一起来画画

知识点：

JFrame窗体类关键属性、方法和事件的应用
Canvas画板类的关键方法和事件的应用
窗体菜单栏的创建和层级关系
工具栏、按钮的配合使用
鼠标点击、移动事件的使用
AWT绘图方法的使用

Swing组件：

JFrame窗体类
JWindow无边框窗体类
JButton窗体类
JToggleButton按钮类
JMenuBar菜单栏类
JMenu菜单类
JMenuItem菜单项类

Swing事件监听：

鼠标点击
鼠标拖曳

Java技术：

Graphics2D绘图类
Java继承
主类、主方法概念
File文件类
Image图片类
Ellipse2D圆形图形类
Rectangle2D方形图形类

1.创建项目和导入资源

在Package Explorer的Other Projects，右键-New-Other-Java Project-next-(输入项目名:一起来画画)Finish;

在项目名上，右键-New-Folder-(选择文件夹：一起来画画,在Folder name输入:lib)Finish;

将外部包DrawUtil.mr.jar复制到lib里，然后在项目名上，右键-Build Path-Configure Build Path-Libraries-Add JARs...-选中"一起来画画/lib/DrawUtil.mr.jar"-OK;

2.编码

  1 package com.mr.draw;
  2 
  3 import javax.swing.JFrame;
  4 
  5 import java.awt.Color;
  6 import java.awt.Graphics;
  7 import java.awt.Graphics2D;
  8 import java.awt.image.BufferedImage;
  9 
 10 import java.awt.event.MouseAdapter;
 11 import java.awt.event.MouseEvent;
 12 import java.awt.event.MouseMotionAdapter;
 13 
 14 import java.awt.BorderLayout;
 15 import javax.swing.ButtonGroup;
 16 import javax.swing.JButton;//按钮类
 17 import javax.swing.JToggleButton;///画线类
 18 import javax.swing.JToolBar;//工具栏类
 19 
 20 import java.awt.BasicStroke;
 21 import java.awt.event.ActionEvent;
 22 import java.awt.event.ActionListener;//调整画笔粗细
 23 
 24 import javax.swing.JColorChooser;//实现添加颜色功能
 25 
 26 import java.awt.geom.Ellipse2D;
 27 import java.awt.geom.Rectangle2D;
 28 import com.mr.util.FrameGetShape;
 29 import com.mr.util.ShapeWindow;
 30 import com.mr.util.Shapes; ///实现绘制图形功能
 31 
 32 import com.mr.util.DrawImageUtil;//实现图片保存功能
 33 
 34 import javax.swing.JMenu;
 35 import javax.swing.JMenuBar;
 36 import javax.swing.JMenuItem;//实现 添加菜单栏
 37 
 38 import java.awt.AlphaComposite;
 39 import java.awt.Font;
 40 import javax.swing.JOptionPane;//实现添加水印，为自己作品署名
 41 
 42 import java.awt.Image;
 43 import java.awt.Point;
 44 import java.awt.Toolkit;//工具箱
 45 import java.awt.Cursor;//光标，实现更改鼠标图标功能
 46 import javax.swing.ImageIcon;  
 47 
 48 //画图主窗体
 49 public class DrawPictureFrame extends JFrame implements FrameGetShape{//继承窗体类,实现绘制图形的接口
 50     //创建一个8位BGR颜色分量的图像
 51     BufferedImage image = new BufferedImage(570,390,BufferedImage.TYPE_3BYTE_BGR);
 52     Graphics gs = image.getGraphics();
 53     Graphics2D g = (Graphics2D)gs;
 54     DrawPictureCanvas canvas = new DrawPictureCanvas();        //创建画布对象
 55     Color foreColor = Color.red;                            //前景色
 56     Color backgroundColor = Color.green;                    //背景色
 57     
 58     int x=-1;
 59     int y=-1;//上一次鼠标绘制点的横纵坐标
 60     boolean rubber=false;//橡皮识别变量
 61     
 62     private JToolBar toolBar;//工具栏目
 63     private JButton eraserButton;
 64     private JToggleButton strokeButton1;
 65     private JToggleButton strokeButton2;
 66     private JToggleButton strokeButton3;//细中粗按钮
 67     private JButton backgroundButton;
 68     private JButton foregroundButton;
 69     private JButton clearButton;
 70     private JButton saveButton;
 71     private JButton shapeButton;//图形按钮
 72     boolean drawShape = false;
 73     Shapes shape;
 74     private JMenuItem strokeMenuItem1;
 75     private JMenuItem strokeMenuItem2;
 76     private JMenuItem strokeMenuItem3;
 77     private JMenuItem clearMenuItem;
 78     private JMenuItem foregroundMenuItem;
 79     private JMenuItem backgroundMenuItem;
 80     private JMenuItem eraserMenuItem;
 81     private JMenuItem exitMenuItem;//退出菜单
 82     private JMenuItem saveMenuItem;
 83     private JMenuItem shuiyinMenuItem;//水印菜单
 84     private String shuiyin = "";//水印字符内容
 85     private PictureWindow picWindow;//简笔画展示窗体
 86     private JButton showPicButton;//展开简笔画按钮
 87     
 88     
 89     public DrawPictureFrame() 
 90     {
 91         setResizable(false);                                 // 窗体大小不能改变
 92         //setTitle("画图程序");
 93         setTitle("画图程序(水印内容:[" + shuiyin + "] )" );
 94         setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);     // 窗体关闭则立即停止程序
 95         setBounds(500, 100, 574, 460);                         // 设置窗口的位置和宽高
 96         
 97         init();//组件初始化
 98         addListener();//添加组件监听
 99     }
100     
101     private void init()
102     {
103         g.setColor(backgroundColor);//用前景色设置绘图对象的颜色
104         g.fillRect(0, 0, 570, 390);//用背景色填充整个画布,第一个0和570表示位置从0开始到57
105         g.setColor(foreColor);//用前景色设置绘图对象的颜色
106         canvas.setImage(image);//设置画布的图像
107         getContentPane().add(canvas);//将画布添加到窗体容器默认布局中的中部位置
108         
109         toolBar = new JToolBar();//初始化工具栏
110         toolBar.setFloatable(false);//工具栏固定
111         getContentPane().add(toolBar,BorderLayout.NORTH);//将工具栏添加到窗体最北位置
112         
113         //showPicButton = new JButton("展开简笔画");
114         showPicButton = new JButton();
115         showPicButton.setToolTipText("展开简笔画");
116         showPicButton.setIcon( new ImageIcon("src/img/icon/展开.png") );//需要导入ImageIcon
117         toolBar.add(showPicButton);
118         
119         saveButton = new JButton("保存");
120         toolBar.add(saveButton);
121         toolBar.addSeparator();//添加工具栏
122         strokeButton1 = new JToggleButton("细线");
123         strokeButton1.setSelected(true);//细线按钮处于被选中状态
124         toolBar.add(strokeButton1);
125         
126         strokeButton2 = new JToggleButton("粗线");
127         toolBar.add(strokeButton2);
128         
129         strokeButton3 = new JToggleButton("较粗");
130         toolBar.add(strokeButton3);
131         toolBar.addSeparator();
132         ButtonGroup strokeGroup = new ButtonGroup();//画笔粗细按钮组，保证同时只有一个被选中
133         strokeGroup.add(strokeButton1);
134         strokeGroup.add(strokeButton2);
135         strokeGroup.add(strokeButton3);
136         
137         backgroundButton = new JButton("背景颜色");
138         toolBar.add(backgroundButton);
139         foregroundButton = new JButton("前景颜色");
140         toolBar.add(foregroundButton);
141         toolBar.addSeparator();
142         
143         shapeButton = new JButton("图形");
144         toolBar.add(shapeButton);
145         clearButton = new JButton("清除");
146         toolBar.add(clearButton);
147         eraserButton = new JButton("橡皮");
148         toolBar.add(eraserButton);
149         toolBar.addSeparator();
150         
151         JMenuBar menuBar = new JMenuBar();
152         setJMenuBar(menuBar);
153         
154         JMenu systemMenu = new JMenu("系统");
155         menuBar.add(systemMenu);
156         shuiyinMenuItem = new JMenuItem("设置水印");
157         systemMenu.add(shuiyinMenuItem);
158         saveMenuItem = new JMenuItem("保存");
159         systemMenu.add(saveMenuItem);
160         systemMenu.addSeparator();
161         exitMenuItem = new JMenuItem("退出");
162         systemMenu.add(exitMenuItem);
163         JMenu strokeMenu = new JMenu("线型");
164         menuBar.add(strokeMenu);
165         strokeMenuItem1 = new JMenuItem("细线");
166         strokeMenu.add(strokeMenuItem1);
167         strokeMenuItem2 = new JMenuItem("粗线");
168         strokeMenu.add(strokeMenuItem2);
169         strokeMenuItem3 = new JMenuItem("较线");
170         strokeMenu.add(strokeMenuItem3);
171         
172         JMenu colorMenu = new JMenu("颜色");
173         menuBar.add(colorMenu);
174         foregroundMenuItem = new JMenuItem("前景颜色");
175         colorMenu.add(foregroundMenuItem);
176         backgroundMenuItem = new JMenuItem("背景颜色");
177         colorMenu.add(backgroundMenuItem);
178         
179         JMenu editMenu = new JMenu("编辑");
180         menuBar.add(editMenu);
181         clearMenuItem = new JMenuItem("清除");
182         editMenu.add(clearMenuItem);
183         eraserMenuItem = new JMenuItem("橡皮");
184         editMenu.add(eraserMenuItem);
185         
186         picWindow = new PictureWindow(DrawPictureFrame.this);
187     }
188     
189     //动作监听
190     private void addListener()
191     {
192         canvas.addMouseMotionListener(new MouseMotionAdapter(){
193         
194             public void mouseDragged( final MouseEvent e )//鼠标拖曳监听
195             {
196                 if(x>0 && y>0)//如果x和y存在鼠标记录
197                 {
198                     if(rubber)//如果是橡皮则画出背景色，相当于擦掉前景色
199                     {
200                         g.setColor(backgroundColor);
201                         g.fillRect(x, y, 10, 10);
202                     }
203                     else //否则画出
204                         g.drawLine(x,y,e.getX(),e.getY());
205                 }
206                 x=e.getX();
207                 y=e.getY();//上一次鼠标绘制点的横纵坐标
208                 canvas.repaint();//更新画布
209             }
210             public void mouseMoved(final MouseEvent arg0) {
211                 if(rubber)//如果使用橡皮
212                 {
213                     Toolkit kit = Toolkit.getDefaultToolkit();//获得系统默认的组件工具包
214                     Image img = kit.createImage("src/img/icon/鼠标橡皮.png");//利用工具包获取图片
215                     Cursor c = kit.createCustomCursor(img,new Point(0,0),"clear");//参数为图片，光标热点和光标描述的字符串
216                     setCursor(c);//使用自定义光标
217                 }
218                 else 
219                     setCursor(Cursor.getPredefinedCursor(Cursor.CROSSHAIR_CURSOR));//不是橡皮则是画笔，则设置光标为十字形
220             }
221         });
222         canvas.addMouseListener(new MouseAdapter() {//鼠标点击监听
223             public void mouseReleased( final MouseEvent arg0 )//按键抬起时
224             {
225                 x=-1;
226                 y=-1;//将上一次鼠标绘制点的横纵坐标恢复成-1
227                 //改成x=11,y=11？？？
228             }
229             
230             public void mousePressed(MouseEvent e)//当按键按下时
231             {
232                 if( drawShape )//如果此时鼠标画的是
233                 {
234                     switch( shape.getType() )//判断图形种类
235                     {
236                         case Shapes.YUAN:
237                             int yuanX = e.getX()-shape.getWidth()/2;
238                             int yuanY = e.getY()-shape.getHeigth()/2;
239                             /*
240                             System.out.println(e.getX()+"  "+e.getY());
241                             System.out.println(shape.getWidth()/2+"  "+shape.getHeigth()/2);
242                             System.out.println(yuanX+"  "+yuanY);*/
243                             //创建圆形图形，根据长宽可能是椭圆，指定坐标和宽高
244                             Ellipse2D yuan = new Ellipse2D.Double(yuanX,yuanY,shape.getWidth(),shape.getHeigth());
245                             g.draw(yuan);
246                             break;
247                         case Shapes.FANG:
248                             int fangX=e.getX()-shape.getWidth()/2;
249                             int fangY=e.getY()-shape.getHeigth()/2;
250                             Rectangle2D fang = new Rectangle2D.Double(fangX,fangY,shape.getWidth(),shape.getHeigth());
251                             g.draw(fang);
252                             break;
253                     }
254                     canvas.repaint();
255                     drawShape = false;//画一个就不能画了
256                 }
257             }
258         });
259         
260         toolBar.addMouseMotionListener(new MouseMotionAdapter() {//工具栏添加鼠标移动监听
261             public void mouseMoved(final MouseEvent arg0) {//鼠标移动时，设置鼠标指针的形状为默认光标
262                 setCursor(Cursor.getPredefinedCursor(Cursor.DEFAULT_CURSOR));
263             }
264         });
265         
266         //调整画笔粗细
267         strokeButton1.addActionListener(new ActionListener() {//细线按钮添加监听
268             public void actionPerformed(final ActionEvent arg0)//单击时
269             {    //声明画笔的属性，粗细为1像素，线条末端无修饰，折线处呈尖角
270                 BasicStroke bs = new BasicStroke(1, BasicStroke.CAP_BUTT,BasicStroke.JOIN_MITER);
271                 g.setStroke(bs);//画图工具使用此笔
272             }
273         });
274         strokeButton2.addActionListener(new ActionListener() {//中线按钮添加监听
275             public void actionPerformed(final ActionEvent arg0)//单击时
276             {    //声明画笔的属性，中线为2像素，线条末端无修饰，折线处呈尖角
277                 BasicStroke bs = new BasicStroke(2,BasicStroke.CAP_BUTT,BasicStroke.JOIN_MITER);
278                 g.setStroke(bs);//画图工具使用此笔
279             }
280             
281         });
282         strokeButton3.addActionListener(new ActionListener() {//粗线按钮添加监听
283             public void actionPerformed(final ActionEvent arg0)//单击时
284             {    //声明画笔的属性，粗线为4像素，线条末端无修饰，折线处呈尖角
285                 BasicStroke bs = new BasicStroke(4,BasicStroke.CAP_BUTT,BasicStroke.JOIN_MITER);
286                 g.setStroke(bs);//画图工具使用此笔
287             }
288         });
289         
290         //实现颜色添加功能
291         backgroundButton.addActionListener( new ActionListener() {
292             public void actionPerformed( final ActionEvent arg0 )
293             {    //打开选择颜色对话框，参数依次是：符窗体、标题、默认选中的颜色（青色）
294                 Color bgColor = JColorChooser.showDialog(DrawPictureFrame.this, "选择颜色对话框", Color.CYAN);
295                 if ( bgColor !=null )///选中的颜色不是空的
296                     backgroundColor = bgColor;//则将选中的颜色赋给背景色
297                 backgroundButton.setBackground(backgroundColor);
298                 g.setColor(backgroundColor);
299                 g.fillRect(0, 0, 570, 390);//画一个背景颜色的方形填满整个画布
300                 g.setColor(foreColor);
301                 canvas.repaint();//更新画布
302             }
303         });
304         foregroundButton.addActionListener(new ActionListener() {
305             public void actionPerformed(final ActionEvent arg0)
306             {
307                 Color fColor = JColorChooser.showDialog(DrawPictureFrame.this, "选择颜色对话框", Color.CYAN);
308                 if(fColor != null)
309                     foreColor = fColor;
310                 foregroundButton.setForeground(foreColor);
311                 g.setColor(foreColor);
312             }
313             
314         });
315         
316         //清除按钮和橡皮按钮
317         clearButton.addActionListener(new ActionListener() {
318             public void actionPerformed( final ActionEvent arg0 ) {
319                 g.setColor(backgroundColor);
320                 g.fillRect(0, 0, 570, 390);//用背景色填充以达到清除效果，然后画笔换成前景色，继续作画
321                 g.setColor(foreColor);
322                 canvas.repaint();//更新画布
323             }
324         });    
325         eraserButton.addActionListener(new ActionListener() {
326             public void actionPerformed(final ActionEvent arg0)
327             {
328                 if( eraserButton.getText().equals("橡皮") )
329                 {
330                     rubber = true;
331                     eraserButton.setText("画图");
332                 }
333                 else
334                 {
335                     rubber = false;
336                     eraserButton.setText("橡皮");
337                     g.setColor(foreColor);
338                     
339                 }
340             }
341         });
342         
343         
344         //图形绘制按钮
345         shapeButton.addActionListener(new ActionListener() {
346             public void actionPerformed(ActionEvent e)//单击时
347             {
348                 //创建图形选择组件
349                 ShapeWindow shapeWindow = new ShapeWindow(DrawPictureFrame.this);
350                 int shapeButtonWidth = shapeButton.getWidth();
351                 int shapeWindowWidth = shapeWindow.getWidth();
352                 int shapeButtonX = shapeButton.getX();
353                 int shapeButtonY = shapeButton.getY();
354                 int shapeWindowX = getX() - shapeButtonX - ( shapeWindowWidth-shapeButtonWidth )/2;
355                 int shapeWindowY = getY() - shapeButtonY + 80;
356                 shapeWindow.setLocation(shapeWindowX,shapeWindowY);
357                 shapeWindow.setVisible(true);//图形组件可见，如果是false点击图形啥都没有
358             }
359             
360         });
361         
362         //保存按钮实现保存功能
363         saveButton.addActionListener(new ActionListener() {
364             public void actionPerformed(final ActionEvent arg0) {//单击时
365                 addWatermark();//添加水印
366                 DrawImageUtil.saveImage(DrawPictureFrame.this,image );//打印图片
367             }
368             
369         });
370         
371         exitMenuItem.addActionListener(new ActionListener() {///退出菜单动作监听
372             public void actionPerformed(final ActionEvent e)///单击时程序退出
373             {
374                 System.exit(0);
375             }
376         });
377         
378         eraserMenuItem.addActionListener(new ActionListener() {
379             public void actionPerformed(final ActionEvent e) {
380                 if( eraserMenuItem.getText().contentEquals("橡皮") ) {
381                     rubber = true;
382                     eraserMenuItem.setText("画图");
383                     eraserButton.setText("画图");
384                 }
385                 else
386                 {
387                     rubber = false;
388                     eraserMenuItem.setText("橡皮");
389                     eraserButton.setText("橡皮");
390                     g.setColor(foreColor);
391                 }
392             }
393         });
394         
395         clearMenuItem.addActionListener(new ActionListener() {
396             public void actionPerformed(final ActionEvent e) {
397                 g.setColor(backgroundColor);
398                 g.fillRect(0, 0, 570, 390);
399                 g.setColor(foreColor);
400                 canvas.repaint();
401                 
402             }
403         });
404         
405         strokeMenuItem1.addActionListener(new ActionListener() {//细线菜单添加动作监听
406             public void actionPerformed(final ActionEvent e) {
407                 //像素为1，线条末端无修饰，折线处呈尖角
408                 BasicStroke bs = new BasicStroke(1,BasicStroke.CAP_BUTT,BasicStroke.JOIN_MITER);
409                 g.setStroke(bs);//画图工具使用此笔
410                 strokeButton1.setSelected(true);//细线按钮设为选中状态
411             }
412         });
413         
414         strokeMenuItem2.addActionListener(new ActionListener() {
415             public void actionPerformed(final ActionEvent e) {
416                 BasicStroke bs = new BasicStroke(2,BasicStroke.CAP_BUTT,BasicStroke.JOIN_MITER);
417                 g.setStroke(bs);
418                 strokeButton2.setSelected(true);
419             }
420         });
421         
422         strokeMenuItem3.addActionListener(new ActionListener() {
423             public void actionPerformed(final ActionEvent e) {
424                 BasicStroke bs = new BasicStroke(4,BasicStroke.CAP_BUTT,BasicStroke.JOIN_MITER);
425                 g.setStroke(bs);
426                 strokeButton3.setSelected(true);
427             }
428         });
429         
430         foregroundMenuItem.addActionListener(new ActionListener() {
431             public void actionPerformed(final ActionEvent e) {
432                 Color fColor = JColorChooser.showDialog(DrawPictureFrame.this, "选择颜色对话框", Color.CYAN);
433                 if( fColor != null )
434                     foreColor = fColor;
435                 foregroundButton.setForeground(foreColor);
436                 g.setColor(foreColor);
437             }
438         });
439         
440         backgroundMenuItem.addActionListener(new ActionListener() {
441             public void actionPerformed(final ActionEvent e) {
442                 Color bgColor = JColorChooser.showDialog(DrawPictureFrame.this, "选择颜色对话框", Color.CYAN);
443                 if( bgColor != null )
444                     backgroundColor = bgColor;
445                 backgroundButton.setBackground(backgroundColor);
446                 g.setColor(backgroundColor);
447                 g.fillRect(0, 0, 570, 390);
448                 g.setColor(foreColor);
449                 canvas.repaint();
450             }
451         });
452         
453         saveMenuItem.addActionListener(new ActionListener() {
454             public void actionPerformed(ActionEvent e) {
455                 addWatermark();//添加水印
456                 DrawImageUtil.saveImage(DrawPictureFrame.this,image);//打印图片
457             }
458         });
459         
460         shuiyinMenuItem.addActionListener(new ActionListener() {
461             public void actionPerformed(ActionEvent e) {
462                 //输入对话框
463                 System.out.println("facai1");
464                 shuiyin = JOptionPane.showInputDialog(DrawPictureFrame.this,"你想添加什么水印？");
465                 System.out.println("facai2");
466                 if ( null == shuiyin)
467                     shuiyin="";
468                 else 
469                     setTitle("画图程序(水印内容：[ " + shuiyin + " ])");//修改窗体标题
470                 System.out.println("facai3");
471             }
472         });
473         
474         showPicButton.addActionListener(new ActionListener() {
475             public void actionPerformed(ActionEvent e) {
476                 boolean isVisible = picWindow.isVisible();
477                 if(isVisible) {
478                     showPicButton.setText("展开简笔画");
479                     picWindow.setVisible(false);
480                 }
481                 else 
482                 {
483                     showPicButton.setText("隐藏简笔画");
484                     //重新指定简笔画展示窗体的显示位置
485                     //横坐标 = 主窗体横坐标 - 简笔画窗体宽度 - 5； 纵坐标 = 主窗体纵坐标
486                     picWindow.setLocation(getX()-picWindow.getWidth()-5,getY());
487                     picWindow.setVisible(true);
488                 }
489             }
490         });
491         
492         
493     
494     }
495     
496     //添加水印
497     private void addWatermark() {
498         if( !"".equals(shuiyin.trim()) )///shuiyin变量删除头尾空白字符后 不等于空 
499         {
500             g.rotate(Math.toRadians(-30));//将图片旋转-30弧度
501             Font font = new Font("楷体",Font.BOLD,72);//设置字体
502             g.setFont(font);
503             g.setColor(Color.GRAY);
504             AlphaComposite alpha = AlphaComposite.SrcOver.derive(0.4f);//设置透明效果
505             g.setComposite(alpha);
506             g.drawString(shuiyin, 75, 400);//绘制文字
507             canvas.repaint();
508             g.rotate(Math.toRadians(30));//将旋转的图片再旋转回来
509             alpha = AlphaComposite.SrcOver.derive(1f);//不透明效果
510             g.setComposite(alpha);//使用不透明效果
511             g.setColor(foreColor);//画笔恢复之前颜色
512         }
513     }
514     
515     //恢复展开简笔画按钮的文本内容，此方法供简笔画面板的"隐藏"按钮调用
516     public void initShowPicButton() {
517         showPicButton.setText("展开简笔画");
518     }
519     
520     
521     //FrameGetShape接口实现类，用于获得图形空间返回的被选中的图形
522     public void getShape(Shapes shape)
523     {
524         this.shape=shape;//将返回的图形对象赋给类的全局变量
525         drawShape = true;//画图形标识变量为true，说明现在鼠标画的是图形，而不是线条
526     }
527     
528     
529     
530     
531 
532     public static void main(String[] args) 
533     {
534         DrawPictureFrame frame = new DrawPictureFrame();//创建窗体对象
535         frame.setVisible(true);//让窗体可见
536     }
537 
538 }

DrawPictureFrame.java

 1 package com.mr.draw;
 2 
 3 import java.awt.Canvas;
 4 import java.awt.Graphics;
 5 import java.awt.Image;
 6 
 7 
 8 public class DrawPictureCanvas extends Canvas{
 9     private Image image = null;//创建画板中展示的图片对象
10     //设置画板中的图片
11     public void setImage( Image image)
12     {
13         this.image = image;
14     }
15     //重写，在画布上绘制图像
16     public void paint( Graphics g )
17     {
18         g.drawImage( image,0,0,null );
19     }
20     
21     //重写，解决屏幕闪烁问题
22     public void update( Graphics g )
23     {
24         paint(g);
25     }
26 }

DrawPictureCanvas.java

 1 package com.mr.draw;
 2 
 3 import java.awt.BorderLayout;
 4 import java.awt.Container;
 5 import java.awt.FlowLayout;
 6 import java.awt.Image;
 7 import java.awt.event.ActionEvent;
 8 import java.awt.event.ActionListener;
 9 import java.io.File;
10 import javax.swing.ImageIcon;
11 import javax.swing.JButton;
12 import javax.swing.JPanel;//面板
13 import javax.swing.JWindow;
14 import com.mr.util.BackgroundPanel;
15 
16 
17 
18 public class PictureWindow extends JWindow {
19     private JButton changeButton;
20     private JButton hiddenButton;
21     private BackgroundPanel centerPanel;
22     File list[];
23     int index;
24     DrawPictureFrame frame;
25     
26     //构造方法
27     public PictureWindow(DrawPictureFrame frame) {
28         this.frame = frame;//构造参数的值赋给父窗体
29         setSize(400,460);
30         init();
31         addListener();
32     }
33     
34     private void init() {
35         Container c = getContentPane();
36         File dir = new File("src/img/picture");
37         list = dir.listFiles();
38         centerPanel = new BackgroundPanel(getListImage());
39         c.add(centerPanel,BorderLayout.CENTER);//背景面板放到主容器的中部
40         FlowLayout flow = new FlowLayout(FlowLayout.RIGHT);//右对齐流布局
41         flow.setHgap(20);//水平间隔20像素
42         JPanel southPanel = new JPanel();//创建南部面板
43         southPanel.setLayout(flow);//使用刚才建好的流布局
44         changeButton = new JButton("更换图片");
45         southPanel.add(changeButton);
46         hiddenButton = new JButton("隐藏");
47         southPanel.add(hiddenButton);
48         c.add(southPanel,BorderLayout.SOUTH);//南部面板放在主容器的南部
49     }
50     
51     //添加监听
52     private void addListener() {
53         hiddenButton.addActionListener(new ActionListener() {
54             public void actionPerformed(ActionEvent e) {
55                 setVisible(false);//隐藏按钮点击时窗体不可见
56                 frame.initShowPicButton();
57             }
58         });
59         changeButton.addActionListener(new ActionListener() {
60             public void actionPerformed(ActionEvent e) {
61                 centerPanel.setImage(getListImage());//更换图片按钮点击时背景面板重新载入图片
62             }
63         });
64     }
65     
66     private Image getListImage() {
67         String imgPath = list[index].getAbsolutePath();
68         ImageIcon image = new ImageIcon(imgPath);
69         index++;
70         if(index>=list.length)
71             index=0;
72         return image.getImage();
73     }
74     
75 }

PictureWindow.java

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