in book/master_middleman/source/javascripts/waypoints/context.js [1:300]
(function() {
'use strict'
function requestAnimationFrameShim(callback) {
window.setTimeout(callback, 1000 / 60)
}
var keyCounter = 0
var contexts = {}
var Waypoint = window.Waypoint
var oldWindowLoad = window.onload
/* http://imakewebthings.com/waypoints/api/context */
function Context(element) {
this.element = element
this.Adapter = Waypoint.Adapter
this.adapter = new this.Adapter(element)
this.key = 'waypoint-context-' + keyCounter
this.didScroll = false
this.didResize = false
this.oldScroll = {
x: this.adapter.scrollLeft(),
y: this.adapter.scrollTop()
}
this.waypoints = {
vertical: {},
horizontal: {}
}
element.waypointContextKey = this.key
contexts[element.waypointContextKey] = this
keyCounter += 1
this.createThrottledScrollHandler()
this.createThrottledResizeHandler()
}
/* Private */
Context.prototype.add = function(waypoint) {
var axis = waypoint.options.horizontal ? 'horizontal' : 'vertical'
this.waypoints[axis][waypoint.key] = waypoint
this.refresh()
}
/* Private */
Context.prototype.checkEmpty = function() {
var horizontalEmpty = this.Adapter.isEmptyObject(this.waypoints.horizontal)
var verticalEmpty = this.Adapter.isEmptyObject(this.waypoints.vertical)
if (horizontalEmpty && verticalEmpty) {
this.adapter.off('.waypoints')
delete contexts[this.key]
}
}
/* Private */
Context.prototype.createThrottledResizeHandler = function() {
var self = this
function resizeHandler() {
self.handleResize()
self.didResize = false
}
this.adapter.on('resize.waypoints', function() {
if (!self.didResize) {
self.didResize = true
Waypoint.requestAnimationFrame(resizeHandler)
}
})
}
/* Private */
Context.prototype.createThrottledScrollHandler = function() {
var self = this
function scrollHandler() {
self.handleScroll()
self.didScroll = false
}
this.adapter.on('scroll.waypoints', function() {
if (!self.didScroll || Waypoint.isTouch) {
self.didScroll = true
Waypoint.requestAnimationFrame(scrollHandler)
}
})
}
/* Private */
Context.prototype.handleResize = function() {
Waypoint.Context.refreshAll()
}
/* Private */
Context.prototype.handleScroll = function() {
var triggeredGroups = {}
var axes = {
horizontal: {
newScroll: this.adapter.scrollLeft(),
oldScroll: this.oldScroll.x,
forward: 'right',
backward: 'left'
},
vertical: {
newScroll: this.adapter.scrollTop(),
oldScroll: this.oldScroll.y,
forward: 'down',
backward: 'up'
}
}
for (var axisKey in axes) {
var axis = axes[axisKey]
var isForward = axis.newScroll > axis.oldScroll
var direction = isForward ? axis.forward : axis.backward
for (var waypointKey in this.waypoints[axisKey]) {
var waypoint = this.waypoints[axisKey][waypointKey]
var wasBeforeTriggerPoint = axis.oldScroll < waypoint.triggerPoint
var nowAfterTriggerPoint = axis.newScroll >= waypoint.triggerPoint
var crossedForward = wasBeforeTriggerPoint && nowAfterTriggerPoint
var crossedBackward = !wasBeforeTriggerPoint && !nowAfterTriggerPoint
if (crossedForward || crossedBackward) {
waypoint.queueTrigger(direction)
triggeredGroups[waypoint.group.id] = waypoint.group
}
}
}
for (var groupKey in triggeredGroups) {
triggeredGroups[groupKey].flushTriggers()
}
this.oldScroll = {
x: axes.horizontal.newScroll,
y: axes.vertical.newScroll
}
}
/* Private */
Context.prototype.innerHeight = function() {
/*eslint-disable eqeqeq */
if (this.element == this.element.window) {
return Waypoint.viewportHeight()
}
/*eslint-enable eqeqeq */
return this.adapter.innerHeight()
}
/* Private */
Context.prototype.remove = function(waypoint) {
delete this.waypoints[waypoint.axis][waypoint.key]
this.checkEmpty()
}
/* Private */
Context.prototype.innerWidth = function() {
/*eslint-disable eqeqeq */
if (this.element == this.element.window) {
return Waypoint.viewportWidth()
}
/*eslint-enable eqeqeq */
return this.adapter.innerWidth()
}
/* Public */
/* http://imakewebthings.com/waypoints/api/context-destroy */
Context.prototype.destroy = function() {
var allWaypoints = []
for (var axis in this.waypoints) {
for (var waypointKey in this.waypoints[axis]) {
allWaypoints.push(this.waypoints[axis][waypointKey])
}
}
for (var i = 0, end = allWaypoints.length; i < end; i++) {
allWaypoints[i].destroy()
}
}
/* Public */
/* http://imakewebthings.com/waypoints/api/context-refresh */
Context.prototype.refresh = function() {
/*eslint-disable eqeqeq */
var isWindow = this.element == this.element.window
/*eslint-enable eqeqeq */
var contextOffset = isWindow ? undefined : this.adapter.offset()
var triggeredGroups = {}
var axes
this.handleScroll()
axes = {
horizontal: {
contextOffset: isWindow ? 0 : contextOffset.left,
contextScroll: isWindow ? 0 : this.oldScroll.x,
contextDimension: this.innerWidth(),
oldScroll: this.oldScroll.x,
forward: 'right',
backward: 'left',
offsetProp: 'left'
},
vertical: {
contextOffset: isWindow ? 0 : contextOffset.top,
contextScroll: isWindow ? 0 : this.oldScroll.y,
contextDimension: this.innerHeight(),
oldScroll: this.oldScroll.y,
forward: 'down',
backward: 'up',
offsetProp: 'top'
}
}
for (var axisKey in axes) {
var axis = axes[axisKey]
for (var waypointKey in this.waypoints[axisKey]) {
var waypoint = this.waypoints[axisKey][waypointKey]
var adjustment = waypoint.options.offset
var oldTriggerPoint = waypoint.triggerPoint
var elementOffset = 0
var freshWaypoint = oldTriggerPoint == null
var contextModifier, wasBeforeScroll, nowAfterScroll
var triggeredBackward, triggeredForward
if (waypoint.element !== waypoint.element.window) {
elementOffset = waypoint.adapter.offset()[axis.offsetProp]
}
if (typeof adjustment === 'function') {
adjustment = adjustment.apply(waypoint)
}
else if (typeof adjustment === 'string') {
adjustment = parseFloat(adjustment)
if (waypoint.options.offset.indexOf('%') > - 1) {
adjustment = Math.ceil(axis.contextDimension * adjustment / 100)
}
}
contextModifier = axis.contextScroll - axis.contextOffset
waypoint.triggerPoint = elementOffset + contextModifier - adjustment
wasBeforeScroll = oldTriggerPoint < axis.oldScroll
nowAfterScroll = waypoint.triggerPoint >= axis.oldScroll
triggeredBackward = wasBeforeScroll && nowAfterScroll
triggeredForward = !wasBeforeScroll && !nowAfterScroll
if (!freshWaypoint && triggeredBackward) {
waypoint.queueTrigger(axis.backward)
triggeredGroups[waypoint.group.id] = waypoint.group
}
else if (!freshWaypoint && triggeredForward) {
waypoint.queueTrigger(axis.forward)
triggeredGroups[waypoint.group.id] = waypoint.group
}
else if (freshWaypoint && axis.oldScroll >= waypoint.triggerPoint) {
waypoint.queueTrigger(axis.forward)
triggeredGroups[waypoint.group.id] = waypoint.group
}
}
}
Waypoint.requestAnimationFrame(function() {
for (var groupKey in triggeredGroups) {
triggeredGroups[groupKey].flushTriggers()
}
})
return this
}
/* Private */
Context.findOrCreateByElement = function(element) {
return Context.findByElement(element) || new Context(element)
}
/* Private */
Context.refreshAll = function() {
for (var contextId in contexts) {
contexts[contextId].refresh()
}
}
/* Public */
/* http://imakewebthings.com/waypoints/api/context-find-by-element */
Context.findByElement = function(element) {
return contexts[element.waypointContextKey]
}
window.onload = function() {
if (oldWindowLoad) {
oldWindowLoad()
}
Context.refreshAll()
}
Waypoint.requestAnimationFrame = function(callback) {
var requestFn = window.requestAnimationFrame ||
window.mozRequestAnimationFrame ||
window.webkitRequestAnimationFrame ||
requestAnimationFrameShim
requestFn.call(window, callback)
}
Waypoint.Context = Context
}())