part's CyberPartExtension object and send the Cyberdog-related messages to it.

A Cyberdog item's Open method creates a Cyberdog display part to display the content referenced by the Cyberdog item and calls the display part's OpenCyberItem method. Typically, the OpenCyberItem method performs the following tasks:

• It calls SetCyberItem to store a reference to the Cyberdog item in the display part.
• It performs any tasks necessary to prepare to display the data referenced by the Cyberdog item. For example, the display part might request a stream from the Cyberdog item and use it to download the data referenced by the Cyberdog item.
• Calls its inherited OpenCyberItem method. If an opener part was passed in as a parameter to OpenCyberItem, the inherited method calls the opener part's OpenPart method to open the display part. If no opener part was passed in, OpenCyberItem calls the display part's Open method.

The display part's ShowCyberItem method, on the other hand, assumes that the display part is already displaying the content referenced by the Cyberdog item. You call ShowCyberItem once you have determined (by calling CanShowCyberItem or GetCyberItemWindow) that the display part is already displaying a Cyberdog item equal to (or, for example, on the same page as) the Cyberdog item whose referenced content you want to display. Typically, you call ShowCyberItem when you want a display part to scroll to display a particular Cyberdog item.

Methods

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

Initialization and Cleanup

ICyberPartExtension

Initializes this CyberPartExtension object.

Displaying Cyberdog Items

CanShowCyberItem

Tests whether this part is displaying content referenced by the specified Cyberdog item.

GetCyberItem

Retrieves the Cyberdog item whose referenced content is displayed by this part.

GetCyberItemWindow

Retrieves the window in which a Cyberdog item's referenced content is displayed.

OpenCyberItem

Opens a Cyberdog item in this display part.

SetCyberItem

Assigns the specified Cyberdog item to this display part.

ShowCyberItem

Displays the content referenced by the specified Cyberdog item in this display part.

Embedding Cyberdog Items

AcquireSelectedCyberItems

Acquires references to the selected Cyberdog items.

IsCyberItemSelected

Tests whether any Cyberdog items are selected in this part.

Opening a Selected URL

GetSelectedURL

Retrieves the selected URL.

IsURLSelected

Tests whether the selected text in this part is a URL.

Adding Commands

HandleCommand

Handles semantic events for this Cyberdog display part.

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Methods

AcquireSelectedCyberItems

CanShowCyberItem

GetCyberItem

GetCyberItemWindow

GetSelectedURL

HandleCommand

ICyberPartExtension

IsCyberItemSelected

IsURLSelected

OpenCyberItem

SetCyberItem

ShowCyberItem