Java - 保存草图

Question

我创建了一个让人在画布上绘制或涂鸦的程序，例如Microsoft Paint。您也可以选择不同的颜色。当您最小化草图时，它将保留所有内容，并在您最大化草图时，草图在您离开草图时显示。我希望能够保存草图并打开草图。我将如何能够做到这一点？

SketchPad.java

package drs; 

import java.awt.BorderLayout; 
import javax.swing.JFrame; 

/** 
* 
* @author Sameer Anand 
* 
*/ 

public class SketchPad extends JFrame { 

    public static void main(String[] args) { 

     SketchPad sp = new SketchPad("My Sketch Pad"); 

     sp.setVisible(true); 

    } 

    public SketchPad(String title) { 

     super(title); 

     this.setLayout(new BorderLayout()); 

     Canvas c = new Canvas(); 

     this.add(c,BorderLayout.CENTER); 

     ButtonPanel bp = new ButtonPanel(c); 

     this.add(bp,BorderLayout.NORTH); 

     this.setSize(400,400); 

    } 

} 

Doodle.java

package drs; 

import java.awt.Color; 
import java.awt.Point; 
import java.util.ArrayList; 


/** 
* 
* @author Sameer Anand 
* 
*/ 

class Doodle { 

    private ArrayList<Point> points = new ArrayList<Point>(); 

    private Color theColor; 

    public Doodle(Color color) { 

     theColor = color; 

    } 

    public ArrayList<Point> getPoints() { 

     return points; 

    } 

    public Color getColor() { 

     return theColor; 

    } 

    public void add(Point p) { 

     points.add(p); 

    } 

} 

Canvas.java

package drs; 

import java.awt.Color; 
import java.awt.Graphics; 
import java.awt.Point; 
import java.awt.event.MouseEvent; 
import java.awt.event.MouseListener; 
import java.awt.event.MouseMotionListener; 
import java.util.ArrayList; 
import javax.swing.JPanel; 

/** 
* 
* @author Sameer Anand 
* 
*/ 

class Canvas extends JPanel implements MouseListener, MouseMotionListener { 

    // a canvas has-a current location 

    private int currentX, currentY; 
    private Doodle currentDoodle; 
    private Color currentColor = Color.BLACK; 

    // a canvas has-a bunch of doodles 

    private ArrayList<Doodle> doodles = new ArrayList<Doodle>(); 

    public Canvas() { 

     this.addMouseListener(this); 

     //this.addMouseMotionListener(this); 

    } 

    @Override 
    public void paint(Graphics g) { 

     System.out.println("Painting"); 

     for (Doodle d : doodles) { 

      ArrayList<Point> pts = d.getPoints(); 

      // remember "old" color and use the "current" color instead 

      Color old = g.getColor(); 

      g.setColor(d.getColor()); 


      for (int i = 0; i < pts.size()-1; i++) { 

       g.drawLine((int)pts.get(i).getX(),(int)pts.get(i).getY(), 
        (int)pts.get(i+1).getX(),(int)pts.get(i+1).getY()); 

      } 

      // reset the color 

      g.setColor(old); 

     } 

    } 

    public void setCurrentColor(Color c) { 

     currentColor = c; 

    } 

    @Override 
    public void mouseClicked(MouseEvent e) { 

     System.out.println("Clicked " + e); 

    } 

    @Override 
    public void mousePressed(MouseEvent e) { 

     this.addMouseMotionListener(this); 

     currentX = e.getX(); 

     currentY = e.getY(); 

     Doodle d = new Doodle(currentColor); 

     currentDoodle = d; 

     doodles.add(d); 

     d.add(new Point(currentX,currentY)); 

    } 

    @Override 
    public void mouseReleased(MouseEvent e) { 

     System.out.println("Released " + e); 

     this.removeMouseMotionListener(this); 

    } 

    @Override 
    public void mouseEntered(MouseEvent e) { 

     System.out.println("Entered " + e); 

    } 

    @Override 
    public void mouseExited(MouseEvent e) { 

     System.out.println("Exited " + e);; 

    } 

    @Override 
    public void mouseDragged(MouseEvent e) { 

     Graphics g = this.getGraphics(); 

     Color old = g.getColor(); 

     g.setColor(currentColor); 

     g.drawLine(currentX, currentY, e.getX(), e.getY()); 

     currentX = e.getX(); 

     currentY = e.getY(); 

     Point p = new Point(currentX, currentY); 

     currentDoodle.add(p); 

     g.setColor(old); 

    } 

    @Override 
    public void mouseMoved(MouseEvent e) { 

     System.out.println("Moved " + e);  

    } 

} 

ButtonPanel.java

package drs; 

import java.awt.Color; 
import java.awt.FlowLayout; 
import java.awt.event.ActionEvent; 
import java.awt.event.ActionListener; 
import javax.swing.JButton; 
import javax.swing.JPanel; 

/** 
* 
* @author Sameer Anand 
* 
*/ 

public class ButtonPanel extends JPanel implements ActionListener { 

    private Canvas canvas; 

    public ButtonPanel(Canvas canvas) { 

     this.canvas = canvas; 

     this.setLayout(new FlowLayout()); 

     Color[] colors = {Color.BLACK, Color.RED, Color.GREEN, Color.BLUE }; 

     String[] names = {"Black", "Red", "Green","Blue"}; 

     for (int i = 0; i < colors.length; i++) { 

      Color c = colors[i]; 

      String n = names[i]; 

      JButton jb = new JButton(n); 

      jb.setForeground(c); 

      jb.addActionListener(this); 

      add(jb); 

     } 

    } 

    @Override 
    public void actionPerformed(ActionEvent e) { 

     JButton j = (JButton) e.getSource(); 

     canvas.setCurrentColor(j.getForeground()); 

    } 

} 

Answer 1

如果你想保存到磁盘，有很多方法。最简单的是保存每个像素坐标和颜色的矩阵。你还可以连载Doodle类。一旦保存，您可以阅读并重新创建草图。

Answer 2

你会做涂鸦实现Serializable，那么你可以简单的涂鸦保存为XML这样的：

XMLEncoder enc = null; 
    String fileName = ...; 
    try 
    { 
     enc = new XMLEncoder(new FileOutputStream(new File(fileName))); 
     enc.writeObject(doodle); 
    } 
    catch (IOException e) 
    { 
     ... 
    } 
    finally 
    { 
     if (enc != null) 
      enc.close(); 
    } 

和负载：

 XMLDecoder d = null; 
     try 
     { 
      d = new XMLDecoder(new FileInputStream(new File(...))); 
      return (Doodle)d.readObject(); 
     } 
     finally 
     { 
      if (d != null) 
       d.close(); 
     }