genesis — Thu, 24 Nov 2005 11:57:00 GMT

由GEF所构徏的图形编辑器用户通常的操作流�E�描�q�如下：

1、创建需要绘制图形的文�g�Q��ƈ�Ҏ��文�g�c�d��使用相应的编辑器打开文�g�Q��ؓ�l�制工作初始化一个图形编辑视图�?/SPAN>

2、根据图形编辑器所提供的图元工具创建具体图元，��图元绘制于�~�辑器所提供的图形编辑视图之�?/SPAN>

3、已�l�制囑�Ş元素的持久化

�Ҏ��q�个��程�Q?/SPAN>GEF中的各个�c�L��需要执行的操作基本步骤如下�Q?/SPAN>

1、创建文�Ӟ��Ҏ��文�g�c�d��选择相应�?/SPAN>Editor�?/SPAN>Editor和相关的Viewer的初始化�Q�此部分在以后会详细说明�Q?/SPAN>

2、��?/SPAN>Editor所提供�?/SPAN>Palette�?/SPAN>Viewer上绘制图�?BR>a、用户选择惌��l�制的图元，EditDomain会将用户选择�?/SPAN>Palette中的相应�?/SPAN>ToolEntry�Ȁ�z�R�?BR>

private void handlePaletteToolChanged()
{
    ToolEntry entry = getPaletteViewer().getActiveTool();
    if (entry !=null)
        setActiveTool(entry.createTool());
    else
        setActiveTool(getDefaultTool());
}

b、用户在��L��视图上按下鼠标左键后�Q?/FONT>DomainEventDispatcher会监听鼠标事�?BR>

/**
* @see EventDispatcher#dispatchMousePressed(org.eclipse.swt.events.MouseEvent)
*/
public void dispatchMousePressed(org.eclipse.swt.events.MouseEvent me)
{
    if (!editorCaptured)
{
        super.dispatchMousePressed(me);
        if (draw2dBusy())
            return;
    }
    if (okToDispatch())
{
        setFocus(null);
        control.forceFocus();
        setRouteEventsToEditor(true);
        domain.mouseDown(me, viewer);
    }
}

然后�Ҏ��事�g相应的类型将其�\由到EditDomain�Q?/SPAN>EditDomain则根据事件的�c�d��执行相应的操作。这些操作的主要工作��是获取EditDomain中当前被�Ȁ�zȝ��工具�Q?/SPAN>getActiveTool()�Q�，然后执行该工具对�q�些鼠标事�g的响应�?/SPAN>

public void mouseDown(MouseEvent mouseEvent, EditPartViewer viewer)
{
    Tool tool = getActiveTool();
    if (tool !=null)
        tool.mouseDown(mouseEvent, viewer);
}

�?/SPAN>CreationTool��Z��Q�它�?/SPAN>ButtonDown事�g的响应（handleButtonDown(int)�Q�就是创��Z��?/SPAN>CreateRequest�Q��ƈ赋予其相应的位置信息�Q?/SPAN>setLocation(Point)�Q?/SPAN>

/**
* The creation tool only works by clicking mouse button 1 (the left mouse button in a
* right-handed world).  If any other button is pressed, the tool goes into an invalid
* state.  Otherwise, it goes into the drag state, updates the request's location and
* calls {@link TargetingTool#lockTargetEditPart(EditPart)} with the edit part that was
* just clicked on.
*
* @see org.eclipse.gef.tools.AbstractTool#handleButtonDown(int)
*/
protected boolean handleButtonDown(int button)
{
    if (button !=1)
{
        setState(STATE_INVALID);
        handleInvalidInput();
        return true;
    }
    if (stateTransition(STATE_INITIAL, STATE_DRAG))

{
        getCreateRequest().setLocation(getLocation());
        lockTargetEditPart(getTargetEditPart());
        // Snap only when size on drop is employed
        helper = (SnapToHelper)getTargetEditPart().getAdapter(SnapToHelper.class);
    }
    return true;
}

c�?/SPAN>CreationTool�q�会�Ҏ��Request的类型及位置��其分派�l�相应的EditPart�?/SPAN>[Targeting tools work with a target request. This request is used along with the mouse location to obtain an active target from the current EditPartViewer. This target is then asked for the Command that performs the given request. The target is also asked to show target feedback. (摘自org.eclipse.gef.tools.TargetingTool)]

d、此后的��程基本上就如GEF EMF Redbook�?.3.3Requests节中的Communication chain
Request-EditPart-Command所�q?/FONT>

Command执行所做的操作只是对它所涉及到的模型�q�行相应的设�|�，譬如大小、位�|�、颜色等属性。那么图元如何显�C�在视图之上呢？�q�一部分正是�?/SPAN>GEF中所使用�?/SPAN>MVC模式实现�?/SPAN>

GEF中的每一个模型都实现了某�U?/SPAN>Notifier(org.eclipse.emf.common.notify.Notifier)或�?/SPAN>IPropertySource(org.eclipse.ui.views.properties.IPropertySource)接口作�ؓ消息源，每个EditPart则相应的实现�?/SPAN>Adapter(org.eclipse.emf.common.notify.Adapter)�?/SPAN>PropertyChangeListener(java.beans.PropertyChangeListener)�{�接口作��Z��听器。�ƈ�?/SPAN>EditPart初始化时�Q�将其本�w�注册�ؓ所对应的模型的一个侦听器�Q�当模型中的属性发生变化时�Q?/SPAN>EditPart会执行相应的操作�?BR>
�?SPAN lang=EN-US style="FONT-FAMILY: Verdana">EditPart初始化时�Q�将其本�w�注册�ؓ所对应的模型的一个侦听器�Q��ƈ在销毁之前注销注册�Q?BR>

/**
* Upon activation, attach to the model element as a notification change
* listener.
*/
public void activate() {
    if (!isActive()) {
        super.activate();
        ((ModelElement) getModel()).eAdapters().add(this);
    }
}

/**
* Upon deactivation, detach from the model element as a notification change
* listener.
*/
public void deactivate() {
    if (isActive()) {
        super.deactivate();
        ((ModelElement) getModel()).eAdapters().remove(this);
    }
}

当模型中的属性发生变化时�Q�会向所有的侦听器发出消息：

/**
*
*
* @generated
*/
public void setName(String newName) {
    String oldName = name;
    name = newName;
    if (eNotificationRequired())
        eNotify(new ENotificationImpl(this, Notification.SET, ModelPackage.ARC_MODEL__NAME, oldName, name));
}

对于所有在该模型上注册的侦听器�Q�EditPart�Q�都会接收到属性变化的消息�Q�根据消息做出相应的反应�Q?BR>

/*
* (non-Javadoc)
*
* @see org.eclipse.emf.common.notify.Adapter#notifyChanged(org.eclipse.emf.common.notify.Notification)
*/
public void notifyChanged(Notification notification) {

    int featureID = notification.getFeatureID(ModelPackage.class);

    if (ModelPackage.NODE_MODEL__HEIGHT == featureID
            || ModelPackage.NODE_MODEL__WIDTH == featureID
            || ModelPackage.NODE_MODEL__X == featureID
            || ModelPackage.NODE_MODEL__Y == featureID) {
        refreshVisuals();
    } else if (ModelPackage.NODE_MODEL__INPUT_ARCS == featureID) {
        refreshTargetConnections();
    } else if (ModelPackage.NODE_MODEL__OUTPUT_ARCS == featureID) {
        refreshSourceConnections();
    }
}

�Q�注意：上述�C�Z��代码中，模型部分代码是由EMF自动生成�Q�因此��用了Notifier-Adapter侦听机制�Q?/FONT>

genesis 2005-11-24 19:57 发表评论

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