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;

/**

 * <p>Gif验证码类</p>

 * @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;

    }

}