在Java中单击按钮在JPanel中绘制一条线 [英] Draw a line in a JPanel with button click in Java

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本文介绍了在Java中单击按钮在JPanel中绘制一条线的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

我想在JPanel中画一条线。
这是我的图形用户界面，我希望在JPanel中有一行是白色的。




我找到很多例子，但问题在于如何使用它。



在许多示例中，他们总是绘制一个从JPanel扩展的JFrame。



我想将面板添加到框架并添加一些按钮可以在多个方向上绘制线条，并使用中心的X按钮清理JPanel。



这是界面的代码：

  import java.awt.BorderLayout; 
 import java.awt.EventQueue; 
 
 import javax.swing.JFrame; 
 import javax.swing.JPanel; 
 import javax.swing.border.EmptyBorder; 
 import java.awt.Color; 
 import javax.swing.JScrollPane; 
 import javax.swing.JLabel; 
 import javax.swing.ImageIcon; 
 import java.awt.event.MouseAdapter; 
 import java.awt.event.MouseEvent; 
 
 
公共类电路扩展JFrame {
 
私有JPanel contentPane; 
 
 / ** 
 *启动应用程序。 
 * / 
 public static void main（String [] args）{
 EventQueue.invokeLater（new Runnable（）{
 public void run（）{
 try { 
 circuit frame = new circuit（）; 
 frame.setVisible（true）; 
} catch（Exception e）{
 e.printStackTrace（）; 
} 
} 
}）; 
} 
 
 / ** 
 *创建框架。 
 * / 
 public circuit（）{
 setDefaultCloseOperation（JFrame.EXIT_ON_CLOSE）; 
 setBounds（100，100，559，332）; 
 contentPane = new JPanel（）; 
 contentPane.setBorder（new EmptyBorder（5，5，5））; 
 setContentPane（contentPane）; 
 contentPane.setLayout（null）; 
 
 JScrollPane scrollPane = new JScrollPane（）; 
 scrollPane.setBounds（10，21，359，255）; 
 contentPane.add（scrollPane）; 
 
 JPanel面板=新JPanel（）; 
 scrollPane.setViewportView（panel）; 
 panel.setBackground（Color.WHITE）; 
 
 JLabel标签=新的JLabel（新标签）; 
 label.addMouseListener（new MouseAdapter（）{
 @Override 
 public void mouseClicked（MouseEvent arg0）{
 
 
 /////// ////// 
 
 
 
}）; 
 label.setIcon（new ImageIcon（C：\\ Users \\\\\\\\\\\\\\\\\\\\\\\\\'.png））; 
 label.setBounds（447，66，46，48）; 
 contentPane.add（label）; 
 
 JLabel label_1 =新的JLabel（新标签）; 
 label_1.setIcon（new ImageIcon（C：\\ Users \\\\\\\\\\\\\\\\\\\\\\\\\\））; 
 label_1.setBounds（447，159，46，48）; 
 contentPane.add（label_1）; 
 
 JLabel label_2 = new JLabel（New label）; 
 label_2.setIcon（new ImageIcon（C：\\ Users \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\'））; 
 label_2.setBounds（495,112,46,48）; 
 contentPane.add（label_2）; 
 
 JLabel label_3 =新的JLabel（新标签）; 
 label_3.setIcon（new ImageIcon（C：\\ Users \\\\\\\\\\\\\\\\\\\\\\'））; 
 label_3.setBounds（398,112,46,48）; 
 contentPane.add（label_3）; 
 
 JLabel label_4 =新的JLabel（新标签）; 
 label_4.setIcon（新的ImageIcon（C：\\ Users \\ 
 label_4.setBounds（447,112,46,48）; 
 contentPane.add（label_4）;

这是画线的代码

  public void paint（Graphics graphics）
 {
 graphics.drawLine（10，20，300，310）; 
}

那么如何使用这行......



预先致谢。



祝好，

阿里

解决方案

使用以下方法绘制线条可能更容易：


  1. 点击以标记第一个终结点

  2. 拖动以显示正在进行的行

  3. 发布以标记第二个终结点
    4. >

此相关示例可能会提供一些额外的指导。



附录




  1. 下面的例子实现了上面的概要。

  2. 我已更新示例以显示如何使用一组按钮来影响绘图。这也是相关的 examp le ，它使用带有键绑定的 Action 接口。 我已更新此示例以使用 关键绑定 。



LinePanel.java 



  import java.awt.BasicStroke ; 
 import java.awt.BorderLayout; 
 import java.awt.Color; 
 import java.awt.Dimension; 
 import java.awt.EventQueue; 
 import java.awt.Graphics; 
 import java.awt.Graphics2D; 
 import java.awt.Point; 
 import java.awt.RenderingHints; 
 import java.awt.event.ActionEvent; 
 import java.awt.event.KeyEvent; 
 import java.awt.event.MouseAdapter; 
 import java.awt.event.MouseEvent; 
 import javax.swing.AbstractAction; 
 import javax.swing.JButton; 
 import javax.swing.JFrame; 
 import javax.swing.JPanel; 
 import javax.swing.KeyStroke; 
 
 / ** 
 * @see https://stackoverflow.com/questions/6991648 
 * @see https://stackoverflow.com/questions/6887296 
 * @see https://stackoverflow.com/questions/5797965 
 * / 
 public class LinePanel扩展JPanel {
 
私人MouseHandler mouseHandler = new MouseHandler（）; 
私人点p1 =新点（100，100）; 
私人点p2 =新点（540,380）; 
私有布尔图; 
 
 public LinePanel（）{
 this.setPreferredSize（new Dimension（640，480））; 
 this.addMouseListener（mouseHandler）; 
 this.addMouseMotionListener（mouseHandler）; 
 
 
 @Override 
 protected void paintComponent（Graphics g）{
 super.paintComponent（g）; 
 Graphics2D g2d =（Graphics2D）g; 
 g2d.setColor（Color.blue）; 
 g2d.setRenderingHint（
 RenderingHints.KEY_ANTIALIASING，
 RenderingHints.VALUE_ANTIALIAS_ON）; 
 g2d.setStroke（new BasicStroke（8，
 BasicStroke.CAP_ROUND，BasicStroke.JOIN_BEVEL））; 
 g.drawLine（p1.x，p1.y，p2.x，p2.y）; 
} 
 
 private class MouseHandler extends MouseAdapter {
 
 @Override 
 public void mousePressed（MouseEvent e）{
 drawing = true; 
 p1 = e.getPoint（）; 
 p2 = p1; 
 repaint（）; 
} 
 
 @Override 
 public void mouseReleased（MouseEvent e）{
 drawing = false; 
 p2 = e.getPoint（）; 
 repaint（）; 
} 
 
 @Override 
 public void mouseDragged（MouseEvent e）{
 if（drawing）{
 p2 = e.getPoint（）; 
 repaint（）; 
 
 
 
 
私有类ControlPanel继承JPanel {
 
 private static final int DELTA = 10; 
 
 public ControlPanel（）{
 this.add（new MoveButton（\\\←，KeyEvent.VK_LEFT，-DELTA，0））; 
 this.add（new MoveButton（\\\↑，KeyEvent.VK_UP，0，-DELTA））; 
 this.add（new MoveButton（\\\→，KeyEvent.VK_RIGHT，DELTA，0））; 
 this.add（new MoveButton（\\\↓，KeyEvent.VK_DOWN，0，DELTA））; 
} 
 
私人类MoveButton扩展了JButton {
 
 KeyStroke k; 
 int dx，dy; 
 
 public MoveButton（String name，int code，
 final int dx，final int dy）{
 super（name）; 
 this.k = KeyStroke.getKeyStroke（code，0）; 
 this.dx = dx; 
 this.dy = dy; 
 this.setAction（new AbstractAction（this.getText（））{
 
 @Override 
 public void actionPerformed（ActionEvent e）{
 LinePanel.this.p1。 translate（dx，dy）; 
 LinePanel.this.p2.translate（dx，dy）; 
 LinePanel.this.repaint（）; 
} 
}）; 
 ControlPanel.this.getInputMap（WHEN_IN_FOCUSED_WINDOW）
 .put（k，k.toString（））; 
 ControlPanel.this.getActionMap（）
 .put（k.toString（），new AbstractAction（）{
 
 @Override 
 public void actionPerformed（ActionEvent e） {
 MoveButton.this.doClick（）; 
} 
}）; 
 
 
 
 $ b private void display（）{
 JFrame f = new JFrame（LinePanel）; 
 f.setDefaultCloseOperation（JFrame.EXIT_ON_CLOSE）; 
 f.add（this）; 
 f.add（新的ControlPanel（），BorderLayout.SOUTH）; 
 f.pack（）; 
 f.setLocationRelativeTo（null）; 
 f.setVisible（true）; 
 
 
 public static void main（String [] args）{
 EventQueue.invokeLater（new Runnable（）{
 $ b $ @Override 
 public void run（）{
 new LinePanel（）。display（）; 
} 
}）; 
} 
}


I want to draw a line in a JPanel. This is my GUI and I want a line in the JPanel in white.

I find many examples but the problem is the how to use it.

In many exmples, always they draw in a JFrame that extends from a JPanel.

I want to add the Panel to the Frame and add some buttons to draw lines in many directions and use the X button in center to clean the JPanel.

This is the code of the interface:

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

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import java.awt.Color;
import javax.swing.JScrollPane;
import javax.swing.JLabel;
import javax.swing.ImageIcon;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;


public class circuit extends JFrame {

 private JPanel contentPane;

 /**
  * Launch the application.
  */
 public static void main(String[] args) {
  EventQueue.invokeLater(new Runnable() {
   public void run() {
    try {
     circuit frame = new circuit();
     frame.setVisible(true);
    } catch (Exception e) {
     e.printStackTrace();
    }
   }
  });
 }

 /**
  * Create the frame.
  */
 public circuit() {
  setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  setBounds(100, 100, 559, 332);
  contentPane = new JPanel();
  contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
  setContentPane(contentPane);
  contentPane.setLayout(null);

  JScrollPane scrollPane = new JScrollPane();
  scrollPane.setBounds(10, 21, 359, 255);
  contentPane.add(scrollPane);

  JPanel panel = new JPanel();
  scrollPane.setViewportView(panel);
  panel.setBackground(Color.WHITE);

  JLabel label = new JLabel("New label");
  label.addMouseListener(new MouseAdapter() {
   @Override
   public void mouseClicked(MouseEvent arg0) {


    /////////////


   }
  });
  label.setIcon(new ImageIcon("C:\\Users\\achermen\\Desktop\\up.png"));
  label.setBounds(447, 66, 46, 48);
  contentPane.add(label);

  JLabel label_1 = new JLabel("New label");
  label_1.setIcon(new ImageIcon("C:\\Users\\achermen\\Desktop\\down.png"));
  label_1.setBounds(447, 159, 46, 48);
  contentPane.add(label_1);

  JLabel label_2 = new JLabel("New label");
  label_2.setIcon(new ImageIcon("C:\\Users\\achermen\\Desktop\\right.png"));
  label_2.setBounds(495, 112, 46, 48);
  contentPane.add(label_2);

  JLabel label_3 = new JLabel("New label");
  label_3.setIcon(new ImageIcon("C:\\Users\\achermen\\Desktop\\left.png"));
  label_3.setBounds(398, 112, 46, 48);
  contentPane.add(label_3);

  JLabel label_4 = new JLabel("New label");
  label_4.setIcon(new ImageIcon("C:\\Users\\achermen\\Desktop\\1303860240_list-remove.png"));
  label_4.setBounds(447, 112, 46, 48);
  contentPane.add(label_4);
 }
}

This is the code to draw a line

public void paint(Graphics graphics)
{
    graphics.drawLine(10, 20, 300, 310);
}

So how to use this lines ....

Thanks in advance.

Best regards,

Ali

解决方案

It may be easier to draw lines using the following approach:

  1. click to mark the first endpoint
  2. drag to show the line in progress
  3. release to mark the second endpoint

This related example may offer some additional guidance.

Addendum

  1. The example below implements the outline above.
  2. I've update the example to show how to use a panel of buttons to affect the drawing.
  3. See also this related example that uses the Action interface with key bindings.
  4. I've updated this example to use Key Bindings.

LinePanel.java

import java.awt.BasicStroke;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.RenderingHints;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.AbstractAction;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.KeyStroke;

/**
 * @see https://stackoverflow.com/questions/6991648
 * @see https://stackoverflow.com/questions/6887296
 * @see https://stackoverflow.com/questions/5797965
 */
public class LinePanel extends JPanel {

    private MouseHandler mouseHandler = new MouseHandler();
    private Point p1 = new Point(100, 100);
    private Point p2 = new Point(540, 380);
    private boolean drawing;

    public LinePanel() {
        this.setPreferredSize(new Dimension(640, 480));
        this.addMouseListener(mouseHandler);
        this.addMouseMotionListener(mouseHandler);
    }

    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        Graphics2D g2d = (Graphics2D) g;
        g2d.setColor(Color.blue);
        g2d.setRenderingHint(
            RenderingHints.KEY_ANTIALIASING,
            RenderingHints.VALUE_ANTIALIAS_ON);
        g2d.setStroke(new BasicStroke(8,
            BasicStroke.CAP_ROUND, BasicStroke.JOIN_BEVEL));
        g.drawLine(p1.x, p1.y, p2.x, p2.y);
    }

    private class MouseHandler extends MouseAdapter {

        @Override
        public void mousePressed(MouseEvent e) {
            drawing = true;
            p1 = e.getPoint();
            p2 = p1;
            repaint();
        }

        @Override
        public void mouseReleased(MouseEvent e) {
            drawing = false;
            p2 = e.getPoint();
            repaint();
        }

        @Override
        public void mouseDragged(MouseEvent e) {
            if (drawing) {
                p2 = e.getPoint();
                repaint();
            }
        }
    }

    private class ControlPanel extends JPanel {

        private static final int DELTA = 10;

        public ControlPanel() {
            this.add(new MoveButton("\u2190", KeyEvent.VK_LEFT, -DELTA, 0));
            this.add(new MoveButton("\u2191", KeyEvent.VK_UP, 0, -DELTA));
            this.add(new MoveButton("\u2192", KeyEvent.VK_RIGHT, DELTA, 0));
            this.add(new MoveButton("\u2193", KeyEvent.VK_DOWN, 0, DELTA));
        }

        private class MoveButton extends JButton {

            KeyStroke k;
            int dx, dy;

            public MoveButton(String name, int code,
                    final int dx, final int dy) {
                super(name);
                this.k = KeyStroke.getKeyStroke(code, 0);
                this.dx = dx;
                this.dy = dy;
                this.setAction(new AbstractAction(this.getText()) {

                    @Override
                    public void actionPerformed(ActionEvent e) {
                        LinePanel.this.p1.translate(dx, dy);
                        LinePanel.this.p2.translate(dx, dy);
                        LinePanel.this.repaint();
                    }
                });
                ControlPanel.this.getInputMap(WHEN_IN_FOCUSED_WINDOW)
                    .put(k, k.toString());
                ControlPanel.this.getActionMap()
                    .put(k.toString(), new AbstractAction() {

                    @Override
                    public void actionPerformed(ActionEvent e) {
                        MoveButton.this.doClick();
                    }
                });
            }
        }
    }

    private void display() {
        JFrame f = new JFrame("LinePanel");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.add(this);
        f.add(new ControlPanel(), BorderLayout.SOUTH);
        f.pack();
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }

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

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

这篇关于在Java中单击按钮在JPanel中绘制一条线的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！

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