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resources-impl.js
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resources-impl.js
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/**
* Copyright 2015 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 {Deferred} from '../utils/promise';
import {FiniteStateMachine} from '../finite-state-machine';
import {FocusHistory} from '../focus-history';
import {
INTERSECT_RESOURCES_EXP,
divertIntersectResources,
} from '../experiments/intersect-resources-exp';
import {Pass} from '../pass';
import {READY_SCAN_SIGNAL, ResourcesInterface} from './resources-interface';
import {Resource, ResourceState} from './resource';
import {Services} from '../services';
import {TaskQueue} from './task-queue';
import {VisibilityState} from '../visibility-state';
import {dev, devAssert} from '../log';
import {dict} from '../utils/object';
import {expandLayoutRect} from '../layout-rect';
import {getExperimentBranch, isExperimentOn} from '../experiments';
import {getMode} from '../mode';
import {getSourceUrl} from '../url';
import {hasNextNodeInDocumentOrder, isIframed} from '../dom';
import {ieIntrinsicCheckAndFix} from './ie-intrinsic-bug';
import {ieMediaCheckAndFix} from './ie-media-bug';
import {isBlockedByConsent, reportError} from '../error';
import {listen, loadPromise} from '../event-helper';
import {registerServiceBuilderForDoc} from '../service';
import {remove} from '../utils/array';
import {startupChunk} from '../chunk';
import {throttle} from '../utils/rate-limit';
const TAG_ = 'Resources';
const LAYOUT_TASK_ID_ = 'L';
const LAYOUT_TASK_OFFSET_ = 0;
const PRELOAD_TASK_ID_ = 'P';
const PRELOAD_TASK_OFFSET_ = 2;
const PRIORITY_BASE_ = 10;
const PRIORITY_PENALTY_TIME_ = 1000;
const POST_TASK_PASS_DELAY_ = 1000;
const MUTATE_DEFER_DELAY_ = 500;
const FOCUS_HISTORY_TIMEOUT_ = 1000 * 60; // 1min
const FOUR_FRAME_DELAY_ = 70;
const MAX_BUILD_CHUNK_SIZE = 10;
/**
* @implements {ResourcesInterface}
*/
export class ResourcesImpl {
/**
* @param {!./ampdoc-impl.AmpDoc} ampdoc
*/
constructor(ampdoc) {
/** @const {!./ampdoc-impl.AmpDoc} */
this.ampdoc = ampdoc;
/** @const {!Window} */
this.win = ampdoc.win;
/** @const @private {!./viewer-interface.ViewerInterface} */
this.viewer_ = Services.viewerForDoc(ampdoc);
/** @private {boolean} */
this.isRuntimeOn_ = this.viewer_.isRuntimeOn();
/**
* Used primarily for testing to allow build phase to proceed.
* @const @private {boolean}
*/
this.isBuildOn_ = false;
/** @private {number} */
this.resourceIdCounter_ = 0;
/** @private @const {!Array<!Resource>} */
this.resources_ = [];
/** @private {number} */
this.addCount_ = 0;
/** @private {number} */
this.buildAttemptsCount_ = 0;
/** @private {number} */
this.buildsThisPass_ = 0;
/** @private {boolean} */
this.visible_ = this.ampdoc.isVisible();
/** @private {boolean} */
this.documentReady_ = false;
/**
* We want to do some work in the first pass after
* the document is ready.
* @private {boolean}
*/
this.firstPassAfterDocumentReady_ = true;
/**
* Whether AMP has been fully initialized.
* @private {boolean}
*/
this.ampInitialized_ = false;
/**
* We also adjust the timeout penalty shortly after the first pass.
* @private {number}
*/
this.firstVisibleTime_ = -1;
/** @private {boolean} */
this.relayoutAll_ = true;
/**
* @private {number}
*/
this.relayoutTop_ = -1;
/** @private {time} */
this.lastScrollTime_ = 0;
/** @private {number} */
this.lastVelocity_ = 0;
/** @const @private {!Pass} */
this.pass_ = new Pass(this.win, () => this.doPass());
/** @const @private {!Pass} */
this.remeasurePass_ = new Pass(this.win, () => {
// With IntersectionObserver, "remeasuring" hack no longer needed.
devAssert(!this.intersectionObserver_);
this.relayoutAll_ = true;
this.schedulePass();
});
/** @const {!TaskQueue} */
this.exec_ = new TaskQueue();
/** @const {!TaskQueue} */
this.queue_ = new TaskQueue();
/** @const {function(./task-queue.TaskDef):number} */
this.boundTaskScorer_ = this.calcTaskScore_.bind(this);
/**
* @private {!Array<!./resources-interface.ChangeSizeRequestDef>}
*/
this.requestsChangeSize_ = [];
/** @private {?Array<!Resource>} */
this.pendingBuildResources_ = [];
/** @private {boolean} */
this.isCurrentlyBuildingPendingResources_ = false;
/** @private @const {!./viewport/viewport-interface.ViewportInterface} */
this.viewport_ = Services.viewportForDoc(this.ampdoc);
/** @private @const {!./vsync-impl.Vsync} */
this.vsync_ = Services./*OK*/ vsyncFor(this.win);
/** @private @const {!FocusHistory} */
this.activeHistory_ = new FocusHistory(this.win, FOCUS_HISTORY_TIMEOUT_);
/** @private {boolean} */
this.vsyncScheduled_ = false;
/** @private {number} */
this.contentHeight_ = 0;
/** @private {boolean} */
this.maybeChangeHeight_ = false;
/** @const @private {!Array<function()>} */
this.passCallbacks_ = [];
/** @const @private {!Array<!Element>} */
this.elementsThatScrolled_ = [];
/** @const @private {boolean} */
this.onlyBuildWhenCloseToViewport_ = isExperimentOn(
this.win,
'build-close-to-viewport'
);
/** @const @private {boolean} */
this.buildInChunks_ = isExperimentOn(this.win, 'build-in-chunks');
/** @const @private {boolean} */
this.removeTaskTimeout_ = isExperimentOn(this.win, 'remove-task-timeout');
/** @const @private {!Deferred} */
this.firstPassDone_ = new Deferred();
/** @private @const {!FiniteStateMachine<!VisibilityState>} */
this.visibilityStateMachine_ = new FiniteStateMachine(
this.ampdoc.getVisibilityState()
);
/** @private {?IntersectionObserver} */
this.intersectionObserver_ = null;
/**
* True if the callback for intersectionObserver_ has fired at least once.
* @private {boolean}
*/
this.intersectionObserverCallbackFired_ = false;
divertIntersectResources(this.win);
if (
isExperimentOn(this.win, 'bento') ||
getExperimentBranch(this.win, INTERSECT_RESOURCES_EXP.id) ===
INTERSECT_RESOURCES_EXP.experiment
) {
const iframed = isIframed(this.win);
// Classic IntersectionObserver doesn't support viewport tracking and
// rootMargin in x-origin iframes (#25428). As of 1/2020, only Chrome 81+
// supports it via {root: document}, which throws on other browsers.
const root = /** @type {?Element} */ (this.ampdoc.isSingleDoc() && iframed
? /** @type {*} */ (this.win.document)
: null);
try {
this.intersectionObserver_ = new IntersectionObserver(
(e) => this.intersect(e),
// rootMargin matches size of loadRect: (150vw 300vh) * 1.25.
{root, rootMargin: '250% 31.25%'}
);
// Wait for intersection callback instead of measuring all elements
// during the first pass.
this.relayoutAll_ = false;
} catch (e) {
dev().warn(TAG_, 'Falling back to classic Resources:', e);
}
}
// When user scrolling stops, run pass to check newly in-viewport elements.
// When viewport is resized, we have to re-measure everything.
this.viewport_.onChanged((event) => {
this.lastScrollTime_ = this.win.Date.now();
this.lastVelocity_ = event.velocity;
if (event.relayoutAll) {
this.relayoutAll_ = true;
this.maybeChangeHeight_ = true;
}
// Unfortunately, a viewport size change invalidates all premeasurements.
if (this.relayoutAll_ && this.intersectionObserver_) {
this.resources_.forEach((resource) =>
resource.invalidatePremeasurementAndRequestMeasure()
);
}
this.schedulePass();
});
this.viewport_.onScroll(() => {
this.lastScrollTime_ = this.win.Date.now();
});
// When document becomes visible, e.g. from "prerender" mode, do a
// simple pass.
this.ampdoc.onVisibilityChanged(() => {
if (this.firstVisibleTime_ == -1 && this.ampdoc.isVisible()) {
this.firstVisibleTime_ = this.win.Date.now();
}
this.schedulePass();
});
this.viewer_.onRuntimeState((state) => {
dev().fine(TAG_, 'Runtime state:', state);
this.isRuntimeOn_ = state;
this.schedulePass(1);
});
// Schedule initial passes. This must happen in a startup task
// to avoid blocking body visible.
startupChunk(this.ampdoc, () => {
this.setupVisibilityStateMachine_(this.visibilityStateMachine_);
this.schedulePass(0);
});
this.rebuildDomWhenReady_();
if (!this.intersectionObserver_) {
/** @private @const */
this.throttledScroll_ = throttle(this.win, (e) => this.scrolled_(e), 250);
listen(this.win.document, 'scroll', this.throttledScroll_, {
capture: true,
passive: true,
});
}
}
/** @override */
isIntersectionExperimentOn() {
return !!this.intersectionObserver_;
}
/**
* @param {!Array<!IntersectionObserverEntry>} entries
* @visibleForTesting
*/
intersect(entries) {
devAssert(this.intersectionObserver_);
if (getMode().localDev) {
const inside = [];
const outside = [];
entries.forEach((e) => {
const r = Resource.forElement(e.target);
(e.isIntersecting ? inside : outside).push({e, id: r.debugid});
});
dev().fine(TAG_, 'intersection', inside, outside);
}
this.intersectionObserverCallbackFired_ = true;
entries.forEach((entry) => {
const {boundingClientRect, target} = entry;
const r = Resource.forElement(target);
// Strangely, JSC is missing x/y from typedefs of boundingClientRect
// despite it being a DOMRectReadOnly (ClientRect) by spec.
r.premeasure(/** @type {!ClientRect} */ (boundingClientRect));
});
this.schedulePass();
}
/** @private */
rebuildDomWhenReady_() {
// Ensure that we attempt to rebuild things when DOM is ready.
this.ampdoc.whenReady().then(() => {
this.documentReady_ = true;
this.buildReadyResources_();
this.pendingBuildResources_ = null;
const input = Services.inputFor(this.win);
input.setupInputModeClasses(this.ampdoc);
if (IS_ESM) {
return;
}
ieIntrinsicCheckAndFix(this.win);
// With IntersectionObserver, no need for remeasuring hacks.
if (!this.intersectionObserver_) {
const fixPromise = ieMediaCheckAndFix(this.win);
const remeasure = () => this.remeasurePass_.schedule();
if (fixPromise) {
fixPromise.then(remeasure);
} else {
// No promise means that there's no problem.
remeasure();
}
// Safari 10 and under incorrectly estimates font spacing for
// `@font-face` fonts. This leads to wild measurement errors. The best
// course of action is to remeasure everything on window.onload or font
// timeout (3s), whichever is earlier. This has to be done on the global
// window because this is where the fonts are always added.
// Unfortunately, `document.fonts.ready` cannot be used here due to
// https://bugs.webkit.org/show_bug.cgi?id=174030.
// See https://bugs.webkit.org/show_bug.cgi?id=174031 for more details.
Promise.race([
loadPromise(this.win),
Services.timerFor(this.win).promise(3100),
]).then(remeasure);
// Remeasure the document when all fonts loaded.
if (
this.win.document.fonts &&
this.win.document.fonts.status != 'loaded'
) {
this.win.document.fonts.ready.then(remeasure);
}
}
});
}
/** @override */
get() {
return this.resources_.slice(0);
}
/** @override */
getAmpdoc() {
return this.ampdoc;
}
/** @override */
getResourceForElement(element) {
return Resource.forElement(element);
}
/** @override */
getResourceForElementOptional(element) {
return Resource.forElementOptional(element);
}
/** @override */
getScrollDirection() {
return Math.sign(this.lastVelocity_) || 1;
}
/** @override */
add(element) {
// Ensure the viewport is ready to accept the first element.
this.addCount_++;
if (this.addCount_ == 1) {
this.viewport_.ensureReadyForElements();
}
// First check if the resource is being reparented and if it requires
// reconstruction. Only already built elements are eligible.
let resource = Resource.forElementOptional(element);
if (
resource &&
resource.getState() != ResourceState.NOT_BUILT &&
!element.reconstructWhenReparented()
) {
resource.requestMeasure();
dev().fine(TAG_, 'resource reused:', resource.debugid);
} else {
// Create and add a new resource.
resource = new Resource(++this.resourceIdCounter_, element, this);
dev().fine(TAG_, 'resource added:', resource.debugid);
}
this.resources_.push(resource);
if (this.intersectionObserver_) {
// The observer callback will schedule a pass to process this element.
this.intersectionObserver_.observe(element);
} else {
this.remeasurePass_.schedule(1000);
}
}
/**
* Limits the number of elements being build in pre-render phase to
* a finite number. Returns false if the number has been reached.
* @return {boolean}
*/
isUnderBuildQuota_() {
if (this.buildInChunks_ && this.buildsThisPass_ >= MAX_BUILD_CHUNK_SIZE) {
return false;
}
// For pre-render we want to limit the amount of CPU used, so we limit
// the number of elements build. For pre-render to "seem complete"
// we only need to build elements in the first viewport. We can't know
// which are actually in the viewport (because the decision is pre-layout,
// so we use a heuristic instead.
// Most documents have 10 or less AMP tags. By building 20 we should not
// change the behavior for the vast majority of docs, and almost always
// catch everything in the first viewport.
return this.buildAttemptsCount_ < 20 || this.ampdoc.hasBeenVisible();
}
/**
* Builds the element if ready to be built, otherwise adds it to pending
* resources.
* @param {!Resource} resource
* @param {boolean=} checkForDupes
* @param {boolean=} ignoreQuota
* @private
*/
buildOrScheduleBuildForResource_(
resource,
checkForDupes = false,
ignoreQuota = false
) {
const buildingEnabled = this.isRuntimeOn_ || this.isBuildOn_;
if (!buildingEnabled) {
return;
}
// During prerender mode, don't build elements that aren't allowed to be
// prerendered. This avoids wasting our prerender build quota.
// See isUnderBuildQuota_() for more details.
const shouldBuildResource =
this.ampdoc.getVisibilityState() != VisibilityState.PRERENDER ||
resource.prerenderAllowed();
if (!shouldBuildResource) {
return;
}
if (this.onlyBuildWhenCloseToViewport_) {
const isCloseEnoughToViewport =
ignoreQuota ||
resource.isBuildRenderBlocking() ||
resource.renderOutsideViewport() ||
(this.isIdle_() && resource.idleRenderOutsideViewport());
if (!isCloseEnoughToViewport) {
return;
}
}
if (this.documentReady_) {
// Build resource immediately, the document has already been parsed.
this.buildResourceUnsafe_(resource, ignoreQuota);
} else if (!resource.isBuilt() && !resource.isBuilding()) {
if (!checkForDupes || !this.pendingBuildResources_.includes(resource)) {
// Otherwise add to pending resources and try to build any ready ones.
this.pendingBuildResources_.push(resource);
this.buildReadyResources_();
}
}
}
/**
* Builds resources that are ready to be built.
* @private
*/
buildReadyResources_() {
// Avoid cases where elements add more elements inside of them
// and cause an infinite loop of building - see #3354 for details.
if (this.isCurrentlyBuildingPendingResources_) {
return;
}
try {
this.isCurrentlyBuildingPendingResources_ = true;
this.buildReadyResourcesUnsafe_();
} finally {
this.isCurrentlyBuildingPendingResources_ = false;
}
}
/**
* @private
*/
buildReadyResourcesUnsafe_() {
// This will loop over all current pending resources and those that
// get added by other resources build-cycle, this will make sure all
// elements get a chance to be built.
for (let i = 0; i < this.pendingBuildResources_.length; i++) {
const resource = this.pendingBuildResources_[i];
if (
this.documentReady_ ||
hasNextNodeInDocumentOrder(resource.element, this.ampdoc.getRootNode())
) {
// Remove resource before build to remove it from the pending list
// in either case the build succeed or throws an error.
this.pendingBuildResources_.splice(i--, 1);
this.buildResourceUnsafe_(resource);
}
}
}
/**
* @param {!Resource} resource
* @param {boolean=} ignoreQuota
* @return {?Promise}
* @private
*/
buildResourceUnsafe_(resource, ignoreQuota = false) {
if (
!ignoreQuota &&
!this.isUnderBuildQuota_() &&
// Special case: amp-experiment is allowed to bypass prerender build quota.
!resource.isBuildRenderBlocking()
) {
return null;
}
const promise = resource.build();
if (!promise) {
return null;
}
dev().fine(TAG_, 'build resource:', resource.debugid);
this.buildAttemptsCount_++;
this.buildsThisPass_++;
return promise.then(
() => this.schedulePass(),
(error) => {
// Build failed: remove the resource. No other state changes are
// needed.
this.removeResource_(resource);
if (!isBlockedByConsent(error)) {
throw error;
}
}
);
}
/** @override */
remove(element) {
const resource = Resource.forElementOptional(element);
if (!resource) {
return;
}
this.removeResource_(resource);
}
/**
* @param {!Resource} resource
* @private
*/
removeResource_(resource) {
const index = this.resources_.indexOf(resource);
if (index != -1) {
this.resources_.splice(index, 1);
}
if (resource.isBuilt()) {
resource.pauseOnRemove();
}
if (this.intersectionObserver_) {
// TODO(willchou): Fix observe/unobserve/remeasure churn in reparenting.
this.intersectionObserver_.unobserve(resource.element);
}
if (resource.getState() === ResourceState.LAYOUT_SCHEDULED) {
resource.layoutCanceled();
}
this.cleanupTasks_(resource, /* opt_removePending */ true);
dev().fine(TAG_, 'resource removed:', resource.debugid);
}
/** @override */
upgraded(element) {
const resource = Resource.forElement(element);
this.buildOrScheduleBuildForResource_(resource);
dev().fine(TAG_, 'resource upgraded:', resource.debugid);
}
/** @override */
updateLayoutPriority(element, newLayoutPriority) {
const resource = Resource.forElement(element);
resource.updateLayoutPriority(newLayoutPriority);
// Update affected tasks
this.queue_.forEach((task) => {
if (task.resource == resource) {
task.priority = newLayoutPriority;
}
});
this.schedulePass();
}
/** @override */
schedulePass(opt_delay) {
return this.pass_.schedule(opt_delay);
}
/** @override */
updateOrEnqueueMutateTask(resource, newRequest) {
let request = null;
for (let i = 0; i < this.requestsChangeSize_.length; i++) {
if (this.requestsChangeSize_[i].resource == resource) {
request = this.requestsChangeSize_[i];
break;
}
}
if (request) {
request.newHeight = newRequest.newHeight;
request.newWidth = newRequest.newWidth;
request.marginChange = newRequest.marginChange;
request.event = newRequest.event;
request.force = newRequest.force || request.force;
request.callback = newRequest.callback;
} else {
this.requestsChangeSize_.push(newRequest);
}
}
/** @override */
schedulePassVsync() {
if (this.vsyncScheduled_) {
return;
}
this.vsyncScheduled_ = true;
this.vsync_.mutate(() => this.doPass());
}
/** @override */
ampInitComplete() {
this.ampInitialized_ = true;
dev().fine(TAG_, 'ampInitComplete');
this.schedulePass();
}
/** @override */
setRelayoutTop(relayoutTop) {
if (this.relayoutTop_ == -1) {
this.relayoutTop_ = relayoutTop;
} else {
this.relayoutTop_ = Math.min(relayoutTop, this.relayoutTop_);
}
}
/** @override */
maybeHeightChanged() {
this.maybeChangeHeight_ = true;
}
/** @override */
onNextPass(callback) {
this.passCallbacks_.push(callback);
}
/**
* Runs a pass immediately.
*
* @visibleForTesting
*/
doPass() {
if (!this.isRuntimeOn_) {
dev().fine(TAG_, 'runtime is off');
return;
}
this.visible_ = this.ampdoc.isVisible();
this.buildsThisPass_ = 0;
const firstPassAfterDocumentReady =
this.documentReady_ &&
this.firstPassAfterDocumentReady_ &&
this.ampInitialized_;
if (firstPassAfterDocumentReady) {
this.firstPassAfterDocumentReady_ = false;
const doc = this.win.document;
const documentInfo = Services.documentInfoForDoc(this.ampdoc);
// TODO(choumx, #26687): Update viewers to read data.viewport instead of
// data.metaTags.viewport from 'documentLoaded' message.
this.viewer_.sendMessage(
'documentLoaded',
dict({
'title': doc.title,
'sourceUrl': getSourceUrl(this.ampdoc.getUrl()),
'serverLayout': doc.documentElement.hasAttribute('i-amphtml-element'),
'linkRels': documentInfo.linkRels,
'metaTags': {'viewport': documentInfo.viewport} /* deprecated */,
'viewport': documentInfo.viewport,
}),
/* cancelUnsent */ true
);
this.contentHeight_ = this.viewport_.getContentHeight();
this.viewer_.sendMessage(
'documentHeight',
dict({'height': this.contentHeight_}),
/* cancelUnsent */ true
);
dev().fine(TAG_, 'document height on load: %s', this.contentHeight_);
}
const viewportSize = this.viewport_.getSize();
dev().fine(
TAG_,
'PASS: visible=',
this.visible_,
', relayoutAll=',
this.relayoutAll_,
', relayoutTop=',
this.relayoutTop_,
', viewportSize=',
viewportSize.width,
viewportSize.height
);
this.pass_.cancel();
this.vsyncScheduled_ = false;
this.visibilityStateMachine_.setState(this.ampdoc.getVisibilityState());
this.signalIfReady_();
if (this.maybeChangeHeight_) {
this.maybeChangeHeight_ = false;
this.vsync_.measure(() => {
const measuredContentHeight = this.viewport_.getContentHeight();
if (measuredContentHeight != this.contentHeight_) {
this.viewer_.sendMessage(
'documentHeight',
dict({'height': measuredContentHeight}),
/* cancelUnsent */ true
);
this.contentHeight_ = measuredContentHeight;
dev().fine(TAG_, 'document height changed: %s', this.contentHeight_);
this.viewport_.contentHeightChanged();
}
});
}
for (let i = 0; i < this.passCallbacks_.length; i++) {
const fn = this.passCallbacks_[i];
fn();
}
this.passCallbacks_.length = 0;
}
/**
* If (1) the document is fully parsed, (2) the AMP runtime (services etc.)
* is initialized, and (3) we did a first pass on element measurements,
* then fire the "ready" signal.
* @private
*/
signalIfReady_() {
if (
this.documentReady_ &&
this.ampInitialized_ &&
// With IntersectionObserver, elements are not measured until the first
// intersection callback.
(!this.intersectionObserver_ ||
this.intersectionObserverCallbackFired_) &&
!this.ampdoc.signals().get(READY_SCAN_SIGNAL)
) {
// This signal mainly signifies that most of elements have been measured
// by now. This is mostly used to avoid measuring too many elements
// individually. May not be called in shadow mode.
this.ampdoc.signals().signal(READY_SCAN_SIGNAL);
dev().fine(TAG_, 'signal: ready-scan');
}
}
/**
* Returns `true` when there's mutate work currently batched.
* @return {boolean}
* @private
*/
hasMutateWork_() {
return this.requestsChangeSize_.length > 0;
}
/**
* Performs pre-discovery mutates.
* @private
*/
mutateWork_() {
// Read all necessary data before mutates.
// The height changing depends largely on the target element's position
// in the active viewport. When not in prerendering, we also consider the
// active viewport the part of the visible viewport below 10% from the top
// and above 25% from the bottom.
// This is basically the portion of the viewport where the reader is most
// likely focused right now. The main goal is to avoid drastic UI changes
// in that part of the content. The elements below the active viewport are
// freely resized. The elements above the viewport are resized and request
// scroll adjustment to avoid active viewport changing without user's
// action. The elements in the active viewport are not resized and instead
// the overflow callbacks are called.
const now = this.win.Date.now();
const viewportRect = this.viewport_.getRect();
const topOffset = viewportRect.height / 10;
const bottomOffset = viewportRect.height / 10;
const isScrollingStopped =
(Math.abs(this.lastVelocity_) < 1e-2 &&
now - this.lastScrollTime_ > MUTATE_DEFER_DELAY_) ||
now - this.lastScrollTime_ > MUTATE_DEFER_DELAY_ * 2;
if (this.requestsChangeSize_.length > 0) {
dev().fine(
TAG_,
'change size requests:',
this.requestsChangeSize_.length
);
const requestsChangeSize = this.requestsChangeSize_;
this.requestsChangeSize_ = [];
// Find minimum top position and run all mutates.
let minTop = -1;
const scrollAdjSet = [];
let aboveVpHeightChange = 0;
for (let i = 0; i < requestsChangeSize.length; i++) {
const request = requestsChangeSize[i];
const {
resource,
event,
} = /** @type {!./resources-interface.ChangeSizeRequestDef} */ (request);
const box = resource.getLayoutBox();
let topMarginDiff = 0;
let bottomMarginDiff = 0;
let leftMarginDiff = 0;
let rightMarginDiff = 0;
let {top: topUnchangedBoundary, bottom: bottomDisplacedBoundary} = box;
let newMargins = undefined;
if (request.marginChange) {
newMargins = request.marginChange.newMargins;
const margins = request.marginChange.currentMargins;
if (newMargins.top != undefined) {
topMarginDiff = newMargins.top - margins.top;
}
if (newMargins.bottom != undefined) {
bottomMarginDiff = newMargins.bottom - margins.bottom;
}
if (newMargins.left != undefined) {
leftMarginDiff = newMargins.left - margins.left;
}
if (newMargins.right != undefined) {
rightMarginDiff = newMargins.right - margins.right;
}
if (topMarginDiff) {
topUnchangedBoundary = box.top - margins.top;
}
if (bottomMarginDiff) {
// The lowest boundary of the element that would appear to be
// resized as a result of this size change. If the bottom margin is
// being changed then it is the bottom edge of the margin box,
// otherwise it is the bottom edge of the layout box as set above.
bottomDisplacedBoundary = box.bottom + margins.bottom;
}
}
const heightDiff = request.newHeight - box.height;
const widthDiff = request.newWidth - box.width;
// Check resize rules. It will either resize element immediately, or
// wait until scrolling stops or will call the overflow callback.
let resize = false;
if (
heightDiff == 0 &&
topMarginDiff == 0 &&
bottomMarginDiff == 0 &&
widthDiff == 0 &&
leftMarginDiff == 0 &&
rightMarginDiff == 0
) {
// 1. Nothing to resize.
} else if (request.force || !this.visible_) {
// 2. An immediate execution requested or the document is hidden.
resize = true;
} else if (
this.activeHistory_.hasDescendantsOf(resource.element) ||
(event && event.userActivation && event.userActivation.hasBeenActive)
) {
// 3. Active elements are immediately resized. The assumption is that
// the resize is triggered by the user action or soon after.
resize = true;
} else if (
topUnchangedBoundary >= viewportRect.bottom - bottomOffset ||
(topMarginDiff == 0 &&
box.bottom + Math.min(heightDiff, 0) >=
viewportRect.bottom - bottomOffset)
) {
// 4. Elements under viewport are resized immediately, but only if
// an element's boundary is not changed above the viewport after
// resize.
resize = true;
} else if (
viewportRect.top > 1 &&
bottomDisplacedBoundary <= viewportRect.top + topOffset
) {
// 5. Elements above the viewport can only be resized if we are able
// to compensate the height change by setting scrollTop and only if
// the page has already been scrolled by some amount (1px due to iOS).
// Otherwise the scrolling might move important things like the menu
// bar out of the viewport at initial page load.
if (
heightDiff < 0 &&
viewportRect.top + aboveVpHeightChange < -heightDiff
) {
// Do nothing if height abobe viewport height can't compensate
// height decrease
continue;
}
// Can only resized when scrolling has stopped,
// otherwise defer util next cycle.
if (isScrollingStopped) {
// These requests will be executed in the next animation cycle and
// adjust the scroll position.
aboveVpHeightChange = aboveVpHeightChange + heightDiff;
scrollAdjSet.push(request);
} else {
// Defer till next cycle.
this.requestsChangeSize_.push(request);
}
continue;
} else if (this.elementNearBottom_(resource, box)) {
// 6. Elements close to the bottom of the document (not viewport)
// are resized immediately.
resize = true;
} else if (
heightDiff < 0 ||
topMarginDiff < 0 ||
bottomMarginDiff < 0
) {
// 7. The new height (or one of the margins) is smaller than the
// current one.
} else if (request.newHeight == box.height) {