зеркало из https://github.com/mozilla/gecko-dev.git
341 строка
11 KiB
JavaScript
341 строка
11 KiB
JavaScript
/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*- */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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ChromeUtils.import("resource://gre/modules/Services.jsm");
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var EXPORTED_SYMBOLS = ["AutoScrollController"];
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class AutoScrollController {
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constructor(global) {
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this._scrollable = null;
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this._scrolldir = "";
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this._startX = null;
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this._startY = null;
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this._screenX = null;
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this._screenY = null;
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this._lastFrame = null;
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this._autoscrollHandledByApz = false;
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this._scrollId = null;
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this._global = global;
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this.autoscrollLoop = this.autoscrollLoop.bind(this);
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global.addMessageListener("Autoscroll:Stop", this);
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}
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isAutoscrollBlocker(node) {
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let mmPaste = Services.prefs.getBoolPref("middlemouse.paste");
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let mmScrollbarPosition = Services.prefs.getBoolPref("middlemouse.scrollbarPosition");
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let content = node.ownerGlobal;
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while (node) {
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if ((node instanceof content.HTMLAnchorElement || node instanceof content.HTMLAreaElement) &&
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node.hasAttribute("href")) {
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return true;
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}
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if (mmPaste && (node instanceof content.HTMLInputElement ||
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node instanceof content.HTMLTextAreaElement)) {
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return true;
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}
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if (node instanceof content.XULElement && mmScrollbarPosition
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&& (node.localName == "scrollbar" || node.localName == "scrollcorner")) {
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return true;
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}
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node = node.parentNode;
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}
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return false;
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}
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isScrollableElement(aNode) {
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let content = aNode.ownerGlobal;
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if (aNode instanceof content.HTMLElement) {
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return !(aNode instanceof content.HTMLSelectElement) || aNode.multiple;
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}
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return aNode instanceof content.XULElement;
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}
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getXBLNodes(parent, array) {
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let content = parent.ownerGlobal;
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let anonNodes = content.document.getAnonymousNodes(parent);
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let nodes = Array.from(anonNodes || parent.childNodes || []);
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for (let node of nodes) {
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if (node.nodeName == "children") {
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return true;
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}
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if (this.getXBLNodes(node, array)) {
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array.push(node);
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return true;
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}
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}
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return false;
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}
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* parentNodeIterator(aNode) {
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let content = aNode.ownerGlobal;
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while (aNode) {
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yield aNode;
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let parent = aNode.parentNode;
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if (parent && parent instanceof content.XULElement) {
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let anonNodes = content.document.getAnonymousNodes(parent);
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if (anonNodes && !Array.from(anonNodes).includes(aNode)) {
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// XBL elements are skipped by parentNode property.
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// Yield elements between parent and <children> here.
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let nodes = [];
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this.getXBLNodes(parent, nodes);
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for (let node of nodes) {
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yield node;
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}
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}
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}
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aNode = parent;
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}
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}
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findNearestScrollableElement(aNode) {
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let content = aNode.ownerGlobal;
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// this is a list of overflow property values that allow scrolling
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const scrollingAllowed = ["scroll", "auto"];
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// go upward in the DOM and find any parent element that has a overflow
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// area and can therefore be scrolled
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this._scrollable = null;
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for (let node of this.parentNodeIterator(aNode)) {
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// do not use overflow based autoscroll for <html> and <body>
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// Elements or non-html/non-xul elements such as svg or Document nodes
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// also make sure to skip select elements that are not multiline
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if (!this.isScrollableElement(node)) {
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continue;
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}
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var overflowx = node.ownerGlobal
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.getComputedStyle(node)
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.getPropertyValue("overflow-x");
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var overflowy = node.ownerGlobal
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.getComputedStyle(node)
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.getPropertyValue("overflow-y");
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// we already discarded non-multiline selects so allow vertical
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// scroll for multiline ones directly without checking for a
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// overflow property
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var scrollVert = node.scrollTopMax &&
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(node instanceof content.HTMLSelectElement ||
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scrollingAllowed.includes(overflowy));
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// do not allow horizontal scrolling for select elements, it leads
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// to visual artifacts and is not the expected behavior anyway
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if (!(node instanceof content.HTMLSelectElement) &&
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node.scrollLeftMin != node.scrollLeftMax &&
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scrollingAllowed.includes(overflowx)) {
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this._scrolldir = scrollVert ? "NSEW" : "EW";
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this._scrollable = node;
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break;
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} else if (scrollVert) {
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this._scrolldir = "NS";
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this._scrollable = node;
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break;
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}
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}
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if (!this._scrollable) {
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this._scrollable = aNode.ownerGlobal;
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if (this._scrollable.scrollMaxX != this._scrollable.scrollMinX) {
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this._scrolldir = this._scrollable.scrollMaxY !=
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this._scrollable.scrollMinY ? "NSEW" : "EW";
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} else if (this._scrollable.scrollMaxY != this._scrollable.scrollMinY) {
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this._scrolldir = "NS";
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} else if (this._scrollable.frameElement) {
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this.findNearestScrollableElement(this._scrollable.frameElement);
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} else {
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this._scrollable = null; // abort scrolling
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}
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}
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}
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startScroll(event) {
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this.findNearestScrollableElement(event.originalTarget);
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if (!this._scrollable)
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return;
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let content = event.originalTarget.ownerGlobal;
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// In some configurations like Print Preview, content.performance
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// (which we use below) is null. Autoscrolling is broken in Print
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// Preview anyways (see bug 1393494), so just don't start it at all.
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if (!content.performance)
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return;
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let domUtils = content.windowUtils;
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let scrollable = this._scrollable;
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if (scrollable instanceof Ci.nsIDOMWindow) {
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// getViewId() needs an element to operate on.
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scrollable = scrollable.document.documentElement;
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}
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this._scrollId = null;
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try {
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this._scrollId = domUtils.getViewId(scrollable);
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} catch (e) {
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// No view ID - leave this._scrollId as null. Receiving side will check.
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}
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let presShellId = domUtils.getPresShellId();
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let [result] = this._global.sendSyncMessage("Autoscroll:Start",
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{scrolldir: this._scrolldir,
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screenX: event.screenX,
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screenY: event.screenY,
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scrollId: this._scrollId,
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presShellId});
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if (!result.autoscrollEnabled) {
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this._scrollable = null;
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return;
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}
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Services.els.addSystemEventListener(this._global, "mousemove", this, true);
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this._global.addEventListener("pagehide", this, true);
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this._ignoreMouseEvents = true;
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this._startX = event.screenX;
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this._startY = event.screenY;
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this._screenX = event.screenX;
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this._screenY = event.screenY;
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this._scrollErrorX = 0;
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this._scrollErrorY = 0;
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this._autoscrollHandledByApz = result.usingApz;
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if (!result.usingApz) {
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// If the browser didn't hand the autoscroll off to APZ,
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// scroll here in the main thread.
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this.startMainThreadScroll();
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} else {
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// Even if the browser did hand the autoscroll to APZ,
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// APZ might reject it in which case it will notify us
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// and we need to take over.
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Services.obs.addObserver(this, "autoscroll-rejected-by-apz");
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}
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}
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startMainThreadScroll() {
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let content = this._global.content;
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this._lastFrame = content.performance.now();
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content.requestAnimationFrame(this.autoscrollLoop);
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}
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stopScroll() {
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if (this._scrollable) {
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this._scrollable.mozScrollSnap();
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this._scrollable = null;
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Services.els.removeSystemEventListener(this._global, "mousemove", this, true);
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this._global.removeEventListener("pagehide", this, true);
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if (this._autoscrollHandledByApz) {
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Services.obs.removeObserver(this, "autoscroll-rejected-by-apz");
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}
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}
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}
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accelerate(curr, start) {
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const speed = 12;
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var val = (curr - start) / speed;
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if (val > 1)
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return val * Math.sqrt(val) - 1;
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if (val < -1)
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return val * Math.sqrt(-val) + 1;
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return 0;
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}
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roundToZero(num) {
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if (num > 0)
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return Math.floor(num);
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return Math.ceil(num);
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}
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autoscrollLoop(timestamp) {
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if (!this._scrollable) {
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// Scrolling has been canceled
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return;
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}
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// avoid long jumps when the browser hangs for more than
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// |maxTimeDelta| ms
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const maxTimeDelta = 100;
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var timeDelta = Math.min(maxTimeDelta, timestamp - this._lastFrame);
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// we used to scroll |accelerate()| pixels every 20ms (50fps)
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var timeCompensation = timeDelta / 20;
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this._lastFrame = timestamp;
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var actualScrollX = 0;
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var actualScrollY = 0;
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// don't bother scrolling vertically when the scrolldir is only horizontal
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// and the other way around
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if (this._scrolldir != "EW") {
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var y = this.accelerate(this._screenY, this._startY) * timeCompensation;
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var desiredScrollY = this._scrollErrorY + y;
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actualScrollY = this.roundToZero(desiredScrollY);
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this._scrollErrorY = (desiredScrollY - actualScrollY);
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}
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if (this._scrolldir != "NS") {
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var x = this.accelerate(this._screenX, this._startX) * timeCompensation;
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var desiredScrollX = this._scrollErrorX + x;
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actualScrollX = this.roundToZero(desiredScrollX);
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this._scrollErrorX = (desiredScrollX - actualScrollX);
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}
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this._scrollable.scrollBy({
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left: actualScrollX,
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top: actualScrollY,
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behavior: "instant"
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});
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this._scrollable.ownerGlobal.requestAnimationFrame(this.autoscrollLoop);
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}
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handleEvent(event) {
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if (event.type == "mousemove") {
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this._screenX = event.screenX;
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this._screenY = event.screenY;
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} else if (event.type == "mousedown") {
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if (!this._scrollable &&
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!this.isAutoscrollBlocker(event.originalTarget)) {
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this.startScroll(event);
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}
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} else if (event.type == "pagehide") {
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if (this._scrollable) {
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var doc =
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this._scrollable.ownerDocument || this._scrollable.document;
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if (doc == event.target) {
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this._global.sendAsyncMessage("Autoscroll:Cancel");
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}
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}
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}
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}
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receiveMessage(msg) {
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switch (msg.name) {
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case "Autoscroll:Stop": {
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this.stopScroll();
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break;
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}
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}
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}
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observe(subject, topic, data) {
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if (topic === "autoscroll-rejected-by-apz") {
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// The caller passes in the scroll id via 'data'.
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if (data == this._scrollId) {
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this._autoscrollHandledByApz = false;
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this.startMainThreadScroll();
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Services.obs.removeObserver(this, "autoscroll-rejected-by-apz");
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}
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}
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}
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}
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