rainbow.java

特效之七彩文字 比较经典实用 可直接应用在其它程序中

import java.applet.Applet;
import java.awt.*;


public class Rainbow extends Applet implements Runnable
{
	Thread thread;
	Image offScreenImage;	//位图
	Graphics offScreenG;	//位图刷
	String str;		//输入文字	
	Font f;			//显示字体
	FontMetrics fm;		//字体规格
	char theChars[];	//文字分解后的字符数组
	int charoffsets[];	//字符基线偏移量
	Color colors[];		//显示字符颜色
	int i=20;
	int strlen;		//文字长度
	int phase;
	public void init()
	{
		thread=new Thread(this);
		str=this.getParameter("text");
		if(str==null)
			str="THIS IS A TEST";
		f=new Font("TimesRoman",1,36);
		fm=getFontMetrics(f);
		resize(40+fm.stringWidth(str),40);
		this.setBackground(Color.cyan);
		strlen=str.length();
		theChars=new char[strlen];
		charoffsets=new int[strlen];
		str.getChars(0,strlen,theChars,0);
		colors=new Color[strlen];
		for(int j=0;j<strlen;j++)
		{
		float f1=(float)j/(float)strlen;
		colors[j]=new Color(Color.HSBtoRGB(f1,1F,1F));
		charoffsets[j]=i;
		i+=fm.charWidth(theChars[j]);
		}
		offScreenImage = createImage(size().width,size().height);
		offScreenG=offScreenImage.getGraphics();
		offScreenG.setFont(f);
		thread.start();
	}
	
	public void update(Graphics g)
	{
		offScreenG.setColor(Color.black);
		offScreenG.fillRect(0,0,size().width,size().height);
		phase++;
		phase %=str.length();
		for(int j=0;j<strlen;j++)
		{
			int k=charoffsets[j];
			offScreenG.setColor(colors[(phase+j)%strlen]);
			offScreenG.drawChars(theChars,j,1,k,30);
			}
		paint(g);
		}
	public void paint(Graphics g)
	{
		g.drawImage(offScreenImage,0,0,this);	
		}
		
	public void run()
	{
		while(true)
		{
			try
			{
				Thread.currentThread().sleep(100);
				repaint();			
				}catch(Exception e){}
			}
		}
	
}