PHP学习笔记（5）GD库画验证码

 <?php
    header("content-type:image/png");
    $width = 500;
    $height = 500;
    $img = imagecreatetruecolor($width, $height);
    $string = "hello";
    //7种颜色，存入数组
    $red = imagecolorallocate($img, 255, 0, 0);
    $white = imagecolorallocate($img, 255, 255, 255);
    $green = imagecolorallocate($img, 0, 255, 0);
    $blue = imagecolorallocate($img, 0, 0, 255);
    $aaa = imagecolorallocate($img, 255, 255, 0);
    $bbb = imagecolorallocate($img, 0, 255, 255);
    $ccc = imagecolorallocate($img, 255, 0, 255);
    $colors = array($white,$red,$green,$blue,$aaa,$bbb,$ccc);
    //画点
    for ($i=0; $i < 1000; $i++) {
       imagesetpixel($img, mt_rand(0,$width), mt_rand(0,$height), $colors[mt_rand(0,6)]);
    }
    //划线
    for ($i=0; $i < 200; $i++) {
       imageline($img, mt_rand(0,$width), mt_rand(0,$height), mt_rand(0,$width), mt_rand(0,$height), $colors[mt_rand(0,6)]);
    }
    //生成4位验证码
    $a1 = range(0, 9);
    $a2 = range(a, z);
    $a3 = range(A, Z);
    $a4 = array_merge($a1,$a2,$a3);
    $num = 4;
    $fontsize = 60;
    for ($i=0; $i < 4; $i++) {
       imagettftext($img, $fontsize, mt_rand(-45,45), $width/$num*$i+$fontsize, $height/2, $colors[mt_rand(0,6)], "Fonts/msyh.ttf", $a4[mt_rand(0,61)]);
    }

    imagepng($img);
  ?>

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下面的小一点：

 <?php
    header("content-type:image/png");
    $width = 110;
    $height = 40;
    $img = imagecreatetruecolor($width, $height);
    $string = "hello";
    //7种颜色，存入数组
    $red = imagecolorallocate($img, 255, 0, 0);
    $white = imagecolorallocate($img, 255, 255, 255);
    $green = imagecolorallocate($img, 0, 255, 0);
    $blue = imagecolorallocate($img, 0, 0, 255);
    $aaa = imagecolorallocate($img, 255, 255, 0);
    $bbb = imagecolorallocate($img, 0, 255, 255);
    $ccc = imagecolorallocate($img, 255, 0, 255);
    $colors = array($white,$red,$green,$blue,$aaa,$bbb,$ccc);
    //画点
    for ($i=0; $i < 10; $i++) {
       imagesetpixel($img, mt_rand(0,$width), mt_rand(0,$height), $colors[mt_rand(0,6)]);
    }
    //划线
    for ($i=0; $i < 4; $i++) {
       imageline($img, mt_rand(0,$width), mt_rand(0,$height), mt_rand(0,$width), mt_rand(0,$height), $colors[mt_rand(0,6)]);
    }
    //生成4位验证码
    $a1 = range(0, 9);
    $a2 = range(a, z);
    $a3 = range(A, Z);
    $a4 = array_merge($a1,$a2,$a3);
    $num = 4;
    $fontsize = 20;
    for ($i=0; $i < 4; $i++) {
       imagettftext($img, $fontsize, mt_rand(-45,45), $width/$num*$i+5, 30, $colors[mt_rand(0,6)], "Fonts/msyh.ttf", $a4[mt_rand(0,61)]);
    }
    imagepng($img);
  ?>