Php verification code encapsulation

Php verification code encapsulation /**
* Generate a verification code
* @ Param int $ type 1: only numbers, 2: only letters, 3: mixed numbers and letters
* @ Param int $ length
* @ Return string
*/
Function buildRandomString ($ type = 1, $ length = 4 ){
If ($ type = 1 ){
$ Chars = join ("", range (0, 9 ));
} Elseif ($ type = 2 ){
$ Chars = join ("", array_merge (range ("a", "z"), range ("A", "Z ")));
} Elseif ($ type = 3 ){
$ Chars = join ("", array_merge (range ("a", "z"), range ("A", "Z"), range (0, 9 )));
}
If ($ length> strlen ($ chars )){
Exit ("insufficient string length ");
}
$ Chars = str_shuffle ($ chars );
Return substr ($ chars, 0, $ length );
}

// Use the GD library for verification code

Function verifyImage ($ type = 1, $ length = 4, $ pixel = 0, $ line = 0, $ sess_name = "verify "){

Session_start ();
// Create a canvas
$ Width = 80;
$ Height = 28;
$ Image = imagecreatetruecolor ($ width, $ height );
$ White = imagcolorallocate ($ image, 255,255,255 );
$ Black = imagecolorallocate ($ image, 0, 0, 0 );
// Fill the canvas with a filled rectangle
Imagefilledrectangle ($ image, 1, 1, $ width-2, $ height-2, $ white );
$ Chars = buildRandomString ($ type, $ length );
$ _ SESSION [$ sess_name] = $ chars;
// $ Fontfiles = array ("MSYH. TTF "," MSYHBD. TTF "," SIMLI. TTF "," SIMSUN. TTC "," SIMYOU. TTF "," STZHONGS. TTF ");
$ Fontfiles = array ("SIMYOU. TTF ");
// Because the font file is large, only one font is retained. if necessary, you can add the font on your own. The fonts folder contains the fonts font, run the input fonts command to view the corresponding font.
For ($ I = 0; $ I <$ length; $ I ++ ){
$ Size = mt_rand (14, 18 );
$ Angle = mt_rand (-15, 15 );
$ X = 5 + $ I * $ size;
$ Y = mt_rand (20, 26 );
$ Fontfile = $ fontfiles [mt_rand (0, count ($ fontfiles)-1)];
Putenv ('gdfontpath = '. realpath ('.'));
$ Color = imagecolorallocate ($ image, mt_rand (50, 90), mt_rand (80,200), mt_rand (90,180 ));
$ Text = substr ($ chars, $ I, 1 );
// Putenv ('gdfontpath = '. realpath ('.'));

// Name the font to be used (note the lack of the. ttf extension)
Imagettftext ($ image, $ size, $ angle, $ x, $ y, $ color, $ fontfile, $ text );
}
If ($ pixel ){
For ($ I = 0; $ I <50; $ I ++ ){
Imagesetpixel ($ image, mt_rand (0, $ width-1), mt_rand (0, $ height-1), $ black );
}
}
If ($ line ){
For ($ I = 1; $ I <$ line; $ I ++ ){
$ Color = imagecolorallocate ($ image, mt_rand (50, 90), mt_rand (80,200), mt_rand (90,180 ));
Imageline ($ image, mt_rand (0, $ width-1), mt_rand (0, $ height-1), mt_rand (0, $ width-1), mt_rand (0, $ height-1), $ color );
}
}

Header ("content-type: image/gif"); // sets the header information
Imagegif ($ image );
Imagedestroy ($ image );
}