Detailed explanation of verification code class encapsulated by php

This article shares with you the code, principles and ideas of a PHP-encapsulated verification code class. It is very clear and detailed. Friends in need can refer to it.

Verification codes are often used when we develop The functions used, so I have packaged a verification code class here, which should be used as a PHP class plug-in. I would like to share it with all readers.

The principle of implementation is also very simple. It is to use several functions of the canvas, plus the acquisition of some strings, and piece it all together, haha.

Let’s roughly write down the idea here. In fact, this class has been commented very clearly, but I still want to be wordy before writing.

The first is the explanation of some functions. The explanation here is purely personal experience. If there are any mistakes, please correct me.

1. Create canvas function: imagecreatetruecolor(w,h);

Description: Used to create a canvas.

w The width of the canvas

h The height of the canvas

The return value of this function Resource class (gd)

2. Create a canvas One color: imagecolorallocate(img,red,green,blue)

Description:

img canvas resource

red, green, blue is 0~255 Range

3. Add background color to the canvas

imagefill(img,x,y,color);

Description:

In the image coordinates x, y (the upper left corner of the image is 0, 0)

4. Draw the border

,y2,color);

　　　　　　　　　　　　　　　　　　　　　　

　　　 The coordinates of the upper left corner are x1, y1, and the coordinates of the lower right corner are x2, y2. The upper left corner of the image has coordinates 0, 0.

3. Drawing content (characters)

imagestring(img,size,x,y,string,color);

Description:

img canvas

size is the character size 1 to 5

x,y is the starting point

string is the content to be drawn

color It’s the color

4. Tell the browser the image format

Header("Content-type:image/png"); can be image/gif, etc.

5. Output (or save), you can also use the second parameter to save

imagepng(img【,filename】)

imagejpeg(img【 ,filename])

Imagegif(img【,filename】)

6. Add interference lines, which are essentially straight lines

Imageline(img,x1 ,y1,x2,y2,color);

Description:

img canvas

## Color Color

7. imagettftext (img,size, angle, x, y, color, fontfile,text)

Description: img canvas

size font size, default unit pixel

angle angle

x,y coordinate point

color color

fontfile Font file must be Chinese font

　　　text content

Special note: The color parameters here are all colors created by the imagecolorallocate() function

The following is the idea:

The canvas is first generated here, and then strings, straight lines, noise points, and borders are added to the canvas to generate verification codes. The last two public interfaces returned by the class are: the canvas for generating verification codes that can be called externally and The purpose of the string composition of the verification code is to output the verification code canvas to the outside world and store the string for verification

The following is the code:

<?php
namespace captcha;
/*
*验证码类
*verify方法生成验证码字符串
*entry方法生成验证码
*特别提醒：这里要先用entry生成验证码，再用verify生成验证码的字符串，也就是必须先调用entry，然后才能够调用verify生成验证码的字符串，原因代码已经说明问题了，因为验证码的字符串是在entry方法调用captchaImage生成的，所以必须先调用它才行
*有的地方对中文的字体要求比较高，所以，有的地方不支持中文验证码
*/
class Captcha{
  //配置参数
  private $config = array();
  //验证码
  private $verifyCode = &#39;&#39;;
  //获取配置文件的配置信息，给类传参数就行，例如new Captcha($config);$config是你的配置文件信息
  public function __construct($config=array(&#39;width&#39;=>100,&#39;height&#39;=>40,&#39;length&#39;=>4,&#39;size&#39;=>7,&#39;lines&#39;=>0,&#39;dots&#39;=>0,&#39;font&#39;=>&#39;simfang.ttf&#39;,&#39;rectangle&#39;=>array(255,55,122),&#39;charset&#39;=>true,&#39;chinese&#39;=>&#39;来到新机场主航站楼建设在婚姻关系存续期间所负债务她在收到要求她偿还前夫在婚姻关系存续期间所欠债务的法院传票后要精益求精善始善终&#39;)){
    $this->config = $config;
  }
  //创建验证码
  private function captchaImage(){
    //画布
    $img = imagecreatetruecolor($this->config[&#39;width&#39;],$this->config[&#39;height&#39;]);
    //填充画布颜色
    imagefill($img,0,0,imagecolorallocate($img,mt_rand(200,255),mt_rand(200,255),mt_rand(200,255)));
    //需要边框则画边框
    if($this->config[&#39;rectangle&#39;] && is_array($this->config[&#39;rectangle&#39;]) && count($this->config[&#39;rectangle&#39;]) == 3){
      $this->tangle($img);
    }
    $this->verifyCode = $this->code($img,$this->config[&#39;charset&#39;],$this->config[&#39;chinese&#39;]);
    //存在则添加干扰线
    if($this->config[&#39;lines&#39;]){
      $this->codeLines($img);
    }
    //存在则添加干扰点
    if($this->config[&#39;dots&#39;]){
      $this->codeDots($img);
    }
    return $img;
  }
  private function codeLines($img){
    //绘制干扰线
    for($i=0;$i<$this->config[&#39;lines&#39;];$i++){
      imageline($img,mt_rand(0,$this->config[&#39;width&#39;] / 10),mt_rand(0,$this->config[&#39;height&#39;]),mt_rand($this->config[&#39;width&#39;] * 7/ 10,$this->config[&#39;width&#39;] * 9/ 10),mt_rand(0,$this->config[&#39;height&#39;]),imagecolorallocate($img,mt_rand(0,255),mt_rand(0,255),mt_rand(0,255)));
    }
  }
  private function codeDots($img){
    //添加噪点
    for($i=0;$i<$this->config[&#39;dots&#39;];$i++){
      //噪点颜色
      $color = imagecolorallocate($img,mt_rand(0,180),mt_rand(0,180),mt_rand(0,180));
      imagestring($img,mt_rand(1,3),mt_rand(0,170),mt_rand(0,30),&#39;*&#39;,$color);
    
    }
  }
  /*画布边框*/
  private function tangle($img){
    imagerectangle($img,0,0,$this->config[&#39;width&#39;]-1,$this->config[&#39;height&#39;]-1,imagecolorallocate($img,$this->config[&#39;rectangle&#39;][0],$this->config[&#39;rectangle&#39;][1],$this->config[&#39;rectangle&#39;][2]));
  }
  /*生成验证码,默认英文，$ch为true则为中文*/
  private function code($img,$ch=false,$set=&#39;&#39;){
    $str = "";
    //计算间隔
    $span = ceil($this->config[&#39;width&#39;]/($this->config[&#39;length&#39;]+1));
    if($ch && !empty($set)){
      //随机产生字符
      $set = $this->config[&#39;chinese&#39;];
      for($i=0;$i<$this->config[&#39;length&#39;];$i++){
        $end = strlen($set)/3;
        $pos = mt_rand(0,$end-1);
        $str .= substr($set,$pos*3,3);
      }
      //每次绘制一个字符
      for($i=1;$i<=$this->config[&#39;length&#39;];$i++){
        imagettftext($img,16,mt_rand(-30,60),$i*$span,$this->config[&#39;height&#39;]*3/5,imagecolorallocate($img,mt_rand(0,180),mt_rand(0,180),mt_rand(0,180)),$this->config[&#39;font&#39;],substr($str,($i-1)*3,3));
      }
    }else{
      //随机生成字母或者数字
      for($i=0;$i<$this->config[&#39;length&#39;];$i++){
        switch(mt_rand(0,2)){
          case 0:
          $str .= chr(mt_rand(65,90));
          break;
        case 1:
          $str .= chr(mt_rand(97,122));
          break;
        case 2:
          $str .= chr(mt_rand(48,57));
        }
      }
      //每次绘制一个字符
      for($i=1;$i<=$this->config[&#39;length&#39;];$i++){
        imagestring($img,$this->config[&#39;size&#39;],$i*$span,0,$str[$i-1],imagecolorallocate($img,mt_rand(0,180),mt_rand(0,180),mt_rand(0,180)));
      }
    }
    return $str;
  }
  //获取验证码
  public function verify(){
    return $this->verifyCode;
  }
  //生成验证码
  public function entry(){
    header("content-type:image/png");
    imagepng($this->captchaImage());
  }
}
$ob = new Captcha;
$ob->entry();

Finally, in order not to mislead others, let me emphasize it again:

Here you must first use entry to generate the verification code, and then use verify to generate the verification code string, that is, you must first call entry, and then you can call verify generates a verification code string. The reason code has already explained the problem. Because the verification code string is generated in the captchaImage method of the entry method, it must be called first. Some places have higher requirements for Chinese fonts. Therefore, some places do not support Chinese verification codes

The above is the entire content of this article, I hope it will be helpful to everyone's learning.

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