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Diffstat (limited to 'devtools/server/actors/accessibility/walker.js')
| -rw-r--r-- | devtools/server/actors/accessibility/walker.js | 1313 |
1 files changed, 1313 insertions, 0 deletions
diff --git a/devtools/server/actors/accessibility/walker.js b/devtools/server/actors/accessibility/walker.js new file mode 100644 index 0000000000..85d9388ef5 --- /dev/null +++ b/devtools/server/actors/accessibility/walker.js @@ -0,0 +1,1313 @@ +/* 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/. */ + +"use strict"; + +const { Cc, Ci } = require("chrome"); +const Services = require("Services"); +const { Actor, ActorClassWithSpec } = require("devtools/shared/protocol"); +const { accessibleWalkerSpec } = require("devtools/shared/specs/accessibility"); +const { + simulation: { COLOR_TRANSFORMATION_MATRICES }, +} = require("devtools/server/actors/accessibility/constants"); + +loader.lazyRequireGetter( + this, + "AccessibleActor", + "devtools/server/actors/accessibility/accessible", + true +); +loader.lazyRequireGetter( + this, + ["CustomHighlighterActor"], + "devtools/server/actors/highlighters", + true +); +loader.lazyRequireGetter( + this, + "DevToolsUtils", + "devtools/shared/DevToolsUtils" +); +loader.lazyRequireGetter(this, "events", "devtools/shared/event-emitter"); +loader.lazyRequireGetter( + this, + ["getCurrentZoom", "isWindowIncluded", "isRemoteFrame"], + "devtools/shared/layout/utils", + true +); +loader.lazyRequireGetter(this, "InspectorUtils", "InspectorUtils"); +loader.lazyRequireGetter( + this, + "isXUL", + "devtools/server/actors/highlighters/utils/markup", + true +); +loader.lazyRequireGetter( + this, + [ + "isDefunct", + "loadSheetForBackgroundCalculation", + "removeSheetForBackgroundCalculation", + ], + "devtools/server/actors/utils/accessibility", + true +); +loader.lazyRequireGetter( + this, + "accessibility", + "devtools/shared/constants", + true +); + +const kStateHover = 0x00000004; // NS_EVENT_STATE_HOVER + +const { + EVENT_TEXT_CHANGED, + EVENT_TEXT_INSERTED, + EVENT_TEXT_REMOVED, + EVENT_ACCELERATOR_CHANGE, + EVENT_ACTION_CHANGE, + EVENT_DEFACTION_CHANGE, + EVENT_DESCRIPTION_CHANGE, + EVENT_DOCUMENT_ATTRIBUTES_CHANGED, + EVENT_HIDE, + EVENT_NAME_CHANGE, + EVENT_OBJECT_ATTRIBUTE_CHANGED, + EVENT_REORDER, + EVENT_STATE_CHANGE, + EVENT_TEXT_ATTRIBUTE_CHANGED, + EVENT_VALUE_CHANGE, +} = Ci.nsIAccessibleEvent; + +// TODO: We do not need this once bug 1422913 is fixed. We also would not need +// to fire a name change event for an accessible that has an updated subtree and +// that has its name calculated from the said subtree. +const NAME_FROM_SUBTREE_RULE_ROLES = new Set([ + Ci.nsIAccessibleRole.ROLE_BUTTONDROPDOWN, + Ci.nsIAccessibleRole.ROLE_BUTTONDROPDOWNGRID, + Ci.nsIAccessibleRole.ROLE_BUTTONMENU, + Ci.nsIAccessibleRole.ROLE_CELL, + Ci.nsIAccessibleRole.ROLE_CHECKBUTTON, + Ci.nsIAccessibleRole.ROLE_CHECK_MENU_ITEM, + Ci.nsIAccessibleRole.ROLE_CHECK_RICH_OPTION, + Ci.nsIAccessibleRole.ROLE_COLUMN, + Ci.nsIAccessibleRole.ROLE_COLUMNHEADER, + Ci.nsIAccessibleRole.ROLE_COMBOBOX_OPTION, + Ci.nsIAccessibleRole.ROLE_DEFINITION, + Ci.nsIAccessibleRole.ROLE_GRID_CELL, + Ci.nsIAccessibleRole.ROLE_HEADING, + Ci.nsIAccessibleRole.ROLE_HELPBALLOON, + Ci.nsIAccessibleRole.ROLE_HTML_CONTAINER, + Ci.nsIAccessibleRole.ROLE_KEY, + Ci.nsIAccessibleRole.ROLE_LABEL, + Ci.nsIAccessibleRole.ROLE_LINK, + Ci.nsIAccessibleRole.ROLE_LISTITEM, + Ci.nsIAccessibleRole.ROLE_MATHML_IDENTIFIER, + Ci.nsIAccessibleRole.ROLE_MATHML_NUMBER, + Ci.nsIAccessibleRole.ROLE_MATHML_OPERATOR, + Ci.nsIAccessibleRole.ROLE_MATHML_TEXT, + Ci.nsIAccessibleRole.ROLE_MATHML_STRING_LITERAL, + Ci.nsIAccessibleRole.ROLE_MATHML_GLYPH, + Ci.nsIAccessibleRole.ROLE_MENUITEM, + Ci.nsIAccessibleRole.ROLE_OPTION, + Ci.nsIAccessibleRole.ROLE_OUTLINEITEM, + Ci.nsIAccessibleRole.ROLE_PAGETAB, + Ci.nsIAccessibleRole.ROLE_PARENT_MENUITEM, + Ci.nsIAccessibleRole.ROLE_PUSHBUTTON, + Ci.nsIAccessibleRole.ROLE_RADIOBUTTON, + Ci.nsIAccessibleRole.ROLE_RADIO_MENU_ITEM, + Ci.nsIAccessibleRole.ROLE_RICH_OPTION, + Ci.nsIAccessibleRole.ROLE_ROW, + Ci.nsIAccessibleRole.ROLE_ROWHEADER, + Ci.nsIAccessibleRole.ROLE_SUMMARY, + Ci.nsIAccessibleRole.ROLE_SWITCH, + Ci.nsIAccessibleRole.ROLE_TABLE_COLUMN_HEADER, + Ci.nsIAccessibleRole.ROLE_TABLE_ROW_HEADER, + Ci.nsIAccessibleRole.ROLE_TEAR_OFF_MENU_ITEM, + Ci.nsIAccessibleRole.ROLE_TERM, + Ci.nsIAccessibleRole.ROLE_TOGGLE_BUTTON, + Ci.nsIAccessibleRole.ROLE_TOOLTIP, +]); + +const IS_OSX = Services.appinfo.OS === "Darwin"; + +const { + SCORES: { BEST_PRACTICES, FAIL, WARNING }, +} = accessibility; + +/** + * Helper function that determines if nsIAccessible object is in stale state. When an + * object is stale it means its subtree is not up to date. + * + * @param {nsIAccessible} accessible + * object to be tested. + * @return {Boolean} + * True if accessible object is stale, false otherwise. + */ +function isStale(accessible) { + const extraState = {}; + accessible.getState({}, extraState); + // extraState.value is a bitmask. We are applying bitwise AND to mask out + // irrelevant states. + return !!(extraState.value & Ci.nsIAccessibleStates.EXT_STATE_STALE); +} + +/** + * Get accessibility audit starting with the passed accessible object as a root. + * + * @param {Object} acc + * AccessibileActor to be used as the root for the audit. + * @param {Object} options + * Options for running audit, may include: + * - types: Array of audit types to be performed during audit. + * @param {Map} report + * An accumulator map to be used to store audit information. + * @param {Object} progress + * An audit project object that is used to track the progress of the + * audit and send progress "audit-event" events to the client. + */ +function getAudit(acc, options, report, progress) { + if (acc.isDefunct) { + return; + } + + // Audit returns a promise, save the actual value in the report. + report.set( + acc, + acc.audit(options).then(result => { + report.set(acc, result); + progress.increment(); + }) + ); + + for (const child of acc.children()) { + getAudit(child, options, report, progress); + } +} + +/** + * A helper class that is used to track audit progress and send progress events + * to the client. + */ +class AuditProgress { + constructor(walker) { + this.completed = 0; + this.percentage = 0; + this.walker = walker; + } + + setTotal(size) { + this.size = size; + } + + notify() { + this.walker.emit("audit-event", { + type: "progress", + progress: { + total: this.size, + percentage: this.percentage, + completed: this.completed, + }, + }); + } + + increment() { + this.completed++; + const { completed, size } = this; + if (!size) { + return; + } + + const percentage = Math.round((completed / size) * 100); + if (percentage > this.percentage) { + this.percentage = percentage; + this.notify(); + } + } + + destroy() { + this.walker = null; + } +} + +/** + * The AccessibleWalkerActor stores a cache of AccessibleActors that represent + * accessible objects in a given document. + * + * It is also responsible for implicitely initializing and shutting down + * accessibility engine by storing a reference to the XPCOM accessibility + * service. + */ +const AccessibleWalkerActor = ActorClassWithSpec(accessibleWalkerSpec, { + initialize(conn, targetActor) { + Actor.prototype.initialize.call(this, conn); + this.targetActor = targetActor; + this.refMap = new Map(); + this._loadedSheets = new WeakMap(); + this.setA11yServiceGetter(); + this.onPick = this.onPick.bind(this); + this.onHovered = this.onHovered.bind(this); + this._preventContentEvent = this._preventContentEvent.bind(this); + this.onKey = this.onKey.bind(this); + this.onFocusIn = this.onFocusIn.bind(this); + this.onFocusOut = this.onFocusOut.bind(this); + this.onHighlighterEvent = this.onHighlighterEvent.bind(this); + }, + + get highlighter() { + if (!this._highlighter) { + this._highlighter = CustomHighlighterActor(this, "AccessibleHighlighter"); + + this.manage(this._highlighter); + this._highlighter.on("highlighter-event", this.onHighlighterEvent); + } + + return this._highlighter; + }, + + get tabbingOrderHighlighter() { + if (!this._tabbingOrderHighlighter) { + this._tabbingOrderHighlighter = CustomHighlighterActor( + this, + "TabbingOrderHighlighter" + ); + + this.manage(this._tabbingOrderHighlighter); + } + + return this._tabbingOrderHighlighter; + }, + + setA11yServiceGetter() { + DevToolsUtils.defineLazyGetter(this, "a11yService", () => { + Services.obs.addObserver(this, "accessible-event"); + return Cc["@mozilla.org/accessibilityService;1"].getService( + Ci.nsIAccessibilityService + ); + }); + }, + + get rootWin() { + return this.targetActor && this.targetActor.window; + }, + + get rootDoc() { + return this.targetActor && this.targetActor.window.document; + }, + + get isXUL() { + return isXUL(this.rootWin); + }, + + get colorMatrix() { + if (!this.targetActor.docShell) { + return null; + } + + const colorMatrix = this.targetActor.docShell.getColorMatrix(); + if ( + colorMatrix.length === 0 || + colorMatrix === COLOR_TRANSFORMATION_MATRICES.NONE + ) { + return null; + } + + return colorMatrix; + }, + + reset() { + try { + Services.obs.removeObserver(this, "accessible-event"); + } catch (e) { + // Accessible event observer might not have been initialized if a11y + // service was never used. + } + + this.cancelPick(); + + // Clean up accessible actors cache. + this.clearRefs(); + + this._childrenPromise = null; + delete this.a11yService; + this.setA11yServiceGetter(); + }, + + /** + * Remove existing cache (of accessible actors) from tree. + */ + clearRefs() { + for (const actor of this.refMap.values()) { + actor.destroy(); + } + }, + + destroy() { + Actor.prototype.destroy.call(this); + + this.reset(); + + if (this._highlighter) { + this._highlighter.off("highlighter-event", this.onHighlighterEvent); + this._highlighter = null; + } + + if (this._tabbingOrderHighlighter) { + this._tabbingOrderHighlighter = null; + } + + this.targetActor = null; + this.refMap = null; + }, + + getRef(rawAccessible) { + return this.refMap.get(rawAccessible); + }, + + addRef(rawAccessible) { + let actor = this.refMap.get(rawAccessible); + if (actor) { + return actor; + } + + actor = new AccessibleActor(this, rawAccessible); + // Add the accessible actor as a child of this accessible walker actor, + // assigning it an actorID. + this.manage(actor); + this.refMap.set(rawAccessible, actor); + + return actor; + }, + + /** + * Clean up accessible actors cache for a given accessible's subtree. + * + * @param {null|nsIAccessible} rawAccessible + */ + purgeSubtree(rawAccessible) { + if (!rawAccessible) { + return; + } + + try { + for ( + let child = rawAccessible.firstChild; + child; + child = child.nextSibling + ) { + this.purgeSubtree(child); + } + } catch (e) { + // rawAccessible or its descendants are defunct. + } + + const actor = this.getRef(rawAccessible); + if (actor) { + actor.destroy(); + } + }, + + unmanage: function(actor) { + if (actor instanceof AccessibleActor) { + this.refMap.delete(actor.rawAccessible); + } + Actor.prototype.unmanage.call(this, actor); + }, + + /** + * A helper method. Accessibility walker is assumed to have only 1 child which + * is the top level document. + */ + async children() { + if (this._childrenPromise) { + return this._childrenPromise; + } + + this._childrenPromise = Promise.all([this.getDocument()]); + const children = await this._childrenPromise; + this._childrenPromise = null; + return children; + }, + + /** + * A promise for a root document accessible actor that only resolves when its + * corresponding document accessible object is fully loaded. + * + * @return {Promise} + */ + getDocument() { + if (!this.rootDoc || !this.rootDoc.documentElement) { + return this.once("document-ready").then(docAcc => this.addRef(docAcc)); + } + + if (this.isXUL) { + const doc = this.addRef(this.getRawAccessibleFor(this.rootDoc)); + return Promise.resolve(doc); + } + + const doc = this.getRawAccessibleFor(this.rootDoc); + if (!doc || isStale(doc)) { + return this.once("document-ready").then(docAcc => this.addRef(docAcc)); + } + + return Promise.resolve(this.addRef(doc)); + }, + + /** + * Get an accessible actor for a domnode actor. + * @param {Object} domNode + * domnode actor for which accessible actor is being created. + * @return {Promse} + * A promise that resolves when accessible actor is created for a + * domnode actor. + */ + getAccessibleFor(domNode) { + // We need to make sure that the document is loaded processed by a11y first. + return this.getDocument().then(() => { + const rawAccessible = this.getRawAccessibleFor(domNode.rawNode); + // Not all DOM nodes have corresponding accessible objects. It's usually + // the case where there is no semantics or relevance to the accessibility + // client. + if (!rawAccessible) { + return null; + } + + return this.addRef(rawAccessible); + }); + }, + + /** + * Get a raw accessible object for a raw node. + * @param {DOMNode} rawNode + * Raw node for which accessible object is being retrieved. + * @return {nsIAccessible} + * Accessible object for a given DOMNode. + */ + getRawAccessibleFor(rawNode) { + // Accessible can only be retrieved iff accessibility service is enabled. + if (!Services.appinfo.accessibilityEnabled) { + return null; + } + + return this.a11yService.getAccessibleFor(rawNode); + }, + + async getAncestry(accessible) { + if (!accessible || accessible.indexInParent === -1) { + return []; + } + const doc = await this.getDocument(); + const ancestry = []; + if (accessible === doc) { + return ancestry; + } + + try { + let parent = accessible; + while (parent && (parent = parent.parentAcc) && parent != doc) { + ancestry.push(parent); + } + ancestry.push(doc); + } catch (error) { + throw new Error(`Failed to get ancestor for ${accessible}: ${error}`); + } + + return ancestry.map(parent => ({ + accessible: parent, + children: parent.children(), + })); + }, + + /** + * Run accessibility audit and return relevant ancestries for AccessibleActors + * that have non-empty audit checks. + * + * @param {Object} options + * Options for running audit, may include: + * - types: Array of audit types to be performed during audit. + * + * @return {Promise} + * A promise that resolves when the audit is complete and all relevant + * ancestries are calculated. + */ + async audit(options) { + const doc = await this.getDocument(); + const report = new Map(); + this._auditProgress = new AuditProgress(this); + getAudit(doc, options, report, this._auditProgress); + this._auditProgress.setTotal(report.size); + await Promise.all(report.values()); + + const ancestries = []; + for (const [acc, audit] of report.entries()) { + // Filter out audits that have no failing checks. + if ( + audit && + Object.values(audit).some( + check => + check != null && + !check.error && + [BEST_PRACTICES, FAIL, WARNING].includes(check.score) + ) + ) { + ancestries.push(this.getAncestry(acc)); + } + } + + return Promise.all(ancestries); + }, + + /** + * Start accessibility audit. The result of this function will not be an audit + * report. Instead, an "audit-event" event will be fired when the audit is + * completed or fails. + * + * @param {Object} options + * Options for running audit, may include: + * - types: Array of audit types to be performed during audit. + */ + startAudit(options) { + // Audit is already running, wait for the "audit-event" event. + if (this._auditing) { + return; + } + + this._auditing = this.audit(options) + // We do not want to block on audit request, instead fire "audit-event" + // event when internal audit is finished or failed. + .then(ancestries => + this.emit("audit-event", { + type: "completed", + ancestries, + }) + ) + .catch(() => this.emit("audit-event", { type: "error" })) + .finally(() => { + this._auditing = null; + this._auditProgress.destroy(); + this._auditProgress = null; + }); + }, + + onHighlighterEvent: function(data) { + this.emit("highlighter-event", data); + }, + + /** + * Accessible event observer function. + * + * @param {Ci.nsIAccessibleEvent} subject + * accessible event object. + */ + // eslint-disable-next-line complexity + observe(subject) { + const event = subject.QueryInterface(Ci.nsIAccessibleEvent); + const rawAccessible = event.accessible; + const accessible = this.getRef(rawAccessible); + + if (rawAccessible instanceof Ci.nsIAccessibleDocument && !accessible) { + const rootDocAcc = this.getRawAccessibleFor(this.rootDoc); + if (rawAccessible === rootDocAcc && !isStale(rawAccessible)) { + this.clearRefs(); + // If it's a top level document notify listeners about the document + // being ready. + events.emit(this, "document-ready", rawAccessible); + } + } + + switch (event.eventType) { + case EVENT_STATE_CHANGE: + const { state, isEnabled } = event.QueryInterface( + Ci.nsIAccessibleStateChangeEvent + ); + const isBusy = state & Ci.nsIAccessibleStates.STATE_BUSY; + if (accessible) { + // Only propagate state change events for active accessibles. + if (isBusy && isEnabled) { + if (rawAccessible instanceof Ci.nsIAccessibleDocument) { + // Remove existing cache from tree. + this.clearRefs(); + } + return; + } + events.emit(accessible, "states-change", accessible.states); + } + + break; + case EVENT_NAME_CHANGE: + if (accessible) { + events.emit( + accessible, + "name-change", + rawAccessible.name, + event.DOMNode == this.rootDoc + ? undefined + : this.getRef(rawAccessible.parent) + ); + } + break; + case EVENT_VALUE_CHANGE: + if (accessible) { + events.emit(accessible, "value-change", rawAccessible.value); + } + break; + case EVENT_DESCRIPTION_CHANGE: + if (accessible) { + events.emit( + accessible, + "description-change", + rawAccessible.description + ); + } + break; + case EVENT_REORDER: + if (accessible) { + accessible + .children() + .forEach(child => + events.emit(child, "index-in-parent-change", child.indexInParent) + ); + events.emit(accessible, "reorder", rawAccessible.childCount); + } + break; + case EVENT_HIDE: + if (event.DOMNode == this.rootDoc) { + this.clearRefs(); + } else { + this.purgeSubtree(rawAccessible); + } + break; + case EVENT_DEFACTION_CHANGE: + case EVENT_ACTION_CHANGE: + if (accessible) { + events.emit(accessible, "actions-change", accessible.actions); + } + break; + case EVENT_TEXT_CHANGED: + case EVENT_TEXT_INSERTED: + case EVENT_TEXT_REMOVED: + if (accessible) { + events.emit(accessible, "text-change"); + if (NAME_FROM_SUBTREE_RULE_ROLES.has(rawAccessible.role)) { + events.emit( + accessible, + "name-change", + rawAccessible.name, + event.DOMNode == this.rootDoc + ? undefined + : this.getRef(rawAccessible.parent) + ); + } + } + break; + case EVENT_DOCUMENT_ATTRIBUTES_CHANGED: + case EVENT_OBJECT_ATTRIBUTE_CHANGED: + case EVENT_TEXT_ATTRIBUTE_CHANGED: + if (accessible) { + events.emit(accessible, "attributes-change", accessible.attributes); + } + break; + // EVENT_ACCELERATOR_CHANGE is currently not fired by gecko accessibility. + case EVENT_ACCELERATOR_CHANGE: + if (accessible) { + events.emit( + accessible, + "shortcut-change", + accessible.keyboardShortcut + ); + } + break; + default: + break; + } + }, + + /** + * Ensure that nothing interferes with the audit for an accessible object + * (CSS, overlays) by load accessibility highlighter style sheet used for + * preventing transitions and applying transparency when calculating colour + * contrast as well as temporarily hiding accessible highlighter overlay. + * @param {Object} win + * Window where highlighting happens. + */ + async clearStyles(win) { + const requests = this._loadedSheets.get(win); + if (requests != null) { + this._loadedSheets.set(win, requests + 1); + return; + } + + // Disable potential mouse driven transitions (This is important because accessibility + // highlighter temporarily modifies text color related CSS properties. In case where + // there are transitions that affect them, there might be unexpected side effects when + // taking a snapshot for contrast measurement). + loadSheetForBackgroundCalculation(win); + this._loadedSheets.set(win, 1); + await this.hideHighlighter(); + }, + + /** + * Restore CSS and overlays that could've interfered with the audit for an + * accessible object by unloading accessibility highlighter style sheet used + * for preventing transitions and applying transparency when calculating + * colour contrast and potentially restoring accessible highlighter overlay. + * @param {Object} win + * Window where highlighting was happenning. + */ + async restoreStyles(win) { + const requests = this._loadedSheets.get(win); + if (!requests) { + return; + } + + if (requests > 1) { + this._loadedSheets.set(win, requests - 1); + return; + } + + await this.showHighlighter(); + removeSheetForBackgroundCalculation(win); + this._loadedSheets.delete(win); + }, + + async hideHighlighter() { + // TODO: Fix this workaround that temporarily removes higlighter bounds + // overlay that can interfere with the contrast ratio calculation. + if (this._highlighter) { + const highlighter = this._highlighter.instance; + await highlighter.isReady; + highlighter.hideAccessibleBounds(); + } + }, + + async showHighlighter() { + // TODO: Fix this workaround that temporarily removes higlighter bounds + // overlay that can interfere with the contrast ratio calculation. + if (this._highlighter) { + const highlighter = this._highlighter.instance; + await highlighter.isReady; + highlighter.showAccessibleBounds(); + } + }, + + /** + * Public method used to show an accessible object highlighter on the client + * side. + * + * @param {Object} accessible + * AccessibleActor to be highlighted. + * @param {Object} options + * Object used for passing options. Available options: + * - duration {Number} + * Duration of time that the highlighter should be shown. + * @return {Boolean} + * True if highlighter shows the accessible object. + */ + async highlightAccessible(accessible, options = {}) { + this.unhighlight(); + // Do not highlight if accessible is dead. + if (!accessible || accessible.isDefunct || accessible.indexInParent < 0) { + return false; + } + + this._highlightingAccessible = accessible; + const { bounds } = accessible; + if (!bounds) { + return false; + } + + const { DOMNode: rawNode } = accessible.rawAccessible; + const audit = await accessible.audit(); + if (this._highlightingAccessible !== accessible) { + return false; + } + + const { name, role } = accessible; + const { highlighter } = this; + await highlighter.instance.isReady; + if (this._highlightingAccessible !== accessible) { + return false; + } + + const shown = highlighter.show( + { rawNode }, + { ...options, ...bounds, name, role, audit, isXUL: this.isXUL } + ); + this._highlightingAccessible = null; + + return shown; + }, + + /** + * Public method used to hide an accessible object highlighter on the client + * side. + */ + unhighlight() { + if (!this._highlighter) { + return; + } + + this.highlighter.hide(); + this._highlightingAccessible = null; + }, + + /** + * Picking state that indicates if picking is currently enabled and, if so, + * what the current and hovered accessible objects are. + */ + _isPicking: false, + _currentAccessible: null, + + /** + * Check is event handling is allowed. + */ + _isEventAllowed: function({ view }) { + return ( + this.rootWin instanceof Ci.nsIDOMChromeWindow || + isWindowIncluded(this.rootWin, view) + ); + }, + + /** + * Check if the DOM event received when picking shold be ignored. + * @param {Event} event + */ + _ignoreEventWhenPicking(event) { + return ( + !this._isPicking || + // If the DOM event is about a remote frame, only the WalkerActor for that + // remote frame target should emit RDP events (hovered/picked/...). And + // all other WalkerActor for intermediate iframe and top level document + // targets should stay silent. + isRemoteFrame(event.originalTarget || event.target) + ); + }, + + _preventContentEvent(event) { + if (this._ignoreEventWhenPicking(event)) { + return; + } + + event.stopPropagation(); + event.preventDefault(); + + const target = event.originalTarget || event.target; + if (target !== this._currentTarget) { + this._resetStateAndReleaseTarget(); + this._currentTarget = target; + // We use InspectorUtils to save the original hover content state of the target + // element (that includes its hover state). In order to not trigger any visual + // changes to the element that depend on its hover state we remove the state while + // the element is the most current target of the highlighter. + // + // TODO: This logic can be removed if/when we can use elementsAtPoint API for + // determining topmost DOMNode that corresponds to specific coordinates. We would + // then be able to use a highlighter overlay that would prevent all pointer events + // to content but still render highlighter for the node/element correctly. + this._currentTargetHoverState = + InspectorUtils.getContentState(target) & kStateHover; + InspectorUtils.removeContentState(target, kStateHover); + } + }, + + /** + * Click event handler for when picking is enabled. + * + * @param {Object} event + * Current click event. + */ + onPick(event) { + if (this._ignoreEventWhenPicking(event)) { + return; + } + + this._preventContentEvent(event); + if (!this._isEventAllowed(event)) { + return; + } + + // If shift is pressed, this is only a preview click, send the event to + // the client, but don't stop picking. + if (event.shiftKey) { + if (!this._currentAccessible) { + this._currentAccessible = this._findAndAttachAccessible(event); + } + events.emit(this, "picker-accessible-previewed", this._currentAccessible); + return; + } + + this._unsetPickerEnvironment(); + this._isPicking = false; + if (!this._currentAccessible) { + this._currentAccessible = this._findAndAttachAccessible(event); + } + events.emit(this, "picker-accessible-picked", this._currentAccessible); + }, + + /** + * Hover event handler for when picking is enabled. + * + * @param {Object} event + * Current hover event. + */ + async onHovered(event) { + if (this._ignoreEventWhenPicking(event)) { + return; + } + + this._preventContentEvent(event); + if (!this._isEventAllowed(event)) { + return; + } + + const accessible = this._findAndAttachAccessible(event); + if (!accessible || this._currentAccessible === accessible) { + return; + } + + this._currentAccessible = accessible; + // Highlight current accessible and by the time we are done, if accessible that was + // highlighted is not current any more (user moved the mouse to a new node) highlight + // the most current accessible again. + const shown = await this.highlightAccessible(accessible); + if (this._isPicking && shown && accessible === this._currentAccessible) { + events.emit(this, "picker-accessible-hovered", accessible); + } + }, + + /** + * Keyboard event handler for when picking is enabled. + * + * @param {Object} event + * Current keyboard event. + */ + onKey(event) { + if (!this._currentAccessible || this._ignoreEventWhenPicking(event)) { + return; + } + + this._preventContentEvent(event); + if (!this._isEventAllowed(event)) { + return; + } + + /** + * KEY: Action/scope + * ENTER/CARRIAGE_RETURN: Picks current accessible + * ESC/CTRL+SHIFT+C: Cancels picker + */ + switch (event.keyCode) { + // Select the element. + case event.DOM_VK_RETURN: + this.onPick(event); + break; + // Cancel pick mode. + case event.DOM_VK_ESCAPE: + this.cancelPick(); + events.emit(this, "picker-accessible-canceled"); + break; + case event.DOM_VK_C: + if ( + (IS_OSX && event.metaKey && event.altKey) || + (!IS_OSX && event.ctrlKey && event.shiftKey) + ) { + this.cancelPick(); + events.emit(this, "picker-accessible-canceled"); + } + break; + default: + break; + } + }, + + /** + * Picker method that starts picker content listeners. + */ + pick: function() { + if (!this._isPicking) { + this._isPicking = true; + this._setPickerEnvironment(); + } + }, + + /** + * This pick method also focuses the highlighter's target window. + */ + pickAndFocus: function() { + this.pick(); + this.rootWin.focus(); + }, + + attachAccessible(rawAccessible, accessibleDocument) { + // If raw accessible object is defunct or detached, no need to cache it and + // its ancestry. + if ( + !rawAccessible || + isDefunct(rawAccessible) || + rawAccessible.indexInParent < 0 + ) { + return null; + } + + const accessible = this.addRef(rawAccessible); + // There is a chance that ancestry lookup can fail if the accessible is in + // the detached subtree. At that point the root accessible object would be + // defunct and accessing it via parent property will throw. + try { + let parent = accessible; + while (parent && parent.rawAccessible != accessibleDocument) { + parent = parent.parentAcc; + } + } catch (error) { + throw new Error(`Failed to get ancestor for ${accessible}: ${error}`); + } + + return accessible; + }, + + /** + * When RDM is used, users can set custom DPR values that are different from the device + * they are using. Store true screenPixelsPerCSSPixel value to be able to use accessible + * highlighter features correctly. + */ + get pixelRatio() { + const { contentViewer } = this.targetActor.docShell; + const { windowUtils } = this.rootWin; + const overrideDPPX = contentViewer.overrideDPPX; + let ratio; + if (overrideDPPX) { + contentViewer.overrideDPPX = 0; + ratio = windowUtils.screenPixelsPerCSSPixel; + contentViewer.overrideDPPX = overrideDPPX; + } else { + ratio = windowUtils.screenPixelsPerCSSPixel; + } + + return ratio; + }, + + /** + * Find deepest accessible object that corresponds to the screen coordinates of the + * mouse pointer and attach it to the AccessibilityWalker tree. + * + * @param {Object} event + * Correspoinding content event. + * @return {null|Object} + * Accessible object, if available, that corresponds to a DOM node. + */ + _findAndAttachAccessible(event) { + const target = event.originalTarget || event.target; + const docAcc = this.getRawAccessibleFor(this.rootDoc); + const win = target.ownerGlobal; + const zoom = this.isXUL ? 1 : getCurrentZoom(win); + const scale = this.pixelRatio / zoom; + const rawAccessible = docAcc.getDeepestChildAtPointInProcess( + event.screenX * scale, + event.screenY * scale + ); + return this.attachAccessible(rawAccessible, docAcc); + }, + + /** + * Start picker content listeners. + */ + _setPickerEnvironment: function() { + const target = this.targetActor.chromeEventHandler; + target.addEventListener("mousemove", this.onHovered, true); + target.addEventListener("click", this.onPick, true); + target.addEventListener("mousedown", this._preventContentEvent, true); + target.addEventListener("mouseup", this._preventContentEvent, true); + target.addEventListener("mouseover", this._preventContentEvent, true); + target.addEventListener("mouseout", this._preventContentEvent, true); + target.addEventListener("mouseleave", this._preventContentEvent, true); + target.addEventListener("mouseenter", this._preventContentEvent, true); + target.addEventListener("dblclick", this._preventContentEvent, true); + target.addEventListener("keydown", this.onKey, true); + target.addEventListener("keyup", this._preventContentEvent, true); + }, + + /** + * If content is still alive, stop picker content listeners, reset the hover state for + * last target element. + */ + _unsetPickerEnvironment: function() { + const target = this.targetActor.chromeEventHandler; + + if (!target) { + return; + } + + target.removeEventListener("mousemove", this.onHovered, true); + target.removeEventListener("click", this.onPick, true); + target.removeEventListener("mousedown", this._preventContentEvent, true); + target.removeEventListener("mouseup", this._preventContentEvent, true); + target.removeEventListener("mouseover", this._preventContentEvent, true); + target.removeEventListener("mouseout", this._preventContentEvent, true); + target.removeEventListener("mouseleave", this._preventContentEvent, true); + target.removeEventListener("mouseenter", this._preventContentEvent, true); + target.removeEventListener("dblclick", this._preventContentEvent, true); + target.removeEventListener("keydown", this.onKey, true); + target.removeEventListener("keyup", this._preventContentEvent, true); + + this._resetStateAndReleaseTarget(); + }, + + /** + * When using accessibility highlighter, we keep track of the most current event pointer + * event target. In order to update or release the target, we need to make sure we set + * the content state (using InspectorUtils) to its original value. + * + * TODO: This logic can be removed if/when we can use elementsAtPoint API for + * determining topmost DOMNode that corresponds to specific coordinates. We would then + * be able to use a highlighter overlay that would prevent all pointer events to content + * but still render highlighter for the node/element correctly. + */ + _resetStateAndReleaseTarget() { + if (!this._currentTarget) { + return; + } + + try { + if (this._currentTargetHoverState) { + InspectorUtils.setContentState(this._currentTarget, kStateHover); + } + } catch (e) { + // DOMNode is already dead. + } + + this._currentTarget = null; + this._currentTargetState = null; + }, + + /** + * Cacncel picker pick. Remvoe all content listeners and hide the highlighter. + */ + cancelPick: function() { + this.unhighlight(); + + if (this._isPicking) { + this._unsetPickerEnvironment(); + this._isPicking = false; + this._currentAccessible = null; + } + }, + + /** + * Indicates that the tabbing order current active element (focused) is being + * tracked. + */ + _isTrackingTabbingOrderFocus: false, + + /** + * Current focused element in the tabbing order. + */ + _currentFocusedTabbingOrder: null, + + /** + * Focusin event handler for when interacting with tabbing order overlay. + * + * @param {Object} event + * Most recent focusin event. + */ + async onFocusIn(event) { + if (!this._isTrackingTabbingOrderFocus) { + return; + } + + const target = event.originalTarget || event.target; + if (target === this._currentFocusedTabbingOrder) { + return; + } + + this._currentFocusedTabbingOrder = target; + this.tabbingOrderHighlighter._highlighter.updateFocus({ + node: target, + focused: true, + }); + }, + + /** + * Focusout event handler for when interacting with tabbing order overlay. + * + * @param {Object} event + * Most recent focusout event. + */ + async onFocusOut(event) { + if ( + !this._isTrackingTabbingOrderFocus || + !this._currentFocusedTabbingOrder + ) { + return; + } + + const target = event.originalTarget || event.target; + // Sanity check. + if (target !== this._currentFocusedTabbingOrder) { + console.warn( + `focusout target: ${target} does not match current focused element in tabbing order: ${this._currentFocusedTabbingOrder}` + ); + } + + this.tabbingOrderHighlighter._highlighter.updateFocus({ + node: this._currentFocusedTabbingOrder, + focused: false, + }); + this._currentFocusedTabbingOrder = null; + }, + + /** + * Show tabbing order overlay for a given target. + * + * @param {Object} elm + * domnode actor to be used as the starting point for generating the + * tabbing order. + * @param {Number} index + * Starting index for the tabbing order. + * + * @return {JSON} + * Tabbing order information for the last element in the tabbing + * order. It includes a ContentDOMReference for the node and a tabbing + * index. If we are at the end of the tabbing order for the top level + * content document, the ContentDOMReference will be null. If focus + * manager discovered a remote IFRAME, then the ContentDOMReference + * references the IFRAME itself. + */ + showTabbingOrder(elm, index) { + // Start track focus related events (only once). `showTabbingOrder` will be + // called multiple times for a given target if it contains other remote + // targets. + if (!this._isTrackingTabbingOrderFocus) { + this._isTrackingTabbingOrderFocus = true; + const target = this.targetActor.chromeEventHandler; + target.addEventListener("focusin", this.onFocusIn, true); + target.addEventListener("focusout", this.onFocusOut, true); + } + + return this.tabbingOrderHighlighter.show(elm, { index }); + }, + + /** + * Hide tabbing order overlay for a given target. + */ + hideTabbingOrder() { + if (!this._tabbingOrderHighlighter) { + return; + } + + this.tabbingOrderHighlighter.hide(); + if (!this._isTrackingTabbingOrderFocus) { + return; + } + + this._isTrackingTabbingOrderFocus = false; + this._currentFocusedTabbingOrder = null; + const target = this.targetActor.chromeEventHandler; + if (target) { + target.removeEventListener("focusin", this.onFocusIn, true); + target.removeEventListener("focusout", this.onFocusOut, true); + } + }, +}); + +exports.AccessibleWalkerActor = AccessibleWalkerActor; |