如何在Java中绘制图像？ [英] How to draw on top of an image in Java?

问题描述

我使用JFrame导入并显示图像，并使用mousemotionlistener来检测鼠标点击，我希望能够在图像上绘制。我想能够，如果用户点击，使该像素成为某种颜色，同时保留图像的其余部分，但是，我无法找到如何使用图形这样做而不删除图像的其余部分或者打开一个新窗口。

I used JFrame to import and display an image, and used mousemotionlistener to detect the mouse clicks, and I want to be able to draw on top of the image. I want to be able to, if the user makes a click, make that pixel a certain color while preserving the rest of the image, however, I couldn't find out how to use Graphics to do so without deleting the rest of the image or opening a new window.

public class Simple extends JFrame{
  static ImageIcon icon;
  static JFrame myframe;
  static JLabel mylabel;
  static BufferedImage image = null;
  public static void main(String[] args) {
    try{
      image = ImageIO.read(new File("mypic.png"));
    }
    catch (IOException e) {
      e.printStackTrace();
    }
    icon=new ImageIcon(image);
    myframe=new JFrame();
    myframe.setSize(200,200);
    myframe.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    mylabel=new JLabel();
    mylabel.setIcon(icon);
    myframe.getContentPane().add(mylabel);
    myframe.pack();
    Container container = myframe.getContentPane();
    MouseMotionEvents3 mousemotion = new MouseMotionEvents3();
    container.add(mousemotion);
    myframe.setVisible(true);
    while(1 == 1) {
      if(mousemotion.signal == true) {
        System.out.println("second message");
        mousemotion.signal = false;      
      }
    }
  }
}
  class MouseMotionEvents3 extends JPanel implements MouseListener,
    MouseMotionListener {
    public boolean signal;
    public MouseMotionEvents3() {
      addMouseListener(this);
      addMouseMotionListener(this);
      signal = false;
    }
    public void mouseClicked(MouseEvent me) {
     // System.out.println("i hate you");
    }

    public void mouseEntered(MouseEvent me) {
    }

    public void mouseExited(MouseEvent me) {
    }

    public void mousePressed(MouseEvent me) {
      signal = true;
      System.out.println("message");
    }

    public void mouseReleased(MouseEvent me) {
    }

    public void mouseDragged(MouseEvent me) {
    }

    public void mouseMoved(MouseEvent me) {
    }
  }

推荐答案

我强烈建议您先阅读执行自定义绘画和 2D图形追踪 ，它们将为您提供一个起点。

I would highly recommend that you start by having a read through Performing Custom Painting and the 2D Graphics Trail, they will provide you with a starting point.

您可以通过多种方式实现此目的，此示例只是跟踪点击点并在点上方绘制点图像顶部

There are a number of ways you might achieve this, this example simply keeps track of the click points and draws dots over the top of the image

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

public class Test {

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

    public Test() {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                JFrame frame = new JFrame();
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        private List<Point> points;
        private BufferedImage image;

        public TestPane() {
            points = new ArrayList<>(25);
            try {
                image = ImageIO.read(new File("/Users/shanewhitehead/Desktop/Screen Shot 2017-03-09 at 1.55.18 pm.png"));
            } catch (IOException ex) {
                ex.printStackTrace();
            }

            addMouseListener(new MouseAdapter() {
                @Override
                public void mouseClicked(MouseEvent e) {
                    points.add(e.getPoint());
                    repaint();
                }                
            });
        }

        @Override
        public Dimension getPreferredSize() {
            return image == null ? new Dimension(200, 200) : new Dimension(image.getWidth(), image.getHeight());
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            Graphics2D g2d = (Graphics2D) g.create();
            if (image != null) {
                g2d.drawImage(image, 0, 0, this);
            }
            g2d.setColor(Color.RED);
            for (Point p : points) {
                g2d.fillOval(p.x - 4, p.y - 4, 8, 8);
            }
            g2d.dispose();
        }

    }

}

此示例直接将点绘制到图像本身...

This example draws the dots directly to the image itself...

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

public class Test {

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

    public Test() {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                JFrame frame = new JFrame();
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        private BufferedImage image;

        public TestPane() {
            try {
                image = ImageIO.read(new File("/Users/shanewhitehead/Desktop/Screen Shot 2017-03-09 at 1.55.18 pm.png"));
            } catch (IOException ex) {
                ex.printStackTrace();
            }

            addMouseListener(new MouseAdapter() {
                @Override
                public void mouseClicked(MouseEvent e) {
                    if (image != null) {
                        Point p = e.getPoint();
                        Graphics2D g2d = image.createGraphics();
                        g2d.setColor(Color.RED);
                        g2d.fillOval(p.x - 4, p.y - 4, 8, 8);
                        g2d.dispose();
                        repaint();
                    }
                }
            });
        }

        @Override
        public Dimension getPreferredSize() {
            return image == null ? new Dimension(200, 200) : new Dimension(image.getWidth(), image.getHeight());
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            Graphics2D g2d = (Graphics2D) g.create();
            g2d.drawImage(image, 0, 0, this);
            g2d.dispose();
        }

    }

}

在这两种情况下，他们只是使用 Graphics2D API

In both cases, they simply make use of the Graphics2D API

这篇关于如何在Java中绘制图像？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！