LWUIT的绘图功能
LWUIT的控件，可以算是做得很全，他的设计模式跟J2SE有点类似，而做过J2ME的人要掌握也不需要长时间。LWUIT的控件，是原来高级控件与低级控件的集合，并加入了更多元素，因此你可以在用高级控件的同时，很自然地实现低级控件的功能。例如本文中的绘图功能，就是如此！
在本例中，依然使用大家熟悉的void paint(Graphics g) 函数，作为绘图的主体，然而paint的“上司”(绘图类)并不再是继承Canvas，而是继承Component，并且继承Component之后要这样被调用：form.addComponent(BorderLayout.CENTER, new Painting());//Painting就是“上司”。可见，在LWUIT里，已经没低级控件这个概念，但是有这个用法-----传统的绘图类也作为控件类，被调用了。或许，你想用回原来的javax.microedition.lcdui.Graphics，但是lcdui的Graphics和Display 与 LWUIT的Graphics和Display不兼容(LWUIT多了很多方法)，因此“新欢旧爱不能兼得”！
OK,先给出调用绘图功能的代码：
1. private class ButtonActionListener implements ActionListener {
2. public void actionPerformed(ActionEvent evt) {
3. String sel_button=((Button)(evt.getSource())).getText();//取得所选按钮的名称
4. if(sel_button.equals("Image 1"))
5. new AnimationDemo().form.show();
6. else if(sel_button.equals("Image 2"))
7. new PaintingDemo().form.show();
8. }
9. }
1. /*
2. * Copyright ?2008 Sun Microsystems, Inc. All rights reserved.
3. * Use is subject to license terms.
4. *
5. */
6. package com.sun.lwuit.uidemo;
7.
8. import com.sun.lwuit.Command;
9. import com.sun.lwuit.Component;
10. import com.sun.lwuit.Form;
11. import com.sun.lwuit.Graphics;
12. import com.sun.lwuit.events.ActionEvent;
13. import com.sun.lwuit.events.ActionListener;
14. import com.sun.lwuit.layouts.BorderLayout;
15.
16.
17. /**
18. * Demonstrates simple animation both static and manual
19. *
20. * @author Shai Almog
21. */
22. public class PaintingDemo extends Form implements ActionListener {
23. public Form form = new Form("PaintingDemo");
24. private Command backCommand = new Command("Back", 1);
25. private Command nextCommand = new Command("next", 2);
26. PaintingDemo()
27. {
28. form.addCommand(backCommand);
29. form.addCommand(nextCommand);
30. form.setCommandListener(this);
31. form.setLayout(new BorderLayout());
32. form.addComponent(BorderLayout.CENTER, new Painting());
33.
34. }
35. public class Painting extends Component{
36. private int w;
37. public void paint(Graphics g) {
38. g.setColor(0x000000);
39. g.fillRect(0, 0, this.getWidth(), this.getHeight());
40. w = getWidth();
41. drawSqrt1(g);
42. g.setColor(0xffffff);
43. g.drawString("hellogv", 12, 33);
44.
45. }
46. private void drawSqrt1(Graphics g) {
47. long start = System.currentTimeMillis();
48.
49. int centerY1 = 50;
50.
51. //绘制X轴
52. //设置绘图颜色为蓝色
53. g.setColor(0x0000FF);
54. g.drawLine(0, centerY1, w, centerY1);
55.
56. //设置绘图颜色为白色
57. g.setColor(0xFFFFFF);
58. int oldX = 0;
59. int oldY1 = centerY1;
60.
61. int y1;
62. for(int i=1;i<w;i++) {
63. // 放大3倍
64. y1 = centerY1 - (int)(3*Math.sqrt(i));
65. g.drawLine(oldX, oldY1, i, y1);
66. oldX = i;
67. oldY1 = y1;
68. }
69. long time = System.currentTimeMillis() - start;
70. System.out.println("drawSqrt1 Runtime: " + time);
71. }
72.
73. }
74. public void actionPerformed(ActionEvent arg0) {
75. if(arg0.getCommand()==backCommand)
76. {
77. UIDemoMIDlet.backToMainMenu();
78. }
79. else if(arg0.getCommand()==nextCommand)
80. {
81.
82. }
83. }
84. }
OK，还是那句，希望大家多多支持LWUIT，让它可以做得更加好！