GXT(Ext-GWT):ContentPanel的布局问题

Question

我有一个适合整个窗口的ContentPanel.它有一个topComponent,一个中心的小部件和一个bottomComponent.

当ContentPanel被渲染一次后,当我尝试将小部件添加到topComponent时,我遇到了布局问题:

public void onModuleLoad() {

    final Viewport viewport = new Viewport();
    viewport.setLayout(new FitLayout());

    final ContentPanel contentPanel = new ContentPanel(new FitLayout());
    contentPanel.setHeaderVisible(false);

    final LayoutContainer topContainer = new LayoutContainer(
            new FlowLayout());

    final Button buttonOne = new Button("Top:One");
    topContainer.add(buttonOne);

    contentPanel.setTopComponent(topContainer);
    contentPanel.add(new Button("Center"));
    contentPanel.setBottomComponent(new Button("Bottom"));

    viewport.add(contentPanel);
    RootPanel.get().add(viewport);

    // Later, add a second button to the topComponent ...
    Scheduler.get().scheduleDeferred(new ScheduledCommand() {
        @Override
        public void execute() {
            final Button buttonTwo = new Button("Top:Two");
            topContainer.add(buttonTwo); // Doesn't show up at first.

            topContainer.layout(); // Now, buttonTwo shows up. But we have
                            // a new problem: the "Bottom" button disappears...

            contentPanel.layout(true); // This doesn't do anything, BTW.
        }
    });
}

关于这一点的一个有趣的事情是,只要我调整浏览器窗口大小,布局就会自行纠正.我可以做些什么来使其立即正确重新布局(我已尝试layout()在几个地方和组合中添加几个调用等,但到目前为止还没有运气.)

(我正在使用GWT 2.1.1和GXT 2.2.1.)

Answer 1

发生这种情况是因为当您向FlowLayout添加另一个组件时,它会调整大小,从而增加其自身的高度,从而将底部组件推到可见区域下方.代码中没有任何东西缩小中心组件,因此底部组件保持在其原始位置.

还有一件事是你使用FitLayout为contentPanel包含3个组件,FitLayout用于容器内部只有一个组件,它应该填充其父组件.

您需要考虑以下事项:

1)使用RowLayout,它可以更好地控制组件的布局方式

2)确定您愿意放置垂直滚动条的组件,因为您要动态添加组件.

对于您当前的要求,以下代码应该足够:

public void onModuleLoad() {
       final Viewport viewport = new Viewport();
       viewport.setLayout(new FitLayout());

//     final ContentPanel contentPanel = new ContentPanel(new FlowLayout());
//     contentPanel.setHeaderVisible(false);

        final LayoutContainer topContainer = new LayoutContainer(
                new FlowLayout());

        final Button buttonOne = new Button("Top:One");
        topContainer.add(buttonOne);
//    contentPanel.setTopComponent(topContainer);
        final LayoutContainer centerPanel = new LayoutContainer(new FitLayout());

        centerPanel.add(new Button("Center"));
//    contentPanel.add(centerPanel);
        final LayoutContainer botPanel = new LayoutContainer(new FlowLayout());
        botPanel.add(new Button("Bottom"));
//      contentPanel.setBottomComponent(botPanel);

        final ContentPanel panel = new ContentPanel();  
        panel.setHeaderVisible(false);  
        panel.setLayout(new RowLayout(Orientation.VERTICAL));    


        panel.add(topContainer, new RowData(1, -1, new Margins(4)));  
        panel.add(centerPanel, new RowData(1, 1, new Margins(0, 4, 0, 4)));  
        panel.add(botPanel, new RowData(1, -1, new Margins(4)));  

        viewport.add(panel, new FlowData(10));  


        RootPanel.get().add(viewport);

        // Later, add a second button to the topComponent ...
        Scheduler.get().scheduleDeferred(new ScheduledCommand() {
            @Override
            public void execute() {
                final Button buttonTwo = new Button("Top:Two");
                topContainer.add(buttonTwo); // Doesn't show up at first.
                panel.layout(true);
            }
        });
}