java - 如何在多边形上显示 float 工具提示文本

Question

我编写了一段 Java 代码来在图像上绘制多边形。当我将光标放在多边形内时，它会打印“内部”，否则会打印“外部”。所以多边形内部点的检测工作正常。

但是我想在多边形内部实现setToolTipText的效果，即当鼠标悬停在多边形内部时，它将显示 float 文本“内部”。

类似于此图中的效果:

http://www.java2s.com/Code/Java/Swing-JFC/WorkingwithTooltipText.htm

为了达到预期的效果，需要对以下代码进行哪些最小的更改？

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.*;
import java.awt.image.*;
import java.awt.Graphics.*;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Point;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionAdapter;

class page1 extends JFrame implements MouseListener,MouseMotionListener ,ActionListener
{
    JFrame f;
    JLabel l;
    JPanel p1;
    ImageIcon ii;
    Image img;
    int height;
    int width;
    Container c;
    int pixels[];
    PixelGrabber pg;
    JPanel panel;
    Graphics2D gg;
    Polygon pp1=new Polygon();
    boolean startHovercurrent,startHoverprev=false;


    page1()
    {
        f=new JFrame("Sample Page");
        ii=new ImageIcon("sample.jpg");
        img=ii.getImage();
        height=ii.getIconHeight();
        width=ii.getIconWidth();
        pixels=new int[ii.getIconWidth()*ii.getIconHeight()];
        pg=new PixelGrabber(img,0,0,ii.getIconWidth(),ii.getIconHeight(),pixels,0,ii.getIconWidth());
        try
        {
            pg.grabPixels();
        }
        catch(InterruptedException k)
        {
        }

        //add points of polygon
        pp1.addPoint(300,300);
        pp1.addPoint(380,300);
        pp1.addPoint(380,220);
        pp1.addPoint(300,220);


        l=new JLabel(ii,JLabel.CENTER);
        c=f.getContentPane();
        JDesktopPane desk = new JDesktopPane();
        JInternalFrame p = new JInternalFrame("Image Frame",false, false, true, false);
        JScrollPane scroll = new JScrollPane(l);
        p.setContentPane(scroll);
        p.setBounds(0, 0, 740, 600);
        desk.add(p);
        p.setVisible(true);
        l.addMouseListener(this);
        l.addMouseMotionListener(this);

        c.add(desk, BorderLayout.CENTER);
        f.setSize(1024,738);
        f.setVisible(true);

    }


    public static void main(String args[])
    {
        new page1();    
    }
    public void mouseClicked(MouseEvent me)
    {
    }
    public void mouseEntered(MouseEvent me)
    {
    }
    public void mouseExited(MouseEvent me)
    {
    }
    public void mousePressed(MouseEvent me)
    {     
    }
    public void mouseReleased(MouseEvent me)
    {   
    }
    public void mouseMoved(MouseEvent me)
    {
        boolean contain1;
        int mx,my;
        gg=(Graphics2D)l.getGraphics();         
        gg.setColor(new Color(255,0,0) );
        gg.fillPolygon(pp1);

        mx = me.getX();
        my = me.getY();

        //check if mouse cursor is inside polygon or not
        // do not print anything if next cursor position is in same state
        contain1=pp1.contains(mx,my);
        if (contain1) {
            startHovercurrent = true;
            if(startHovercurrent!=startHoverprev)
                System.out.println("Inside");

            startHoverprev=startHovercurrent;
         } 
         else {
            startHovercurrent = false;
            if(startHovercurrent!=startHoverprev)
                System.out.println("Outside");

            startHoverprev=startHovercurrent;
         }
    }
    public void mouseDragged(MouseEvent me)
    {   
    }
    public void actionPerformed(ActionEvent ae)
    {  
    }   
}

Answer 1

对于此用法，How to Use Tool Tips建议重写封闭的 JComponent 的 getToolTipText() 方法。这个answer概述了 JMapViewer 和 ChartPanel 的方法。在下面的示例中，getToolTipText() 仅返回任何包含()触发鼠标事件的Shape的名称。为了进行比较，窗口底部的 JLabel 通过 setToolTipText() 获取传统的提示。

import java.awt.BasicStroke;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Polygon;
import java.awt.Shape;
import java.awt.event.MouseEvent;
import java.awt.geom.Ellipse2D;
import java.util.ArrayList;
import java.util.List;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.ToolTipManager;

/**
 * @see https://stackoverflow.com/a/53609066/230513
 * @see https://stackoverflow.com/a/25944439/230513
 */
public class ShapeToolTip {

    private static class ShapePanel extends JPanel {

        private final List<Shape> list = new ArrayList<>();

        public ShapePanel() {
            Polygon p = new Polygon();
            p.addPoint(500, 100);
            p.addPoint(500, 400);
            p.addPoint(200, 400);
            list.add(p);
            list.add(new Ellipse2D.Double(100, 100, 200, 200));
            ToolTipManager.sharedInstance().registerComponent(this);
        }

        @Override
        public String getToolTipText(MouseEvent e) {
            for (Shape shape : list) {
                if (shape.contains(e.getX(), e.getY())) {
                    return shape.getClass().getName();
                }
            }
            return "Outside";
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            g.setColor(Color.blue);
            Graphics2D g2d = (Graphics2D) g;
            g2d.setStroke(new BasicStroke(2));
            for (Shape shape : list) {
                g2d.draw(shape);
            }
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(640, 480);
        }
    }

    private void display() {
        JFrame f = new JFrame("ShapeToolTip");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.add(new ShapePanel());
        JLabel title = new JLabel("Shape Tool Tip", JLabel.CENTER);
        title.setToolTipText("Title");
        title.setFont(title.getFont().deriveFont(Font.BOLD, 24));
        f.add(title, BorderLayout.SOUTH);
        f.pack();
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }

    public static void main(String[] args) {
        EventQueue.invokeLater(new ShapeToolTip()::display);
    }
}