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A document object's purpose is to store all the information about what the user is working on so it can be stored away and retrieved at a later time to be edited or displayed again. There's a difference between document state and application state. Document state refers to all the information that must be persisted in order to fully reproduce the user's work; application state refers to all the other information that the application uses like which view is active, what object or objects are selected, what color is currently being used, etc. While there is sometimes a demand to store some application state in the document (for example, some word processors will record the page the user was on) it's important to be aware of the distinction.
The Doodle.Doc class performs this task in the Doodle application.
The constructor sets the object into a pre-initialized state. We'll see later why this is useful. So once created, the document must be initialized.
For now, the document will only support one shape: Line...
The createLine function takes the two end points and a properties collection as arguments. Once again the line is first constructed and then initialized with the appropriate values before being added to the objects collection.
At this stage the Line class is still rudimentary and will gain some more sophistication once we add more properties and different types of shape.
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Created: March 27, 2003
Revised: Sept 27, 2006
URL: http://webreference.com/programming/javascript/gr/column21/1
