PHP output session verification code and the picture is not synchronized, the picture is always fast one step, solve

PHP output session verification code and the picture is not the same step, the picture is always one step faster, solve!
This post was last edited by Xdawei on 2012-04-18 20:07:42

PHP output Session verification code and the picture is not the same step, the picture is always one step faster, solve!

 
  Session_Start ();
function Random ($len)
{
$srcstr = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
Mt_srand ();
$strs = "";
for ($i =0; $i < $len; $i + +) {
$strs. = $srcstr [Mt_rand (0,35)];
}
Return Strtoupper ($STRS);
}



@header ("Content-type:image/png");
$_session["Captcha"] = $str;
Echo $str;
$im =imagecreate ($width, $height);
$back =imagecolorallocate ($im, 0xff,0xff,0xff);
$pix =imagecolorallocate ($im, 187,230,247);
$font =imagecolorallocate ($im, 41,163,238);
Mt_srand ();
for ($i =0; $i <1000; $i + +)
{
Imagesetpixel ($im, Mt_rand (0, $width), Mt_rand (0, $height), $pix);
}
Imagestring ($im, 5, 7, 5, $STR, $font);
Imagerectangle ($im, 0,0, $width-1, $height-1, $font);
Imagepng ($im);
Imagedestroy ($im);
$_session["Captcha"] = $str;
?>

------Solution--------------------
The problem is very strange, the best way is to separate.
Try this one.
checkcode.class.php

 /**
* Generate Verification Code
* Class Usage
* $checkcode = new Checkcode ();
* $checkcode->doimage ();
*//Get Verification
* $_session[' code ']= $checkcode->get_code ();
Session_Start ();
Include './checkcode.class.php ';
$checkcode = new Checkcode (' C:\WINDOWS\Fonts\ARIAL. TTF ');
$checkcode->doimage ();
$_session[' code ']= $checkcode->get_code ();
*/
Class Checkcode {
The width of the verification code
Public $width = 130;

Verification Code of the high
Public $height = 50;

Set the address of the font
Private $font;

Set the font color
Public $font _color;

Set the random generation factor
Public $charset = ' abcdefghkmnprstuvwyzABCDEFGHKLMNPRSTUVWYZ23456789 ';

Set Background color
Public $background = ' #EDF7FF ';

Generate Verification Code character count
Public $code _len = 4;

Font size
Public $font _size = 20;

Verification Code
Private $code;

Image memory
Private $img;

Where the text x-axis begins
Private $x _start;

function __construct ($fontpath) {
$this->font = $fontpath;
}
/**
* Generate random verification code.
*/
protected function Creat_code () {
$code = ";
$charset _len = strlen ($this->charset)-1;
for ($i =0; $i < $this->code_len; $i +) {
$code. = $this->charset[rand (1, $charset _len)];
}
$this->code = $code;
}

/**
* Get Verification Code
*/
Public Function Get_code () {
Return Strtolower ($this->code);
}

/**
* Create picture
*/
Public Function Doimage () {
$code = $this->creat_code ();
$this->img = Imagecreatetruecolor ($this->width, $this->height);
if (! $this->font_color) {
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