Search moodle.org's
Developer Documentation

See Release Notes
Long Term Support Release

  • Bug fixes for general core bugs in 4.1.x will end 13 November 2023 (12 months).
  • Bug fixes for security issues in 4.1.x will end 10 November 2025 (36 months).
  • PHP version: minimum PHP 7.4.0 Note: minimum PHP version has increased since Moodle 4.0. PHP 8.0.x is supported too.
<?php
// This file is part of Moodle - http://moodle.org/
//
// Moodle is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Moodle is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.

require_once('../../../../config.php');

$id = required_param('id', PARAM_INT);

$PAGE->set_url('/mod/feedback/item/captcha/print_captcha.php', array('id'=>$id));

if ($id) {
    if (! $cm = get_coursemodule_from_id('feedback', $id)) {
< print_error('invalidcoursemodule');
> throw new \moodle_exception('invalidcoursemodule');
} if (! $course = $DB->get_record("course", array("id"=>$cm->course))) {
< print_error('coursemisconf');
> throw new \moodle_exception('coursemisconf');
} if (! $feedback = $DB->get_record("feedback", array("id"=>$cm->instance))) {
< print_error('invalidcoursemodule');
> throw new \moodle_exception('invalidcoursemodule');
} } if (!isset($SESSION->feedback->item->captcha)) {
< print_error('captchanotset', 'feedback');
> throw new \moodle_exception('captchanotset', 'feedback');
} $height = 40; $charcount = $SESSION->feedback->item->captcha->charcount; $fontfile = $CFG->libdir.'/default.ttf'; $ttfbox = imagettfbbox ( 30, 0, $fontfile, 'H' );//the text to measure $charwidth = $ttfbox[2]; $width = $charcount * $charwidth; $scale = 0.3; $elipsesize = intval((($width + $height)/2) / 5); $factor_x = intval($width * $scale); $factor_y = intval($height * $scale); //I split the colors in three ranges //given are the max-min-values $colors = array(array(0, 40), array(50, 200), array(210, 255)); list($col_text1, $col_el, $col_text2) = $colors; //if the text is in color_1 so the elipses can be in color_2 or color_3 //if the text is in color_2 so the elipses can be in color_1 or color_3 //and so on. $textcolnum = rand(1, 3); //create the numbers to print out $nums = array(); for ($i = 0; $i < $charcount; $i++) { $nums[] = rand(0, 9); //Ziffern von 0- } //to draw enough elipses so I draw 0.2 * width and 0.2 * height //we need th colors for that $properties = array(); for ($x = 0; $x < $factor_x; $x++) { for ($y = 0; $y < $factor_y; $y++) { $propobj = new stdClass(); $propobj->x = intval($x / $scale); $propobj->y = intval($y / $scale); $propobj->red = get_random_color($col_el[0], $col_el[1]); $propobj->green = get_random_color($col_el[0], $col_el[1]); $propobj->blue = get_random_color($col_el[0], $col_el[1]); $properties[] = $propobj; } } shuffle($properties); // create a blank image $image = imagecreatetruecolor($width, $height); $bg = imagecolorallocate($image, 0, 0, 0); for ($i = 0; $i < ($factor_x * $factor_y); $i++) { $propobj = $properties[$i]; // choose a color for the ellipse $col_ellipse = imagecolorallocate($image, $propobj->red, $propobj->green, $propobj->blue); // draw the white ellipse imagefilledellipse($image, $propobj->x, $propobj->y, $elipsesize, $elipsesize, $col_ellipse); } $checkchar = ''; for ($i = 0; $i < $charcount; $i++) { $colnum = rand(1, 2); $textcol = new stdClass(); $textcol->red = get_random_color(${'col_text'.$colnum}[0], ${'col_text'.$colnum}[1]); $textcol->green = get_random_color(${'col_text'.$colnum}[0], ${'col_text'.$colnum}[1]); $textcol->blue = get_random_color(${'col_text'.$colnum}[0], ${'col_text'.$colnum}[1]); $color_text = imagecolorallocate($image, $textcol->red, $textcol->green, $textcol->blue); $angle_text = rand(-20, 20); $left_text = $i * $charwidth; $text = $nums[$i]; $checkchar .= $text; imagettftext($image, 30, $angle_text, $left_text, 35, $color_text, $fontfile, $text); } $SESSION->feedback->item->captcha->checkchar = $checkchar; // output the picture header("Content-type: image/png"); imagepng($image); function get_random_color($val1 = 0, $val2 = 255) { $min = $val1 < $val2 ? $val1 : $val2; $max = $val1 > $val2 ? $val1 : $val2; return rand($min, $max); }