4

私は持っていCompositeます。SWT では、子は子によって追加され、親によって追加されません。

Composite parent = new Composite(shell, SWT.none);
Composite child = new Composite(parent, SWT.none);

つまり、親の内部では、子がいつどのように親に追加されるかはわかりません。

質問：

新しい子が親に追加されたときに、親の内部を知る必要があります。オーバーライドonChildAddListenerするメソッドを登録する方法はありますか?add()

4

2 に答える 2

3

カスタムを追加し、カスタムとインターフェイスMyCompositeを作成する唯一の方法。は、子が作成されたときにこのイベントのリスナーを登録して発生させることができます。ChildEventChildEventListenerMyCompositeChildEventComposite

import org.eclipse.swt.SWT;
import org.eclipse.swt.events.TypedEvent;
import org.eclipse.swt.internal.SWTEventListener;
import org.eclipse.swt.widgets.*;

/*
 * This example demonstrates the minimum amount of code required
 * to open an SWT Shell and process the events.
 */
public class HelloWorld1 {

public static void main (String [] args) {
    Display display = new Display ();
    Shell shell = new HelloWorld1 ().open (display);
    while (!shell.isDisposed ()) {
        if (!display.readAndDispatch ()) display.sleep ();
    }
    display.dispose ();
}

public Shell open (Display display) {
    Shell shell = new Shell (display);
    MyComposite parent = new MyComposite(shell, SWT.NONE);
    parent.addChildEventListener(new ChildEventListener() {

        @Override
        public void add(ChildEvent e) {
            System.out.println("Child added.");

        }
    });
    MyComposite child = new MyComposite(parent, SWT.NONE);

//  shell.open ();
    return shell;
}
}

class MyComposite extends Composite {

    ChildEventListener[] childEventListeners = new ChildEventListener[0];

    public MyComposite(Composite parent, int style) {
        super(parent, style);
        if (parent instanceof MyComposite){
            ((MyComposite)parent).fireChildEvent(new ChildEvent(this));
        }
    }
    public void addChildEventListener (ChildEventListener listener) {
        checkWidget();
        if (listener == null) SWT.error (SWT.ERROR_NULL_ARGUMENT);
        ChildEventListener[] newChildEventListeners = new ChildEventListener[childEventListeners.length + 1];
        System.arraycopy(childEventListeners, 0, newChildEventListeners, 0, childEventListeners.length);
        childEventListeners = newChildEventListeners;
        childEventListeners[childEventListeners.length - 1] = listener;
    }
    public void removeChildEventListener (ChildEventListener listener) {
        if (childEventListeners.length == 0) return;
        int index = -1;
        for (int i = 0; i < childEventListeners.length; i++) {
            if (listener == childEventListeners[i]){
                index = i;
                break;
            }
        }
        if (index == -1) return;
        if (childEventListeners.length == 1) {
            childEventListeners = new ChildEventListener[0];
            return;
        }
        ChildEventListener[] newChildEventListeners = new ChildEventListener[childEventListeners.length - 1];
        System.arraycopy (childEventListeners, 0, newChildEventListeners, 0, index);
        System.arraycopy (childEventListeners, index + 1, newChildEventListeners, index, childEventListeners.length - index - 1);
        childEventListeners = newChildEventListeners;
    }
    public void fireChildEvent(ChildEvent event){
        for (int i = 0; i < childEventListeners.length; i++) {
            childEventListeners[i].add (event);
        }

    }
}

interface ChildEventListener extends SWTEventListener {
    public void add(ChildEvent e);
}

class ChildEvent extends TypedEvent {

    public ChildEvent(Widget widget) {
        super(widget);
        // TODO Auto-generated constructor stub
    }

}
于 2012-08-25T14:09:40.050 に答える
1

子の追加について知りたかった目的は、子が子に追加されたときに子をレイアウトすることです (例: などLayoutData) 。GridDataGridLayout

追加時に子をレイアウトすることはできないため、ウィジェットのサイズを変更するたびにレイアウトを確認してください。

    /*
     * To make the forms fill the group - laying out the children is necessary.
     * Unfortunately it is not possible to listen for children addition, in order to layout the children addition automatically.
     * This means that the user will have to remember  to layout the children, which is a nogo.
     * 
     * Solution: 
     * istead of adding right layout on child addition -  check if there are new children every time the widget is resized.
     * if a widget without layoutData is found (new child not layed out) - add a layout
     */
    this.addControlListener(new ControlAdapter() {
        @Override
        public void controlResized(ControlEvent e) {
            layoutChildren();
        }
    });
}
private void layoutChildren(){
    for(Control child:getChildren()){
        if(child.getLayoutData() == null){
            child.setLayoutData(new GridData(SWT.FILL, SWT.CENTER, true, false, 1, 1)); 
        }
    }
}

public void addToGroup(Composite child){
    child.setLayoutData(new GridData(SWT.FILL, SWT.CENTER, true, false, 1, 1));
}
于 2014-08-20T13:15:11.110 に答える