画线条的时候，取比较深的颜色值，而画雪花的时候取比较淡的颜色值，目的是尽可能的不影响人眼识别验证码，又能干扰自动识别验证码机制。
3.7对外生成验证码图像，供外部调用。
//对外生成
public function doImg()
{
$this->createBg(); //1.创建验证码背景
$this->createCode(); //2.生成随机码
$this->createLine(); //3.生成线条和雪花
$this->createFont(); //4.生成文字
$this->outPut(); //5.输出验证码图像
}
3.8完整代码：
<?php
/**
* Created by PhpStorm.
* User: andy
* Date: 16-12-22
* Time: 下午1:20
*/
class ValidateCode
{
//随机因子
private $charset = 'abcdefghjkmnprstuvwxyzABCDEFGJKMNPRSTUVWXYZ23456789';
private $code;
private $codeLen = 4;
private $width = 130;
private $heigh = 50;
private $img;//图像
private $font;//字体
private $fontsize = 20;
public function __construct()
{
$this->font = ROOT_PATH.'/font/Chowderhead.ttf';
$this->img = imagecreatetruecolor($this->width, $this->heigh);
}
//生成随机码
private function createCode()
{
$_len = strlen($this->charset) - 1;
for ($i = 0; $i < $this->codeLen; $i++) {
$this->code .= $this->charset[mt_rand(0, $_len)];
}
}
//生成背景
private function createBg()
{
$color = imagecolorallocate($this->img, mt_rand(157, 255), mt_rand(157, 255), mt_rand(157, 255));
imagefilledrectangle($this->img, 0, $this->heigh, $this->width, 0, $color);
}
//生成文字
private function createFont()
{
$_x = $this->width / $this->codeLen;
$_y = $this->heigh / 2;
for ($i = 0; $i < $this->codeLen; $i++) {
$color = imagecolorallocate($this->img, mt_rand(0, 156), mt_rand(0, 156), mt_rand(0, 156));
imagettftext($this->img, $this->fontsize, mt_rand(-30, 30), $_x * $i + mt_rand(3, 5), $_y + mt_rand(2, 4), $color, $this->font, $this->code[$i]);
}
}
//生成线条，雪花
private function createLine()
{
for ($i = 0; $i < 15; $i++) {
$color = imagecolorallocate($this->img, mt_rand(0, 156), mt_rand(0, 156), mt_rand(0, 156));
imageline($this->img, mt_rand(0, $this->width), mt_rand(0, $this->heigh), mt_rand(0, $this->width), mt_rand(0, $this->heigh), $color);
}
for ($i = 0; $i < 150; $i++) {
$color = imagecolorallocate($this->img, mt_rand(200, 255), mt_rand(200, 255), mt_rand(200, 255));
imagestring($this->img, mt_rand(1, 5), mt_rand(0, $this->width), mt_rand(0, $this->heigh), '#', $color);
}
}
//输出图像
private function outPut()
{
header('Content-Type: image/png');
imagepng($this->img);
imagedestroy($this->img);
}
//对外生成
public function doImg()
{
$this->createBg(); //1.创建验证码背景
$this->createCode(); //2.生成随机码
$this->createLine(); //3.生成线条和雪花
$this->createFont(); //4.生成文字
$this->outPut(); //5.输出验证码图像
}
//获取验证码
public function getCode()
{
return strtolower($this->code);
}
}
