画图板的制作

 学会了使用按钮监听以及鼠标监听器之后，我们就可以制作一个属于自己的画图板了，以下是我之前制作的一个简易的画图板，功能方面尚还不足，不过已经可以完成铅笔，橡皮，画直线，圆等基本工作了，还可以完成颜色的自由选择，大家不放自己也动手做做吧。

首先是界面类：

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Graphics;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.ButtonGroup;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JColorChooser;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JRadioButton;

@SuppressWarnings("serial")
public class Draw extends JFrame{
	public Color color=Color.BLACK;//设置初始颜色
	private Color colorselector;
	private JButton colorselectorbu[]=new JButton[6];
	//创建对象时需要new一个对象，否则他的默认值就是NULL
	private JPanel colorjp=new JPanel();
	public static void main(String args[]){
		Draw dr=new Draw();
		dr.showframe();
	}
	public void showframe(){
		JPanel north=new JPanel();        //上方区域，存放颜色按钮以及颜色选择器
		JPanel west=new JPanel();		  //左边区域，存放图形按钮	
		JPanel center=new JPanel();		  //中间区域，存放画板
		JPanel south=new JPanel();		  //下面区域，用来显示当前鼠标所在前位置以及所画图形的大小
		//-----------------中间区域---------------
		center.setLayout(new FlowLayout(FlowLayout.LEFT));//将中间区域的布局设置为左对齐
		JPanel drawjp=new JPanel();
		drawjp.setBackground(Color.white);
		drawjp.setPreferredSize(new Dimension(600,500));
		center.add(drawjp);
		//-----------------上方区域----------------
		JButton colorchooserbu=new JButton("更多颜色");
		colorchooserbu.addActionListener(colorlistener);
		colorjp.setPreferredSize(new Dimension(120,60));
		colorjp.setLayout(new GridLayout(3,6,0,0));
		//创建一个颜色组
		Color color[]=new Color[]{Color.BLACK,Color.BLUE,Color.CYAN,Color.DARK_GRAY,Color.GRAY,Color.GREEN
				,Color.LIGHT_GRAY,Color.GREEN,Color.MAGENTA,Color.ORANGE,Color.PINK,Color.YELLOW};		
		Dimension d=new Dimension(20,20);
		for(int i=0;i<color.length;i++){
			JButton colorbu=new JButton();
			colorbu.setBackground(color[i]);
			colorbu.setPreferredSize(d);
			colorjp.add(colorbu);
			colorbu.addActionListener(listener);
		}
		//按钮选择器的自定义颜色组
		for(int j=0;j<colorselectorbu.length;j++){
			colorselectorbu[j]=new JButton();
			colorselectorbu[j].setPreferredSize(d);
			colorjp.add(colorselectorbu[j]);
			colorselectorbu[j].addActionListener(listener);
		}
		north.add(colorjp);
		north.add(colorchooserbu);
		//-----------------左边区域----------------
		String img[]=new String[]{"Line", "oval", "rect", "roundrect", "eraser", "fill",
				"pencil", "select"}; 
		String img1[]=new String[]{"Line1","oval1","rect1","roundrect1","eraser1","fill1",
				"pencil1","select1"};
		ButtonGroup bg=new ButtonGroup();
		for(int i=0;i<img.length;i++){
			//创建Icon组
			ImageIcon shapeicon=new ImageIcon("back/"+img[i]+".jpg");
			ImageIcon shapeicon1=new ImageIcon("back/"+img1[i]+".jpg");
			JRadioButton shapebu=new JRadioButton(shapeicon);
			bg.add(shapebu);
			shapebu.setPressedIcon(shapeicon1);
			//设置选中时的图案
			shapebu.setSelectedIcon(shapeicon1);
			shapebu.setActionCommand(img[i]);
			west.add(shapebu);
		}
		//---------------下方区域-------------
		JLabel la1=new JLabel();
		JLabel la2=new JLabel();
		JLabel la3=new JLabel("600x500像素");
		JLabel la4=new JLabel();
		south.add(la4);
		south.add(la1);
		south.add(la2);
		south.add(la3);
		south.setLayout(new GridLayout(1,4,20,20));
		north.setPreferredSize(new Dimension(200,80));
		west.setPreferredSize(new Dimension(80,200));
		south.setPreferredSize(new Dimension(200,20));
		north.setBackground(Color.GRAY);
		west.setBackground(Color.DARK_GRAY);
		center.setBackground(Color.LIGHT_GRAY);
		south.setBackground(Color.WHITE);
		this.setLayout(new BorderLayout());
		this.add(north,BorderLayout.NORTH);
		this.add(west,BorderLayout.WEST);
		this.add(south,BorderLayout.SOUTH);
		this.add(center,BorderLayout.CENTER);
		this.setTitle("画图板复习");
		this.setSize(900,700);
		this.setLocationRelativeTo(null);
		this.setDefaultCloseOperation(3);
		this.setVisible(true);
		//在画板上获取画布权限
		Graphics g=drawjp.getGraphics();
		DrawListener listener=new DrawListener(g,bg,this,la1,la2);
		drawjp.addMouseListener(listener);
		drawjp.addMouseMotionListener(listener);
	}
	//添加按钮监听，获取按钮的背景颜色
	ActionListener listener=new ActionListener(){
		public void actionPerformed(ActionEvent e) {
			//获取事件源，发生事件的对象
			Object obj=e.getSource();
			if(obj instanceof JButton){
				color=((JButton) obj).getBackground();
			}
		}
	};
	ActionListener colorlistener=new ActionListener(){
		//按钮数组累加器
		int i = 0;
		public void actionPerformed(ActionEvent e){
				colorselector=JColorChooser.showDialog(null, "颜色选择器", Color.BLACK);
				colorselectorbu[i].setBackground(colorselector);
				i++;
				if(i>=6){
					//超出六个按钮,返回0
					i=0;
				}
		}
	};
}

 下面是监听类：

 

 

import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.util.Random;

import javax.swing.ButtonGroup;
import javax.swing.ButtonModel;
import javax.swing.JLabel;

public class DrawListener extends MouseAdapter{
	private int x1,x2,y1,y2;
	private Graphics g;                   //将画布对象传过来
	private ButtonGroup bg;               //将按钮组传过来
	private Draw dr;
	private JLabel la1;
	private JLabel la2;
	public DrawListener(Graphics g,ButtonGroup bg,Draw dr,JLabel la1,JLabel la2){
		this.g=g;
		this.bg=bg;
		this.dr=dr;
		this.la1=la1;
		this.la2=la2;
	}
	//鼠标按下
	public void mousePressed(MouseEvent e){
		x1=e.getX();
		y1=e.getY();
		g.setColor(dr.color);
	}
	
	//鼠标释放
	public void mouseReleased(MouseEvent e){
		x2=e.getX();
		y2=e.getY();
		ButtonModel bm=bg.getSelection();
		String com=bm.getActionCommand();
			if(com.equals("Line")){
				g.drawLine(x1, y1, x2, y2);
				//改变la2中的数字
				la2.setText(Math.abs(x1-x2)+"x"+Math.abs(y1-y2));
			}
			else if(com.equals("oval")){
				g.drawOval(Math.min(x1, x2),Math.min(y1, y2),Math.abs(x1-x2),Math.abs(y1-y2));
				la2.setText(Math.abs(x1-x2)+"x"+Math.abs(y1-y2));
			}
			else if(com.equals("rect")){
				g.drawRect(Math.min(x1,x2), Math.min(y1,y2), Math.abs(x1-x2),Math.abs(y1-y2));
				la2.setText(Math.abs(x1-x2)+"x"+Math.abs(y1-y2));
			}
			else if(com.equals("roundrect")){
				g.drawRoundRect(Math.min(x1,x2), Math.min(y1,y2),Math.abs(x1-x2),Math.abs(y1-y2), Math.abs(x1-x2)/4,Math.abs(y1-y2)/4);
				la2.setText(Math.abs(x1-x2)+"x"+Math.abs(y1-y2));
			}
	}
	
	//
	public void mouseMoved(MouseEvent e){
		int X=e.getX();
		int Y=e.getY();
		la1.setText(X+","+Y);
	}
	
	public void mouseExited(MouseEvent e) {
		la1.setText("");
	}
	//鼠标拖动
	public void mouseDragged(MouseEvent e){
		int X=e.getX();
		int Y=e.getY();
		la1.setText(X+","+Y);
		x2=e.getX();
		y2=e.getY();
		String com=bg.getSelection().getActionCommand();
		if(com.equals("pencil")){
			g.drawLine(x1, y1, x2, y2);
			x1=x2;
			y1=y2;
		}
		else if(com.equals("eraser")){
			g.setColor(Color.WHITE);
			for(int i=-8;i<8;i++){
				g.drawLine(x1+i,y1+i,x2+i,y2+i);
			}
			x1=x2;
			y1=y2;
		}
		else if(com.equals("select")){
			g.drawLine(x1,y1,x2,y2);
		}
		else if(com.equals("fill")){
			Random ran=new Random();
			int a=ran.nextInt(16)-8;
			g.drawLine(x1+a, y1+a, x2+a, y2+a);
			x1=x2;
			y1=y2;
		}
	}
}

 

使用到的图片是从WINDOWS中的画图板中截图下来的，附件中已提供给大家，自己也动手试试吧