Refactor intent usage in ChromeVox

This is a purely refactoring change to set up ChromeVox to use all
possible intents. IntentHandler, the newly introduced class, will
cleanly process all intents, along with whatever computed metadata is
needed (e.g. EditableLine).

R=akihiroota@chromium.org, nektar@chromium.org

AX-Relnotes: n/a
Test: existing browser_tests --gtest_filter=ChromeVoxEditing*.*
Change-Id: I74d9454794fc6a40075bbf56fb0037b607c2b974
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2594240
Commit-Queue: David Tseng <dtseng@chromium.org>
Reviewed-by: Akihiro Ota <akihiroota@chromium.org>
Cr-Commit-Position: refs/heads/master@{#838241}

chrome/browser/resources/chromeos/accessibility/chromevox/BUILD.gn

@@ -48,7 +48,9 @@ chromevox_modules = [
   "background/desktop_automation_handler.js",
   "background/download_handler.js",
   "background/earcon_engine.js",
-  "background/editing.js",
+  "background/editing/editable_line.js",
+  "background/editing/editing.js",
+  "background/editing/intent_handler.js",
   "background/event_source.js",
   "background/find_handler.js",
   "background/focus_automation_handler.js",
@@ -450,7 +452,7 @@ if (is_chromeos_ash) {
       "background/color_test.js",
       "background/cursors_test.js",
       "background/download_handler_test.js",
-      "background/editing_test.js",
+      "background/editing/editing_test.js",
       "background/keyboard_handler_test.js",
       "background/live_regions_test.js",
       "background/locale_output_helper_test.js",

chrome/browser/resources/chromeos/accessibility/chromevox/background/editing_test.js → chrome/browser/resources/chromeos/accessibility/chromevox/background/editing/editing_test.js

@@ -267,7 +267,8 @@ TEST_F(
           `
     <div role="textbox" contenteditable>
       <p style="font-size:20px; font-family:times">
-        <b style="color:#ff0000">Move</b> <i>through</i> <u style="font-family:georgia">text</u>
+        <b style="color:#ff0000">Move</b>
+        <i>through</i> <u style="font-family:georgia">text</u>
         by <strike style="font-size:12px; color:#0000ff">character</strike>
         <a href="#">test</a>!
       </p>

chrome/browser/resources/chromeos/accessibility/chromevox/background/editing/intent_handler.js

+// Copyright 2020 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 Handles automation intents for speech feedback.
+ */
+
+goog.provide('IntentHandler');
+
+goog.require('editing.EditableLine');
+
+goog.scope(function() {
+const AutomationIntent = chrome.automation.AutomationIntent;
+const IntentCommandType = chrome.automation.IntentCommandType;
+const IntentTextBoundaryType = chrome.automation.IntentTextBoundaryType;
+
+/**
+ * A stateless class that turns intents into speech.
+ */
+IntentHandler = class {
+  /**
+   * Called when intents are received from an AutomationEvent.
+   * @param {!Array<AutomationIntent>} intents
+   * @param {!editing.EditableLine} cur The current line.
+   * @param {editing.EditableLine} prev The previous line.
+   * @return {boolean} Whether intents are handled.
+   */
+  static onIntents(intents, cur, prev) {
+    if (intents.length === 0) {
+      return false;
+    }
+
+    // Currently, discard all other intents once one is handled.
+    for (let i = 0; i < intents.length; i++) {
+      if (IntentHandler.onIntent(intents[i], cur, prev)) {
+        return true;
+      }
+    }
+
+    return false;
+  }
+
+  /**
+   * Called when an intent is received.
+   * @param {!AutomationIntent} intent
+   * @param {!editing.EditableLine} cur The current line.
+   * @param {editing.EditableLine} prev The previous line.
+   * @return {boolean} Whether the intent was handled.
+   */
+  static onIntent(intent, cur, prev) {
+    switch (intent.command) {
+      case IntentCommandType.MOVE_SELECTION:
+        return IntentHandler.onMoveSelection(intent, cur, prev);
+
+        // TODO: implement support.
+      case IntentCommandType.CLEAR_SELECTION:
+      case IntentCommandType.DELETE:
+      case IntentCommandType.DICTATE:
+      case IntentCommandType.EXTEND_SELECTION:
+      case IntentCommandType.FORMAT:
+      case IntentCommandType.HISTORY:
+      case IntentCommandType.INSERT:
+      case IntentCommandType.MARKER:
+      case IntentCommandType.SET_SELECTION:
+        break;
+    }
+
+    return false;
+  }
+
+  /**
+   * Called when the text selection moves.
+   * @param {!AutomationIntent} intent A move selection
+   *     intent.
+   * @param {!editing.EditableLine} cur The current line.
+   * @param {editing.EditableLine} prev The previous line.
+   * @return {boolean} Whether the intent was handled.
+   */
+  static onMoveSelection(intent, cur, prev) {
+    switch (intent.textBoundary) {
+      case IntentTextBoundaryType.CHARACTER:
+        // Read character to the right of the cursor. It is assumed to be a new
+        // line if empty.
+        // TODO: detect when this is the end of the document; read "end of text"
+        // if so.
+        ChromeVox.tts.speak(
+            cur.text.substring(cur.startOffset, cur.startOffset + 1) || '\n',
+            QueueMode.CATEGORY_FLUSH);
+        return true;
+
+      case IntentTextBoundaryType.LINE_END:
+      case IntentTextBoundaryType.LINE_START:
+      case IntentTextBoundaryType.LINE_START_OR_END:
+        cur.speakLine(prev);
+        return true;
+
+        // TODO: implement support.
+      case IntentTextBoundaryType.FORMAT:
+      case IntentTextBoundaryType.OBJECT:
+      case IntentTextBoundaryType.PAGE_END:
+      case IntentTextBoundaryType.PAGE_START:
+      case IntentTextBoundaryType.PAGE_START_OR_END:
+      case IntentTextBoundaryType.PARAGRAPH_END:
+      case IntentTextBoundaryType.PARAGRAPH_START:
+      case IntentTextBoundaryType.PARAGRAPH_START_OR_END:
+      case IntentTextBoundaryType.SENTENCE_END:
+      case IntentTextBoundaryType.SENTENCE_START:
+      case IntentTextBoundaryType.SENTENCE_START_OR_END:
+      case IntentTextBoundaryType.WEB_PAGE:
+      case IntentTextBoundaryType.WORD_END:
+      case IntentTextBoundaryType.WORD_START:
+      case IntentTextBoundaryType.WORD_START_OR_END:
+        break;
+    }
+
+    return false;
+  }
+};
+});  // goog.scope