package com.paic.bics.common.utils.vcode;
import java.awt.AlphaComposite;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.OutputStream;
/**
*

Gif验证码类

* @version:1.0
*/
public class GifCaptcha extends Captcha
{
public GifCaptcha()
{
}

public GifCaptcha(int width,int height){  
    this.width = width;  
    this.height = height;  
}

public GifCaptcha(int width,int height,int len){  
    this(width,height);  
    this.len = len;  
}

public GifCaptcha(int width,int height,int len,Font font)  
{  
    this(width,height,len);  
    this.font = font;  
}

@Override  
public void out(OutputStream os)  
{  
    try  
    {  
        GifEncoder gifEncoder = new GifEncoder();   // gif编码类，这个利用了洋人写的编码类，所有类都在附件中  
        //生成字符  
        gifEncoder.start(os);  
        gifEncoder.setQuality(180);  
        gifEncoder.setDelay(100);  
        gifEncoder.setRepeat(0);  
        BufferedImage frame;  
        char\[\] rands =alphas();  
        Color fontcolor\[\]=new Color\[len\];  
        for(int i=0;i<len;i++)  
        {  
            fontcolor\[i\]=new Color(20 + num(110), 20 + num(110), 20 + num(110));  
        }  
        for(int i=0;i<len;i++)  
        {  
            frame=graphicsImage(fontcolor, rands, i);  
            gifEncoder.addFrame(frame);  
            frame.flush();  
        }  
        gifEncoder.finish();  
    }finally  
    {  
        try {  
            os.close();  
        } catch (IOException e) {  
            // TODO Auto-generated catch block  
            e.printStackTrace();  
        }  
    }

}

/\*\*  
 \* 画随机码图  
 \* @param fontcolor 随机字体颜色  
 \* @param strs 字符数组  
 \* @param flag 透明度使用  
 \* @return BufferedImage  
 \*/  
private BufferedImage graphicsImage(Color\[\] fontcolor,char\[\] strs,int flag)  
{  
    BufferedImage image = new BufferedImage(width, height,BufferedImage.TYPE\_INT\_RGB);  
    //或得图形上下文  
    //Graphics2D g2d=image.createGraphics();  
    Graphics2D g2d = (Graphics2D)image.getGraphics();  
    //利用指定颜色填充背景  
    g2d.setColor(Color.WHITE);  
    g2d.fillRect(0, 0, width, height);  
    AlphaComposite ac3;  
    int h  = height - ((height - font.getSize()) >>1) ;  
    int w = width/len;  
    g2d.setFont(font);  
    for(int i=0;i<len;i++)  
    {  
        ac3 = AlphaComposite.getInstance(AlphaComposite.SRC\_OVER, getAlpha(flag, i));  
        g2d.setComposite(ac3);  
        g2d.setColor(fontcolor\[i\]);  
        g2d.drawOval(num(width), num(height), 5+num(10), 5+num(10));  
        g2d.drawString(strs\[i\]+"", (width-(len-i)\*w)+(w-font.getSize())+1, h-4);  
    }  
    g2d.dispose();  
    return image;  
}

/\*\*  
 \* 获取透明度,从0到1,自动计算步长  
 \* @return float 透明度  
 \*/  
private float getAlpha(int i,int j)  
{  
    int num = i+j;  
    float r = (float)1/len,s = (len+1) \* r;  
    return num > len ? (num \*r - s) : num \* r;  
}

}