php圖片驗證碼函數實現扭曲字元的實現代碼

/** * CaptchaImage() - 建立扭曲字元的驗證碼圖片 * $session_name string 驗證碼圖片建立時所需產生Session的變數名 * $width int 驗證圖片的寬度，預設120，註：圖片高度與寬度比例相對固定 * $noise int 幹擾素的點數，預設0 * $disturb int 幹擾字元個數，預設0 * $curve bool 是否增加幹擾曲線，預設ture * */ function CaptchaImage($session_name = '', $width = 120, $noise = 0, $disturb = 0, $curve = true){ $im_x = $width; $im_y = ceil(0.25 * $width); $im = imagecreatetruecolor($im_x, $im_y); $text_c = ImageColorAllocate($im, mt_rand(0, 100), mt_rand(0, 100), mt_rand(0, 100)); $gray_rand = mt_rand(160, 220); $buttum_c = ImageColorAllocate($im, $gray_rand, $gray_rand, $gray_rand); imagefill($im, 0, 0, $buttum_c); session_start(); $text = ''; $characters = 'ABCEFGHJKLMNPQRSTUVWXYZ'; for($i = 0, $len = strlen($characters); $i < 4; $i++){ $text .= $characters{rand(0, $len - 1)}; if(isset($session_name{0}) && session_start()){ $_SESSION[$session_name] = $text; $_SESSION['CaptchaSessionTime'] = time(); } } $font = 'arial.ttf'; $size = floor(0.2 * $width); $ttfbox = imagettfbbox($size, 0, $font, $text); $text_width = abs($ttfbox[2] - $ttfbox[0]); $side = floor(($im_x - $text_width) / 2); $array = array(-1, 1); for ($i = 0; $i < strlen($text); $i++){ $p = array_rand($array); $an = $array[$p] * mt_rand(5, 10); // 字元傾斜角度 imagettftext($im, $size, $an, $side + $i * ($size - 1), $im_y - 3, $text_c, $font, $text{$i}); } $distortion_im = imagecreatetruecolor ($im_x, $im_y); imagefill($distortion_im, 0, 0, $buttum_c); $distortion = floor(0.04 * $width); // 扭曲程度 for ($i = 0; $i < $im_x; $i++){ for ($j = 0; $j < $im_y; $j++){ $rgb = imagecolorat($im, $i , $j); if( (int)($i + sin($j / $im_y * 2 * M_PI) * $distortion) <= $im_x && (int)($i + sin($j / $im_y * 2 * M_PI) * $distortion) >= 0 ){ imagesetpixel($distortion_im, (int)($i + sin($j / $im_y * 2 * M_PI - M_PI * 0.1) * $distortion) , $j, $rgb); } } } if($disturb > 0){ $chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789'; for($i = 0; $i < $disturb; $i++){ imagestring($distortion_im, 3, mt_rand(-10, $im_x), mt_rand(-10, $im_y), $chars[mt_rand(0, 35)], $text_c); } } //加入幹擾象素; if($noise > 0){ for($i = 0; $i < $noise; $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 , $randcolor); } } // 加幹擾曲線 if($curve){ $rand = mt_rand(5, 30); $rand1 = mt_rand(15, 25); $rand2 = mt_rand(5, 10); for ($yy = $rand; $yy <= $rand + 2; $yy++){ for ($px = -60; $px <= 60; $px++){ $x = $px / $rand1; $y = ($x != 0) ? sin($x) : $y; $py = $y * $rand2; imagesetpixel($distortion_im, $px + 60, $py + $yy, $text_c); } } } //設定檔案頭; Header("Content-type: image/JPEG"); //以PNG格式將映像輸出到瀏覽器或檔案; ImagePNG($distortion_im); //銷毀一映像，釋放與image關聯的記憶體; ImageDestroy($distortion_im); ImageDestroy($im); } CaptchaImage('code', 100); //產生一張圖片 並將隨機數字存放到key為code的session中 複製代碼

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