Implement support for chorded braille commands

chrome/browser/resources/chromeos/chromevox/cvox2/background/braille_command_handler.js

+// Copyright 2016 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.
+
+/**
+ * @fileoverview ChromeVox braille commands.
+ */
+
+goog.provide('BrailleCommandHandler');
+
+goog.require('ChromeVoxState');
+goog.require('CommandHandler');
+
+
+goog.scope(function() {
+/**
+ * Maps a dot pattern to a command.
+ * @type {!Object<number, string>}
+ */
+BrailleCommandHandler.DOT_PATTERN_TO_COMMAND = {
+};
+
+/**
+ * Makes a dot pattern given a list of dots numbered from 1 to 8 arranged in a
+ * braille cell (a 2 x 4 dot grid).
+ * @param {Array<number>} dots The dots to be set in the returned pattern.
+ * @return {number}
+ */
+BrailleCommandHandler.makeDotPattern = function(dots) {
+  return dots.reduce(function(p, c) {
+    return p | (1 << c - 1);
+  }, 0);
+};
+
+/**
+ * Perform a braille command based on a dot pattern from a chord.
+ * @param {number} dots Braille dot pattern
+ */
+BrailleCommandHandler.onBrailleCommand = function(dots) {
+  var command = BrailleCommandHandler.DOT_PATTERN_TO_COMMAND[dots];
+  if (command)
+    CommandHandler.onCommand(command);
+};
+
+/**
+ * @private
+ */
+BrailleCommandHandler.init_ = function() {
+  var map = function(dots, command) {
+    BrailleCommandHandler.DOT_PATTERN_TO_COMMAND[
+      BrailleCommandHandler.makeDotPattern(dots)] = command;
+  };
+
+  map([2, 3], 'previousGroup');
+  map([5, 6], 'nextGroup');
+  map([1], 'previousObject');
+  map([4], 'nextObject');
+  map([2], 'previousWord');
+  map([5], 'nextWord');
+  map([3], 'previousCharacter');
+  map([6], 'nextCharacter');
+  map([1, 2, 3], 'jumpToTop');
+  map([4, 5, 6], 'jumpToBottom');
+
+  map([1, 4], 'fullyDescribe');
+  map([1, 3, 4], 'contextMenu');
+  map([1, 2, 3, 5], 'readFromHere');
+  map([2, 3, 4], 'toggleSelection');
+
+  // Forward jump.
+  map([1, 2], 'nextButton');
+  map([1, 5], 'nextEditText');
+  map([1, 2, 4], 'nextFormField');
+  map([1, 2, 5], 'nextHeading');
+  map([4, 5], 'nextLink');
+  map([2, 3, 4, 5], 'nextTable');
+
+  // Backward jump.
+  map([1, 2, 7], 'previousButton');
+  map([1, 5, 7], 'previousEditText');
+  map([1, 2, 4, 7], 'previousFormField');
+  map([1, 2, 5, 7], 'previousHeading');
+  map([4, 5, 7], 'previousLink');
+  map([2, 3, 4, 5, 7], 'previousTable');
+
+  map([8], 'forceClickOnCurrentItem');
+  map([3, 4], 'toggleSearchWidget');
+
+  // Question.
+  map([1, 4, 5, 6], 'toggleKeyboardHelp');
+};
+
+BrailleCommandHandler.init_();
+
+}); //  goog.scope