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Diffstat (limited to '')
| -rw-r--r-- | browser/components/urlbar/UrlbarEventBufferer.sys.mjs | 364 |
1 files changed, 364 insertions, 0 deletions
diff --git a/browser/components/urlbar/UrlbarEventBufferer.sys.mjs b/browser/components/urlbar/UrlbarEventBufferer.sys.mjs new file mode 100644 index 0000000000..e881d3114b --- /dev/null +++ b/browser/components/urlbar/UrlbarEventBufferer.sys.mjs @@ -0,0 +1,364 @@ +/* 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/. */ + +import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs"; + +import { AppConstants } from "resource://gre/modules/AppConstants.sys.mjs"; + +const lazy = {}; + +ChromeUtils.defineESModuleGetters(lazy, { + UrlbarUtils: "resource:///modules/UrlbarUtils.sys.mjs", + clearTimeout: "resource://gre/modules/Timer.sys.mjs", + setTimeout: "resource://gre/modules/Timer.sys.mjs", +}); + +XPCOMUtils.defineLazyGetter(lazy, "logger", () => + lazy.UrlbarUtils.getLogger({ prefix: "EventBufferer" }) +); + +// Maximum time events can be deferred for. In automation providers can be quite +// slow, thus we need a longer timeout to avoid intermittent failures. +const DEFERRING_TIMEOUT_MS = Cu.isInAutomation ? 1000 : 300; + +// Array of keyCodes to defer. +const DEFERRED_KEY_CODES = new Set([ + KeyboardEvent.DOM_VK_RETURN, + KeyboardEvent.DOM_VK_DOWN, + KeyboardEvent.DOM_VK_TAB, +]); + +// Status of the current or last query. +const QUERY_STATUS = { + UKNOWN: 0, + RUNNING: 1, + COMPLETE: 2, +}; + +/** + * The UrlbarEventBufferer can queue up events and replay them later, to make + * the urlbar results more predictable. + * + * Search results arrive asynchronously, which means that keydown events may + * arrive before results do, and therefore not have the effect the user intends. + * That's especially likely to happen with the down arrow and enter keys, due to + * the one-off search buttons: if the user very quickly pastes something in the + * input, presses the down arrow key, and then hits enter, they are probably + * expecting to visit the first result. But if there are no results, then + * pressing down and enter will trigger the first one-off button. + * To prevent that undesirable behavior, certain keys are buffered and deferred + * until more results arrive, at which time they're replayed. + */ +export class UrlbarEventBufferer { + /** + * Initialises the class. + * + * @param {UrlbarInput} input The urlbar input object. + */ + constructor(input) { + this.input = input; + this.input.inputField.addEventListener("blur", this); + + // A queue of {event, callback} objects representing deferred events. + // The callback is invoked when it's the right time to handle the event, + // but it may also never be invoked, if the context changed and the event + // became obsolete. + this._eventsQueue = []; + // If this timer fires, we will unconditionally replay all the deferred + // events so that, after a certain point, we don't keep blocking the user's + // actions, when nothing else has caused the events to be replayed. + // At that point we won't check whether it's safe to replay the events, + // because otherwise it may look like we ignored the user's actions. + this._deferringTimeout = null; + + // Tracks the current or last query status. + this._lastQuery = { + // The time at which the current or last search was started. This is used + // to check how much time passed while deferring the user's actions. Must + // be set using the monotonic Cu.now() helper. + startDate: Cu.now(), + // Status of the query; one of QUERY_STATUS.* + status: QUERY_STATUS.UKNOWN, + // The query context. + context: null, + }; + + // Start listening for queries. + this.input.controller.addQueryListener(this); + } + + // UrlbarController listener methods. + onQueryStarted(queryContext) { + this._lastQuery = { + startDate: Cu.now(), + status: QUERY_STATUS.RUNNING, + context: queryContext, + }; + if (this._deferringTimeout) { + lazy.clearTimeout(this._deferringTimeout); + this._deferringTimeout = null; + } + } + + onQueryCancelled(queryContext) { + this._lastQuery.status = QUERY_STATUS.COMPLETE; + } + + onQueryFinished(queryContext) { + this._lastQuery.status = QUERY_STATUS.COMPLETE; + } + + onQueryResults(queryContext) { + // Ensure this runs after other results handling code. + Services.tm.dispatchToMainThread(() => { + this.replayDeferredEvents(true); + }); + } + + /** + * Handles DOM events. + * + * @param {Event} event DOM event from the input. + */ + handleEvent(event) { + if (event.type == "blur") { + lazy.logger.debug("Clearing queue on blur"); + // The input field was blurred, pending events don't matter anymore. + // Clear the timeout and the queue. + this._eventsQueue.length = 0; + if (this._deferringTimeout) { + lazy.clearTimeout(this._deferringTimeout); + this._deferringTimeout = null; + } + } + } + + /** + * Receives DOM events, eventually queues them up, and calls back when it's + * the right time to handle the event. + * + * @param {Event} event DOM event from the input. + * @param {Function} callback to be invoked when it's the right time to handle + * the event. + */ + maybeDeferEvent(event, callback) { + if (!callback) { + throw new Error("Must provide a callback"); + } + if (this.shouldDeferEvent(event)) { + this.deferEvent(event, callback); + return; + } + // If it has not been deferred, handle the callback immediately. + callback(); + } + + /** + * Adds a deferrable event to the deferred event queue. + * + * @param {Event} event The event to defer. + * @param {Function} callback to be invoked when it's the right time to handle + * the event. + */ + deferEvent(event, callback) { + // TODO Bug 1536822: once one-off buttons are implemented, figure out if the + // following is true for the quantum bar as well: somehow event.defaultPrevented + // ends up true for deferred events. Autocomplete ignores defaultPrevented + // events, which means it would ignore replayed deferred events if we didn't + // tell it to bypass defaultPrevented through urlbarDeferred. + // Check we don't try to defer events more than once. + if (event.urlbarDeferred) { + throw new Error(`Event ${event.type}:${event.keyCode} already deferred!`); + } + lazy.logger.debug(`Deferring ${event.type}:${event.keyCode} event`); + // Mark the event as deferred. + event.urlbarDeferred = true; + // Also store the current search string, as an added safety check. If the + // string will differ later, the event is stale and should be dropped. + event.searchString = this._lastQuery.context.searchString; + this._eventsQueue.push({ event, callback }); + + if (!this._deferringTimeout) { + let elapsed = Cu.now() - this._lastQuery.startDate; + let remaining = DEFERRING_TIMEOUT_MS - elapsed; + this._deferringTimeout = lazy.setTimeout(() => { + this.replayDeferredEvents(false); + this._deferringTimeout = null; + }, Math.max(0, remaining)); + } + } + + /** + * Replays deferred key events. + * + * @param {boolean} onlyIfSafe replays only if it's a safe time to do so. + * Setting this to false will replay all the queue events, without any + * checks, that is something we want to do only if the deferring + * timeout elapsed, and we don't want to appear ignoring user's input. + */ + replayDeferredEvents(onlyIfSafe) { + if (typeof onlyIfSafe != "boolean") { + throw new Error("Must provide a boolean argument"); + } + if (!this._eventsQueue.length) { + return; + } + + let { event, callback } = this._eventsQueue[0]; + if (onlyIfSafe && !this.isSafeToPlayDeferredEvent(event)) { + return; + } + + // Remove the event from the queue and play it. + this._eventsQueue.shift(); + // Safety check: handle only if the search string didn't change meanwhile. + if (event.searchString == this._lastQuery.context.searchString) { + callback(); + } + Services.tm.dispatchToMainThread(() => { + this.replayDeferredEvents(onlyIfSafe); + }); + } + + /** + * Checks whether a given event should be deferred + * + * @param {Event} event The event that should maybe be deferred. + * @returns {boolean} Whether the event should be deferred. + */ + shouldDeferEvent(event) { + // If any event has been deferred for this search, then defer all subsequent + // events so that the user does not experience them out of order. + // All events will be replayed when _deferringTimeout fires. + if (this._eventsQueue.length) { + return true; + } + + // At this point, no events have been deferred for this search; we must + // figure out if this event should be deferred. + let isMacNavigation = + AppConstants.platform == "macosx" && + event.ctrlKey && + this.input.view.isOpen && + (event.key === "n" || event.key === "p"); + if (!DEFERRED_KEY_CODES.has(event.keyCode) && !isMacNavigation) { + return false; + } + + if (DEFERRED_KEY_CODES.has(event.keyCode)) { + // Defer while the user is composing. + if (this.input.editor.composing) { + return true; + } + if (this.input.controller.keyEventMovesCaret(event)) { + return false; + } + } + + // This is an event that we'd defer, but if enough time has passed since the + // start of the search, we don't want to block the user's workflow anymore. + if (this._lastQuery.startDate + DEFERRING_TIMEOUT_MS <= Cu.now()) { + return false; + } + + if ( + event.keyCode == KeyEvent.DOM_VK_TAB && + !this.input.view.isOpen && + !this.waitingDeferUserSelectionProviders + ) { + // The view is closed and the user pressed the Tab key. The focus should + // move out of the urlbar immediately. + return false; + } + + return !this.isSafeToPlayDeferredEvent(event); + } + + /** + * Checks if the bufferer is deferring events. + * + * @returns {boolean} Whether the bufferer is deferring events. + */ + get isDeferringEvents() { + return !!this._eventsQueue.length; + } + + /** + * Checks if any of the current query provider asked to defer user selection + * events. + * + * @returns {boolean} Whether a provider asked to defer events. + */ + get waitingDeferUserSelectionProviders() { + return !!this._lastQuery.context?.deferUserSelectionProviders.size; + } + + /** + * Returns true if the given deferred event can be played now without possibly + * surprising the user. This depends on the state of the view, the results, + * and the type of event. + * Use this method only after determining that the event should be deferred, + * or after it has been deferred and you want to know if it can be played now. + * + * @param {Event} event The event. + * @returns {boolean} Whether the event can be played. + */ + isSafeToPlayDeferredEvent(event) { + if (this._lastQuery.status != QUERY_STATUS.RUNNING) { + // The view can't get any more results, so there's no need to further + // defer events. + return true; + } + + let waitingFirstResult = + this._lastQuery.status == QUERY_STATUS.RUNNING && + !this._lastQuery.context.results.length; + if (event.keyCode == KeyEvent.DOM_VK_RETURN) { + // Check if we're waiting for providers that requested deferring. + if (this.waitingDeferUserSelectionProviders) { + return false; + } + // Play a deferred Enter if the heuristic result is not selected, or we + // are not waiting for the first results yet. + let selectedResult = this.input.view.selectedResult; + return ( + (selectedResult && !selectedResult.heuristic) || !waitingFirstResult + ); + } + + if ( + waitingFirstResult || + !this.input.view.isOpen || + this.waitingDeferUserSelectionProviders + ) { + // We're still waiting on some results, or the popup hasn't opened yet. + return false; + } + + let isMacDownNavigation = + AppConstants.platform == "macosx" && + event.ctrlKey && + this.input.view.isOpen && + event.key === "n"; + if (event.keyCode == KeyEvent.DOM_VK_DOWN || isMacDownNavigation) { + // Don't play the event if the last result is selected so that the user + // doesn't accidentally arrow down into the one-off buttons when they + // didn't mean to. Note TAB is unaffected because it only navigates + // results, not one-offs. + return !this.lastResultIsSelected; + } + + return true; + } + + get lastResultIsSelected() { + // TODO Bug 1536818: Once one-off buttons are fully implemented, it would be + // nice to have a better way to check if the next down will focus one-off buttons. + let results = this._lastQuery.context.results; + return ( + results.length && + results[results.length - 1] == this.input.view.selectedResult + ); + } +} |