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amp-lightbox-gallery.js
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amp-lightbox-gallery.js
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/**
* Copyright 2016 The AMP HTML Authors. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS-IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import {Animation} from '../../../src/animation';
import {CSS} from '../../../build/amp-lightbox-gallery-0.1.css';
import {CommonSignals} from '../../../src/common-signals';
import {
ELIGIBLE_TAP_TAGS,
LightboxManager,
LightboxThumbnailDataDef,
VIDEO_TAGS,
} from './service/lightbox-manager-impl';
import {Gestures} from '../../../src/gesture';
import {Keys} from '../../../src/utils/key-codes';
import {Services} from '../../../src/services';
import {SwipeYRecognizer} from '../../../src/gesture-recognizers';
import {bezierCurve} from '../../../src/curve';
import {
childElementByTag,
closest,
closestAncestorElementBySelector,
elementByTag,
scopedQuerySelector,
scopedQuerySelectorAll,
} from '../../../src/dom';
import {clamp} from '../../../src/utils/math';
import {dev, devAssert, user, userAssert} from '../../../src/log';
import {dict} from '../../../src/utils/object';
import {escapeCssSelectorIdent} from '../../../src/css';
import {getData, isLoaded, listen} from '../../../src/event-helper';
import {
getElementServiceForDoc,
} from '../../../src/element-service';
import {htmlFor} from '../../../src/static-template';
import {
numeric,
setStyles as setStylesTransition,
} from '../../../src/transition';
import {
prepareImageAnimation,
} from '@ampproject/animations/dist/animations.mjs';
import {setStyle, setStyles, toggle} from '../../../src/style';
import {toArray} from '../../../src/types';
import {triggerAnalyticsEvent} from '../../../src/analytics';
/** @const */
const TAG = 'amp-lightbox-gallery';
const DEFAULT_GALLERY_ID = 'amp-lightbox-gallery';
const SLIDE_ITEM_SELECTOR =
'.i-amphtml-slide-item, .i-amphtml-carousel-slotted';
/**
* Set of namespaces that indicate the lightbox controls mode.
* Lightbox controls include top bar, description box
*
* @enum {number}
*/
const LightboxControlsModes = {
CONTROLS_DISPLAYED: 1,
CONTROLS_HIDDEN: 0,
};
const SWIPE_TO_CLOSE_THRESHOLD = 10;
// Use S Curves for entry and exit animations
const TRANSITION_CURVE = {x1: 0.8, y1: 0, x2: 0.2, y2: 1};
const FADE_CURVE = bezierCurve(0.8, 0, 0.2, 1);
const MAX_TRANSITION_DURATION = 1000; // ms
const MIN_TRANSITION_DURATION = 500; // ms
const MAX_DISTANCE_APPROXIMATION = 250; // px
const MOTION_DURATION_RATIO = 0.8; // fraction of animation
/**
* The structure that represents the metadata of a lightbox element
*
* @typedef {{
* descriptionText: string,
* tagName: string,
* imageViewer: ?Element,
* sourceElement: !Element,
* element: !Element
* }}
*/
let LightboxElementMetadataDef;
/**
* @private visible for testing.
*/
export class AmpLightboxGallery extends AMP.BaseElement {
/** @param {!AmpElement} element */
constructor(element) {
super(element);
/** @private {Document} */
this.doc_ = this.win.document;
/** @private {boolean} */
this.isActive_ = false;
/** @private {number} */
this.historyId_ = -1;
/** @private {number} */
this.currentElemId_ = -1;
/** @private {function(!Event)} */
this.boundOnKeyDown_ = this.onKeyDown_.bind(this);
/**
* @private {?./service/lightbox-manager-impl.LightboxManager}
*/
this.manager_ = null;
/** @private {?../../../src/service/history-impl.History}*/
this.history_ = null;
/** @private {?../../../src/service/action-impl.ActionService} */
this.action_ = null;
/** @private {!Object<string,!Array<!LightboxElementMetadataDef>>} */
this.elementsMetadata_ = {
default: [],
};
/** @private {?Element} */
this.container_ = null;
/** @private {?Element} */
this.carouselContainer_ = null;
/** @private {?Element} */
this.controlsContainer_ = null;
/** @private {?Element} */
this.navControls_ = null;
/** @private {?Element} */
this.carousel_ = null;
/** @private {?Element} */
this.descriptionBox_ = null;
/** @private {?Element} */
this.descriptionTextArea_ = null;
/** @private {?Element} */
this.descriptionOverflowMask_ = null;
/** @private {?Element} */
this.gallery_ = null;
/** @private {?Element} */
this.topBar_ = null;
/** @private {!LightboxControlsModes} */
this.controlsMode_ = LightboxControlsModes.CONTROLS_DISPLAYED;
/** @private {?UnlistenDef} */
this.unlistenClick_ = null;
/** @private {string} */
this.currentLightboxGroupId_ = 'default';
/** @private {?Element} */
this.sourceElement_ = null;
}
/** @override */
renderOutsideViewport() {
return true;
}
/** @override */
buildCallback() {
return lightboxManagerForDoc(this.element).then(manager => {
this.manager_ = manager;
this.history_ = Services.historyForDoc(this.getAmpDoc());
this.action_ = Services.actionServiceForDoc(this.element);
const viewer = Services.viewerForDoc(this.getAmpDoc());
return viewer.whenFirstVisible();
}).then(() => {
this.container_ = htmlFor(this.doc_)`
<div class="i-amphtml-lbg">
<div class="i-amphtml-lbg-mask"></div>
</div>`;
this.element.appendChild(this.container_);
this.manager_.maybeInit();
this.registerDefaultAction(
invocation => this.open_(invocation),
'open');
});
}
/** @override */
layoutCallback() {
// DO NOT ADD CODE HERE
// layoutCallback for lightbox-viewer is meaningless, lightbox-viewer
// doesn't have children, it just manages elements elsewhere in the page in
// `open_` `close_` and `updateViewer_` methods.
return Promise.resolve();
}
/**
* Builds all controls (top bar and description) and appends them to the
* lightbox container
* @private
*/
buildControls_() {
this.controlsContainer_ = htmlFor(this.doc_)`
<div class="i-amphtml-lbg-controls"></div>`;
this.buildDescriptionBox_();
this.buildTopBar_();
this.buildNavControls_();
this.mutateElement(() => {
this.container_.appendChild(this.controlsContainer_);
});
}
/**
* @param {string} lightboxGroupId
* @return {!Promise}
* @private
*/
findOrInitializeLightbox_(lightboxGroupId) {
if (!this.carouselContainer_) {
this.carouselContainer_ = this.doc_.createElement('div');
this.container_.appendChild(this.carouselContainer_);
}
if (!this.controlsContainer_) {
this.buildControls_();
}
return this.findOrBuildCarousel_(lightboxGroupId);
}
/**
* Return a cleaned clone of the given element for building
* carousel slides with.
* @param {!Element} element
* @private
*/
cloneLightboxableElement_(element) {
const deepClone = !element.classList.contains(
'i-amphtml-element');
const clonedNode = element.cloneNode(deepClone);
clonedNode.removeAttribute('on');
clonedNode.removeAttribute('id');
clonedNode.removeAttribute('i-amphtml-layout');
return clonedNode;
}
/**
* Given a list of lightboxable elements, build the internal carousel slides
* @param {!Array<!Element>} lightboxableElements
* @private
*/
buildCarouselSlides_(lightboxableElements) {
let index = 0;
this.elementsMetadata_[this.currentLightboxGroupId_] = [];
lightboxableElements.forEach(element => {
element.lightboxItemId = index++;
const clonedNode = this.cloneLightboxableElement_(element);
const descText = this.manager_.getDescription(element);
const metadata = {
descriptionText: descText,
tagName: clonedNode.tagName,
sourceElement: element,
element: clonedNode,
};
let slide = clonedNode;
if (ELIGIBLE_TAP_TAGS[clonedNode.tagName]) {
const container = this.doc_.createElement('div');
const imageViewer = htmlFor(this.doc_)`
<amp-image-viewer layout="fill"></amp-image-viewer>`;
clonedNode.removeAttribute('class');
imageViewer.appendChild(clonedNode);
container.appendChild(imageViewer);
slide = container;
metadata.imageViewer = imageViewer;
}
this.carousel_.appendChild(slide);
this.elementsMetadata_[this.currentLightboxGroupId_].push(metadata);
});
}
/**
* Returns the existing carousel corresponding to the group id
* or builds a new one.
* @param {string} lightboxGroupId
* @return {!Promise}
* @private
*/
findOrBuildCarousel_(lightboxGroupId) {
devAssert(this.container_);
const existingCarousel = this.element.querySelector(
`amp-carousel[amp-lightbox-group=${
escapeCssSelectorIdent(lightboxGroupId)
}]`);
if (existingCarousel) {
this.carousel_ = existingCarousel;
return this.showCarousel_(lightboxGroupId);
} else {
return this.buildCarousel_(lightboxGroupId);
}
}
/**
* @param {string} lightboxGroupId
* @return {!Promise}
* @private
*/
showCarousel_(lightboxGroupId) {
return this.mutateElement(() => {
const {length} = this.elementsMetadata_[lightboxGroupId];
this.maybeEnableMultipleItemControls_(length);
toggle(dev().assertElement(this.carousel_), true);
});
}
/**
* Builds the carousel and appends it to the container.
* @param {string} lightboxGroupId
* @return {!Promise}
* @private
*/
buildCarousel_(lightboxGroupId) {
return Promise.all([
Services.extensionsFor(this.win).installExtensionForDoc(
this.getAmpDoc(), 'amp-carousel'),
Services.extensionsFor(this.win).installExtensionForDoc(
this.getAmpDoc(), 'amp-image-viewer'),
]).then(() => {
return this.manager_.getElementsForLightboxGroup(lightboxGroupId);
}).then(list => {
this.carousel_ = htmlFor(this.doc_)`
<amp-carousel type="slides" layout="fill" loop="true"></amp-carousel>`;
this.carousel_.setAttribute('amp-lightbox-group', lightboxGroupId);
this.buildCarouselSlides_(list);
return this.mutateElement(() => {
this.carouselContainer_.appendChild(this.carousel_);
this.maybeEnableMultipleItemControls_(list.length);
});
});
}
/**
* @param {number} itemLength
* @private
*/
maybeEnableMultipleItemControls_(itemLength) {
const isDisabled = itemLength <= 1;
const ghost = 'i-amphtml-ghost';
const container = dev().assertElement(this.controlsContainer_);
[
'.i-amphtml-lbg-button-next',
'.i-amphtml-lbg-button-prev',
'.i-amphtml-lbg-button-gallery',
].forEach(selector => {
dev().assertElement(scopedQuerySelector(container, selector))
.classList.toggle(ghost, isDisabled);
});
}
/**
* Handles slide change.
* @param {!Event} event
* @private
*/
slideChangeHandler_(event) {
this.currentElemId_ = getData(event)['index'];
this.updateDescriptionBox_();
}
/**
* Build description box and append it to the container.
* @private
*/
buildDescriptionBox_() {
this.descriptionBox_ = htmlFor(this.doc_)`
<div class="i-amphtml-lbg-desc-box i-amphtml-lbg-standard">
<div class="i-amphtml-lbg-desc-text"></div>
<div class="i-amphtml-lbg-desc-mask"></div>
</div>`;
this.descriptionTextArea_ = this.descriptionBox_.querySelector(
'.i-amphtml-lbg-desc-text');
this.descriptionOverflowMask_ = this.descriptionBox_.querySelector(
'.i-amphtml-lbg-desc-mask');
this.descriptionBox_.addEventListener('click', event => {
this.toggleDescriptionOverflow_();
event.stopPropagation();
});
this.controlsContainer_.appendChild(this.descriptionBox_);
}
/**
* Update description box text.
* @private
*/
updateDescriptionBox_() {
const descText = this.getCurrentElement_().descriptionText;
if (!descText) {
this.mutateElement(() => {
toggle(dev().assertElement(this.descriptionBox_), false);
});
} else {
this.mutateElement(() => {
// The problem with setting innerText is that it not only removes child
// nodes from the element, but also permanently destroys all descendant
// text nodes. It is okay in this case because the description text area
// is a div that does not contain descendant elements.
this.descriptionTextArea_./*OK*/innerText = descText;
// Avoid flickering out if transitioning from a slide with no text
this.descriptionBox_.classList.remove('i-amphtml-lbg-fade-out');
toggle(dev().assertElement(this.descriptionBox_), true);
}).then(() => {
let descriptionOverflows, isInOverflowMode;
const measureOverflowState = () => {
// The height of the description without overflow is set to 4 rem.
// The height of the overflow mask is set to 1 rem. We allow 3 lines
// for the description and consider it to have overflow if more than 3
// lines of text.
descriptionOverflows = this.descriptionBox_./*OK*/scrollHeight
- this.descriptionBox_./*OK*/clientHeight
>= this.descriptionOverflowMask_./*OK*/clientHeight;
isInOverflowMode = this.descriptionBox_.classList
.contains('i-amphtml-lbg-overflow');
};
const mutateOverflowState = () => {
// We toggle visibility instead of display because we rely on the
// height of this element to measure 1 rem.
setStyles(dev().assertElement(this.descriptionOverflowMask_), {
visibility: descriptionOverflows || isInOverflowMode
? 'visible' : 'hidden',
});
if (isInOverflowMode) {
this.clearDescOverflowState_();
}
};
this.measureMutateElement(measureOverflowState, mutateOverflowState);
});
}
}
/**
* Toggle the overflow state of description box
* @private
*/
toggleDescriptionOverflow_() {
triggerAnalyticsEvent(this.element, 'descriptionOverflowToggled', dict({}));
let isInStandardMode, isInOverflowMode, descriptionOverflows;
const measureOverflowState = () => {
isInStandardMode = this.descriptionBox_.classList
.contains('i-amphtml-lbg-standard');
isInOverflowMode = this.descriptionBox_.classList
.contains('i-amphtml-lbg-overflow');
// The height of the description without overflow is set to 4 rem.
// The height of the overflow mask is set to 1 rem. We allow 3 lines
// for the description and consider it to have overflow if more than 3
// lines of text.
descriptionOverflows = this.descriptionBox_./*OK*/scrollHeight
- this.descriptionBox_./*OK*/clientHeight
>= this.descriptionOverflowMask_./*OK*/clientHeight;
};
const mutateOverflowState = () => {
if (isInStandardMode && descriptionOverflows) {
this.descriptionBox_.classList.remove('i-amphtml-lbg-standard');
this.descriptionBox_.classList.add('i-amphtml-lbg-overflow');
toggle(user().assertElement(this.navControls_,
'E#19457 this.navControls_'), false);
toggle(user().assertElement(this.topBar_, 'E#19457 this.topBar_'),
false);
} else if (isInOverflowMode) {
this.clearDescOverflowState_();
}
};
this.measureMutateElement(measureOverflowState, mutateOverflowState);
}
/**
* @private
*/
clearDescOverflowState_() {
this.descriptionBox_./*OK*/scrollTop = 0;
this.descriptionBox_.classList.remove('i-amphtml-lbg-overflow');
this.descriptionBox_.classList.add('i-amphtml-lbg-standard');
toggle(user().assertElement(this.navControls_,
'E#19457 this.navControls_'), true);
toggle(user().assertElement(this.topBar_,
'E#19457 this.topBar_'), true);
}
/**
* @private
*/
nextSlide_() {
devAssert(this.carousel_).getImpl().then(carousel => {
carousel.interactionNext();
});
}
/**
* @private
*/
prevSlide_() {
devAssert(this.carousel_).getImpl().then(carousel => {
carousel.interactionPrev();
});
}
/**
* @private
*/
buildNavControls_() {
this.navControls_ = this.doc_.createElement('div');
const nextSlide = this.nextSlide_.bind(this);
const prevSlide = this.prevSlide_.bind(this);
const nextButton = this.buildButton_('Next',
'i-amphtml-lbg-button-next', nextSlide);
const prevButton = this.buildButton_('Prev',
'i-amphtml-lbg-button-prev', prevSlide);
const input = Services.inputFor(this.win);
if (!input.isMouseDetected()) {
prevButton.classList.add('i-amphtml-screen-reader');
nextButton.classList.add('i-amphtml-screen-reader');
}
this.navControls_.appendChild(prevButton);
this.navControls_.appendChild(nextButton);
this.controlsContainer_.appendChild(this.navControls_);
}
/**
* Builds the top bar containing buttons and appends them to the container.
* @private
*/
buildTopBar_() {
devAssert(this.container_);
this.topBar_ = this.doc_.createElement('div');
this.topBar_.classList.add('i-amphtml-lbg-top-bar');
const close = this.close_.bind(this);
const openGallery = this.openGallery_.bind(this);
const closeGallery = this.closeGallery_.bind(this);
// TODO(aghassemi): i18n and customization. See https://git.io/v6JWu
const closeButton = this.buildButton_('Close',
'i-amphtml-lbg-button-close', close);
const openGalleryButton = this.buildButton_('Gallery',
'i-amphtml-lbg-button-gallery', openGallery);
const closeGalleryButton = this.buildButton_('Content',
'i-amphtml-lbg-button-slide', closeGallery);
this.topBar_.appendChild(closeButton);
this.topBar_.appendChild(openGalleryButton);
this.topBar_.appendChild(closeGalleryButton);
this.controlsContainer_.appendChild(this.topBar_);
}
/**
* Builds a button and appends it to the container.
* @param {string} label Text of the button for a11y
* @param {string} className Css classname
* @param {function()} action function to call when tapped
* @private
*/
buildButton_(label, className, action) {
devAssert(this.topBar_);
const button = htmlFor(this.doc_)`
<div role="button" class="i-amphtml-lbg-button">
<span class="i-amphtml-lbg-icon"></span>
</div>`;
button.setAttribute('aria-label', label);
button.classList.add(className);
button.addEventListener('click', event => {
action();
event.stopPropagation();
event.preventDefault();
});
return button;
}
/**
* We should not try to toggle controls or otherwise handle a click on
* the lightbox if the click has already been handled by a link, a button,
* or an existing tap action handler.
* @param {!Event} e
* @return {boolean}
*/
shouldHandleClick_(e) {
const target = dev().assertElement(e.target);
const consumingElement = closest(target, element => {
return element.tagName == 'BUTTON'
|| element.tagName == 'A'
|| element.getAttribute('role') == 'button';
}, this.container_);
const clickConsumed = consumingElement !== null;
const hasTap = this.action_.hasAction(target, 'tap',
dev().assertElement(this.container_));
return !(clickConsumed || hasTap);
}
/**
* Toggle lightbox controls including topbar and description.
* @param {!Event} e
* @private
*/
onToggleControls_(e) {
if (this.shouldHandleClick_(e)) {
if (this.controlsMode_ == LightboxControlsModes.CONTROLS_HIDDEN) {
this.showControls_();
} else if (!this.container_.hasAttribute('gallery-view')) {
this.hideControls_();
}
}
triggerAnalyticsEvent(this.element, 'controlsToggled', dict({}));
}
/**
* Show lightbox controls.
* @private
*/
showControls_() {
this.controlsContainer_.classList.remove('i-amphtml-lbg-fade-out');
this.controlsContainer_.classList.remove('i-amphtml-lbg-hidden');
this.controlsContainer_.classList.add('i-amphtml-lbg-fade-in');
if (!this.container_.hasAttribute('gallery-view')) {
this.updateDescriptionBox_();
}
this.controlsMode_ = LightboxControlsModes.CONTROLS_DISPLAYED;
}
/**
* Hide lightbox controls without fade effect.
* @private
*/
hideControls_() {
this.controlsContainer_.classList.remove('i-amphtml-lbg-fade-in');
this.controlsContainer_.classList.add('i-amphtml-lbg-fade-out');
this.controlsMode_ = LightboxControlsModes.CONTROLS_HIDDEN;
}
/**
* Set up event listeners.
* @private
*/
setupEventListeners_() {
devAssert(this.container_);
const onToggleControls = this.onToggleControls_.bind(this);
this.unlistenClick_ = listen(dev().assertElement(this.container_),
'click', onToggleControls);
}
/**
* Clean up event listeners.
* @private
*/
cleanupEventListeners_() {
if (this.unlistenClick_) {
this.unlistenClick_();
this.unlistenClick_ = null;
}
}
/**
* Set up gestures
* @private
*/
setupGestures_() {
const gestures = Gestures.get(dev().assertElement(this.carousel_));
gestures.onGesture(SwipeYRecognizer, e => {
if (e.data.last) {
this.onMoveRelease_(e.data.deltaY);
}
});
}
/**
* Pauses lightbox childred.
*/
pauseLightboxChildren_() {
const lbgId = this.currentLightboxGroupId_;
const slides = this.elementsMetadata_[lbgId]
.map(elemMetadata => elemMetadata.element);
this.schedulePause(slides);
}
/**
* @return {!LightboxElementMetadataDef}
* @private
*/
getCurrentElement_() {
const lbgId = this.currentLightboxGroupId_;
const currentElement = devAssert(
this.elementsMetadata_[lbgId][this.currentElemId_]
);
return currentElement;
}
/**
* Closes the lightbox gallery on a tiny upwards swipe.
* @param {number} deltaY
* @private
*/
onMoveRelease_(deltaY) {
if (Math.abs(deltaY) > SWIPE_TO_CLOSE_THRESHOLD) {
this.close_();
}
}
/**
* Opens the lightbox-gallery with either the invocation source or
* the element referenced by the `id` argument.
* Examples:
* // Opens the element tapped.
* on="tap:myLightboxGallery'
*
* // Opens the element referenced by elementId
* on="tap:myLightboxGallery.open(id='<elementId>')
* @param {!../../../src/service/action-impl.ActionInvocation} invocation
* @private
*/
open_(invocation) {
let target = invocation.caller;
if (invocation.args && invocation.args['id']) {
const targetId = invocation.args['id'];
target = this.getAmpDoc().getElementById(targetId);
userAssert(target,
'amp-lightbox-gallery.open: element with id: %s not found', targetId);
}
this.openLightboxGallery_(dev().assertElement(target)).then(() => {
return this.history_.push(this.close_.bind(this));
}).then(historyId => {
this.historyId_ = historyId;
});
}
/**
* Opens the lightbox-gallery and displays the given element inside.
* @param {!Element} element Element to lightbox.
* @return {!Promise}
* @private
*/
openLightboxGallery_(element) {
this.sourceElement_ = element;
const lightboxGroupId = element.getAttribute('lightbox')
|| 'default';
this.currentLightboxGroupId_ = lightboxGroupId;
return this.findOrInitializeLightbox_(lightboxGroupId).then(() => {
return this.mutateElement(() => {
toggle(this.element, true);
setStyles(this.element, {
opacity: 0,
});
this.controlsContainer_.classList.remove('i-amphtml-lbg-fade-in');
this.controlsContainer_.classList.add('i-amphtml-lbg-hidden');
this.getViewport().enterLightboxMode();
});
}).then(() => {
this.isActive_ = true;
this.updateInViewport(dev().assertElement(this.container_), true);
this.scheduleLayout(dev().assertElement(this.container_));
this.doc_.documentElement.addEventListener(
'keydown', this.boundOnKeyDown_);
this.carousel_.addEventListener(
'slideChange', event => this.slideChangeHandler_(event)
);
this.setupGestures_();
this.setupEventListeners_();
return this.carousel_.signals().whenSignal(CommonSignals.LOAD_END);
}).then(() => this.openLightboxForElement_(element))
.then(() => {
this.showControls_();
triggerAnalyticsEvent(this.element, 'lightboxOpened', dict({}));
});
}
/**
* Given a single lightbox element, opens the internal carousel slide
* associated with said element, updates the description, and initializes
* the image viewer if the element is an amp-img.
* @param {!Element} element
* @return {!Promise}
* @private
*/
openLightboxForElement_(element) {
this.currentElemId_ = element.lightboxItemId;
devAssert(this.carousel_).getImpl()
.then(carousel => carousel.goToSlide(this.currentElemId_));
this.updateDescriptionBox_();
return this.enter_();
}
/**
* Returns true if the element is loaded and contains an img.
* @param {!Element} element
* @return {boolean}
* @private
*/
elementTypeCanBeAnimated_(element) {
if (!element || !isLoaded(element)) {
return false;
}
if (!ELIGIBLE_TAP_TAGS[element.tagName]) {
return false;
}
const img = elementByTag(dev().assertElement(element), 'img');
if (!img) {
return false;
}
return true;
}
/**
* It's possible for the current lightbox to be displaying an image that
* is not visible in the viewport. We should not transition those images.
* This function checks if the currently lightboxed image is the source image
* that we transitioned on (in which case it is guaranteed to be in viewport)
* or if it belongs to a carousel, in which case we sync the carousel.
* @return {boolean}
* @private
*/
shouldAnimateOut_() {
const target = this.getCurrentElement_().sourceElement;
if (!this.transitionTargetIsInViewport_(target)) {
return false;
}
if (!this.elementTypeCanBeAnimated_(target)) {
return false;
}
return true;
}
/**
*
* @param {!Element} target
* @return {boolean}
* @private
*/
transitionTargetIsInViewport_(target) {
if (target == this.sourceElement_) {
return true;
}
if (target.isInViewport()) {
return true;
}
// Note that `<amp-carousel>` type='carousel' does not support goToSlide
const parentCarousel = closestAncestorElementBySelector(target,
'amp-carousel[type="slides"]');
if (parentCarousel && parentCarousel.isInViewport()) {
return true;
}
return false;
}
/**
* Transitions the sourceElement into the lightbox or the lightbox to the
* sourceElement.
* @param {!Element} sourceElement The element that is the source of what is
* rendered in the lightbox.
* @param {boolean} enter Whether this is an enter or exit transition.
* @return {!Promise} A Promise that resolves once the transition is complete.
* @private
*/
transitionImg_(sourceElement, enter) {
return this.getCurrentElement_().imageViewer.getImpl()
.then(imageViewer => {
const {width, height} = imageViewer.getImageBoxWithOffset() || {};
// Check if our imageBox has a width or height. We may be in the
// gallery view if not, and we do not want to animate.
if (!width || !height) {
return this.fade_(/*fadeIn*/enter);
}
const lightboxImg = imageViewer.getImage();
const sourceImg = childElementByTag(sourceElement, 'img');
return this.runImgTransition_(
enter ? sourceImg : lightboxImg,
enter ? lightboxImg : sourceImg,
enter);
});
}
/**
* Gets the duration for how long to animate the transition, based on the
* distance and size of the viewport.
* @param {!Element} srcImg The img to transition from.
* @param {!Element} targetImg The img to transition to.
* @return {number} How long to animate for, in milliseconds.
* @private
*/
getTransitionDurationFromElements_(srcImg, targetImg) {
const srcRect = srcImg./*OK*/getBoundingClientRect();
const destRect = targetImg./*OK*/getBoundingClientRect();
const viewportHeight = this.getViewport().getSize().height;
const dy = Math.abs(destRect.top - srcRect.top);
return this.getTransitionDuration_(Math.abs(dy), viewportHeight);
}
/**
* Runs an img transition, both transitioning the `<img>` itself as well as
* the lightbox background.
* @param {!HTMLImageElement} srcImg The img to transition from.
* @param {!HTMLImageElement} targetImg The img to transition to.
* @param {boolean} enter Whether this is an enter or exxit transition.
* @return {Promise} A Promise that resolves once the transition is complete.
* @private
*/
runImgTransition_(srcImg, targetImg, enter) {
const carousel = dev().assertElement(this.carousel_);
const container = dev().assertElement(this.container_);
let duration;
let motionDuration;
let imageAnimation;
const measure = () => {
duration = this.getTransitionDurationFromElements_(srcImg, targetImg);
motionDuration = MOTION_DURATION_RATIO * duration;
// Prepare the actual image animation.
imageAnimation = prepareImageAnimation({
styleContainer: this.getAmpDoc().getHeadNode(),
transitionContainer: this.getAmpDoc().getBody(),
srcImg,
targetImg,
srcImgRect: undefined,
targetImgRect: undefined,
styles: {
'animationDuration': `${motionDuration}ms`,
// Matches z-index for `.i-amphtml-lbg`.
'zIndex': 2147483642,
},
keyframesNamespace: undefined,
curve: TRANSITION_CURVE,
});
};
const mutate = () => {
toggle(carousel, enter);
// Undo opacity 0 from `openLightboxGallery_`
setStyle(this.element, 'opacity', '');
// Fade in/out the background in sync with the motion.
setStyles(container, {
animationName: enter ? 'fadeIn' : 'fadeOut',
animationTimingFunction: 'cubic-bezier(0.8, 0, 0.2, 1)',
animationDuration: `${motionDuration}ms`,
animationFillMode: 'forwards',
});
// Fade in the carousel at the end of the movement.
setStyles(carousel, {
animationName: 'fadeIn',
animationDelay: `${motionDuration - 0.01}ms`,
animationDuration: '0.01ms',
animationFillMode: 'forwards',
});
srcImg.classList.add('i-amphtml-ghost');
targetImg.classList.add('i-amphtml-ghost');
// Apply the image animation prepared in the measure step.
imageAnimation.applyAnimation();
};