Support braille dot or chorded typing conversions to standard keyboard keys

chrome/browser/resources/chromeos/chromevox/braille/braille_key_event_rewriter.js

+// Copyright 2017 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 Rewrites a braille key event.
+ */
+
+goog.provide('BrailleKeyEventRewriter');
+
+goog.require('Output');
+goog.require('cvox.BrailleKeyEvent');
+
+/**
+ * A class that transforms a sequence of braille key events into a standard key
+ * event.
+ * @constructor
+ */
+BrailleKeyEventRewriter = function() {
+  /** @private {Object} */
+  this.incrementalKey_ = null;
+};
+
+BrailleKeyEventRewriter.prototype = {
+  /**
+   * Accumulates and optionally modifies in-coming braille key events.
+   * @param {cvox.BrailleKeyEvent} evt
+   * @return {boolean} False to continue event propagation.
+   */
+  onBrailleKeyEvent: function(evt) {
+    var standardKeyCode;
+    var dots = evt.brailleDots;
+    if (!dots) {
+      this.incrementalKey_ = null;
+      return false;
+    }
+
+    if (evt.command == cvox.BrailleKeyCommand.CHORD) {
+      Output.forceModeForNextSpeechUtterance(cvox.QueueMode.CATEGORY_FLUSH);
+      var modifiers = cvox.BrailleKeyEvent.brailleDotsToModifiers[dots];
+
+      // Check for a modifier mapping.
+      if (modifiers) {
+        this.incrementalKey_ = this.incrementalKey_ || {};
+        for (var key in modifiers) {
+          this.incrementalKey_[key] = true;
+        }
+
+        return true;
+      }
+
+      // Check for a chord to standard key mapping.
+      standardKeyCode =
+          cvox.BrailleKeyEvent.brailleChordsToStandardKeyCode[dots];
+    }
+
+    // Check for a 'dots' command, which is typed on the keyboard with a
+    // previous incremental key press.
+    if (evt.command == cvox.BrailleKeyCommand.DOTS && this.incrementalKey_) {
+      // Check if this braille pattern has a standard key mapping.
+      standardKeyCode =
+          cvox.BrailleKeyEvent.brailleDotsToStandardKeyCode[dots];
+    }
+
+    if (standardKeyCode) {
+      evt.command = cvox.BrailleKeyCommand.STANDARD_KEY;
+      evt.standardKeyCode = standardKeyCode;
+      if (this.incrementalKey_) {
+        // Apply all modifiers seen so far to the outgoing event as a standard
+        // keyboard command.
+        evt.altKey = this.incrementalKey_.altKey;
+        evt.ctrlKey = this.incrementalKey_.ctrlKey;
+        evt.shiftKey = this.incrementalKey_.shiftKey;
+        this.incrementalKey_ = null;
+      }
+      return false;
+    }
+
+    this.incrementalKey_ = null;
+    return false;
+  }
+};