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// 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/>.
/**
* JavaScript required by the question engine.
*
* @package moodlecore
* @subpackage questionengine
* @copyright 2008 The Open University
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
/**
* Scroll manager is a class that help with saving the scroll positing when you
* click on an action icon, and then when the page is reloaded after processing
* the action, it scrolls you to exactly where you were. This is much nicer for
* the user.
*
* To use this in your code, you need to ensure that:
* 1. The button that triggers the action has to have a click event handler that
* calls M.core_scroll_manager.save_scroll_pos
* 2. The script that process the action has to grab the scrollpos parameter
* using $scrollpos = optional_param('scrollpos', 0, PARAM_INT);
* 3. After doing the processing, it must add ->param('scrollpos', $scrollpos)
* to the URL that it redirects to.
* 4. Finally, on the page that is reloaded (which should be the same as the one
* the user started on) you need to call M.core_scroll_manager.scroll_to_saved_pos
* on page load.
*/
M.core_scroll_manager = M.core_scroll_manager || {};
/**
* In the form that contains the element, set the value of the form field with
* name scrollpos to the current scroll position. If there is no element with
* that name, it creates a hidden form field wiht that name within the form.
* @param element the element in the form. Should be something that can be
* passed to Y.one.
*/
M.core_scroll_manager.save_scroll_pos = function(Y, element) {
if (typeof(element) == 'string') {
// Have to use getElementById here because element id can contain :.
element = Y.one(document.getElementById(element));
}
var form = element.ancestor('form');
if (!form) {
return;
}
var scrollpos = form.one('input[name=scrollpos]');
if (!scrollpos) {
scrollpos = form.appendChild(form.create('<input type="hidden" name="scrollpos" />'));
}
scrollpos.set('value', form.get('docScrollY'));
}
/**
* Event handler that can be used on a link. Assumes that the link already
* contains at least one URL parameter.
*/
M.core_scroll_manager.save_scroll_action = function(e) {
var link = e.target.ancestor('a[href]');
if (!link) {
M.core_scroll_manager.save_scroll_pos({}, e.target);
return;
}
link.set('href', link.get('href') + '&scrollpos=' + link.get('docScrollY'));
}
/**
* If there is a parameter like scrollpos=123 in the URL, scroll to that saved position.
*/
M.core_scroll_manager.scroll_to_saved_pos = function(Y) {
var matches = window.location.href.match(/^.*[?&]scrollpos=(\d*)(?:&|$|#).*$/, '$1');
if (matches) {
// onDOMReady is the effective one here. I am leaving the immediate call to
// window.scrollTo in case it reduces flicker.
window.scrollTo(0, matches[1]);
Y.on('domready', function() { window.scrollTo(0, matches[1]); });
// And the following horror is necessary to make it work in IE 8.
// Note that the class ie8 on body is only there in Moodle 2.0 and OU Moodle.
if (Y.one('body').hasClass('ie')) {
M.core_scroll_manager.force_ie_to_scroll(Y, matches[1])
}
}
}
/**
* Beat IE into submission.
* @param targetpos the target scroll position.
*/
M.core_scroll_manager.force_ie_to_scroll = function(Y, targetpos) {
var hackcount = 25;
function do_scroll() {
window.scrollTo(0, targetpos);
hackcount -= 1;
if (hackcount > 0) {
setTimeout(do_scroll, 10);
}
}
Y.on('load', do_scroll, window);
}
M.core_question_engine = M.core_question_engine || {};
/**
* Flag used by M.core_question_engine.prevent_repeat_submission.
*/
M.core_question_engine.questionformalreadysubmitted = false;
/**
* Initialise a question submit button. This saves the scroll position and
* sets the fragment on the form submit URL so the page reloads in the right place.
* @param id the id of the button in the HTML.
* @param slot the number of the question_attempt within the usage.
*/
M.core_question_engine.init_submit_button = function(Y, button, slot) {
var buttonel = document.getElementById(button);
Y.on('click', function(e) {
M.core_scroll_manager.save_scroll_pos(Y, button);
buttonel.form.action = buttonel.form.action + '#q' + slot;
}, buttonel);
}
/**
* Initialise a form that contains questions printed using print_question.
* This has the effect of:
* 1. Turning off browser autocomlete.
* 2. Stopping enter from submitting the form (or toggling the next flag) unless
* keyboard focus is on the submit button or the flag.
* 3. Removes any '.questionflagsavebutton's, since we have JavaScript to toggle
* the flags using ajax.
* 4. Scroll to the position indicated by scrollpos= in the URL, if it is there.
* 5. Prevent the user from repeatedly submitting the form.
* @param Y the Yahoo object. Needs to have the DOM and Event modules loaded.
* @param form something that can be passed to Y.one, to find the form element.
*/
M.core_question_engine.init_form = function(Y, form) {
Y.one(form).setAttribute('autocomplete', 'off');
Y.on('submit', M.core_question_engine.prevent_repeat_submission, form, form, Y);
Y.on('key', function (e) {
if (!e.target.test('a') && !e.target.test('input[type=submit]') &&
!e.target.test('input[type=img]') && !e.target.test('textarea') && !e.target.test('[contenteditable=true]')) {
e.preventDefault();
}
}, form, 'press:13');
Y.one(form).all('.questionflagsavebutton').remove();
M.core_scroll_manager.scroll_to_saved_pos(Y);
}
/**
* Event handler to stop a question form being submitted more than once.
* @param e the form submit event.
* @param form the form element.
*/
M.core_question_engine.prevent_repeat_submission = function(e, Y) {
if (M.core_question_engine.questionformalreadysubmitted) {
e.halt();
return;
}
setTimeout(function() {
Y.all('input[type=submit]').set('disabled', true);
}, 0);
M.core_question_engine.questionformalreadysubmitted = true;
}