如何在Java中绘制线条

java coordinates coordinate-systems

2022-09-01 20:06:22

我想知道Java中是否有一个函数可以从坐标（x1，x2）到（y1，y2）绘制一条线？

我想要的是做这样的事情：

drawLine(x1, x2, x3, x4);

我希望能够在代码中随时执行此操作，使几行同时出现。

我试图这样做：

public void paint(Graphics g){
   g.drawLine(0, 0, 100, 100);
}

但是这让我无法控制何时使用该函数，并且我不知道如何多次调用它。

希望你明白我的意思！

附言：我想创建一个包含许多坐标的坐标系。

答案 1

用于绘制线条的摆动组件的一个非常简单的示例。它在内部保留一个列表，其中包含已使用方法 addLine 添加的行。每次添加新行时，都会调用重绘以通知图形子系统需要新绘制。

该类还包括一些用法示例。

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.LinkedList;

import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class LinesComponent extends JComponent{

private static class Line{
    final int x1; 
    final int y1;
    final int x2;
    final int y2;   
    final Color color;

    public Line(int x1, int y1, int x2, int y2, Color color) {
        this.x1 = x1;
        this.y1 = y1;
        this.x2 = x2;
        this.y2 = y2;
        this.color = color;
    }               
}

private final LinkedList<Line> lines = new LinkedList<Line>();

public void addLine(int x1, int x2, int x3, int x4) {
    addLine(x1, x2, x3, x4, Color.black);
}

public void addLine(int x1, int x2, int x3, int x4, Color color) {
    lines.add(new Line(x1,x2,x3,x4, color));        
    repaint();
}

public void clearLines() {
    lines.clear();
    repaint();
}

@Override
protected void paintComponent(Graphics g) {
    super.paintComponent(g);
    for (Line line : lines) {
        g.setColor(line.color);
        g.drawLine(line.x1, line.y1, line.x2, line.y2);
    }
}

public static void main(String[] args) {
    JFrame testFrame = new JFrame();
    testFrame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
    final LinesComponent comp = new LinesComponent();
    comp.setPreferredSize(new Dimension(320, 200));
    testFrame.getContentPane().add(comp, BorderLayout.CENTER);
    JPanel buttonsPanel = new JPanel();
    JButton newLineButton = new JButton("New Line");
    JButton clearButton = new JButton("Clear");
    buttonsPanel.add(newLineButton);
    buttonsPanel.add(clearButton);
    testFrame.getContentPane().add(buttonsPanel, BorderLayout.SOUTH);
    newLineButton.addActionListener(new ActionListener() {

        @Override
        public void actionPerformed(ActionEvent e) {
            int x1 = (int) (Math.random()*320);
            int x2 = (int) (Math.random()*320);
            int y1 = (int) (Math.random()*200);
            int y2 = (int) (Math.random()*200);
            Color randomColor = new Color((float)Math.random(), (float)Math.random(), (float)Math.random());
            comp.addLine(x1, y1, x2, y2, randomColor);
        }
    });
    clearButton.addActionListener(new ActionListener() {

        @Override
        public void actionPerformed(ActionEvent e) {
            comp.clearLines();
        }
    });
    testFrame.pack();
    testFrame.setVisible(true);
}

}

答案 2

将行存储在某种类型的列表中。当需要绘制它们时，请迭代列表并绘制每个列表。喜欢这个：

截图

enter image description here

DrawLines

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.geom.Line2D;

import javax.swing.JOptionPane;
import javax.swing.JComponent;
import javax.swing.SwingUtilities;

import java.util.ArrayList;
import java.util.Random;

class DrawLines {

    public static void main(String[] args) {

        Runnable r = new Runnable() {
            public void run() {
                LineComponent lineComponent = new LineComponent(400,400);
                for (int ii=0; ii<30; ii++) {
                    lineComponent.addLine();
                }
                JOptionPane.showMessageDialog(null, lineComponent);
            }
        };
        SwingUtilities.invokeLater(r);
    }
}

class LineComponent extends JComponent {

    ArrayList<Line2D.Double> lines;
    Random random;

    LineComponent(int width, int height) {
        super();
        setPreferredSize(new Dimension(width,height));
        lines = new ArrayList<Line2D.Double>();
        random = new Random();
    }

    public void addLine() {
        int width = (int)getPreferredSize().getWidth();
        int height = (int)getPreferredSize().getHeight();
        Line2D.Double line = new Line2D.Double(
            random.nextInt(width),
            random.nextInt(height),
            random.nextInt(width),
            random.nextInt(height)
            );
        lines.add(line);
        repaint();
    }

    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        g.setColor(Color.white);
        g.fillRect(0, 0, getWidth(), getHeight());
        Dimension d = getPreferredSize();
        g.setColor(Color.black);
        for (Line2D.Double line : lines) {
            g.drawLine(
                (int)line.getX1(),
                (int)line.getY1(),
                (int)line.getX2(),
                (int)line.getY2()
                );
        }
    }
}