The Tor Browser / file revision

 const nsIDOMKeyEvent = Components.interfaces.nsIDOMKeyEvent;

 /**

  * Create grid object based on HTML table.

  */

 function grid(aTableIdentifier)

 {

   this.getRowCount = function getRowCount()

   {

     return this.table.rows.length - (this.table.tHead ? 1 : 0);

   }

   this.getColsCount = function getColsCount()

   {

     return this.table.rows[0].cells.length;

   }

   this.getRowAtIndex = function getRowAtIndex(aIndex)

   {

     return this.table.rows[this.table.tHead ? aIndex + 1 : aIndex];

   }

   this.getMaxIndex = function getMaxIndex()

   {

     return this.getRowCount() * this.getColsCount() - 1;

   }

   this.getCellAtIndex = function getCellAtIndex(aIndex)

   {

     var rowCount = this.getRowCount();

     var colsCount = this.getColsCount();

     var rowIdx = Math.floor(aIndex / colsCount);

     var colIdx = aIndex % colsCount;

     var row = this.getRowAtIndex(rowIdx);

     return row.cells[colIdx];

   }

   this.getIndexByCell = function getIndexByCell(aCell)

   {

     var colIdx = aCell.cellIndex;

     var rowIdx = aCell.parentNode.rowIndex;

     if (this.table.tHead)

       rowIdx -= 1;

     var colsCount = this.getColsCount();

     return rowIdx * colsCount + colIdx;

   }

   this.getCurrentCell = function getCurrentCell()

   {

     var rowCount = this.table.rows.length;

     var colsCount = this.getColsCount();

     for (var rowIdx = 0; rowIdx < rowCount; rowIdx++) {

       for (var colIdx = 0; colIdx < colsCount; colIdx++) {

         var cell = this.table.rows[rowIdx].cells[colIdx];

         if (cell.hasAttribute("tabindex"))

           return cell;

       }

     }

     return null;

   }

   this.initGrid = function initGrid()

   {

     this.table.addEventListener("keypress", this, false);

     this.table.addEventListener("click", this, false);

   }

   this.handleEvent = function handleEvent(aEvent)

   {

     if (aEvent instanceof nsIDOMKeyEvent)

       this.handleKeyEvent(aEvent);

     else

       this.handleClickEvent(aEvent);

   }

   this.handleKeyEvent = function handleKeyEvent(aEvent)

   {

     if (aEvent.target.localName != "td")

       return;

     var cell = aEvent.target;

     switch(aEvent.keyCode) {

       case nsIDOMKeyEvent.DOM_VK_UP:

         var colsCount = this.getColsCount();

         var idx = this.getIndexByCell(cell);

         var upidx = idx - colsCount;

         if (upidx >= 0) {

           cell.removeAttribute("tabindex");

           var upcell = this.getCellAtIndex(upidx);

           upcell.setAttribute("tabindex", "0");

           upcell.focus();

         }

         break;

       case nsIDOMKeyEvent.DOM_VK_DOWN:

         var colsCount = this.getColsCount();

         var idx = this.getIndexByCell(cell);

         var downidx = idx + colsCount;

         if (downidx <= this.getMaxIndex()) {

           cell.removeAttribute("tabindex");

           var downcell = this.getCellAtIndex(downidx);

           downcell.setAttribute("tabindex", "0");

           downcell.focus();

         }

         break;

       case nsIDOMKeyEvent.DOM_VK_LEFT:

         var idx = this.getIndexByCell(cell);

         if (idx > 0) {

           cell.removeAttribute("tabindex");

           var prevcell = this.getCellAtIndex(idx - 1);

           prevcell.setAttribute("tabindex", "0");

           prevcell.focus();

         }

         break;

       case nsIDOMKeyEvent.DOM_VK_RIGHT:

         var idx = this.getIndexByCell(cell);

         if (idx < this.getMaxIndex()) {

           cell.removeAttribute("tabindex");

           var nextcell = this.getCellAtIndex(idx + 1);

           nextcell.setAttribute("tabindex", "0");

           nextcell.focus();

         }

         break;

     }

   }

   this.handleClickEvent = function handleClickEvent(aEvent)

   {

     if (aEvent.target.localName != "td")

       return;

     var curCell = this.getCurrentCell();

     var cell = aEvent.target;

     if (cell != curCell) {

       curCell.removeAttribute("tabindex");

       cell.setAttribute("tabindex", "0");

       cell.focus();

     }

   }

   this.table = getNode(aTableIdentifier);

   this.initGrid();

 }