How to generate image verification code in PHP

This article mainly introduces the method of generating image verification code in PHP, and analyzes the two methods of addition operation verification code and character verification code in the form of examples for your reference. Friends in need can refer to it

1. Generate an addition operation verification code image

session_start ();
/*定义头文件为图片*/
header("Content-type: image/png");
/*生成验证码*/
/*创建图片设置字体颜色*/
$im = imagecreate($w, $h);
$red = imagecolorallocate($im, 255, 255, 255);
$white = imagecolorallocate($im, 255, 255, 255);
/*随机生成两个数字*/
$num1 = rand(1, 20);
$num2 = rand(1, 20);
$_SESSION ["administratorConfirmCode"] = $num1+$num2;
/*设置图片背景颜色*/
$gray = imagecolorallocate($im, 118, 151, 199);
$black = imagecolorallocate($im, mt_rand(0, 100), mt_rand(0, 100), mt_rand(0, 100));
/*创建图片背景*/
imagefilledrectangle($im, 0, 0, 100, 24, $black);
/*在画布上随机生成大量点*/
for ($i = 0; $i < 80; $i++) {
  imagesetpixel($im, rand(0, $w), rand(0, $h), $gray);
}
/*将计算验证码写入到图片中*/
imagestring($im, 5, 5, 4, $num1, $red);
imagestring($im, 5, 30, 3, "+", $red);
imagestring($im, 5, 45, 4, $num2, $red);
imagestring($im, 5, 70, 3, "=", $red);
imagestring($im, 5, 80, 2, "?", $white);
/*输出图片*/
imagepng($im);
imagedestroy($im);

2. Generate a character verification code image [It is worth noting that where the font is, you need to introduce the actual Font path, otherwise, the image may not display the verification code】

session_start ();
/*设置文件头为图片输出*/
Header("Content-type: image/JPEG");
/*调用生成验证码函数*/
$str="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz01234565789";
$result="";
for($i=0;$i<$length;$i++){
  $num[$i]=rand(0,61);
  $result.=$str[$num[$i]];
}
$text = $result;
$_SESSION ["administratorConfirmCode"] = $text;
/*设置图片的宽度和高度*/
$im_x = $w;
$im_y = $y;
/*创建图片*/
$im = imagecreatetruecolor($im_x,$im_y);
$text_c = ImageColorAllocate($im, mt_rand(0,100),mt_rand(0,100),mt_rand(0,100));
$tmpC0=mt_rand(100,255);
$tmpC1=mt_rand(100,255);
$tmpC2=mt_rand(100,255);
$buttum_c = ImageColorAllocate($im,$tmpC0,$tmpC1,$tmpC2);
imagefill($im, 16, 13, $buttum_c);
/*字体文件*/
$font = _WEB_DIR_.&#39;/font/comic.ttf&#39;;
for ($i=0;$i<strlen($text);$i++){
  $tmp =substr($text,$i,1);
  $array = array(-1,1);
  $p = array_rand($array);
  $an = $array[$p]*mt_rand(1,10);//角度
  $size = 28;
  imagettftext($im, $size, $an, 15+$i*$size, 35, $text_c, $font, $tmp);
}
/*将字符写入文件中*/
$distortion_im = imagecreatetruecolor ($im_x, $im_y);
imagefill($distortion_im, 16, 13, $buttum_c);
for ( $i=0; $i<$im_x; $i++) {
  for ( $j=0; $j<$im_y; $j++) {
    $rgb = imagecolorat($im, $i , $j);
    if( (int)($i+20+sin($j/$im_y*2*M_PI)*10) <= imagesx($distortion_im)&& (int)($i+20+sin($j/$im_y*2*M_PI)*10) >=0 ) {
      imagesetpixel ($distortion_im, (int)($i+10+sin($j/$im_y*2*M_PI-M_PI*0.1)*4) , $j , $rgb);
    }
  }
}
/*干扰元素点的数量*/
$count = 160;
/*创建干扰元素点*/
for($i=0; $i<$count; $i++){
  $randcolor = ImageColorallocate($distortion_im,mt_rand(0,255),mt_rand(0,255),mt_rand(0,255));
  imagesetpixel($distortion_im, mt_rand()%$im_x , mt_rand()%$im_y , $randcolor);
}
/*创建干扰线条*/
$rand = mt_rand(5,30);
$rand1 = mt_rand(15,25);
$rand2 = mt_rand(5,10);
for ($yy=$rand; $yy<=+$rand+2; $yy++){
  for ($px=-80;$px<=80;$px=$px+0.1){
    $x=$px/$rand1;
    if ($x!=0){
      $y=sin($x);
    }
    $py=$y*$rand2;
    imagesetpixel($distortion_im, $px+80, $py+$yy, $text_c);
  }
}
/*以PNG格式将图像输出到浏览器*/
ImagePNG($distortion_im);
/*销毁图像*/
ImageDestroy($distortion_im);
ImageDestroy($im);

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