Add a blinking braille cursor

Bug: 851654
Cq-Include-Trybots: luci.chromium.try:closure_compilation
Change-Id: Ic3ef45567f53eef44a92e0adb51ef592a9e5bfe2
Reviewed-on: https://chromium-review.googlesource.com/1132117Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Commit-Queue: David Tseng <dtseng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#574199}

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

@@ -103,9 +103,8 @@ cvox.BrailleDisplayManager = function(translatorManager) {
 /**
  * Dots representing a cursor.
  * @const
- * @private
  */
-cvox.BrailleDisplayManager.CURSOR_DOTS_ = 1 << 6 | 1 << 7;
+cvox.BrailleDisplayManager.CURSOR_DOTS = 1 << 6 | 1 << 7;
 
 
 /**
@@ -139,6 +138,14 @@ cvox.BrailleDisplayManager.COORDS_TO_BRAILLE_DOT_ =
     [0x1, 0x2, 0x4, 0x40, 0x8, 0x10, 0x20, 0x80];
 
 
+/**
+ * Time elapsed before a cursor changes state. This results in a blinking
+ * effect.
+ * @const {number}
+ */
+cvox.BrailleDisplayManager.CURSOR_BLINK_TIME_MS = 1000;
+
+
 /**
  * @param {!cvox.NavBraille} content Content to send to the braille display.
  * @param {!cvox.ExpandingBrailleTranslator.ExpansionType} expansionType
@@ -310,10 +317,29 @@ cvox.BrailleDisplayManager.prototype.onCaptionsStateChanged_ = function() {
  * @private
  */
 cvox.BrailleDisplayManager.prototype.refresh_ = function() {
+  if (this.blinkerId_ !== undefined) {
+    window.clearInterval(this.blinkerId_);
+  }
+
+  this.refreshInternal_(true);
+
+  var showCursor = false;
+  this.blinkerId_ = window.setInterval(function() {
+    this.refreshInternal_(showCursor);
+    showCursor = !showCursor;
+  }.bind(this), cvox.BrailleDisplayManager.CURSOR_BLINK_TIME_MS);
+};
+
+/**
+ * @param {boolean} showCursor Whether to show the cursor.
+ * @private
+ */
+cvox.BrailleDisplayManager.prototype.refreshInternal_ = function(showCursor) {
   if (!this.displayState_.available) {
     return;
   }
-  var brailleBuf = this.panStrategy_.getCurrentBrailleViewportContents();
+  var brailleBuf =
+      this.panStrategy_.getCurrentBrailleViewportContents(showCursor);
   var textBuf = this.panStrategy_.getCurrentTextViewportContents();
   if (this.realDisplayState_.available) {
     chrome.brailleDisplayPrivate.writeDots(
@@ -365,9 +391,10 @@ cvox.BrailleDisplayManager.prototype.translateContent_ = function(
         translatedEndIndex = textToBraille[endIndex];
       }
       // Add the cursor to cells.
-      this.writeCursor_(cells, translatedStartIndex, translatedEndIndex);
+      this.setCursor_(cells, translatedStartIndex, translatedEndIndex);
       targetPosition = translatedStartIndex;
     } else {
+      this.setCursor_(cells, -1, -1);
       targetPosition = 0;
     }
     this.panStrategy_.setContent(
@@ -443,28 +470,23 @@ cvox.BrailleDisplayManager.prototype.panRight_ = function() {
 };
 
 /**
- * Writes a cursor in the specified range into translated content.
+ * Sets a cursor within 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(
+cvox.BrailleDisplayManager.prototype.setCursor_ = function(
     buffer, startIndex, endIndex) {
   if (startIndex < 0 || startIndex >= buffer.byteLength ||
       endIndex < startIndex || endIndex > buffer.byteLength) {
+    this.panStrategy_.setCursor(-1, -1);
     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++;
-  }
+  this.panStrategy_.setCursor(startIndex, endIndex);
 };
 
 /**

chrome/browser/resources/chromeos/chromevox/braille/braille_display_manager_test.unitjs

@@ -70,7 +70,7 @@ CvoxBrailleDisplayManagerUnitTest.prototype = {
     assertEquals(1, this.writtenCells.length);
     var a = new Uint8Array(this.writtenCells[0]);
     this.writtenCells.length = 0;
-    var firstCell = a[0] & ~cvox.BrailleDisplayManager.CURSOR_DOTS_;
+    var firstCell = a[0] & ~cvox.BrailleDisplayManager.CURSOR_DOTS;
     // We are asserting that start, which is an index, and firstCell,
     // which is a value, are the same because the fakeTranslator generates
     // the values of the braille cells based on indices.
@@ -78,8 +78,8 @@ CvoxBrailleDisplayManagerUnitTest.prototype = {
                  ' Start mismatch: ' + start + ' vs. ' + firstCell);
     if (opt_selStart !== undefined) {
       for (var i = opt_selStart; i < opt_selEnd; ++i) {
-        assertEquals(cvox.BrailleDisplayManager.CURSOR_DOTS_,
-                     a[i] & cvox.BrailleDisplayManager.CURSOR_DOTS_,
+        assertEquals(cvox.BrailleDisplayManager.CURSOR_DOTS,
+                     a[i] & cvox.BrailleDisplayManager.CURSOR_DOTS,
                      'Missing cursor marker at position ' + i);
       }
     }

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

@@ -75,6 +75,11 @@ cvox.PanStrategy = function() {
    */
   this.panStrategyWrapped_ = false;
 
+  /** @typedef {{start: (number), end: (number)}} */
+  this.cursor_ = {start: -1, end: -1};
+
+  /** @typedef {{start: (number), end: (number)}} */
+  this.wrappedCursor_ = {start: -1, end: -1};
 };
 
 /**
@@ -142,12 +147,39 @@ cvox.PanStrategy.prototype = {
   },
 
   /**
+   * @param {boolean=} opt_showCursor Defaults to true.
    * @return {ArrayBuffer} Buffer of the slice of braille cells within the
    *    bounds of the viewport.
    */
-  getCurrentBrailleViewportContents: function() {
+  getCurrentBrailleViewportContents: function(opt_showCursor) {
+    opt_showCursor = opt_showCursor === undefined ? true : opt_showCursor;
     var buf =
         this.panStrategyWrapped_ ? this.wrappedBuffer_ : this.fixedBuffer_;
+
+    var startIndex, endIndex;
+    if (this.panStrategyWrapped_) {
+      startIndex = this.wrappedCursor_.start;
+      endIndex = this.wrappedCursor_.end;
+    } else {
+      startIndex = this.cursor_.start;
+      endIndex = this.cursor_.end;
+    }
+
+    if (startIndex >= 0 && startIndex < buf.byteLength &&
+        endIndex >= startIndex && endIndex <= buf.byteLength) {
+      var dataView = new DataView(buf);
+      while (startIndex < endIndex) {
+        var value = dataView.getUint8(startIndex);
+        if (opt_showCursor) {
+          value |= cvox.BrailleDisplayManager.CURSOR_DOTS;
+        } else {
+          value &= ~cvox.BrailleDisplayManager.CURSOR_DOTS;
+        }
+        dataView.setUint8(startIndex, value);
+        startIndex++;
+      }
+    }
+
     return buf.slice(
         this.viewPort_.firstRow * this.displaySize_.columns,
         (this.viewPort_.lastRow + 1) * this.displaySize_.columns);
@@ -252,6 +284,8 @@ cvox.PanStrategy.prototype = {
         } else {
           // |lastBreak| is at the beginning of a line, so current word is
           // bigger than |this.displaySize_.columns| so we shouldn't wrap.
+          this.maybeSetWrappedCursor_(
+              index - cellsPadded, wrappedBrailleArray.length);
           wrappedBrailleArray.push(view[index - cellsPadded]);
           this.wrappedBrailleToText_.push(
               fixedBrailleToText[index - cellsPadded]);
@@ -260,6 +294,8 @@ cvox.PanStrategy.prototype = {
         if (view[index - cellsPadded] == 0) {
           lastBreak = index;
         }
+        this.maybeSetWrappedCursor_(
+            index - cellsPadded, wrappedBrailleArray.length);
         wrappedBrailleArray.push(view[index - cellsPadded]);
         this.wrappedBrailleToText_.push(
             fixedBrailleToText[index - cellsPadded]);
@@ -273,6 +309,29 @@ cvox.PanStrategy.prototype = {
     this.panToPosition_(targetPosition);
   },
 
+  /**
+   * Sets a braille cursor.
+   * @param {number} startIndex
+   * @param {number} endIndex
+   */
+  setCursor: function(startIndex, endIndex) {
+    this.cursor_ = {start: startIndex, end: endIndex};
+  },
+
+  /**
+   *
+   */
+  maybeSetWrappedCursor_: function(unwrappedIndex, wrappedIndex) {
+    // We only care about the bounds of the index start/end.
+    if (this.cursor_.start != unwrappedIndex &&
+        this.cursor_.end != unwrappedIndex)
+      return;
+    if (this.cursor_.start == unwrappedIndex)
+      this.wrappedCursor_.start = wrappedIndex;
+    else if (this.cursor_.end == unwrappedIndex)
+      this.wrappedCursor_.end = wrappedIndex;
+  },
+
   /**
    * If possible, changes the viewport to a part of the line that follows
    * the current viewport.