/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*- */ /* This Source Code Form is subject to the terms of the Mozilla Public * License, v. 2.0. If a copy of the MPL was not distributed with this * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ const { Services } = ChromeUtils.import("resource://gre/modules/Services.jsm"); var EXPORTED_SYMBOLS = ["AutoScrollChild"]; class AutoScrollChild extends JSWindowActorChild { constructor() { super(); this._scrollable = null; this._scrolldir = ""; this._startX = null; this._startY = null; this._screenX = null; this._screenY = null; this._lastFrame = null; this._autoscrollHandledByApz = false; this._scrollId = null; this.observer = new AutoScrollObserver(this); this.autoscrollLoop = this.autoscrollLoop.bind(this); } isAutoscrollBlocker(node) { let mmPaste = Services.prefs.getBoolPref("middlemouse.paste"); let mmScrollbarPosition = Services.prefs.getBoolPref( "middlemouse.scrollbarPosition" ); let content = node.ownerGlobal; while (node) { if ( (node instanceof content.HTMLAnchorElement || node instanceof content.HTMLAreaElement) && node.hasAttribute("href") ) { return true; } if ( mmPaste && (node instanceof content.HTMLInputElement || node instanceof content.HTMLTextAreaElement) ) { return true; } if ( node instanceof content.XULElement && ((mmScrollbarPosition && (node.localName == "scrollbar" || node.localName == "scrollcorner")) || node.localName == "treechildren") ) { return true; } node = node.parentNode; } return false; } isScrollableElement(aNode) { let content = aNode.ownerGlobal; if (aNode instanceof content.HTMLElement) { return !(aNode instanceof content.HTMLSelectElement) || aNode.multiple; } return aNode instanceof content.XULElement; } computeWindowScrollDirection(global) { if (!global.scrollbars.visible) { return null; } if (global.scrollMaxX != global.scrollMinX) { return global.scrollMaxY != global.scrollMinY ? "NSEW" : "EW"; } if (global.scrollMaxY != global.scrollMinY) { return "NS"; } return null; } computeNodeScrollDirection(node) { if (!this.isScrollableElement(node)) { return null; } let global = node.ownerGlobal; // this is a list of overflow property values that allow scrolling const scrollingAllowed = ["scroll", "auto"]; let cs = global.getComputedStyle(node); let overflowx = cs.getPropertyValue("overflow-x"); let overflowy = cs.getPropertyValue("overflow-y"); // we already discarded non-multiline selects so allow vertical // scroll for multiline ones directly without checking for a // overflow property let scrollVert = node.scrollTopMax && (node instanceof global.HTMLSelectElement || scrollingAllowed.includes(overflowy)); // do not allow horizontal scrolling for select elements, it leads // to visual artifacts and is not the expected behavior anyway if ( !(node instanceof global.HTMLSelectElement) && node.scrollLeftMin != node.scrollLeftMax && scrollingAllowed.includes(overflowx) ) { return scrollVert ? "NSEW" : "EW"; } if (scrollVert) { return "NS"; } return null; } findNearestScrollableElement(aNode) { // go upward in the DOM and find any parent element that has a overflow // area and can therefore be scrolled this._scrollable = null; for (let node = aNode; node; node = node.flattenedTreeParentNode) { // do not use overflow based autoscroll for and // Elements or non-html/non-xul elements such as svg or Document nodes // also make sure to skip select elements that are not multiline let direction = this.computeNodeScrollDirection(node); if (direction) { this._scrolldir = direction; this._scrollable = node; break; } } if (!this._scrollable) { let direction = this.computeWindowScrollDirection(aNode.ownerGlobal); if (direction) { this._scrolldir = direction; this._scrollable = aNode.ownerGlobal; } else if (aNode.ownerGlobal.frameElement) { // Note, in case of out of process iframes frameElement is null, and // a caller is supposed to communicate to iframe's parent on its own to // support cross process scrolling. this.findNearestScrollableElement(aNode.ownerGlobal.frameElement); } } } async startScroll(event) { this.findNearestScrollableElement(event.originalTarget); if (!this._scrollable) { this.sendAsyncMessage("Autoscroll:MaybeStartInParent", { browsingContextId: this.browsingContext.id, screenX: event.screenX, screenY: event.screenY, }); return; } let content = event.originalTarget.ownerGlobal; // In some configurations like Print Preview, content.performance // (which we use below) is null. Autoscrolling is broken in Print // Preview anyways (see bug 1393494), so just don't start it at all. if (!content.performance) { return; } let domUtils = content.windowUtils; let scrollable = this._scrollable; if (scrollable instanceof Ci.nsIDOMWindow) { // getViewId() needs an element to operate on. scrollable = scrollable.document.documentElement; } this._scrollId = null; try { this._scrollId = domUtils.getViewId(scrollable); } catch (e) { // No view ID - leave this._scrollId as null. Receiving side will check. } let presShellId = domUtils.getPresShellId(); let { autoscrollEnabled, usingApz } = await this.sendQuery( "Autoscroll:Start", { scrolldir: this._scrolldir, screenX: event.screenX, screenY: event.screenY, scrollId: this._scrollId, presShellId, browsingContext: this.browsingContext, } ); if (!autoscrollEnabled) { this._scrollable = null; return; } Services.els.addSystemEventListener(this.document, "mousemove", this, true); this.document.addEventListener("pagehide", this, true); this._ignoreMouseEvents = true; this._startX = event.screenX; this._startY = event.screenY; this._screenX = event.screenX; this._screenY = event.screenY; this._scrollErrorX = 0; this._scrollErrorY = 0; this._autoscrollHandledByApz = usingApz; if (!usingApz) { // If the browser didn't hand the autoscroll off to APZ, // scroll here in the main thread. this.startMainThreadScroll(); } else { // Even if the browser did hand the autoscroll to APZ, // APZ might reject it in which case it will notify us // and we need to take over. Services.obs.addObserver(this.observer, "autoscroll-rejected-by-apz"); } if (Cu.isInAutomation) { Services.obs.notifyObservers(content, "autoscroll-start"); } } startMainThreadScroll() { let content = this.document.defaultView; this._lastFrame = content.performance.now(); content.requestAnimationFrame(this.autoscrollLoop); const kAutoscroll = 15; // defined in mozilla/layers/ScrollInputMethods.h Services.telemetry .getHistogramById("SCROLL_INPUT_METHODS") .add(kAutoscroll); } stopScroll() { if (this._scrollable) { this._scrollable.mozScrollSnap(); this._scrollable = null; Services.els.removeSystemEventListener( this.document, "mousemove", this, true ); this.document.removeEventListener("pagehide", this, true); if (this._autoscrollHandledByApz) { Services.obs.removeObserver( this.observer, "autoscroll-rejected-by-apz" ); } } } accelerate(curr, start) { const speed = 12; var val = (curr - start) / speed; if (val > 1) { return val * Math.sqrt(val) - 1; } if (val < -1) { return val * Math.sqrt(-val) + 1; } return 0; } roundToZero(num) { if (num > 0) { return Math.floor(num); } return Math.ceil(num); } autoscrollLoop(timestamp) { if (!this._scrollable) { // Scrolling has been canceled return; } // avoid long jumps when the browser hangs for more than // |maxTimeDelta| ms const maxTimeDelta = 100; var timeDelta = Math.min(maxTimeDelta, timestamp - this._lastFrame); // we used to scroll |accelerate()| pixels every 20ms (50fps) var timeCompensation = timeDelta / 20; this._lastFrame = timestamp; var actualScrollX = 0; var actualScrollY = 0; // don't bother scrolling vertically when the scrolldir is only horizontal // and the other way around if (this._scrolldir != "EW") { var y = this.accelerate(this._screenY, this._startY) * timeCompensation; var desiredScrollY = this._scrollErrorY + y; actualScrollY = this.roundToZero(desiredScrollY); this._scrollErrorY = desiredScrollY - actualScrollY; } if (this._scrolldir != "NS") { var x = this.accelerate(this._screenX, this._startX) * timeCompensation; var desiredScrollX = this._scrollErrorX + x; actualScrollX = this.roundToZero(desiredScrollX); this._scrollErrorX = desiredScrollX - actualScrollX; } this._scrollable.scrollBy({ left: actualScrollX, top: actualScrollY, behavior: "instant", }); this._scrollable.ownerGlobal.requestAnimationFrame(this.autoscrollLoop); } handleEvent(event) { if (event.type == "mousemove") { this._screenX = event.screenX; this._screenY = event.screenY; } else if (event.type == "mousedown") { if ( event.isTrusted & !event.defaultPrevented && event.button == 1 && !this._scrollable && !this.isAutoscrollBlocker(event.originalTarget) ) { this.startScroll(event); } } else if (event.type == "pagehide") { if (this._scrollable) { var doc = this._scrollable.ownerDocument || this._scrollable.document; if (doc == event.target) { this.sendAsyncMessage("Autoscroll:Cancel"); this.stopScroll(); } } } } receiveMessage(msg) { let data = msg.data; switch (msg.name) { case "Autoscroll:MaybeStart": for (let child of this.browsingContext.children) { if (data.browsingContextId == child.id) { this.startScroll({ screenX: data.screenX, screenY: data.screenY, originalTarget: child.embedderElement, }); break; } } break; case "Autoscroll:Stop": { this.stopScroll(); break; } } } rejectedByApz(data) { // The caller passes in the scroll id via 'data'. if (data == this._scrollId) { this._autoscrollHandledByApz = false; this.startMainThreadScroll(); Services.obs.removeObserver(this.observer, "autoscroll-rejected-by-apz"); } } } class AutoScrollObserver { constructor(actor) { this.actor = actor; } observe(subject, topic, data) { if (topic === "autoscroll-rejected-by-apz") { this.actor.rejectedByApz(data); } } }