/
in-viewport.js
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/
in-viewport.js
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import Ember from 'ember';
import canUseDOM from 'ember-in-viewport/utils/can-use-dom';
import canUseRAF from 'ember-in-viewport/utils/can-use-raf';
import isInViewport from 'ember-in-viewport/utils/is-in-viewport';
import checkScrollDirection from 'ember-in-viewport/utils/check-scroll-direction';
import getOwner from 'ember-getowner-polyfill';
const {
Mixin,
setProperties,
merge,
typeOf,
assert,
$,
get,
set,
run: { scheduleOnce, debounce, bind, next },
computed: { not }
} = Ember;
const rAFIDS = {};
const lastDirection = {};
const lastPosition = {};
export default Mixin.create({
viewportExited: not('viewportEntered').readOnly(),
init() {
this._super(...arguments);
const options = merge({
viewportUseRAF: canUseRAF(),
viewportEntered: false
}, this._buildOptions());
setProperties(this, options);
},
didInsertElement() {
this._super(...arguments);
if (!canUseDOM) {
return;
}
this._setInitialViewport(window);
this._addObserverIfNotSpying();
this._bindScrollDirectionListener(window, get(this, 'viewportScrollSensitivity'));
if (!get(this, 'viewportUseRAF')) {
get(this, 'viewportListeners').forEach((listener) => {
const { context, event } = listener;
this._bindListeners(context, event);
});
}
},
willDestroyElement() {
this._super(...arguments);
this._unbindListeners();
},
_buildOptions(defaultOptions = {}) {
const owner = getOwner(this);
if (owner) {
return merge(defaultOptions, owner.lookup('config:in-viewport'));
}
},
_addObserverIfNotSpying() {
if (!get(this, 'viewportSpy')) {
this.addObserver('viewportEntered', this, this._unbindIfEntered);
}
},
_setViewportEntered(context = null) {
assert('You must pass a valid context to _setViewportEntered', context);
const element = get(this, 'element');
if (!element) {
return;
}
const $contextEl = $(context);
const boundingClientRect = element.getBoundingClientRect();
this._triggerDidAccessViewport(
isInViewport(
boundingClientRect,
$contextEl.height(),
$contextEl.width(),
get(this, 'viewportTolerance')
)
);
if (boundingClientRect && get(this, 'viewportUseRAF')) {
rAFIDS[get(this, 'elementId')] = window.requestAnimationFrame(
bind(this, this._setViewportEntered, context)
);
}
},
_triggerDidScrollDirection($contextEl = null, sensitivity = 1) {
assert('You must pass a valid context element to _triggerDidScrollDirection', $contextEl);
assert('sensitivity cannot be 0', sensitivity);
const elementId = get(this, 'elementId');
const lastDirectionForEl = lastDirection[elementId];
const lastPositionForEl = lastPosition[elementId];
const newPosition = {
top: $contextEl.scrollTop(),
left: $contextEl.scrollLeft()
};
const scrollDirection = checkScrollDirection(lastPositionForEl, newPosition, sensitivity);
const directionChanged = scrollDirection !== lastDirectionForEl;
if (scrollDirection && directionChanged && get(this, 'viewportEntered')) {
this.trigger('didScroll', scrollDirection);
lastDirection[elementId] = scrollDirection;
}
lastPosition[elementId] = newPosition;
},
_triggerDidAccessViewport(hasEnteredViewport = false) {
const viewportEntered = get(this, 'viewportEntered');
const didEnter = !viewportEntered && hasEnteredViewport;
const didLeave = viewportEntered && !hasEnteredViewport;
let triggeredEventName = '';
if (didEnter) {
triggeredEventName = 'didEnterViewport';
}
if (didLeave) {
triggeredEventName = 'didExitViewport';
}
if (get(this, 'viewportSpy') || !viewportEntered) {
set(this, 'viewportEntered', hasEnteredViewport);
}
this.trigger(triggeredEventName);
},
_unbindIfEntered() {
if (!get(this, 'viewportSpy') && get(this, 'viewportEntered')) {
this._unbindListeners();
this.removeObserver('viewportEntered', this, this._unbindIfEntered);
set(this, 'viewportEntered', true);
}
},
_setInitialViewport(context = null) {
assert('You must pass a valid context to _setInitialViewport', context);
return scheduleOnce('afterRender', this, () => {
this._setViewportEntered(context);
});
},
_debouncedEventHandler(methodName, ...args) {
assert('You must pass a methodName to _debouncedEventHandler', methodName);
assert('methodName must be a string', typeOf(methodName) === 'string');
debounce(this, () => this[methodName](...args), get(this, 'viewportRefreshRate'));
},
_bindScrollDirectionListener(context = null, sensitivity = 1) {
assert('You must pass a valid context to _bindScrollDirectionListener', context);
assert('sensitivity cannot be 0', sensitivity);
const $contextEl = $(context);
$contextEl.on(`scroll.directional#${get(this, 'elementId')}`, () => {
this._debouncedEventHandler('_triggerDidScrollDirection', $contextEl, sensitivity);
});
},
_unbindScrollDirectionListener(context = null) {
assert('You must pass a valid context to _bindScrollDirectionListener', context);
const elementId = get(this, 'elementId');
$(context).off(`scroll.directional#${elementId}`);
delete lastPosition[elementId];
delete lastDirection[elementId];
},
_bindListeners(context = null, event = null) {
assert('You must pass a valid context to _bindListeners', context);
assert('You must pass a valid event to _bindListeners', event);
$(context).on(`${event}.${get(this, 'elementId')}`, () => {
this._debouncedEventHandler('_setViewportEntered', context);
});
},
_unbindListeners() {
const elementId = get(this, 'elementId');
if (get(this, 'viewportUseRAF')) {
next(this, () => {
window.cancelAnimationFrame(rAFIDS[elementId]);
delete rAFIDS[elementId];
});
}
get(this, 'viewportListeners').forEach((listener) => {
const { context, event } = listener;
$(context).off(`${event}.${elementId}`);
});
this._unbindScrollDirectionListener(window);
}
});