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| <title>Providing Resize Functionality</title> |
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| <link href="../code.css" rel="Stylesheet" type="text/css"> |
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| <h1>Providing Resize Functionality</h1> |
| <h2>Creating a Resize Feature</h2> |
| <p>In our current editor the resize functionality is already provided by the framework. |
| Nevertheless this tutorial should explain how the resize behavior can be customized. |
| Therefore we constructed the following example behavior:</p> |
| <p>Resizing EClasses should be restricted to EClasses whose name is longer than |
| one character (just an example without logical reason).</p> |
| <p>Remember, that we already <a href="move-feature.htm">provided move functionality</a>, |
| which restricted the move of EClasses whose name is longer than one character. Now |
| we want to additionally restrict the resize. </p> |
| <p>A resize feature has to implement the interface |
| <a href="../../../javadoc/org/eclipse/graphiti/features/IResizeShapeFeature.html"> |
| IResizeShapeFeature</a>. Instead of implementing this directly you should extend |
| one of the available base classes.</p> |
| <p>In this example we extend the base class<a href="../../../javadoc/org/eclipse/graphiti/features/impl/DefaultResizeShapeFeature.html">DefaultResizeShapeFeature</a>. |
| </p> |
| <p>There are two methods to overwrite: </p> |
| <ul> |
| <li>The method |
| <a href="../../../javadoc/org/eclipse/graphiti/func/IResizeShape.html#canResizeShape(org.eclipse.graphiti.features.context.IResizeShapeContext)"> |
| canResizeShape</a> has to check if this feature can do the resize corresponding |
| to the given context. In this case the location information contained in the |
| context consists of the shape to be resized.</li> |
| <li>The method |
| <a href="../../../javadoc/org/eclipse/graphiti/func/IResizeShape.html#resizeShape(org.eclipse.graphiti.features.context.IResizeShapeContext)"> |
| resizeShape</a> does the final resize. </li> |
| </ul> |
| <p>You can see the complete implementation of the resize feature here:</p> |
| <!-- Begin code ------------------------------------------------------------------------------- --> |
| <p> </p> |
| <div class="literallayout"> |
| <div class="incode"> |
| <p class="code"><span class="keyword">package </span>org.eclipse.graphiti.examples.tutorial.features;<br> <br> |
| <span class="keyword">public class</span> TutorialResizeEClassFeature |
| <span class="keyword">extends </span>DefaultResizeShapeFeature {<br> |
| <br> <span class="keyword">public </span>TutorialResizeEClassFeature(IFeatureProvider |
| fp) {<br> |
| <span class="keyword">super</span>(fp);<br> }<br> <br> |
| @Override<br> <span class="keyword">public boolean</span> |
| canResizeShape(IResizeShapeContext context) {<br> |
| <span class="keyword">boolean</span> canResize = <span class="keyword">super</span>.canResizeShape(context);<br> <br> |
| <span class="comment">// perform further check only if move allowed by default |
| feature</span><br> |
| <span class="keyword">if</span> (canResize) {<br> |
| <span class="comment">// don't allow resize if the class name has the length |
| of 1</span><br> |
| Shape shape = context.getShape();<br> |
| Object bo = getBusinessObjectForPictogramElement(shape);<br> |
| <span class="keyword">if</span> (bo <span class="keyword">instanceof |
| </span>EClass) {<br> |
| EClass c = (EClass) bo;<br> |
| <span class="keyword">if </span>(c.getName() != <span class="keyword">null |
| </span>&& c.getName().length() == 1) {<br> |
| canResize = <span class="keyword">false</span>;<br> |
| }<br> |
| }<br> }<br> |
| <span class="keyword">return </span>canResize;<br> }<br> |
| }<br></p> |
| </div> |
| </div> |
| <p> </p> |
| <!-- End code ------------------------------------------------------------------------------- --> |
| <p>Additionally the feature provider has to deliver our newly created feature (overwrite |
| the method |
| <a href="../../../javadoc/org/eclipse/graphiti/features/IFeatureProvider.html#getResizeShapeFeature(org.eclipse.graphiti.features.context.IResizeShapeContext)"> |
| getResizeShapeFeature</a>).</p> |
| <p>This implementation can be seen here:</p> |
| <!-- Begin code ------------------------------------------------------------------------------- --> |
| <p> </p> |
| <div class="literallayout"> |
| <div class="incode"> |
| <p class="code">@Override<br><span class="keyword">public </span>IResizeShapeFeature |
| getResizeShapeFeature(<br> IResizeShapeContext |
| context) {<br> Shape shape = context.getShape();<br> |
| Object bo = getBusinessObjectForPictogramElement(shape);<br> |
| <span class="keyword">if </span>(bo <span class="keyword">instanceof</span> |
| EClass) {<br> |
| <span class="keyword">return new</span> TutorialResizeEClassFeature(this);<br> |
| }<br> <span class="keyword">return super</span>.getResizeShapeFeature(context);<br> |
| }<br></p> |
| </div> |
| </div> |
| <p> </p> |
| <!-- End code ------------------------------------------------------------------------------- --> |
| <h2>Test: Resize EClass Is Restricted</h2> |
| <p>Now start the editor again and test it: Just create a EClass whose name is only |
| one character long. This EClass can no longer be resized, because on selection the |
| resize-handles do not appear any more. For EClasses whose name has more than one |
| character the resize should still work.</p> |
| <p> </p> |
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