java - SWT JFace如何在moveBelow()后重绘

Question

我有一个 View ，其中显示元素，具体取决于之前的选择。 dispose() 和parent.layout() 确实按预期删除元素。问题是，我怎样才能把它们找回来？我想， dispose() 不会删除元素，只是将其从元素列表中取出来渲染。那么，我怎样才能拿回一个呢？

提前致谢，马库斯

<小时/> 编辑:

刚刚发现，dispose() 释放了对象并递归地释放了它的子对象，所以一旦我处置了它们，我就必须重新创建它们？如果是这样，我怎样才能找到例如内的位置？网格布局？

<小时/> 编辑(2):

根据下面的答案，我已经尝试过:

public class TestTab extends Composite 
{
    org.eclipse.swt.layout.GridLayout layout = null;

    GridData griddata = null;

    Button upperButton = null;
    Text textInTheMiddle = null;
    Button lowerButton = null;

    public InvoiceTab(Composite parent, int arg2) {

        super(parent, arg2);
        final Composite myParent = parent;

        layout = new org.eclipse.swt.layout.GridLayout(GridData.FILL_BOTH,
                false);
        layout.numColumns = 1;

        this.setLayout(layout);


        upperButton = new Button(this, SWT.PUSH);
        upperButton.setText("upper Button");

        textInTheMiddle = new Text(this, SWT.BORDER);

        lowerButton = new Button(this, SWT.PUSH);
        lowerButton.setText("lower Button");

        upperButton.addSelectionListener(new SelectionAdapter() {
            public void widgetSelected(SelectionEvent e) {

                if (textInTheMiddle.isVisible()) {
                    textInTheMiddle.setVisible(false);
                    lowerButton.moveBelow(upperButton);
                } else {
                    textInTheMiddle.setVisible(true);
                    lowerButton.moveBelow(textInTheMiddle);
                }
                myParent.layout();
            }
        });
    }   
}

文本字段按预期可见，但下部按钮没有改变位置？再次感谢您的任何想法...

Answer 1

是的，dispose() 释放该对象并递归地释放它的子对象。所以你必须重新创建你已经处理过的控件/小部件。在像您这样的情况下，建议隐藏控件并重新布局您的组合/容器。例如see here

代码!!

重点是 GridData::exclude 属性的使用。

import org.eclipse.swt.SWT;
import org.eclipse.swt.events.SelectionAdapter;
import org.eclipse.swt.events.SelectionEvent;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.widgets.Text;

class TestTab extends Composite 
{
    Button upperButton = null;
    Text textInTheMiddle = null;
    Button lowerButton = null;

    boolean state = true;

    public TestTab(Composite parent, int style) 
    {
        super(parent, style);


        GridLayout layout = new GridLayout(1, false);
        setLayout(layout);


        upperButton = new Button(this, SWT.PUSH);
        upperButton.setText("upper Button");

        textInTheMiddle = new Text(this, SWT.BORDER);
        GridData data = new GridData(SWT.FILL, SWT.FILL, true, false);
        data.exclude = false;
        textInTheMiddle.setLayoutData(data);

        lowerButton = new Button(this, SWT.PUSH);
        lowerButton.setText("lower Button");

        upperButton.addSelectionListener(new SelectionAdapter() 
        {
            public void widgetSelected(SelectionEvent e) {


                GridData griddata = (GridData) textInTheMiddle.getLayoutData();
                griddata.exclude = state;
                textInTheMiddle.setVisible(!state);
                textInTheMiddle.getParent().layout(false);
                state = !state;
            }
        });
    }   

}
public class Test
{
    public static void main(String[] args) 
    {
        Display display = new Display();
        Shell shell = new Shell(display);
        shell.setLayout(new GridLayout(1, false));

        new TestTab(shell, SWT.NONE);

        shell.open();
        while (!shell.isDisposed()) {
            if (!display.readAndDispatch())
                display.sleep();
        }
        display.dispose();
    }
}