Implement word wrapping and panning in multiline Braille.

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

 // 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.
 
 /**
  * @fileoverview Puts text on a braille display.
  *
  */
 
 goog.provide('cvox.BrailleDisplayManager');
@@ skipping 22 matching lines @@
    * @private
    */
   this.content_ = new cvox.NavBraille({});
   /**
    * @type {!cvox.ExpandingBrailleTranslator.ExpansionType} valueExpansion
    * @private
    */
   this.expansionType_ =
       cvox.ExpandingBrailleTranslator.ExpansionType.SELECTION;
   /**
-   * @type {!ArrayBuffer}
-   * @private
-   */
-  this.translatedContent_ = new ArrayBuffer(0);
-  /**
-   * @type {!ArrayBuffer}
-   * @private
-   */
-  this.displayedContent_ = this.translatedContent_;
-  /**
    * @type {cvox.PanStrategy}
    * @private
    */
-  this.panStrategy_ = new cvox.WrappingPanStrategy();
+  this.panStrategy_ = new cvox.PanStrategy();
   /**
    * @type {function(!cvox.BrailleKeyEvent, !cvox.NavBraille)}
    * @private
    */
   this.commandListener_ = function() {};
   /**
-   * Current display state used for width calculations.  This is different from
-   * realDisplayState_ if the braille captions feature is enabled and there is
-   * no hardware display connected.  Otherwise, it is the same object
-   * as realDisplayState_.
+   * Current display state to show in the Virtual Braille Captions display.
+   * This is different from realDisplayState_ if the braille captions feature
+   * is enabled and there is no hardware display connected.  Otherwise, it is
+   * the same object as realDisplayState_.
    * @type {!cvox.BrailleDisplayState}
    * @private
    */
   this.displayState_ = {available: false, textRowCount: undefined,
       textColumnCount: undefined};
   /**
    * State reported from the chrome api, reflecting a real hardware
    * display.
    * @type {!cvox.BrailleDisplayState}
    * @private
    */
   this.realDisplayState_ = this.displayState_;
-  /**
-   * @type {!Array<number>}
-   * @private
-   */
-  this.textToBraille_ = [];
-  /**
-   * @type {!Array<number>}
-   * @private
-   */
-  this.brailleToText_ = [];
 
   translatorManager.addChangeListener(function() {
     this.translateContent_(this.content_, this.expansionType_);
   }.bind(this));
 
   chrome.storage.onChanged.addListener(function(changes, area) {
     if (area == 'local' && 'brailleWordWrap' in changes) {
       this.updatePanStrategy_(changes.brailleWordWrap.newValue);
     }
   }.bind(this));
@@ skipping 52 matching lines @@
 };
 
 
 /**
  * @param {!cvox.BrailleDisplayState} newState Display state reported
  *     by the extension API.
  * @private
  */
 cvox.BrailleDisplayManager.prototype.refreshDisplayState_ = function(
     newState) {
-  var oldSize = this.displayState_.textColumnCount *
-                this.displayState_.textRowCount || 0;
+  var oldColumnCount = this.displayState_.textColumnCount || 0;
+  var oldRowCount = this.displayState_.textRowCount || 0;
   this.realDisplayState_ = newState;
   if (newState.available) {
     this.displayState_ = newState;
+    // Update the dimensions of the virtual braille captions display to those
+    // of a real physical display when one is plugged in.
   } else {
     this.displayState_ =
         cvox.BrailleCaptionsBackground.getVirtualDisplayState();
   }
-  var newSize = this.displayState_.textColumnCount *
-                this.displayState_.textRowCount || 0;
-  if (oldSize != newSize) {
-    this.panStrategy_.setDisplaySize(newSize);
+  var newColumnCount = this.displayState_.textColumnCount || 0;
+  var newRowCount = this.displayState_.textRowCount || 0;
+
+  if (oldColumnCount != newColumnCount || oldRowCount != newRowCount) {
+    this.panStrategy_.setDisplaySize(newRowCount, newColumnCount);
   }
   this.refresh_();
 };
 
 
 /**
  * Called when the state of braille captions changes.
  * @private
  */
 cvox.BrailleDisplayManager.prototype.onCaptionsStateChanged_ = function() {
   // Force reevaluation of the display state based on our stored real
   // hardware display state, meaning that if a real display is connected,
   // that takes precedence over the state from the captions 'virtual' display.
   this.refreshDisplayState_(this.realDisplayState_);
 };
 
 
-/** @private */
+/**
+ * Refreshes what is shown on the physical braille display and the virtual
+ * braille captions display.
+ * @private */

[David Tseng, 2016/11/30 22:11:54]

nit: move */ to a new line

[ultimatedbz, 2016/12/01 05:12:14]

Done.

 cvox.BrailleDisplayManager.prototype.refresh_ = function() {
   if (!this.displayState_.available) {
     return;
   }
-  var viewPort = this.panStrategy_.viewPort;
-  var buf = this.displayedContent_.slice(viewPort.start, viewPort.end);
+  var brailleBuf = this.panStrategy_.getCurrentBrailleViewportContents();
+  var textBuf = this.panStrategy_.getCurrentTextSlice();

[David Tseng, 2016/11/30 22:11:54]

Maybe make this getCurrentTextViewPortContents

[ultimatedbz, 2016/12/01 05:12:15]

Done.

   if (this.realDisplayState_.available) {
-    chrome.brailleDisplayPrivate.writeDots(buf, buf.byteLength, 1);
+    chrome.brailleDisplayPrivate.writeDots(brailleBuf,
+        brailleBuf.byteLength, 1);
   }
   if (cvox.BrailleCaptionsBackground.isEnabled()) {
-    var start = this.brailleToTextPosition_(viewPort.start);
-    var end = this.brailleToTextPosition_(viewPort.end);
-    cvox.BrailleCaptionsBackground.setContent(
-        this.content_.text.toString().substring(start, end), buf,
-        this.brailleToText_);
+    cvox.BrailleCaptionsBackground.setContent(textBuf, brailleBuf,
+        this.panStrategy_.brailleToText, this.panStrategy_.offsetsForSlices,
+        this.displayState_.textRowCount, this.displayState_.textColumnCount);
   }
 };
 
-
 /**
  * @param {!cvox.NavBraille} newContent New display content.
  * @param {cvox.ExpandingBrailleTranslator.ExpansionType} newExpansionType
  *     How the value part of of the new content should be expanded
  *     with regards to contractions.
  * @private
  */
 cvox.BrailleDisplayManager.prototype.translateContent_ = function(
     newContent, newExpansionType) {
   var writeTranslatedContent = function(cells, textToBraille, brailleToText) {
     this.content_ = newContent;
     this.expansionType_ = newExpansionType;
-    this.textToBraille_ = textToBraille;
-    this.brailleToText_ = brailleToText;
     var startIndex = this.content_.startIndex;
     var endIndex = this.content_.endIndex;
     var targetPosition;
     if (startIndex >= 0) {
       var translatedStartIndex;
       var translatedEndIndex;
       if (startIndex >= textToBraille.length) {
         // Allow the cells to be extended with one extra cell for
         // a carret after the last character.
         var extCells = new ArrayBuffer(cells.byteLength + 1);
         new Uint8Array(extCells).set(new Uint8Array(cells));
         // Last byte is initialized to 0.
         cells = extCells;
         translatedStartIndex = cells.byteLength - 1;
       } else {
         translatedStartIndex = textToBraille[startIndex];
       }
       if (endIndex >= textToBraille.length) {
         // endIndex can't be past-the-end of the last cell unless
         // startIndex is too, so we don't have to do another
         // extension here.
         translatedEndIndex = cells.byteLength;
       } else {
         translatedEndIndex = textToBraille[endIndex];
       }
-      this.translatedContent_ = cells;
-      // Copy the translated content to a separate buffer and  add the cursor
-      // to it.
-      this.displayedContent_ = new ArrayBuffer(cells.byteLength);
-      new Uint8Array(this.displayedContent_).set(new Uint8Array(cells));
-      this.writeCursor_(this.displayedContent_,
-                        translatedStartIndex, translatedEndIndex);
+      // Add the cursor to cells.
+      this.writeCursor_(cells, translatedStartIndex, translatedEndIndex);
       targetPosition = translatedStartIndex;
     } else {
-      this.translatedContent_ = this.displayedContent_ = cells;
       targetPosition = 0;
     }
-    this.panStrategy_.setContent(this.translatedContent_, targetPosition);
+    this.panStrategy_.setContent(this.content_.text.toString(),
+        cells, brailleToText, targetPosition);

[David Tseng, 2016/11/30 22:11:54]

Optional: to help the reviewer and any future readers, pass a json-object to
this function e.g.
setContent({text: text, braille: braille, ...})

[ultimatedbz, 2016/12/01 05:12:15]

Acknowledged.

+
     this.refresh_();
   }.bind(this);
 
   var translator = this.translatorManager_.getExpandingTranslator();
   if (!translator) {
     writeTranslatedContent(new ArrayBuffer(0), [], []);
   } else {
     translator.translate(
         newContent.text,
         newExpansionType,
         writeTranslatedContent);
   }
 };
 
 
 /**
  * @param {cvox.BrailleKeyEvent} event The key event.
  * @private
  */
 cvox.BrailleDisplayManager.prototype.onKeyEvent_ = function(event) {
   switch (event.command) {
     case cvox.BrailleKeyCommand.PAN_LEFT:
       this.panLeft_();
       break;
     case cvox.BrailleKeyCommand.PAN_RIGHT:
       this.panRight_();
       break;
     case cvox.BrailleKeyCommand.ROUTING:
       event.displayPosition = this.brailleToTextPosition_(
-          event.displayPosition + this.panStrategy_.viewPort.start);
+          event.displayPosition + this.panStrategy_.viewPort.firstRow *
+          this.panStrategy_.displaySize.columns);
       // fall through
     default:
       this.commandListener_(event, this.content_);
       break;
   }
 };
 
 
 /**
  * Shift the display by one full display size and refresh the content.
@@ skipping 21 matching lines @@
 cvox.BrailleDisplayManager.prototype.panRight_ = function() {
   if (this.panStrategy_.next()) {
     this.refresh_();
   } else {
     this.commandListener_({
       command: cvox.BrailleKeyCommand.PAN_RIGHT
     }, this.content_);
   }
 };
 
-
 /**
  * Writes a cursor in the specified range into translated content.
  * @param {ArrayBuffer} buffer Buffer to add cursor to.
  * @param {number} startIndex The start index to place the cursor.
  * @param {number} endIndex The end index to place the cursor (exclusive).
  * @private
  */
 cvox.BrailleDisplayManager.prototype.writeCursor_ = function(
     buffer, startIndex, endIndex) {
   if (startIndex < 0 || startIndex >= buffer.byteLength ||
       endIndex < startIndex || endIndex > buffer.byteLength) {
     return;
   }
   if (startIndex == endIndex) {
     endIndex = startIndex + 1;
   }
   var dataView = new DataView(buffer);
   while (startIndex < endIndex) {
     var value = dataView.getUint8(startIndex);
     value |= cvox.BrailleDisplayManager.CURSOR_DOTS_;
     dataView.setUint8(startIndex, value);
     startIndex++;
   }
 };
 
-
 /**
  * Returns the text position corresponding to an absolute braille position,
  * that is not accounting for the current pan position.
  * @private
  * @param {number} braillePosition Braille position relative to the startof
  *        the translated content.
  * @return {number} The mapped position in code units.
  */
 cvox.BrailleDisplayManager.prototype.brailleToTextPosition_ =
     function(braillePosition) {
-  var mapping = this.brailleToText_;
+  var mapping = this.panStrategy_.brailleToText;
   if (braillePosition < 0) {
     // This shouldn't happen.
-    console.error('WARNING: Braille position < 0: ' + braillePosition);

[David Tseng, 2016/11/30 22:11:54]

Doesn't seem like this should be removed.

[ultimatedbz, 2016/12/01 05:12:15]

Thanks for catching this!

     return 0;
   } else if (braillePosition >= mapping.length) {
     // This happens when the user clicks on the right part of the display
     // when it is not entirely filled with content.  Allow addressing the
     // position after the last character.
     return this.content_.text.length;
   } else {
     return mapping[braillePosition];
   }
 };
 
-
 /**
  * @param {boolean} wordWrap
  * @private
  */
 cvox.BrailleDisplayManager.prototype.updatePanStrategy_ = function(wordWrap) {
-  var newStrategy = wordWrap ? new cvox.WrappingPanStrategy() :
-      new cvox.FixedPanStrategy();
-  newStrategy.setDisplaySize(this.displayState_.textColumnCount || 0);
-  newStrategy.setContent(this.translatedContent_,
-                         this.panStrategy_.viewPort.start);
-  this.panStrategy_ = newStrategy;
+  this.panStrategy_.setPanStrategy(wordWrap);
   this.refresh_();
 };