Implement word wrapping and panning in multiline Braille.

chrome/browser/resources/chromeos/chromevox/chromevox/background/braille_captions_background.js

Index: chrome/browser/resources/chromeos/chromevox/chromevox/background/braille_captions_background.js
diff --git a/chrome/browser/resources/chromeos/chromevox/chromevox/background/braille_captions_background.js b/chrome/browser/resources/chromeos/chromevox/chromevox/background/braille_captions_background.js
index 47fdd0e6188fbcf8dd084a40458f9f63cb398c53..506e24644fd056c9a84088ee7a68b57ba4223161 100644
--- a/chrome/browser/resources/chromeos/chromevox/chromevox/background/braille_captions_background.js
+++ b/chrome/browser/resources/chromeos/chromevox/chromevox/background/braille_captions_background.js
@@ -58,9 +58,11 @@ cvox.BrailleCaptionsBackground.isEnabled = function() {
  * @param {ArrayBuffer} cells Braille cells shown on the display.
  * @param {Array<number>} brailleToText Map of Braille letters to the first
  *     index of corresponding text letter.
+ * @param {Array<number>} offsetsForSlices Offsets to use for caculating
+ *    indices. The element is the braille offset, the second is the text offset.
  */
 cvox.BrailleCaptionsBackground.setContent = function(text, cells,
-    brailleToText) {
+    brailleToText, offsetsForSlices) {
   var self = cvox.BrailleCaptionsBackground;
   // Convert the cells to Unicode braille pattern characters.
   var byteBuf = new Uint8Array(cells);
@@ -70,9 +72,8 @@ cvox.BrailleCaptionsBackground.setContent = function(text, cells,
     brailleChars += String.fromCharCode(
         self.BRAILLE_UNICODE_BLOCK_START | byteBuf[i]);
   }
-
-  var groups = this.groupBrailleAndText(brailleChars, text, brailleToText);
-
+  var groups = this.groupBrailleAndText(brailleChars, text, brailleToText,
+      offsetsForSlices);
   if (cvox.ChromeVox.isChromeOS) {
     var data = {groups: groups};
     (new PanelCommand(PanelCommandType.UPDATE_BRAILLE, data)).send();
@@ -88,26 +89,36 @@ cvox.BrailleCaptionsBackground.setContent = function(text, cells,
 /**
  * @param {string} brailleChars Braille characters shown on the display.
  * @param {string} text Text of the shown braille.
- * @param {Array<number>} brailleToText Map of Braille letters to the first
+ * @param {Array<number>} brailleToText Map of Braille cells to the first
  *     index of corresponding text letter.
- * @return {Array}
+ * @param {Array<number>} offsets Offsets to use for caculating indices. The
+ *     element is the braille offset, the second is the text offset.
+ * @return {Array} The groups of braille and texts to be displayed.
  */
 cvox.BrailleCaptionsBackground.groupBrailleAndText = function(brailleChars,
-    text, brailleToText) {
+    text, brailleToText, offsets) {
   var brailleBuf = '';
   var groups = [];
   var textIndex = 0;
+  var brailleOffset = offsets[0];
+  var textOffset = offsets[1];
+  var calculateTextIndex = function(index) {
+    return brailleToText[index + brailleOffset] - textOffset;
+  };
+
   for (var i = 0; i < brailleChars.length; ++i) {
-    if ((i != 0) && ((brailleToText[i] != textIndex))) {
-      groups.push([text.substr(textIndex, brailleToText[i] - textIndex),
+    var textSliceIndex = calculateTextIndex(i);
+    if (i != 0 && textSliceIndex != textIndex) {
+      groups.push([text.substr(textIndex,
+          textSliceIndex - textIndex),
           brailleBuf]);
       brailleBuf = '';
-      textIndex = brailleToText[i];
+      textIndex = textSliceIndex;
     }
     brailleBuf += brailleChars.charAt(i);
   }
   // Puts the rest of the text into the last group.
-  if (brailleBuf.length > 0) {
+  if (brailleBuf.length > 0 && text.charAt(textIndex) != ' ') {
     groups.push([text.substr(textIndex), brailleBuf]);
   }
   return groups;