// Utility functions for ordering and stacking of items
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var EPSILON = 0.001; // used when checking collisions, to prevent round-off errors
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/**
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* Order items by their start data
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* @param {Item[]} items
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*/
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exports.orderByStart = function(items) {
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items.sort(function (a, b) {
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return a.data.start - b.data.start;
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});
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};
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/**
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* Order items by their end date. If they have no end date, their start date
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* is used.
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* @param {Item[]} items
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*/
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exports.orderByEnd = function(items) {
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items.sort(function (a, b) {
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var aTime = ('end' in a.data) ? a.data.end : a.data.start,
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bTime = ('end' in b.data) ? b.data.end : b.data.start;
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return aTime - bTime;
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});
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};
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/**
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* Adjust vertical positions of the items such that they don't overlap each
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* other.
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* @param {Item[]} items
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* All visible items
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* @param {{item: {horizontal: number, vertical: number}, axis: number}} margin
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* Margins between items and between items and the axis.
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* @param {boolean} [force=false]
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* If true, all items will be repositioned. If false (default), only
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* items having a top===null will be re-stacked
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*/
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exports.stack = function(items, margin, force) {
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var i, iMax;
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if (force) {
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// reset top position of all items
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for (i = 0, iMax = items.length; i < iMax; i++) {
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items[i].top = null;
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}
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}
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// calculate new, non-overlapping positions
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for (i = 0, iMax = items.length; i < iMax; i++) {
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var item = items[i];
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if (item.stack && item.top === null) {
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// initialize top position
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item.top = margin.axis;
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do {
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// TODO: optimize checking for overlap. when there is a gap without items,
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// you only need to check for items from the next item on, not from zero
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var collidingItem = null;
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for (var j = 0, jj = items.length; j < jj; j++) {
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var other = items[j];
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if (other.top !== null && other !== item && other.stack && exports.collision(item, other, margin.item)) {
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collidingItem = other;
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break;
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}
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}
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if (collidingItem != null) {
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// There is a collision. Reposition the items above the colliding element
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item.top = collidingItem.top + collidingItem.height + margin.item.vertical;
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}
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} while (collidingItem);
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}
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}
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};
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/**
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* Adjust vertical positions of the items without stacking them
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* @param {Item[]} items
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* All visible items
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* @param {{item: {horizontal: number, vertical: number}, axis: number}} margin
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* Margins between items and between items and the axis.
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*/
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exports.nostack = function(items, margin, subgroups) {
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var i, iMax, newTop;
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// reset top position of all items
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for (i = 0, iMax = items.length; i < iMax; i++) {
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if (items[i].data.subgroup !== undefined) {
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newTop = margin.axis;
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for (var subgroup in subgroups) {
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if (subgroups.hasOwnProperty(subgroup)) {
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if (subgroups[subgroup].visible == true && subgroups[subgroup].index < subgroups[items[i].data.subgroup].index) {
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newTop += subgroups[subgroup].height + margin.item.vertical;
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}
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}
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}
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items[i].top = newTop;
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}
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else {
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items[i].top = margin.axis;
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}
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}
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};
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/**
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* Test if the two provided items collide
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* The items must have parameters left, width, top, and height.
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* @param {Item} a The first item
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* @param {Item} b The second item
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* @param {{horizontal: number, vertical: number}} margin
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* An object containing a horizontal and vertical
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* minimum required margin.
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* @return {boolean} true if a and b collide, else false
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*/
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exports.collision = function(a, b, margin) {
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return ((a.left - margin.horizontal + EPSILON) < (b.left + b.width) &&
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(a.left + a.width + margin.horizontal - EPSILON) > b.left &&
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(a.top - margin.vertical + EPSILON) < (b.top + b.height) &&
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(a.top + a.height + margin.vertical - EPSILON) > b.top);
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};
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