Question

我正在使用JLayeredPane添加3个JPanel。

我使JPanels透明（没有设置背景和setOpaque（false））。我在JPanels上绘制线条，只有最后一个JPanel上的线条可见。通过顶级JPanel看不到其他JPanel的行（即使我在添加它们时添加了不同的zIndexes）。

有谁知道这方面的解决方案？为什么他们不透明？

我创建了一个小测试程序（3个类）。（TestJPanel和TestJPanel1绘制一条线，但是在不同的位置，但我只看到最后添加的JPanel的行。我没有看到2行，因为它不透明:(）

Main.Java

import java.awt.BorderLayout;
import java.awt.Color;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLayeredPane;

public class Main extends JFrame {
  public Main() {
    setSize(400, 350);
    setDefaultCloseOperation(EXIT_ON_CLOSE);
    JLayeredPane lp = getLayeredPane();
    lp.setLayout(new BorderLayout());
    TestJPanel top = new TestJPanel();
    top.setOpaque(false);
    TestJPanel middle = new TestJPanel();
    middle.setOpaque(false);
    TestJPanel1 bottom = new TestJPanel1();
    bottom.setOpaque(false);

    lp.add(middle, BorderLayout.CENTER, new Integer(4));
    lp.add(top, BorderLayout.CENTER, new Integer(3));
    lp.add(bottom, BorderLayout.CENTER, new Integer(2));
    // the last one I have added (bottom) is visible and can't see the others through it

    setVisible(true);
  }

  public static void main(String[] args) {
    new Main();

  }
}

TestJPanel.java

import java.awt.Graphics;


public class TestJPanel extends javax.swing.JPanel {

    /** Creates new form TestJPanel */
    public TestJPanel() {
        initComponents();
    }

    @Override
    public void paintComponent(Graphics g) {
        super.paintComponent(g);

        g.drawLine(25, 0, 25, 50);
    }

    /** This method is called from within the constructor to
     * initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is
     * always regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">
    private void initComponents() {

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(this);
        this.setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 400, Short.MAX_VALUE)
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 300, Short.MAX_VALUE)
        );
    }// </editor-fold>


    // Variables declaration - do not modify
    // End of variables declaration

}

TestJPanel1.java

import java.awt.Graphics;


public class TestJPanel1 extends javax.swing.JPanel {

    /** Creates new form TestJPanel */
    public TestJPanel1() {
        initComponents();
    }

    @Override
    public void paintComponent(Graphics g) {
        super.paintComponent(g);

        g.drawLine(50, 0, 50, 50);
    }

    /** This method is called from within the constructor to
     * initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is
     * always regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">
    private void initComponents() {

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(this);
        this.setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 400, Short.MAX_VALUE)
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 300, Short.MAX_VALUE)
        );
    }// </editor-fold>


    // Variables declaration - do not modify
    // End of variables declaration

}

我真的希望有人可以帮助我a.s.a.p.有这个问题。

Answer 1

删除行

lp.setLayout(new BorderLayout());

并用

替换你的add（）调用

lp.add(component, layer);

您正在错误地使用LayeredPane - 使用LayeredPane，您（通常）不想设置布局。我相信（但必须检查）您只看到一行的原因是，使用BorderLayout，如果您将多个组件添加到同一区域（例如BorderLayout.CENTER），则只添加您添加的最后一个组件;其他人被有效地从布局中删除。

有关详细信息，请参阅the Swing tutorial on Layered Panes

Answer 2

您正在将面板添加到相同的BorderLayout区域。

Java Swing透明的JPanels问题

2 个答案: