PHP generate dynamic captcha gif picture, _php tutorial

PHP generates dynamic captcha GIF images,

This is an example of a dynamic CAPTCHA image generated by PHP, and the point is that you can run it! The following first sent:

Here are the related classes and functions that PHP needs to generate the dynamic verification code.

<?php/** *imagecode generates a function that contains a GIF picture of the captcha * @param $string String * @param $width Width * @param $height height **/function Imagecode ($ String= ", $width =75, $height =25) {$authstr = $string? $string:((Time ()%2==0)? Mt_rand (1000,9999): Mt_rand (10000,99999   ));   $board _width= $width;   $board _height= $height;     Generates a 32-frame animated GIF for ($i =0; $i <32; $i + +) {Ob_start ();     $image =imagecreate ($board _width, $board _height);     Imagecolorallocate ($image, 0,0,0);     Sets the text color array $colorList []=imagecolorallocate ($image, 15,73,210);     $colorList []=imagecolorallocate ($image, 0,64,0);     $colorList []=imagecolorallocate ($image, 0,0,64);     $colorList []=imagecolorallocate ($image, 0,128,128);     $colorList []=imagecolorallocate ($image, 27,52,47);     $colorList []=imagecolorallocate ($image, 51,0,102);     $colorList []=imagecolorallocate ($image, 0,0,145);     $colorList []=imagecolorallocate ($image, 0,0,113);     $colorList []=imagecolorallocate ($image, 0,51,51);     $colorList []=imagecolorallocate ($image, 158,180,35); $colOrlist[]=imagecolorallocate ($image, 59,59,59);     $colorList []=imagecolorallocate ($image, 0,0,0);     $colorList []=imagecolorallocate ($image, 1,128,180);     $colorList []=imagecolorallocate ($image, 0,153,51);     $colorList []=imagecolorallocate ($image, 60,131, 1);     $colorList []=imagecolorallocate ($image, 0,0,0);     $fontcolor =imagecolorallocate ($image, 0,0,0);     $gray =imagecolorallocate ($image, 245,245,245);     $color =imagecolorallocate ($image, 255,255,255);     $color 2=imagecolorallocate ($image, 255,0,0);     Imagefill ($image, 0,0, $gray);       $space =15;//Character Spacing if ($i >0) {//Mask first frame $top = 0; for ($k =0; $k
 
  
Getanimation ();       }/** *gifencoder class **/classes gifencoder{var $GIF = "gif89a";   /* GIF Header 6 bytes */var $VER = "Gifencoder V2.06";   /* Encoder version */var $BUF =array ();   var $LOP = 0;   var $DIS = 2;   var $COL =-1;   var $IMG =-1; var $ERR =array (' ERR00 ' = ' Does ' supported function for only one image! ", ' ERR01 ' = ' = ' Source is not a GIF IM   age! ", ' ERR02 ' =" unintelligible flag ", ' ERR03 ' + ' Could not make animation from animated GIF source ',); function Gifencoder ($GIF _src, $GIF _dly=100, $GIF _lop=0, $GIF _dis=0, $GIF _red=0, $GIF _grn=0, $GIF _blu=0, $GIF _mod= ' bin '       {if (!is_array ($GIF _src) &&!is_array ($GIF _tim)) {printf ("%s:%s", $this->ver, $this->err[' ERR00 ']);     Exit (0);     } $this->lop= ($GIF _lop>-1)? $GIF _lop:0; $this->dis= ($GIF _dis>-1)?     (($GIF _dis<3)? $GIF _dis:3): 2; $this->col= ($GIF _red>-1&& $GIF _grn>-1&& $GIF _blu>-1)? ($GIF _red | ($GIF _grn<<8) | ($GIF _blu<&LT;16)):-1; For ($i =0, $src _count=count ($GIF _src), $i < $src _count, $i + +) {if (Strtolower ($GIF _mod) = = "url") {$this->buf[]       =fread (fopen ($GIF _src [$i], "RB"), FileSize ($GIF _src [$i]));       }elseif (Strtolower ($GIF _mod) = = "Bin") {$this->buf []= $GIF _src [$i];         }else{printf ("%s:%s (%s)!", $this->ver, $this->err [' ERR02 '], $GIF _mod);       Exit (0); } if (substr ($this->buf[$i],0,6)! = "gif87a" &&substr ($this->buf [$i],0,6)! = "gif89a") {printf ("%s         :%d%s ", $this->ver, $i, $this->err [' ERR01 ']);       Exit (0); } for ($j = (13+3* (2<< ($this->buf[$i]{10})), $k &0x07, $k, $j + +) {switch ($this =true [$i  ]{$j}) {case "!": if (substr ($this->buf[$i], ($j +3), 8) = = "NETSCAPE") {printf ("%s:                 %s (%s source)! ", $this->ver, $this->err [' ERR03 '], ($i + 1));             Exit (0);           } break; Case ";": $k=false;         Break     }}} gifencoder::gifaddheader ();     For ($i =0, $count _buf=count ($this->buf); $i < $count _buf; $i + +) {gifencoder::gifaddframes ($i, $GIF _dly[$i]);   } gifencoder::gifaddfooter ();     } function Gifaddheader () {$cmap = 0;       if (Ord ($this->buf[0]{10}) &0x80) {$cmap =3* (2<< (Ord ($this->buf [0]{10] &0x07));       $this->gif.=substr ($this->buf [0],6,7);       $this->gif.=substr ($this->buf [0],13, $cmap); $this->gif.= "!\377\13netscape2.0\3\1". Gifencoder::gifword ($this->lop). "     ";     }} function Gifaddframes ($i, $d) {$Locals _str=13+3* (2 << (ord ($this->buf[$i]{10}));     $Locals _end=strlen ($this->buf[$i])-$Locals _str-1;     $Locals _tmp=substr ($this->buf[$i], $Locals _str, $Locals _end);     $Global _len=2<< (Ord ($this->buf [0]{10}) &0x07);     $Locals _len=2<< (Ord ($this->buf[$i]{10}) &0x07); $Global _rgb=substr ($this->buf[0],13,3* (2<< (Ord ($this->buf[0]{10) &0x07));     $Locals _rgb=substr ($this->buf[$i],13,3* (2<< (Ord ($this->buf[$i]{10}))); $Locals _ext= "!\xf9\x04". Chr (($this->dis<<2) +0). Chr (($d >>0) &0xff). Chr (($d >>8) &0xff )."     \x0\x0 "; if ($this->col>-1&&ord ($this->buf[$i]{10}) {for ($j =0; $j < (2<< (Ord. $this buf[$i]{10}) ($j + +) {if (Ord ($Locals _rgb{3* $j +0}) = = ($this->col>> 0) &0xff&&ord ($ locals_rgb{3* $j +1}) = = ($this->col>> 8) &0xff&&ord ($Locals _rgb{3* $j +2}) = = ($this->col> &GT;16) (&0xff) {$Locals _ext= "!\xf9\x04". Chr (($this->dis<<2) +1). Chr (($d >>0) &0xff). chr ($d & GT;&GT;8) &0xff). chr ($j). "           \x0 ";         Break         }}} switch ($Locals _tmp{0}) {case "!": $Locals _img=substr ($Locals _tmp,8,10);         $Locals _tmp=substr ($Locals _tmp,18,strlen ($Locals _tmp)-18);     Break  Case ",": $Locals _img=substr ($Locals _tmp,0,10);         $Locals _tmp=substr ($Locals _tmp,10,strlen ($Locals _tmp)-10);     Break if (Ord ($this->buf[$i]{10}) &0x80&& $this->img>-1) {if ($Global _len== $Locals _len) {i F (Gifencoder::gifblockcompare ($Global _rgb, $Locals _rgb, $Global _len)) {$this->gif.= ($Locals _ext. $Locals _img. $L         OCALS_TMP);           }else{$byte =ord ($Locals _img{9});           $byte |=0x80;           $byte &=0xF8;           $byte |= (Ord ($this->buf [0]{10}) &0x07);           $Locals _IMG{9}=CHR ($byte);         $this->gif.= ($Locals _ext. $Locals _img. $Locals _rgb. $Locals _tmp);         }}else{$byte =ord ($Locals _img{9});         $byte |=0x80;         $byte &=0xF8;         $byte |= (Ord ($this->buf[$i]{10}) &0x07);         $Locals _img {9}=CHR ($byte);       $this->gif.= ($Locals _ext. $Locals _img. $Locals _rgb. $Locals _tmp); }}else{$this->gif.= ($Locals _ext. $LocalS_img. $Locals _tmp);   } $this->img=1;    } function Gifaddfooter () {$this->gif.= ";";} function Gifblockcompare ($GlobalBlock, $LocalBlock, $Len) {for ($i =0; $i < $Len; $i + +) {if ($GlobalBlock {$i +0}!= $Lo calblock{3* $i +0}| | $GlobalBlock {$i +1}!= $LocalBlock {$i +1}| |       $GlobalBlock {$i +2}!= $LocalBlock {$i +2}) {return (0);   }} return (1);   } function Gifword ($int) {return (Chr ($int &0xff). Chr (($int >>8) &0xff));   } function Getanimation () {return ($this->gif);  }  }
 

Example of PHP generated dynamic CAPTCHA usage:

/* Call Example */session_start (); $checkCode = "; $chars = ' abcdefghjkmnpqrstuvwxyzABCDEFGHJKLMNPRSTUVWXYZ23456789 '; for ($i =0; $i <4; $i + +) {   

The above is how PHP generated dynamic verification code implementation method, I hope that everyone's learning is helpful.

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