Proyectos de Subversion Moodle

// 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 to allow dragging options to slots (using mouse down or touch) or tab through slots using keyboard.

 *

 * @module     qtype_ddimageortext/form

 * @copyright  2018 The Open University

 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later

 */

define(['jquery', 'core/dragdrop'], function($, dragDrop) {

    "use strict";

    /**

     * Singleton object to handle progressive enhancement of the

     * drag-drop onto image question editing form.

     * @type {Object}

     */

    var dragDropToImageForm = {

        /**

         * @var {Object} maxBgImageSize Properties width and height.

         * @private

         */

        maxBgImageSize: null,

        /**

         * @var {Object} maxDragImageSize with properties width and height.

         * @private

         */

        maxDragImageSize: null,

        /**

         * @property {object} fp for interacting with the file pickers.

         * @private

         */

        fp: null, // Object containing functions associated with the file picker.

        /**

         * Initialise the form javascript features.

         *

         * @method

         */

        init: function() {

            dragDropToImageForm.fp = dragDropToImageForm.filePickers();

            dragDropToImageForm.updateVisibilityOfFilePickers();

            dragDropToImageForm.setOptionsForDragItemSelectors();

            dragDropToImageForm.setupEventHandlers();

            dragDropToImageForm.waitForFilePickerToInitialise();

        },

        /**

         * Add html for the preview area.

         */

        setupPreviewArea: function() {

            $('#id_previewareaheader').append(

                '<div class="ddarea que ddimageortext">' +

                '  <div id="id_droparea" class="droparea">' +

                '    <img class="dropbackground" />' +

                '    <div class="dropzones"></div>' +

                '  </div>' +

                '  <div class="dragitems"></div>' +

                '</div>');

        },

        /**

         * Waits for the file-pickers to be sufficiently ready before initialising the preview.

         */

        waitForFilePickerToInitialise: function() {

            if (dragDropToImageForm.fp.file('bgimage').href === null) {

                // It would be better to use an onload or onchange event rather than this timeout.

                // Unfortunately attempts to do this early are overwritten by filepicker during its loading.

                setTimeout(dragDropToImageForm.waitForFilePickerToInitialise, 1000);

                return;

            }

            M.util.js_pending('dragDropToImageForm');

            // From now on, when a new file gets loaded into the filepicker, update the preview.

            // This is not in the setupEventHandlers section as it needs to be delayed until

            // after filepicker's javascript has finished.

            $('form.mform[data-qtype="ddimageortext"]').on('change', '.filepickerhidden', function() {

                M.util.js_pending('dragDropToImageForm');

                dragDropToImageForm.loadPreviewImage();

            });

            if ($('#id_droparea').length) {

                dragDropToImageForm.loadPreviewImage();

            } else {

                // Setup preview area when the background image is uploaded the first time.

                dragDropToImageForm.setupPreviewArea();

                dragDropToImageForm.loadPreviewImage();

            }

        },

        /**

         * Loads the preview background image.

         */

        loadPreviewImage: function() {

            $('fieldset#id_previewareaheader .dropbackground')

                .one('load', dragDropToImageForm.afterPreviewImageLoaded)

                .attr('src', dragDropToImageForm.fp.file('bgimage').href);

        },

        /**

         * After the background image is loaded, continue setting up the preview.

         */

        afterPreviewImageLoaded: function() {

            dragDropToImageForm.createDropZones();

            M.util.js_complete('dragDropToImageForm');

        },

        /**

         * Create, or recreate all the drop zones.

         */

        createDropZones: function() {

            var dropZoneHolder = $('.dropzones');

            dropZoneHolder.empty();

            var bgimageurl = dragDropToImageForm.fp.file('bgimage').href;

            if (bgimageurl === null) {

                return; // There is not currently a valid preview to update.

            }

            var numDrops = dragDropToImageForm.form.getFormValue('nodropzone', []);

            for (var dropNo = 0; dropNo < numDrops; dropNo++) {

                var dragNo = dragDropToImageForm.form.getFormValue('drops', [dropNo, 'choice']);

                if (dragNo === '0') {

                    continue;

                }

                dragNo = dragNo - 1;

                var group = dragDropToImageForm.form.getFormValue('drags', [dragNo, 'draggroup']),

                    label = dragDropToImageForm.form.getFormValue('draglabel', [dragNo]);

                if ('image' === dragDropToImageForm.form.getFormValue('drags', [dragNo, 'dragitemtype'])) {

                    var imgUrl = dragDropToImageForm.fp.file('dragitem[' + dragNo + ']').href;

                    if (imgUrl === null) {

                        continue;

                    }

                    // Althoug these are previews of drops, we also add the class name 'drag',

                    dropZoneHolder.append('<img class="droppreview group' + group + ' drop' + dropNo +

                            '" src="' + imgUrl + '" alt="' + label + '" data-drop-no="' + dropNo + '">');

                } else if (label !== '') {

                    dropZoneHolder.append('<div class="droppreview group' + group + ' drop' + dropNo +

                        '"  data-drop-no="' + dropNo + '">' + label + '</div>');

                }

            }

            dragDropToImageForm.waitForAllDropImagesToBeLoaded();

        },

        /**

         * This polls until all the drop-zone images have loaded, and then calls updateDropZones().

         */

        waitForAllDropImagesToBeLoaded: function() {

            var notYetLoadedImages = $('.dropzones img').not(function(i, imgNode) {

                return dragDropToImageForm.imageIsLoaded(imgNode);

            });

            if (notYetLoadedImages.length > 0) {

                setTimeout(function() {

                    dragDropToImageForm.waitForAllDropImagesToBeLoaded();

                }, 100);

                return;

            }

            dragDropToImageForm.updateDropZones();

        },

        /**

         * Check if an image has loaded without errors.

         *

         * @param {HTMLImageElement} imgElement an image.

         * @returns {boolean} true if this image has loaded without errors.

         */

        imageIsLoaded: function(imgElement) {

            return imgElement.complete && imgElement.naturalHeight !== 0;

        },

        /**

         * Set the size and position of all the drop zones.

         */

        updateDropZones: function() {

            var bgimageurl = dragDropToImageForm.fp.file('bgimage').href;

            if (bgimageurl === null) {

                return; // There is not currently a valid preview to update.

            }

            var dropBackgroundPosition = $('fieldset#id_previewareaheader .dropbackground').offset(),

                numDrops = dragDropToImageForm.form.getFormValue('nodropzone', []);

            // Move each drop to the right position and update the text.

            for (var dropNo = 0; dropNo < numDrops; dropNo++) {

                var drop = $('.dropzones .drop' + dropNo);

                if (drop.length === 0) {

                    continue;

                }

                var dragNo = dragDropToImageForm.form.getFormValue('drops', [dropNo, 'choice']) - 1;

                drop.offset({

                    left: dropBackgroundPosition.left +

                            parseInt(dragDropToImageForm.form.getFormValue('drops', [dropNo, 'xleft'])),

                    top: dropBackgroundPosition.top +

                            parseInt(dragDropToImageForm.form.getFormValue('drops', [dropNo, 'ytop']))

                });

                var label = dragDropToImageForm.form.getFormValue('draglabel', [dragNo]);

                if (drop.is('img')) {

                    drop.attr('alt', label);

                } else {

                    drop.html(label);

                }

            }

            // Resize them to the same size.

            $('.dropzones .droppreview').css('padding', '0');

            var numGroups = $('.draggroup select').first().find('option').length;

            for (var group = 1; group <= numGroups; group++) {

                dragDropToImageForm.resizeAllDragsAndDropsInGroup(group);

            }

        },

        /**

         * In a given group, set all the drags and drops to be the same size.

         *

         * @param {int} group the group number.

         */

        resizeAllDragsAndDropsInGroup: function(group) {

            var drops = $('.dropzones .droppreview.group' + group),

                maxWidth = 0,

                maxHeight = 0;

            // Find the maximum size of any drag in this groups.

            drops.each(function(i, drop) {

                maxWidth = Math.max(maxWidth, Math.ceil(drop.offsetWidth));

                maxHeight = Math.max(maxHeight, Math.ceil(drop.offsetHeight));

            });

            // The size we will want to set is a bit bigger than this.

            maxWidth += 10;

            maxHeight += 10;

            // Set each drag home to that size.

            drops.each(function(i, drop) {

                var left = Math.round((maxWidth - drop.offsetWidth) / 2),

                    top = Math.floor((maxHeight - drop.offsetHeight) / 2);

                // Set top and left padding so the item is centred.

                $(drop).css({

                    'padding-left': left + 'px',

                    'padding-right': (maxWidth - drop.offsetWidth - left) + 'px',

                    'padding-top': top + 'px',

                    'padding-bottom': (maxHeight - drop.offsetHeight - top) + 'px'

                });

            });

        },

        /**

         * Events linked to form actions.

         */

        setupEventHandlers: function() {

            // Changes to settings in the draggable items section.

            $('fieldset#id_draggableitemheader')

                .on('change input', 'input, select', function(e) {

                    var input = $(e.target).closest('select, input');

                    if (input.hasClass('dragitemtype')) {

                        dragDropToImageForm.updateVisibilityOfFilePickers();

                    }

                    dragDropToImageForm.setOptionsForDragItemSelectors();

                    if (input.is('.dragitemtype, .draggroup')) {

                        dragDropToImageForm.createDropZones();

                    } else if (input.is('.draglabel')) {

                        dragDropToImageForm.updateDropZones();

                    }

                });

            // Changes to Drop zones section: left, top and drag item.

            $('fieldset#id_dropzoneheader').on('change input', 'input, select', function(e) {

                var input = $(e.target).closest('select, input');

                if (input.is('select')) {

                    dragDropToImageForm.createDropZones();

                } else {

                    dragDropToImageForm.updateDropZones();

                }

            });

            // Moving drop zones in the preview.

            $('fieldset#id_previewareaheader').on('mousedown touchstart', '.droppreview', function(e) {

                dragDropToImageForm.dragStart(e);

            });

            $(window).on('resize', function() {

                dragDropToImageForm.updateDropZones();

            });

        },

        /**

         * Update all the drag item filepickers, so they are only shown for

         */

        updateVisibilityOfFilePickers: function() {

            var numDrags = dragDropToImageForm.form.getFormValue('noitems', []);

            for (var dragNo = 0; dragNo < numDrags; dragNo++) {

                var picker = $('input#id_dragitem_' + dragNo).closest('.fitem_ffilepicker');

                if ('image' === dragDropToImageForm.form.getFormValue('drags', [dragNo, 'dragitemtype'])) {

                    picker.show();

                } else {

                    picker.hide();

                }

            }

        },

        setOptionsForDragItemSelectors: function() {

            var dragItemOptions = {'0': ''},

                numDrags = dragDropToImageForm.form.getFormValue('noitems', []),

                numDrops = dragDropToImageForm.form.getFormValue('nodropzone', []);

            // Work out the list of options.

            for (var dragNo = 0; dragNo < numDrags; dragNo++) {

                var label = dragDropToImageForm.form.getFormValue('draglabel', [dragNo]);

                var file = dragDropToImageForm.fp.file(dragDropToImageForm.form.toNameWithIndex('dragitem', [dragNo]));

                if ('image' === dragDropToImageForm.form.getFormValue('drags', [dragNo, 'dragitemtype']) && file.name !== null) {

                    dragItemOptions[dragNo + 1] = (dragNo + 1) + '. ' + label + ' (' + file.name + ')';

                } else if (label !== '') {

                    dragItemOptions[dragNo + 1] = (dragNo + 1) + '. ' + label;

                }

            }

            // Initialise each select.

            for (var dropNo = 0; dropNo < numDrops; dropNo++) {

                var selector = $('#id_drops_' + dropNo + '_choice');

                var selectedvalue = selector.val();

                selector.find('option').remove();

                for (var value in dragItemOptions) {

                    if (!dragItemOptions.hasOwnProperty(value)) {

                        continue;

                    }

                    selector.append('<option value="' + value + '">' + dragItemOptions[value] + '</option>');

                    var optionnode = selector.find('option[value="' + value + '"]');

                    if (parseInt(value) === parseInt(selectedvalue)) {

                        optionnode.attr('selected', true);

                    } else if (dragDropToImageForm.isItemUsed(parseInt(value))) {

                        optionnode.attr('disabled', true);

                    }

                }

            }

        },

        /**

         * Checks if the specified drag option is already used somewhere.

         *

         * @param {Number} value of the drag item to check

         * @return {Boolean} true if item is allocated to dropzone

         */

        isItemUsed: function(value) {

            if (value === 0) {

                return false; // None option can always be selected.

            }

            if (dragDropToImageForm.form.getFormValue('drags', [value - 1, 'infinite'])) {

                return false; // Infinite, so can't be used up.

            }

            return $('fieldset#id_dropzoneheader select').filter(function(i, selectNode) {

                return parseInt($(selectNode).val()) === value;

            }).length !== 0;

        },

        /**

         * Handles when a dropzone in dragged in the preview.

         * @param {Object} e Event object

         */

        dragStart: function(e) {

            var drop = $(e.target).closest('.droppreview');

            var info = dragDrop.prepare(e);

            if (!info.start) {

                return;

            }

            dragDrop.start(e, drop, function(x, y, drop) {

                dragDropToImageForm.dragMove(drop);

            }, function() {

                dragDropToImageForm.dragEnd();

            });

        },

        /**

         * Handles update while a drop is being dragged.

         *

         * @param {jQuery} drop the drop preview being moved.

         */

        dragMove: function(drop) {

            var backgroundImage = $('fieldset#id_previewareaheader .dropbackground'),

                backgroundPosition = backgroundImage.offset(),

                dropNo = drop.data('dropNo'),

                dropPosition = drop.offset(),

                left = Math.round(dropPosition.left - backgroundPosition.left),

                top = Math.round(dropPosition.top - backgroundPosition.top);

            // Constrain coordinates to be inside the background.

            left = Math.round(Math.max(0, Math.min(left, backgroundImage.outerWidth() - drop.outerWidth())));

            top = Math.round(Math.max(0, Math.min(top, backgroundImage.outerHeight() - drop.outerHeight())));

            // Update the form.

            dragDropToImageForm.form.setFormValue('drops', [dropNo, 'xleft'], left);

            dragDropToImageForm.form.setFormValue('drops', [dropNo, 'ytop'], top);

        },

        /**

         * Handles when the drag ends.

         */

        dragEnd: function() {

            // Redraw, in case the position was constrained.

            dragDropToImageForm.updateDropZones();

        },

        /**

         * Low level operations on form.

         */

        form: {

            toNameWithIndex: function(name, indexes) {

                var indexString = name;

                for (var i = 0; i < indexes.length; i++) {

                    indexString = indexString + '[' + indexes[i] + ']';

                }

                return indexString;

            },

            getEl: function(name, indexes) {

                var form = $('form.mform[data-qtype="ddimageortext"]')[0];

                return form.elements[this.toNameWithIndex(name, indexes)];

            },

            /**

             * Helper to get the value of a form elements with name like "drops[0][xleft]".

             *

             * @param {String} name the base name, e.g. 'drops'.

             * @param {String[]} indexes the indexes, e.g. ['0', 'xleft'].

             * @return {String} the value of that field.

             */

            getFormValue: function(name, indexes) {

                var el = this.getEl(name, indexes);

                if (!el.type) {

                    el = el[el.length - 1];

                }

                if (el.type === 'checkbox') {

                    return el.checked;

                } else {

                    return el.value;

                }

            },

            /**

             * Helper to get the value of a form elements with name like "drops[0][xleft]".

             *

             * @param {String} name the base name, e.g. 'drops'.

             * @param {String[]} indexes the indexes, e.g. ['0', 'xleft'].

             * @param {String|Number} value the value to set.

             */

            setFormValue: function(name, indexes, value) {

                var el = this.getEl(name, indexes);

                if (el.type === 'checkbox') {

                    el.checked = value;

                } else {

                    el.value = value;

                }

            }

        },

        /**

         * Utility to get the file name and url from the filepicker.

         * @returns {Object} object containing functions {file, name}

         */

        filePickers: function() {

            var draftItemIdsToName;

            var nameToParentNode;

            if (draftItemIdsToName === undefined) {

                draftItemIdsToName = {};

                nameToParentNode = {};

                var fp = $('form.mform[data-qtype="ddimageortext"] input.filepickerhidden');

                fp.each(function(index, filepicker) {

                    draftItemIdsToName[filepicker.value] = filepicker.name;

                    nameToParentNode[filepicker.name] = filepicker.parentNode;

                });

            }

            return {

                file: function(name) {

                    var parentNode = $(nameToParentNode[name]);

                    var fileAnchor = parentNode.find('div.filepicker-filelist a');

                    if (fileAnchor.length) {

                        return {href: fileAnchor.get(0).href, name: fileAnchor.get(0).innerHTML};

                    } else {

                        return {href: null, name: null};

                    }

                },

                name: function(draftitemid) {

                    return draftItemIdsToName[draftitemid];

                }

            };

        }

    };

    return {

        init: dragDropToImageForm.init

    };

});