| <body> |
| <h1>Model-View-Controller Architecture</h1> |
| <h3> |
| <img border="0" src="org/eclipse/gef/doc-files/mvc-generic.gif" width="249" height="177"></h3> |
| <h3>Model</h3> |
| <p>The <i>model</i> portion is somewhat self-explanatory. The model should |
| know nothing about the view or controller. It does however usually know |
| about listeners to which it fires notifications (listener-notifier pattern). |
| The model should be changed using {@link org.eclipse.gef.commands.Command |
| Commands}, and the view should be updated in response to notification.</p> |
| <h3>View</h3> |
| <p>The <i>view</i> can be several things. It includes the <i>visual part</i> |
| representing a model object(s). The most flexible visual parts are {@link |
| org.eclipse.draw2d.Figure Figures} from draw2d. GEF also provides |
| support for SWT TreeItems, but support for other visuals can easily be added. While "visual part" refers to an object directly representing a |
| model object, the more encompassing "view" includes feedback, handles, tooltips, |
| and all things visible to the user. All of these make up the view, and it |
| is the controller's job to construct and manage them.</p> |
| <h3>Controller</h3> |
| <p>The <i>controller</i> is the most interesting part and is the primary focus |
| of GEF. The controller is responsible for:</p> |
| <ol> |
| <li>Building the <b>visual part</b> and all parts of the view</li> |
| <li>Modifying the model through Commands in response to user input</li> |
| <li>Observing the model and updating the view accordingly</li> |
| </ol> |
| <p>User input can be a wide variety of things. A part may support |
| multiple, unrelated types of editing behavior. To support this, GEF |
| provides a controller implementation whose entire behavior is provided by |
| plugging in one or more helper objects. This allows for higher code reuse |
| and easier code maintenance.</p> |
| <p>A controller in GEF is an {@link org.eclipse.gef.EditPart EditPart}.</p> |
| <p> |
| <img border="0" src="org/eclipse/gef/doc-files/mvc-gef.gif" width="438" height="380"></p> |
| </body> |
