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/*******************************************************************************
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* Copyright (c) 2000, 2010 IBM Corporation and others.
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* All rights reserved. This program and the accompanying materials
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* are made available under the terms of the Eclipse Public License v1.0
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* which accompanies this distribution, and is available at
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* http://www.eclipse.org/legal/epl-v10.html
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*
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* Contributors:
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* IBM Corporation - initial API and implementation
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*******************************************************************************/
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package org.eclipse.gef;
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/**
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* A specialization of {@link GraphicalEditPart GraphicalEditPart} for
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* representing connections. ConnectionEditParts must join a <I>source</I> and
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* <I>target</I> EditPart. Its Figure is typically a line between two "nodes",
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* with possible decorations on that line.
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* <P>
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* In GEF, ConnectionEditParts are <EM><I>structural features</I></EM> of their
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* source and target "nodes", which are EditParts. However, the model does not
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* have this requirement. The application may store the connection model in any
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* way, or there may even be no real model. The burden is on the source and
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* target EditPart to obtain their appropriate connections in the methods
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* {@link org.eclipse.gef.editparts.AbstractGraphicalEditPart#getModelSourceConnections()
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* getModelSourceConnections()} and
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* {@link org.eclipse.gef.editparts.AbstractGraphicalEditPart#getModelTargetConnections()
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* getModelTargetConnections()}. How this is done is application specific.
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* <P>
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* Since ConnectionEditParts are features of their node EditPart, it is those
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* EditParts that must create and manage the connection. Creation is performed
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* by whichever end happens to "intialize" itself first. Therefore an end always
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* looks first in the
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* {@link org.eclipse.gef.EditPartViewer#getEditPartRegistry() EditPartRegistry}
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* to see if the connection was already created by the other end.
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* <P>
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* ConnectionEditParts are EditParts, and therefore can have children. This is a
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* common way to implement labels and other selectable decorations on
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* connections. Similarly, a ConnectionEditPart can also be a "node", meaning it
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* can serve as the source or target of some other ConnectionEditPart. This
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* makes connection to connection possible.
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* <P>
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* IMPORTANT: The need to display something as a line does not automatically
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* mean that a ConnectionEditPart is required. There are several situations in
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* which ConnectionEditParts should not be used. You should use
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* ConnectionEditParts in general if:
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* <UL>
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* <LI>The connection should be selectable by the user independant of its
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* "nodes".
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* <LI>The connection can be deleted, leaving the source and target intact.
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* <LI>The connection cannot exist without a source and target. A instance of
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* when this is <B>not</B> true is <I>assocations</I>. Associations are
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* top-level object that are children of the diagram. They are probably only
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* valid if they have a source and target, but many applications allow you to
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* create things in any order.
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* </UL>
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*/
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public interface ConnectionEditPart extends GraphicalEditPart {
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/**
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* @return the EditPart at the <i>source</i> end of this connection.
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*/
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EditPart getSource();
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/**
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* @return the EditPart at the <i>target</i> end of this connection.
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*/
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EditPart getTarget();
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/**
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* Sets the <i>source</i> of this connection.
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*
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* @param source
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* the source of this connection
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*/
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void setSource(EditPart source);
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/**
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* Sets the<i>target</i> of this connection.
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*
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* @param target
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* the target of this connection
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*/
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void setTarget(EditPart target);
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}
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