SWT-GEF事件转义相关类

在Draw2d中，Lightweight是gef图形系统的”shell”及”display”，其在swt中的代理是canvas,所以所有的GEF的事件来源于这个canvas，下面就看下gef事件处理的流程，首先肯定要监听canvas的事件，这个通过LightweightSystem的addListeners函数注册其内的canvas的各种事件监听器。

1.SWT层事件监听器安装：

Class ScrollingGraphicalViewer. createControl(Composite parent)
Class FigureCanvas(int style, Composite parent, LightweightSystem lws)-> lws.setControl(this);
Class LightweightSystem. setControl(Canvas c)-> addListeners();
getEventDispatcher()

protected class EventHandler
handleEvent(Event event)

2. LightweightSystem层消息分发器安装：
class GraphicalEditor. createGraphicalViewer(Composite parent). setGraphicalViewer(viewer);

class EditDomain. addViewer(EditPartViewer viewer): viewer.setEditDomain(this);

class GraphicalViewer. setEditDomain(EditDomain domain):
getLightweightSystem()
.setEventDispatcher(eventDispatcher = new DomainEventDispatcher(domain, this));

class LightweightSystem.setEventDispatcher(EventDispatcher dispatcher) ;

3. LightweightSystem消息分发器处理流程：
以键盘消息为例
class EventDispatcher.dispatchMousePressed(org.eclipse.swt.events.MouseEvent me)-> domain.mouseDown(me, viewer);

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

之后就是具体的Tool层的实现类中的事件处理了