www.pudn.com > circumgyrate.rar > ViewCanvas.java

//package com.circumgyrate; 
 
import javax.microedition.lcdui.*; 
 
/** 
 * 
Title: 
 
 * 
Description: 
 
 * 
Copyright: Copyright (c) 2004
 
 * 
Company: 
 
 * @author not attributable 
 * @version 1.0 
 */ 
 
public class ViewCanvas 
    extends Canvas 
    implements CommandListener, Runnable { 
  private Command cmExit; // Exit midlet 
  private String keyText = "0"; // Key code text,用来记录用户的击键，在这个例子里不使用 
  private int angle = 0; // 旋转的角度 
  private Image originImage; // 原始图像 
  private circumgyrate midlet; 
  private boolean alive = true; 
  private int interval = 100; 
  private Thread thread = null; 
 
  /*-------------------------------------------------- 
   * Constructor 
   *-------------------------------------------------*/ 
  public ViewCanvas(circumgyrate midlet) { 
    this.midlet = midlet; 
    try { 
      originImage = Image.createImage("/start.png"); 
    } 
    catch (Exception e) { 
      System.out.println("load image fail!!!!!"); 
    } 
    // Create exit command and listen for events 
    cmExit = new Command("退出", Command.EXIT, 1); 
    addCommand(cmExit); 
    setCommandListener(this); 
    thread = new Thread(this); 
    thread.start(); 
  } 
 
  // 这是一个把图像绕中心点旋转一个角度的程序代码 
  // OriginImage传入原始图像，函数的返回值是旋转后的图像 
  // 这段代码只能旋转30度的整数倍角度，如果要旋转更精细 
  // 改一下tabCos,tabSin就行了，这两个数组保存的是cos和sin乘于4096的值 
  // 由于j2me不支持符点运算以及三角函数，所以用查表的方式计算sin,cos 
  int[] tabCos = { 
      4096, 3547, 2048, 0, -2048, -3547, -4096, -3547, -2048, 0, 2048, 3547}; 
  int[] tabSin = { 
      0, 2048, 3547, 4096, 3547, 2048, 0, -2048, -3547, -4096, -3547, -2048}; 
  private Image TransferImage(Image OriginImage, int angle) { 
    int w = OriginImage.getWidth(); 
    int h = OriginImage.getHeight(); 
    int ARGBData[] = new int[w * h]; 
    int TranARGBData[] = new int[w * h]; 
    OriginImage.getRGB(ARGBData, 0, w, 0, 0, w, h); 
    int centerX = w / 2; 
    int centerY = h / 2; 
    int i = ( (360 - angle) % 360) / 30; 
    for (int y1 = 0; y1 < h; y1++) { 
      for (int x1 = 0; x1 < w; x1++) { 
        // 这是坐标变换，不清楚的同志查一下坐标变换公式吧 
        int x2 = ( ( (x1 - centerX) * tabCos[i]) >> 12) - 
            ( ( (y1 - centerY) * tabSin[i]) >> 12) + centerX; 
        int y2 = ( ( (x1 - centerX) * tabSin[i]) >> 12) + 
            ( ( (y1 - centerY) * tabCos[i]) >> 12) + centerY; 
        if ( (x2 >= 0) && (x2 < w) && (y2 >= 0) && (y2 < h)) { 
          TranARGBData[y1 * w + x1] = ARGBData[y2 * w + x2]; 
        } 
        else { 
          TranARGBData[y1 * w + x1] = 255 << 24; 
        } 
      } 
    } 
    return Image.createRGBImage(TranARGBData, w, h, true); 
  } 
 
  /*-------------------------------------------------- 
   * Paint the text representing the key code 
   *-------------------------------------------------*/ 
  protected void paint(Graphics g) { 
    // Clear the background (to white) 
    g.setColor(255, 255, 255); 
    g.fillRect(0, 0, getWidth(), getHeight()); 
    g.drawImage(TransferImage(originImage, angle), 0, 0, 
                Graphics.TOP | Graphics.LEFT); 
    angle = (angle + 30) % 360; // 下一个旋转角度 
  } 
 
  public void run() { 
    while (true) { 
      if (alive) { 
        repaint(); 
        try { 
          Thread.sleep(interval); 
        } 
        catch (InterruptedException e) { 
        } 
      } 
    } 
  } 
 
  /*-------------------------------------------------- 
   * Command event handling 
   *-------------------------------------------------*/ 
  public void commandAction(Command c, Displayable d) { 
    if (c == cmExit) { 
      midlet.exitMIDlet(); 
    } 
  } 
 
  /*-------------------------------------------------- 
   * Key code event handling 
   *-------------------------------------------------*/ 
  protected void keyPressed(int keyCode) { 
    keyText = getKeyName(keyCode); 
    repaint(); 
  } 
}