GEF圖形顯示機制（二）

比如我們使用：

getGraphicalViewer().setRootEditPart(rooteditpart);

到此LightweightSystem的建構完成，關鍵是怎麼往rootfigure加其他figure了。這個就是GraphicalViewer的setcontens的作用。

public void setContents(Object contents) {

    Assert.isTrue(getEditPartFactory() != null,

        "An EditPartFactory is required to call setContents(Object)");//$NON-NLS-1$

    setContents(getEditPartFactory().

            createEditPart(null, contents));

}

public void setContents(EditPart editpart) {

    getRootEditPart().setContents(editpart);

}

下面這個是rooteditpart的setcontents.

public void setContents(EditPart editpart) {

    if (contents == editpart)

        return;

    if (contents != null)

        removeChild(contents);

    contents = editpart;

//隻能有一個contents.

    if (contents != null)

        addChild(contents, 0);

//注意這個0,表示contentsfigure在最上面。

}

這樣就添加了，也就是說contentfigure是rootfigure的child.

比如我們使用：

  getGraphicalViewer().setContents(this.diagram);

然後contentmodel的childemode對應的editpart的figure如何添加到contentfigue的呢？

當這Contentfigure(一個Layer)的載體contentseditpart的model添加一個child時就要通知

Contenteditpart,然後Contenteditpart執行refreshchildren;

protected void refreshChildren() {

    int i;

    EditPart editPart;

    Object model;

    Map modelToEditPart = new HashMap();

    List children = getChildren();

    for (i = 0; i < children.size(); i++) {

        editPart = (EditPart)children.get(i);

        modelToEditPart.put(editPart.getModel(), editPart);

    }

    List modelObjects = getModelChildren();

    for (i = 0; i < modelObjects.size(); i++) {

        model = modelObjects.get(i);

        //Do a quick check to see if editPart[i] == model[i]

        if (i < children.size()

            && ((EditPart) children.get(i)).getModel() == model)

                continue;

        //Look to see if the EditPart is already around but in the wrong location

        editPart = (EditPart)modelToEditPart.get(model);

        if (editPart != null)

            reorderChild (editPart, i);

        else {

            //An editpart for this model doesn't exist yet.  Create and insert one.

            editPart = createChild(model);

//

            addChild(editPart, i);

        }

    }

    List trash = new ArrayList();

    for (; i < children.size(); i++)

        trash.add(children.get(i));

    for (i = 0; i < trash.size(); i++) {

        EditPart ep = (EditPart)trash.get(i);

        removeChild(ep);

    }

}

protected EditPart createChild(Object model) {

    return getViewer().getEditPartFactory().createEditPart(this, model);

}

protected void addChild(EditPart child, int index) {

    Assert.isNotNull(child);

    if (index == -1)

        index = getChildren().size();

    if (children == null)

        children = new ArrayList(2);

    children.add(index, child);

    child.setParent(this);

    addChildVisual(child, index);

    child.addNotify();

    if (isActive())

        child.activate();

    fireChildAdded(child, index);

}

protected void addChildVisual(EditPart childEditPart, int index) {

    IFigure child = ((GraphicalEditPart)childEditPart).getFigure();

//getfigure會調用createfigure。

    getContentPane().add(child, index);

}

public IFigure getContentPane() {

    return getFigure();

}

這樣就把一個child添加到primary layer裡。

到此完成了所有editpart的figure。

Rooteditpart的figure是一個ScalableRootEditPart

public ScalableRootEditPart() {

    zoomManager =

        new ZoomManager((ScalableLayeredPane)getScaledLayers(), ((Viewport)getFigure()));

}

protected IFigure createFigure() {

    Viewport viewport = createViewport();

innerLayers = new LayeredPane();

    createLayers(innerLayers);

    viewport.setContents(innerLayers);

    return viewport;

}

public void setContents(IFigure figure) {

    if (view == figure)

        return;

    if (view != null)

        remove(view);

    view = figure;

    if (view != null)

        add(figure);

}

protected void createLayers(LayeredPane layeredPane) {

    layeredPane.add(getScaledLayers(), SCALABLE_LAYERS);

    layeredPane.add(new Layer() {

        public Dimension getPreferredSize(int wHint, int hHint) {

            return new Dimension();

        }

    }, HANDLE_LAYER);

    layeredPane.add(new FeedbackLayer(), FEEDBACK_LAYER);

    layeredPane.add(new GuideLayer(), GUIDE_LAYER);

}

然後inerlayer添加了EEDBACK_LAYER等層。

其實在lightwigetsystem裡，layer就是composite（所有figure都是）的感覺，隻不過它是透明的，即沒有背景色，而Label這些不行。

Contenteditpart就是一個layer.

protected IFigure createFigure() {

        // TODO Auto-generated method stub

        Layer figure = new Layer();

        figure.setLayoutManager(new XYLayout());

        return figure;                                                                                                             

    }

轉載自http://sjj0412.cublog.cn/