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j2me实现图像旋转
摘要: j2me实现图像旋转
/*
* Created on 2004-12-4
*
* Abstract :这是一个显示图像旋转算法的例子，
* 为了显示如何旋转一副图像，创建一个MIDlet，然后在上面显示一个Canvas的子类ViewCanvas,
* ViewCanvas是一个自动化对象，不停的旋转图像然后显示。
* 使用者只需要把originImage = Image.createImage("/resource/popo.png");这一行里的图像文件改成
* 真实存在的图像文件就可以运行了。
*/
package SayWord;
import javax.microedition.midlet.MIDlet;
import javax.microedition.lcdui.*;
import javax.microedition.midlet.MIDletStateChangeException;
/**
* @author 快让我睡个好觉 wzhh@ustc.edu
*
* 这是一个MIDlet子类
*/
public class Hello extends MIDlet {
/**
*
*/
private Display display;
private ViewCanvas canvas;
public Hello() {
super();
display =Display.getDisplay(this);
canvas = new ViewCanvas(this);
}
protected void startApp() throws MIDletStateChangeException {
display.setCurrent( canvas ); // 设置显示画布对象
}
protected void pauseApp() {
}
protected void destroyApp(boolean arg0) throws MIDletStateChangeException {
}
public void exitMIDlet()
{
try
{
destroyApp( true);
}
catch(MIDletStateChangeException e)
{
}
notifyDestroyed();
}
}
// 自动化对象，同时也是Canvas的子类
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 Hello midlet;
private boolean alive = true;
private int interval = 100;
private Thread thread = null;
/*--------------------------------------------------
* Constructor
*-------------------------------------------------*/
public ViewCanvas(Hello midlet)
{
this.midlet = midlet;
try
{
originImage = Image.createImage("/resource/popo.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();
}
}