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BorderLayout - 防止“居中”被“切断”的部件

发布于 2025-01-02 11:03:48 字数 575 浏览 0 评论 0原文

我有一个包含两个 JLabel 的 JPanel。该面板使用 BorderLayout。

一个 JLabel 放置在 BorderLayout.CENTER 位置，另一个放置在 BorderLayout.PAGE_END 位置。

当我调整面板大小，使其没有足够的垂直空间来显示两个标签时，居中的标签始终会被 PAGE_END 位置的标签覆盖（截断）。

由于居中标签中显示的信息比其他标签更重要，因此我希望居中标签重叠（或切断）其下方的标签。

似乎 BorderLayout （以及 GridBagLayout ）总是从“从上到下”绘制组件，而那些“稍后”绘制的组件将覆盖之前绘制的组件。

有什么方法可以说服 BorderLayout （或任何其他 LayoutManager）假设某个组件应该始终位于“顶部”？

我尝试使用

panel.setComponentZOrder(label1, 1);
panel.setComponentZOrder(label2, 0);

但这没有什么区别。

原文

I have a JPanel that contains two JLabel. The panel uses a BorderLayout.

One JLabel is put into BorderLayout.CENTER position, the other in BorderLayout.PAGE_END

When I resize the panel so that it does not have enough vertical space to show both labels, the centered label is always overwritten (cut off) by the label in the PAGE_END position.

As the information displayed in the centered label is more important than the other, I would like the centered label to overlap (or cut off) the label below it.

It seems that BorderLayout (and GridBagLayout as well) always paints the components from "top to bottom" and those that are painted "later" will overwrite the ones painted before.

Is there some way I can convince BorderLayout (or any other LayoutManager) to assume that a certain component should always be "at the top"?

I tried using

panel.setComponentZOrder(label1, 1);
panel.setComponentZOrder(label2, 0);

but that didn't make a difference.

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━╋う一瞬間旳綻放 2025-01-09 11:03:48

一种方法是使用符合首选尺寸的 GridLayout 自定义变体。 PreferredSizeGridLayout 使用PreferredBoundable 实现就是一个示例。

附录：这是我尝试过的测试代码。如果不进行更改，下部标签将“滑动”到上部标签下方，但您必须处理 horizontalAlignment 属性。

public class PreferredLayoutTest extends JPanel {

    public PreferredLayoutTest() {
        this.setLayout(new PreferredSizeGridLayout(0, 1));
        this.add(createLabel("One"));
        this.add(createLabel("Two"));
    }

    private JLabel createLabel(String s) {
        JLabel label = new JLabel(s);
        label.setOpaque(true);
        label.setBackground(Color.lightGray);
        label.setFont(label.getFont().deriveFont(36f));
        return label;
    }

    private void display() {
        JFrame f = new JFrame("PreferredLayoutTest");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.add(this);
        f.pack();
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {

            @Override
            public void run() {
                new PreferredLayoutTest().display();
            }
        });
    }
}

One approach would be to use a custom variation of GridLayout that respects preferred sizes. PreferredSizeGridLayout using the PreferredBoundable implementation is an example.

Addendum: Here's the test code I tried. Without change, the lower label "slides" beneath the upper, but you'll have to handle the horizontalAlignment property.

public class PreferredLayoutTest extends JPanel {

    public PreferredLayoutTest() {
        this.setLayout(new PreferredSizeGridLayout(0, 1));
        this.add(createLabel("One"));
        this.add(createLabel("Two"));
    }

    private JLabel createLabel(String s) {
        JLabel label = new JLabel(s);
        label.setOpaque(true);
        label.setBackground(Color.lightGray);
        label.setFont(label.getFont().deriveFont(36f));
        return label;
    }

    private void display() {
        JFrame f = new JFrame("PreferredLayoutTest");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.add(this);
        f.pack();
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {

            @Override
            public void run() {
                new PreferredLayoutTest().display();
            }
        });
    }
}

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