// Copyright 2016 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
/**
* @fileoverview ChromeVox keyboard handler.
*/
import {KeyCode} from '/common/key_code.js';
import {TestImportManager} from '/common/testing/test_import_manager.js';
import {EventSourceType} from '../../common/event_source_type.js';
import {ChromeVoxKbHandler} from '../../common/keyboard_handler.js';
import {Msgs} from '../../common/msgs.js';
import {QueueMode} from '../../common/tts_types.js';
import {ChromeVox} from '../chromevox.js';
import {ChromeVoxRange} from '../chromevox_range.js';
import {EventSource} from '../event_source.js';
import {ForcedActionPath} from '../forced_action_path.js';
import {MathHandler} from '../math_handler.js';
import {Output} from '../output/output.js';
import {ChromeVoxPrefs} from '../prefs.js';
/**
* Internal pass through mode state (see usage below).
*/
enum KeyboardPassThroughState {
// No pass through is in progress.
NO_PASS_THROUGH = 'no_pass_through',
// The pass through shortcut command has been pressed (keydowns), waiting for
// user to release (keyups) all the shortcut keys.
PENDING_PASS_THROUGH_SHORTCUT_KEYUPS = 'pending_pass_through_keyups',
// The pass through shortcut command has been pressed and released, waiting
// for the user to press/release a shortcut to be passed through.
PENDING_SHORTCUT_KEYUPS = 'pending_shortcut_keyups',
}
class InternalKeyEvent extends KeyboardEvent {
stickyMode?: boolean;
}
export class BackgroundKeyboardHandler {
static instance?: BackgroundKeyboardHandler;
private static passThroughModeEnabled_: boolean = false;
private eatenKeyDowns_: Set<number>;
private passThroughState_: KeyboardPassThroughState;
private passedThroughKeyDowns_: Set<number>;
private constructor() {
this.eatenKeyDowns_ = new Set();
this.passThroughState_ = KeyboardPassThroughState.NO_PASS_THROUGH;
this.passedThroughKeyDowns_ = new Set();
document.addEventListener(
'keydown', (event) => this.onKeyDown(event), false);
document.addEventListener('keyup', (event) => this.onKeyUp(event), false);
chrome.accessibilityPrivate.setKeyboardListener(
true, ChromeVoxPrefs.isStickyPrefOn);
}
static init(): void {
if (BackgroundKeyboardHandler.instance) {
throw 'Error: trying to create two instances of singleton BackgroundKeyboardHandler.';
}
BackgroundKeyboardHandler.instance = new BackgroundKeyboardHandler();
}
static enablePassThroughMode(): void {
ChromeVox.tts.speak(Msgs.getMsg('pass_through_key'), QueueMode.QUEUE);
BackgroundKeyboardHandler.passThroughModeEnabled_ = true;
}
/**
* Handles key down events.
* The return value has no effect since we ignore it in
* SpokenFeedbackEventRewriterDelegate::HandleKeyboardEvent.
*/
onKeyDown(evt: InternalKeyEvent): boolean {
EventSource.set(EventSourceType.STANDARD_KEYBOARD);
evt.stickyMode = ChromeVoxPrefs.isStickyModeOn();
// If somehow the user gets into a state where there are dangling key downs
// don't get a key up, clear the eaten key downs. This is detected by a set
// list of modifier flags.
if (!evt.altKey && !evt.ctrlKey && !evt.metaKey && !evt.shiftKey) {
this.eatenKeyDowns_.clear();
this.passedThroughKeyDowns_.clear();
}
if (BackgroundKeyboardHandler.passThroughModeEnabled_) {
this.passedThroughKeyDowns_.add(evt.keyCode);
return false;
}
Output.forceModeForNextSpeechUtterance(QueueMode.FLUSH);
// Try to restore to the last valid range.
ChromeVoxRange.restoreLastValidRangeIfNeeded();
if (!this.callOnKeyDownHandlers_(evt) ||
this.shouldConsumeSearchKey_(evt)) {
if (BackgroundKeyboardHandler.passThroughModeEnabled_) {
this.passThroughState_ =
KeyboardPassThroughState.PENDING_PASS_THROUGH_SHORTCUT_KEYUPS;
}
evt.preventDefault();
evt.stopPropagation();
this.eatenKeyDowns_.add(evt.keyCode);
}
return false;
}
/** Returns true if the key should continue propagation. */
private callOnKeyDownHandlers_(evt: KeyboardEvent): boolean {
// Defer first to the math handler, if it exists, then ordinary keyboard
// commands.
if (!MathHandler.onKeyDown(evt)) {
return false;
}
const forcedActionPath = ForcedActionPath.instance;
if (forcedActionPath && !forcedActionPath.onKeyDown(evt)) {
return false;
}
return ChromeVoxKbHandler.basicKeyDownActionsListener(evt);
}
private shouldConsumeSearchKey_(evt: InternalKeyEvent): boolean {
// We natively always capture Search, so we have to be very careful to
// either eat it here or re-inject it; otherwise, some components, like
// ARC++ with TalkBack never get it. We only want to re-inject when
// ChromeVox has no range.
if (!ChromeVoxRange.current) {
return false;
}
// TODO(accessibility): address this awkward indexing once we convert
// key_code.js to TS.
return Boolean(evt.metaKey) || evt.keyCode === KeyCode['SEARCH'];
}
/**
* The return value has no effect since we ignore it in
* SpokenFeedbackEventRewriterDelegate::HandleKeyboardEvent.
*/
onKeyUp(evt: InternalKeyEvent): boolean {
if (this.eatenKeyDowns_.has(evt.keyCode)) {
evt.preventDefault();
evt.stopPropagation();
this.eatenKeyDowns_.delete(evt.keyCode);
}
if (BackgroundKeyboardHandler.passThroughModeEnabled_) {
this.passedThroughKeyDowns_.delete(evt.keyCode);
// Assuming we have no keys held (detected by held modifiers + keys we've
// eaten in key down), we can start pass through for the next keys.
if (this.passThroughState_ ===
KeyboardPassThroughState.PENDING_PASS_THROUGH_SHORTCUT_KEYUPS &&
!evt.altKey && !evt.ctrlKey && !evt.metaKey && !evt.shiftKey &&
this.eatenKeyDowns_.size === 0) {
// All keys of the pass through shortcut command have been released.
// Ready to pass through the next shortcut.
this.passThroughState_ =
KeyboardPassThroughState.PENDING_SHORTCUT_KEYUPS;
} else if (
this.passThroughState_ ===
KeyboardPassThroughState.PENDING_SHORTCUT_KEYUPS &&
this.passedThroughKeyDowns_.size === 0) {
// All keys of the passed through shortcut have been released. Ready to
// go back to normal processing (aka no pass through).
BackgroundKeyboardHandler.passThroughModeEnabled_ = false;
this.passThroughState_ = KeyboardPassThroughState.NO_PASS_THROUGH;
}
}
return false;
}
}
TestImportManager.exportForTesting(BackgroundKeyboardHandler);
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