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// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
goog.provide('cvox.ChromeVoxKbHandler');
goog.require('cvox.ChromeVox');
goog.require('cvox.ChromeVoxUserCommands');
goog.require('cvox.History');
goog.require('cvox.KeyMap');
goog.require('cvox.KeySequence');
goog.require('cvox.KeyUtil');
goog.require('cvox.KeyboardHelpWidget');
/**
* @fileoverview Handles user keyboard input events.
*
*/
cvox.ChromeVoxKbHandler = {};
/**
* The key map
*
* @type {cvox.KeyMap}
*/
cvox.ChromeVoxKbHandler.handlerKeyMap;
/**
* Loads the key bindings into the keyToFunctionsTable.
*
* @param {string} keyToFunctionsTable The key bindings table in JSON form.
*/
cvox.ChromeVoxKbHandler.loadKeyToFunctionsTable = function(
keyToFunctionsTable) {
if (!window.JSON) {
return;
}
cvox.ChromeVoxKbHandler.handlerKeyMap =
cvox.KeyMap.fromJSON(keyToFunctionsTable);
};
/**
* Converts the key bindings table into an array that is sorted by the lengths
* of the key bindings. After the sort, the key bindings that describe single
* keys will come before the key bindings that describe multiple keys.
* @param {Object<string>} keyToFunctionsTable Contains each key binding and its
* associated function name.
* @return {Array<Array<string>>} The sorted key bindings table in
* array form. Each entry in the array is itself an array containing the
* key binding and its associated function name.
* @private
*/
cvox.ChromeVoxKbHandler.sortKeyToFunctionsTable_ = function(
keyToFunctionsTable) {
var sortingArray = [];
for (var keySeqStr in keyToFunctionsTable) {
sortingArray.push([keySeqStr, keyToFunctionsTable[keySeqStr]]);
}
function compareKeyStr(a, b) {
// Compare the lengths of the key bindings.
if (a[0].length < b[0].length) {
return -1;
} else if (b[0].length < a[0].length) {
return 1;
} else {
// The keys are the same length. Sort lexicographically.
return a[0].localeCompare(b[0]);
}
};
sortingArray.sort(compareKeyStr);
return sortingArray;
};
/**
* Handles key down events.
*
* @param {Event} evt The key down event to process.
* @return {boolean} True if the default action should be performed.
*/
cvox.ChromeVoxKbHandler.basicKeyDownActionsListener = function(evt) {
var keySequence = cvox.KeyUtil.keyEventToKeySequence(evt);
var functionName;
if (cvox.ChromeVoxKbHandler.handlerKeyMap != undefined) {
functionName =
cvox.ChromeVoxKbHandler.handlerKeyMap.commandForKey(keySequence);
} else {
functionName = null;
}
// TODO (clchen): Disambiguate why functions are null. If the user pressed
// something that is not a valid combination, make an error noise so there
// is some feedback.
if (!functionName) {
return !cvox.KeyUtil.sequencing;
}
// If ChromeVox isn't active, ignore every command except the one
// to toggle ChromeVox active again.
if (!cvox.ChromeVox.isActive && functionName != 'toggleChromeVox') {
return true;
}
// This is the key event handler return value - true if the event should
// propagate and the default action should be performed, false if we eat
// the key.
var returnValue = true;
var func = cvox.ChromeVoxUserCommands.commands[functionName];
if (func) {
var history = cvox.History.getInstance();
history.enterUserCommand(functionName);
returnValue = func();
history.exitUserCommand(functionName);
} else if (keySequence.cvoxModifier) {
// Modifier/prefix is active -- prevent default action
returnValue = false;
}
// If the whole document is hidden from screen readers, let the app
// catch keys as well.
if (cvox.ChromeVox.entireDocumentIsHidden) {
returnValue = true;
}
return returnValue;
};
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