不应该有的油漆

Question

我目前正在编写一个自定义的BasicTabbedPaneUI类，但是当JTabbedPane's标签位置为JTabbedPane.RIGHT时，我遇到了问题。当它像这样设置时，在选项卡上方和下方都会绘制背景。据我所知，我的代码并不打算这样做。

这可以在下图中清楚地看到。

^{顶部JTabbedPane.TOP和底部是JTabbedPane.RIGHT}
我的预期了。

^{顶部JTabbedPane.TOP和底部是JTabbedPane.RIGHT}
我会apprieciate任何帮助解决问题。

---

GUI.java

import java.awt.BorderLayout; 
import java.awt.Dimension; 
import java.awt.EventQueue; 

import javax.swing.JFrame; 
import javax.swing.JLabel; 
import javax.swing.JPanel; 
import javax.swing.JTabbedPane; 

@SuppressWarnings("serial") 
public class GUI extends JFrame { 

    JTabbedPane tabs = new JTabbedPane(); 
    //JTabbedPane tabs = new JTabbedPane(JTabbedPane.RIGHT); 

    private GUI() { 
     super("GUI"); 
     setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 

     setLayout(new BorderLayout()); 
     createLayout(); 
     add(tabs); 

     pack(); 
     setLocationRelativeTo(null); 

     setVisible(true); 
    } 

    private void createLayout() { 
     tabs.setPreferredSize(new Dimension(600, 200)); 
     tabs.setUI(new TabsUI()); 

     JPanel p1 = new JPanel(); 
     p1.add(new JLabel("Panel 1")); 
     tabs.addTab("Panel 1", p1); 

     JPanel p2 = new JPanel(); 
     p2.add(new JLabel("Panel 2")); 
     tabs.addTab("Panel 2", p2); 

     JPanel p3 = new JPanel(); 
     p3.add(new JLabel("Panel 3")); 
     tabs.addTab("Panel 3", p3); 

     JPanel p4 = new JPanel(); 
     p4.add(new JLabel("Panel 4")); 
     tabs.addTab("Panel 4", p4); 
    } 

    public static void main(String[] args) { 
     EventQueue.invokeLater(() -> new GUI()); 
    } 
} 

---

TabsUI.java

import java.awt.Color; 
import java.awt.FontMetrics; 
import java.awt.Graphics; 
import java.awt.Rectangle; 

import javax.swing.JComponent; 
import javax.swing.plaf.ComponentUI; 
import javax.swing.plaf.basic.BasicTabbedPaneUI; 

public class TabsUI extends BasicTabbedPaneUI{ 
    public static ComponentUI createUI(JComponent c) { 
     return new TabsUI(); 
    } 

    int wSep = 10; 
    int hSep = 10; 

    @Override 
    protected void paintTabBackground(Graphics g, int tabPlacement, int tabIndex, int x, int y, int w, int h, boolean isSelected) { 
     int greyScale = 150; 
     g.setColor(new Color(greyScale, greyScale, greyScale)); 

     switch(tabPlacement) { 
      case LEFT: 
      case RIGHT: 
       g.fillRect(x, y + (hSep/2), w, h - hSep); 
      case BOTTOM: 
      case TOP: 
      default: 
       g.fillRect(x + (wSep/2), y, w - wSep, h); 
     } 
    } 

    @Override 
    protected int calculateTabWidth(int tabPlacement, int tabIndex, FontMetrics metrics) { 
     if (tabPlacement == LEFT || tabPlacement == RIGHT) { 
      return 50 + super.calculateTabWidth(tabPlacement, tabIndex, metrics); 
     } else { 
      return 50 + (wSep * 2) + super.calculateTabWidth(tabPlacement, tabIndex, metrics); 
     } 
    } 

    @Override 
    protected int calculateTabHeight(int tabPlacement, int tabIndex, int fontHeight) { 
     if (tabPlacement == LEFT || tabPlacement == RIGHT) { 
      return 5 + hSep + super.calculateTabHeight(tabPlacement, tabIndex, fontHeight); 
     } else { 
      return 5 + super.calculateTabHeight(tabPlacement, tabIndex, fontHeight); 
     } 
    } 

    @Override 
    protected void paintTabBorder(Graphics g, int tabPlacement, int tabIndex, int x, int y, int w, int h, boolean isSelected) {} 

    @Override 
    protected void paintFocusIndicator(Graphics g, int tabPlacement, Rectangle[] rects, int tabIndex, Rectangle iconRect, Rectangle textRect, boolean isSelected) {} 
} 

Answer 1

switch(tabPlacement) { 
    case LEFT: 
    case RIGHT: 
     g.fillRect(x, y + (hSep/2), w, h - hSep); 
    case BOTTOM: 
    case TOP: 
    default: 
     g.fillRect(x + (wSep/2), y, w - wSep, h); 
} 

您似乎缺少 “突破”;语句，所以默认的绘画代码也正在执行。

代码应该是：

 g.fillRect(x, y + (hSep/2), w, h - hSep); 
     break;