[zt]第四章 GEF框架(1)

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Eclipse

框架 Eclipse UI MFC MVC

FROM:http://www.blog.edu.cn/user1/19180/archives/2005/375044.shtml

4.1 概述

GEF是一套建立在Draw2D基础之上的eclipse插件，它为Draw2D提供控制功能，它监听各种事件，如鼠标、键盘、Workbench的事件，并进行响应。GEF是一套框架，它提供一套完整的图形用户接口系统的基本处理方式，但是具体的功能需要我们实现，这一点和MFC的窗口系统不同。

GEF使用MVC模式，它成功的将模型、视图、控制器三个部分剥离。模型是由用户编写的任何类，视图则采用Draw2D系统，控制器则是之前提到过的EditPart。

M-V-C三个部分的交互式这样完成的：当用户直接对V进行了操作，比如改变V的形状或者修改了Label中的文字，系统就会产生一个Request，并将这个Request传递给相应的EditPart进行处理；EditPart根据Request的类型生成相应的Command（Command需要用户编写），并将Command在传递出去；系统得到Command后，就会在合适的时机执行这个Command。如果M发生了变化，并且需要更新视图，它可以使用一个PropertyChangeSupport实例，提示EditPart对V进行改变。PropertyChangeSupport实际上是M与EditPart的一个桥梁，只要在EditPart中实现PropertyChangeListener接口，就可以向M的PropertyChangeSupport实例注册自己为监听者。具体的例子将在第3节给出。

实现一个模型是很简单，但是注意一般来说应该让模型包含一个PropertyChangeSupport类的实例。调用PropertyChangeSupport的addPropertyChangeListener方法可以向其中注册一个监听者，调用removePropertyChangeListener的移出一个监听者，调用firePropertyChange方法则向所有注册的监听者通知发生了变化。

实现一个EditPart一般来说需要重载performRequest、getCommand、activate、deactivate和refreshVisuals函数，并实现createEditPolicies、createFigure接口函数，为了让EditPart能够成为PropertyChangeListener，你还必须实现PropertyChangeListener接口。performRequest和getCommand将在第3节介绍，activate和deactivate用于处理当EditPart处于激活或者非激活状态时的操作，一般来说，可以在这两个函数中注册和移除自己监听者的角色。refreshVisuals函数用于更新自己的视图。

下面给出一个模型和它对应的EditPart的例子：
Element.java:

java 代码

package com.example.model;
import java.beans.PropertyChangeListener;
import java.beans.PropertyChangeSupport;
import java.io.Serializable;
public abstract class Element implements Cloneable, Serializable {
PropertyChangeSupport listeners = new PropertyChangeSupport(this);
public void addPropertyChangeListener(PropertyChangeListener l) {
listeners.addPropertyChangeListener(l);
}
protected void firePropertyChange(String prop, Object old, Object newValue) {
listeners.firePropertyChange(prop, old, newValue);
}
protected void fireStructureChange(String prop, Object child) {
listeners.firePropertyChange(prop, null, child);
}
public void removePropertyChangeListener(PropertyChangeListener l) {
listeners.removePropertyChangeListener(l);
}
}

注意这个Element类中包含了一个PropertyChangeSupport对象。

Node.java:

java 代码

package com.example.model;
import java.util.ArrayList;
import java.util.List;
import org.eclipse.draw2d.geometry.Dimension;
import org.eclipse.draw2d.geometry.Point;
import org.eclipse.ui.views.properties.ComboBoxPropertyDescriptor;
import org.eclipse.ui.views.properties.IPropertyDescriptor;
import org.eclipse.ui.views.properties.IPropertySource;
import org.eclipse.ui.views.properties.TextPropertyDescriptor;
public class Node extends Element implements IPropertySource {
final public static String PROP_LOCATION = "LOCATION";
final public static String PROP_NAME = "NAME";
final public static String PROP_VISIBLE = "VISIBLE";
final public static String PROP_INPUTS = "INPUTS";
final public static String PROP_OUTPUTS = "OUTPUTS";
protected Point location = new Point(0, 0);
private Dimension size=new Dimension(150,40);
protected String name = "Node";
protected boolean visible = true;
protected IPropertyDescriptor[] descriptors = new IPropertyDescriptor[] {
new TextPropertyDescriptor(PROP_NAME, "Name"),
new ComboBoxPropertyDescriptor(PROP_VISIBLE, "Visible", new String[] { "true", "false" }) };
protected List outputs = new ArrayList(5);
protected List inputs = new ArrayList(5);
public void addInput(Connection connection) {
this.inputs.add(connection);
fireStructureChange(PROP_INPUTS, connection);
}
public void addOutput(Connection connection) {
this.outputs.add(connection);
fireStructureChange(PROP_OUTPUTS, connection);
}
public List getIncomingConnections() {
return this.inputs;
}
public List getOutgoingConnections() {
return this.outputs;
}
public void removeInput(Connection connection) {
this.inputs.remove(connection);
fireStructureChange(PROP_INPUTS, connection);
}
public void removeOutput(Connection connection) {
this.outputs.remove(connection);
fireStructureChange(PROP_OUTPUTS, connection);
}
public boolean isVisible() {
return visible;
}
public void setVisible(boolean visible) {
if (this.visible == visible) {
return;
}
this.visible = visible;
firePropertyChange(PROP_VISIBLE, null, Boolean.valueOf(visible));
}
public String getName() {
return name;
}
public void setName(String name) {
if (this.name.equals(name)) {
return;
}
this.name = name;
firePropertyChange(PROP_NAME, null, name);
}
public void setLocation(Point p) {
if (this.location.equals(p)) {
return;
}
this.location = p;
firePropertyChange(PROP_LOCATION, null, p);
}
public Point getLocation() {
return location;
}
public void setSize(Dimension size) {
this.size = size;
}
public Dimension getSize() {
return size;
}
//------------------------------------------------------------------------
// Abstract methods from IPropertySource
public Object getEditableValue() {
return this;
}
public IPropertyDescriptor[] getPropertyDescriptors() {
return descriptors;
}
public Object getPropertyValue(Object id) {
if (PROP_NAME.equals(id))
return getName();
if (PROP_VISIBLE.equals(id))
return isVisible() ? new Integer(0) : new Integer(1);
return null;
}
public boolean isPropertySet(Object id) {
return true;
}
public void resetPropertyValue(Object id) {
}
public void setPropertyValue(Object id, Object value) {
if (PROP_NAME.equals(id))
setName((String) value);
if (PROP_VISIBLE.equals(id))
setVisible(((Integer) value).intValue() == 0);
}
}

这个Node继承自Element，并且实现了IPropertySource，这表明它可以作为属性页的数据源。下面再看对应的EditPart：
NodePart.java:

java 代码

package com.example.parts;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.util.List;
import org.eclipse.draw2d.ChopboxAnchor;
import org.eclipse.draw2d.ConnectionAnchor;
import org.eclipse.draw2d.IFigure;
import org.eclipse.draw2d.geometry.Dimension;
import org.eclipse.draw2d.geometry.Point;
import org.eclipse.draw2d.geometry.Rectangle;
import org.eclipse.gef.ConnectionEditPart;
import org.eclipse.gef.EditPolicy;
import org.eclipse.gef.GraphicalEditPart;
import org.eclipse.gef.NodeEditPart;
import org.eclipse.gef.Request;
import org.eclipse.gef.RequestConstants;
import org.eclipse.gef.commands.Command;
import org.eclipse.gef.editparts.AbstractGraphicalEditPart;
import org.eclipse.gef.requests.ChangeBoundsRequest;
import org.eclipse.gef.requests.DirectEditRequest;
import org.eclipse.gef.tools.DirectEditManager;
import org.eclipse.jface.viewers.TextCellEditor;
import com.example.commands.RenameNodeCommand;
import com.example.commands.ResizeNodeCommand;
import com.example.figures.NodeFigure;
import com.example.model.Node;
import com.example.policies.NodeDirectEditPolicy;
import com.example.policies.NodeEditPolicy;
import com.example.policies.NodeGraphicalNodeEditPolicy;
public class NodePart extends AbstractGraphicalEditPart implements PropertyChangeListener, NodeEditPart {
protected DirectEditManager manager;
public void performRequest(Request req) {
if (req.getType().equals(RequestConstants.REQ_DIRECT_EDIT)) {
if (manager == null) {
NodeFigure figure = (NodeFigure) getFigure();
manager = new NodeDirectEditManager(this, TextCellEditor.class, new NodeCellEditorLocator(figure));
}
manager.show();
}
}
public Command getCommand(Request request) {
if(REQ_RESIZE.equals(request.getType())) {
ChangeBoundsRequest req=(ChangeBoundsRequest)request;
Node node=(Node)getModel();
ResizeNodeCommand cmd=new ResizeNodeCommand(node,this);
Rectangle rect=new Rectangle(node.getLocation(),node.getSize());
cmd.setRectangle(req.getTransformedRectangle(rect));
return cmd;
}
return super.getCommand(request);
}
public void propertyChange(PropertyChangeEvent evt) {
if (evt.getPropertyName().equals(Node.PROP_LOCATION))
refreshVisuals();
else if (evt.getPropertyName().equals(Node.PROP_NAME))
refreshVisuals();
else if (evt.getPropertyName().equals(Node.PROP_INPUTS))
refreshTargetConnections();
else if (evt.getPropertyName().equals(Node.PROP_OUTPUTS))
refreshSourceConnections();
}
protected IFigure createFigure() {
return new NodeFigure();
}
protected void createEditPolicies() {
installEditPolicy(EditPolicy.DIRECT_EDIT_ROLE, new NodeDirectEditPolicy());
installEditPolicy(EditPolicy.COMPONENT_ROLE, new NodeEditPolicy());
installEditPolicy(EditPolicy.GRAPHICAL_NODE_ROLE, new NodeGraphicalNodeEditPolicy());
}
public void activate() {
if (isActive()) {
return;
}
super.activate();
((Node) getModel()).addPropertyChangeListener(this);
}
public void deactivate() {
if (!isActive()) {
return;
}
super.deactivate();
((Node) getModel()).removePropertyChangeListener(this);
}
protected void refreshVisuals() {
Node node = (Node) getModel();
Point loc = node.getLocation();
Dimension size = node.getSize();
Rectangle rectangle = new Rectangle(loc, size);
((NodeFigure) this.getFigure()).setName(((Node) this.getModel()).getName());
//this.getFigure().setBounds(rectangle);
((GraphicalEditPart) getParent()).setLayoutConstraint(this, getFigure(), rectangle);
}
//------------------------------------------------------------------------
// Abstract methods from NodeEditPart
public ConnectionAnchor getSourceConnectionAnchor(ConnectionEditPart connection) {
return new ChopboxAnchor(getFigure());
}
public ConnectionAnchor getSourceConnectionAnchor(Request request) {
return new ChopboxAnchor(getFigure());
}
public ConnectionAnchor getTargetConnectionAnchor(ConnectionEditPart connection) {
return new ChopboxAnchor(getFigure());
}
public ConnectionAnchor getTargetConnectionAnchor(Request request) {
return new ChopboxAnchor(getFigure());
}
protected List getModelSourceConnections() {
return ((Node) this.getModel()).getOutgoingConnections();
}
protected List getModelTargetConnections() {
return ((Node) this.getModel()).getIncomingConnections();
}
}

这个EditPart还实现了NodeEditPart接口，这表明它可以被附着。

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[zt]第四章 GEF框架(2) | [zt]第三章 Draw2D简介

2007-02-14 10:13
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