[mandelbrot.git] / xulapp / chrome / mandelbrot / content / mandelbrot.js

/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is KaiRo.at Mandelbrot, XULRunner version.
 *
 * The Initial Developer of the Original Code is
 * Robert Kaiser <kairo@kairo.at>.
 * Portions created by the Initial Developer are Copyright (C) 2008
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *   Robert Kaiser <kairo@kairo.at>
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

var gColorPalette = [];
var gPref = Components.classes["@mozilla.org/preferences-service;1"]
                      .getService(Components.interfaces.nsIPrefService)
                      .getBranch(null);
var gStartTime = 0;
var gMbrotBundle;

function Startup() {
  updateIterMenu();
  updatePaletteMenu();
  gMbrotBundle = document.getElementById("mbrotBundle");
  document.getElementById("statusLabel").value = gMbrotBundle.getString("statusEmpty");
}

function drawImage() {
  let canvas = document.getElementById("mbrotImage");
  let context = canvas.getContext("2d");

  document.getElementById("drawButton").hidden = true;

  document.getElementById("statusLabel").value = gMbrotBundle.getString("statusDrawing");

  let Cr_min = -2.0;
  let Cr_max = 1.0;
  try {
    Cr_min = parseFloat(gPref.getCharPref("mandelbrot.last_image.Cr_min"));
    Cr_max = parseFloat(gPref.getCharPref("mandelbrot.last_image.Cr_max"));
  }
  catch (e) { }
  if ((Cr_min < -2) || (Cr_min > 2) ||
      (Cr_max < -2) || (Cr_max > 2) || (Cr_min >= Cr_max)) {
    Cr_min = -2.0; Cr_max = 1.0;
  }
  gPref.setCharPref("mandelbrot.last_image.Cr_min", Cr_min);
  gPref.setCharPref("mandelbrot.last_image.Cr_max", Cr_max);

  let Ci_min = -1.5;
  let Ci_max = 1.5;
  try {
    Ci_min = parseFloat(gPref.getCharPref("mandelbrot.last_image.Ci_min"));
    Ci_max = parseFloat(gPref.getCharPref("mandelbrot.last_image.Ci_max"));
  }
  catch (e) { }
  if ((Ci_min < -2) || (Ci_min > 2) ||
      (Ci_max < -2) || (Ci_max > 2) || (Ci_min >= Ci_max)) {
    Ci_min = -2.0; Ci_max = 1.0;
  }
  gPref.setCharPref("mandelbrot.last_image.Ci_min", Ci_min);
  gPref.setCharPref("mandelbrot.last_image.Ci_max", Ci_max);

  let iterMax = gPref.getIntPref("mandelbrot.iteration_max");
  let algorithm = gPref.getCharPref("mandelbrot.use_algorithm");

  let iWidth = 0;
  try {
    iWidth = gPref.getIntPref("mandelbrot.image.width");
  }
  catch (e) { }
  if ((iWidth < 10) || (iWidth > 5000)) {
    iWidth = 300;
    gPref.setIntPref("mandelbrot.image.width", iWidth);
  }
  let iHeight = 0;
  try {
    iHeight = gPref.getIntPref("mandelbrot.image.height");
  }
  catch (e) { }
  if ((iHeight < 10) || (iHeight > 5000)) {
    iHeight = 300;
    gPref.setIntPref("mandelbrot.image.height", iHeight);
  }

  canvas.width = iWidth;
  canvas.height = iHeight;

  context.fillStyle = "rgba(255, 255, 255, 127)";
  context.fillRect(0, 0, canvas.width, canvas.height);

  gStartTime = new Date();

  drawLine(0, [Cr_min, Cr_max, Ci_min, Ci_max],
              canvas, context, iterMax, algorithm);
}

function drawLine(line, dimensions, canvas, context, iterMax, algorithm) {
    let Cr_min = dimensions[0];
    let Cr_max = dimensions[1];
    let Cr_scale = Cr_max - Cr_min;

    let Ci_min = dimensions[2];
    let Ci_max = dimensions[3];
    let Ci_scale = Ci_max - Ci_min;

    let pixels = [];
    for (var img_y = line; img_y < canvas.height && img_y < line+8; img_y++)
      for (let img_x = 0; img_x < canvas.width; img_x++) {
        let C = new complex(Cr_min + (img_x / canvas.width) * Cr_scale,
                            Ci_min + (img_y / canvas.height) * Ci_scale);
        pixels.push.apply(pixels, drawPoint(context, img_x, img_y, C, iterMax, algorithm));
      }
    context.putImageData({width: canvas.width, height: pixels.length/4/canvas.width, data: pixels}, 0, line);

    if (img_y < canvas.height)
      setTimeout(drawLine, 0, img_y, dimensions, canvas, context, iterMax, algorithm);
    else if (gStartTime)
      EndCalc();
}

function EndCalc() {
  let endTime = new Date();
  let timeUsed = (endTime.getTime() - gStartTime.getTime()) / 1000;
  document.getElementById("statusLabel").value =
      gMbrotBundle.getFormattedString("statusTime", [timeUsed.toFixed(3)]);
  gStartTime = 0;
}

function complex(aReal, aImag) {
  this.r = aReal;
  this.i = aImag;
}
complex.prototype = {
  square: function() {
    return new complex(this.r * this.r - this.i * this.i,
                       2 * this.r * this.i);
  },
  dist: function() {
    return Math.sqrt(this.r * this.r + this.i * this.i);
  },
  add: function(aComplex) {
    return new complex(this.r + aComplex.r, this.i + aComplex.i);
  }
}

function mandelbrotValueOO (aC, aIterMax) {
  // this would be nice code in general but it looks like JS objects are too heavy for normal use.
  let Z = new complex(0.0, 0.0);
  for (var iter = 0; iter < aIterMax; iter++) {
    Z = Z.square().add(aC);
    if (Z.r * Z.r + Z.i * Z.i > 256) { break; }
  }
  return iter;
}

function mandelbrotValueNumeric (aC, aIterMax) {
  // optimized numeric code for fast calculation
  let Cr = aC.r, Ci = aC.i;
  let Zr = 0.0, Zi = 0.0;
  let Zr2 = Zr * Zr, Zi2 = Zi * Zi;
  for (var iter = 0; iter < aIterMax; iter++) {
    Zi = 2 * Zr * Zi + Ci;
    Zr = Zr2 - Zi2 + Cr;

    Zr2 = Zr * Zr; Zi2 = Zi * Zi;
    if (Zr2 + Zi2 > 256) { break; }
  }
  return iter;
}

function getColor(aIterValue, aIterMax) {
  let standardizedValue = Math.round(aIterValue * 1024 / aIterMax);
  if (gColorPalette && gColorPalette.length)
    return gColorPalette[standardizedValue];

  // fallback to simple b/w if for some reason we don't have a palette
  if (aIterValue == aIterMax)
    return [0, 0, 0, 255];
  else
    return [255, 255, 255, 255];
}

function getColorPalette(palName) {
  var palette = [];
  switch (palName) {
    case 'bw':
      for (let i = 0; i < 1024; i++) {
        palette[i] = [255, 255, 255, 255];
      }
      palette[1024] = [0, 0, 0, 255];
      break;
    case 'kairo':
      // outer areas
      for (let i = 0; i < 32; i++) {
        let cc1 = Math.floor(i * 127 / 31);
        let cc2 = 170 - Math.floor(i * 43 / 31);
        palette[i] = [cc1, cc2, cc1, 255];
      }
      // inner areas
      for (let i = 0; i < 51; i++) {
        let cc = Math.floor(i * 170 / 50);
        palette[32 + i] = [cc, 0, (170-cc), 255];
      }
      // corona
      for (let i = 0; i < 101; i++) {
        let cc = Math.floor(i * 200 / 100);
        palette[83 + i] = [255, cc, 0, 255];
      }
      // inner corona
      for (let i = 0; i < 201; i++) {
        let cc1 = 255 - Math.floor(i * 85 / 200);
        let cc2 = 200 - Math.floor(i * 30 / 200);
        let cc3 = Math.floor(i * 170 / 200);
        palette[184 + i] = [cc1, cc2, cc3, 255];
      }
      for (let i = 0; i < 301; i++) {
        let cc1 = 170 - Math.floor(i * 43 / 300);
        let cc2 = 170 + Math.floor(i * 85 / 300);
        palette[385 + i] = [cc1, cc1, cc2, 255];
      }
      for (let i = 0; i < 338; i++) {
        let cc = 127 + Math.floor(i * 128 / 337);
        palette[686 + i] = [cc, cc, 255, 255];
      }
      palette[1024] = [0, 0, 0, 255];
      break;
    case 'rainbow-linear1':
      for (let i = 0; i < 256; i++) {
        palette[i] = [i, 0, 0, 255];
        palette[256 + i] = [255, i, 0, 255];
        palette[512 + i] = [255 - i, 255, i, 255];
        palette[768 + i] = [i, 255-i, 255, 255];
      }
      palette[1024] = [0, 0, 0, 255];
      break;
  }
/*
Select Case palnr
Case 1  'Standard-Palette (QB-Colors)
     For i = 0 To 1024
         xx = CInt(i * 500 / 1024 + 2)
         If xx <= 15 Then clr = xx
         If xx > 15 Then clr = CInt(Sqr((xx - 15 + 1) * 15 ^ 2 / 485))
         If xx >= 500 Then clr = 0
         palette(i) = QBColor(clr)
     Next
Case 3  'Regenbogen-Palette 1 (qu.)
     For i = 0 To 33
         clr = CInt(i * 255 / 33)
         palette(i) = RGB(clr, 0, 0)
     Next
     For i = 0 To 136
         clr = CInt(i * 255 / 136)
         palette(34 + i) = RGB(255, clr, 0)
     Next
     For i = 0 To 306
         clr = CInt(i * 255 / 306)
         palette(171 + i) = RGB(255 - clr, 255, clr)
     Next
     For i = 0 To 545
         clr = CInt(i * 255 / 545)
         palette(478 + i) = RGB(clr, 255 - clr, 255)
     Next
Case 4  'Regenbogen-Palette 2 (linear)
     For i = 0 To 204
         clr = CInt(i * 255 / 204)
         palette(i) = RGB(255, clr, 0)
         palette(204 + i) = RGB(255 - clr, 255, 0)
         palette(409 + i) = RGB(0, 255, clr)
         palette(614 + i) = RGB(0, 255 - clr, 255)
         palette(819 + i) = RGB(clr, 0, 255)
     Next
Case 5  'Regenbogen-Palette 2 (qu.)
     For i = 0 To 18
         clr = CInt(i * 255 / 18)
         palette(i) = RGB(255, clr, 0)
     Next
     For i = 0 To 73
         clr = CInt(i * 255 / 73)
         palette(20 + i) = RGB(255 - clr, 255, 0)
     Next
     For i = 0 To 167
         clr = CInt(i * 255 / 167)
         palette(93 + i) = RGB(0, 255, clr)
     Next
     For i = 0 To 297
         clr = CInt(i * 255 / 297)
         palette(261 + i) = RGB(0, 255 - clr, 255)
     Next
     For i = 0 To 464
         clr = CInt(i * 255 / 464)
         palette(559 + i) = RGB(clr, 0, 255)
     Next
*/
  return palette;
}

function drawPoint(context, img_x, img_y, C, iterMax, algorithm) {
  var itVal;
  switch (algorithm) {
    case 'oo':
      itVal = mandelbrotValueOO(C, iterMax);
      break;
    case 'numeric':
    default:
      itVal = mandelbrotValueNumeric(C, iterMax);
      break;
  }
  return getColor(itVal, iterMax);
}

/***** pure UI functions *****/

var zoomstart;

function mouseevent(etype, event) {
  let canvas = document.getElementById("mbrotImage");
  switch (etype) {
    case 'down':
      if (event.button == 0)
        // left button - start dragzoom
        zoomstart = {x: event.clientX - canvas.offsetLeft,
                     y: event.clientY - canvas.offsetTop};
      break;
    case 'up':
      if (event.button == 0) {
        var prompts = Components.classes["@mozilla.org/embedcomp/prompt-service;1"]
                                .getService(Components.interfaces.nsIPromptService);
        var ok = prompts.confirm(null, gMbrotBundle.getString("zoomConfirmTitle"),
            gMbrotBundle.getString("zoomConfirmLabel") + ' --- ' +
            zoomstart.x + ',' + zoomstart.y + '-' +
            (event.clientX - canvas.offsetLeft) + ',' +
            (event.clientY - canvas.offsetTop));
        // ok is now true if OK was clicked, and false if cancel was clicked
      }
      zoomstart = undefined;
    break;
  }
}

function saveImage() {
  const nsIFilePicker = Components.interfaces.nsIFilePicker;
  var fp = null;
  try {
    fp = Components.classes["@mozilla.org/filepicker;1"]
                   .createInstance(nsIFilePicker);
  } catch (e) {}
  if (!fp) return;
  var promptString = gMbrotBundle.getString("savePrompt");
  fp.init(window, promptString, nsIFilePicker.modeSave);
  fp.appendFilter(gMbrotBundle.getString("pngFilterName"), "*.png");
  fp.defaultString = "mandelbrot.png";

  var fpResult = fp.show();
  if (fpResult != nsIFilePicker.returnCancel) {
    saveCanvas(document.getElementById("mbrotImage"), fp.file);
  }
}

function updateBookmarkMenu(aParent) {
  document.getElementById("bookmarkSave").disabled =
    (!document.getElementById("drawButton").hidden || (gStartTime > 0));

  while (aParent.hasChildNodes() &&
         aParent.lastChild.id != 'bookmarkSeparator')
    aParent.removeChild(aParent.lastChild);

  var file = Components.classes["@mozilla.org/file/directory_service;1"]
                       .getService(Components.interfaces.nsIProperties)
                       .get("ProfD", Components.interfaces.nsIFile);
  file.append("mandelbookmarks.sqlite");
  if (file.exists()) {
    var connection = Components.classes["@mozilla.org/storage/service;1"]
                               .getService(Components.interfaces.mozIStorageService)
                               .openDatabase(file);
    try {
      if (connection.tableExists("bookmarks")) {
        var statement = connection.createStatement(
            "SELECT name FROM bookmarks ORDER BY ROWID DESC");
        while (statement.executeStep())
          aParent.appendChild(document.createElement("menuitem"))
                 .setAttribute("label", statement.getString(0));
        statement.reset();
        statement.finalize();
        return;
      }
    } finally {
      connection.close();
    }
  }
  // Create the "Nothing Available" Menu item and disable it.
  var na = aParent.appendChild(document.createElement("menuitem"));
  na.setAttribute("label", gMbrotBundle.getString("noBookmarks"));
  na.setAttribute("disabled", "true");
}

function callBookmark(evtarget) {
}

function saveBookmark() {
  // retrieve wanted bookmark name with a prompt
  var prompts = Components.classes["@mozilla.org/embedcomp/prompt-service;1"]
                          .getService(Components.interfaces.nsIPromptService);
  var input = {value: ""}; // empty default value
  var ok = prompts.prompt(null, gMbrotBundle.getString("saveBookmarkTitle"), gMbrotBundle.getString("saveBookmarkLabel"), input, null, {});
  // ok is true if OK is pressed, false if Cancel. input.value holds the value of the edit field if "OK" was pressed.
  if (!ok || !input.value)
    return

  var bmName = input.value;

  // Open or create the bookmarks database.
  var file = Components.classes["@mozilla.org/file/directory_service;1"]
                       .getService(Components.interfaces.nsIProperties)
                       .get("ProfD", Components.interfaces.nsIFile);
  file.append("mandelbookmarks.sqlite");
  var connection = Components.classes["@mozilla.org/storage/service;1"]
                             .getService(Components.interfaces.mozIStorageService)
                             .openDatabase(file);
  connection.beginTransaction();
  if (!connection.tableExists("bookmarks"))
    connection.createTable("bookmarks", "name TEXT, iteration_max INTEGER, Cr_min REAL, Cr_max REAL, Ci_min REAL, Ci_max REAL");
  // NULL. The value is a NULL value.
  // INTEGER. The value is a signed integer, stored in 1, 2, 3, 4, 6, or 8 bytes depending on the magnitude of the value.
  // REAL. The value is a floating point value, stored as an 8-byte IEEE floating point number.
  // TEXT. The value is a text string, stored using the database encoding (UTF-8, UTF-16BE or UTF-16-LE).

  // Put value of the current image into the bookmarks table
  var statement = connection.createStatement(
      "INSERT INTO bookmarks (name,iteration_max,Cr_min,Cr_max,Ci_min,Ci_max) VALUES (?1,?2,?3,?4,?5,?6)");
  statement.bindStringParameter(0, bmName);
  statement.bindStringParameter(1, gPref.getIntPref("mandelbrot.iteration_max"));
  statement.bindStringParameter(2, parseFloat(gPref.getCharPref("mandelbrot.last_image.Cr_min")));
  statement.bindStringParameter(3, parseFloat(gPref.getCharPref("mandelbrot.last_image.Cr_max")));
  statement.bindStringParameter(4, parseFloat(gPref.getCharPref("mandelbrot.last_image.Ci_min")));
  statement.bindStringParameter(5, parseFloat(gPref.getCharPref("mandelbrot.last_image.Ci_max")));
  statement.execute();
  statement.finalize();
  connection.commitTransaction();
  connection.close();
}

function updateIterMenu() {
  try {
    var currentIter = gPref.getIntPref("mandelbrot.iteration_max");
  }
  catch(e) {
    var currentIter = 0;
  }
  if (currentIter < 10) {
    currentIter = 500;
    setIter(currentIter);
  }

  var popup = document.getElementById("menu_iterPopup");
  var item = popup.firstChild;
  while (item) {
    if (item.getAttribute("name") == "iter") {
      if (item.getAttribute("value") == currentIter)
        item.setAttribute("checked","true");
      else
        item.removeAttribute("checked");
    }
    item = item.nextSibling;
  }
}

function setIter(aIter) {
  gPref.setIntPref("mandelbrot.iteration_max", aIter);
}

function updatePaletteMenu() {
  try {
    var currentPalette = gPref.getCharPref("mandelbrot.color_palette");
  }
  catch(e) {
    var currentPalette = '';
  }
  if (!currentPalette.length) {
    currentPalette = 'kairo';
    setPalette(currentPalette);
  }
  if (!gColorPalette || !gColorPalette.length)
    gColorPalette = getColorPalette(currentPalette);

  var popup = document.getElementById("menu_palettePopup");
  var item = popup.firstChild;
  while (item) {
    if (item.getAttribute("name") == "palette") {
      if (item.getAttribute("value") == currentPalette)
        item.setAttribute("checked", "true");
      else
        item.removeAttribute("checked");
    }
    item = item.nextSibling;
  }
}

function setPalette(aPaletteID) {
  gPref.setCharPref("mandelbrot.color_palette", aPaletteID);
  gColorPalette = getColorPalette(aPaletteID);
}

function imgSettings() {
  window.openDialog("chrome://mandelbrot/content/image-settings.xul");
}

function updateDebugMenu() {
  var jitMenuItem = document.getElementById("jitEnabled");
  jitMenuItem.setAttribute("checked", gPref.getBoolPref("javascript.options.jit.chrome"));
}

function toggleJITState(jitMenuItem) {
  var jitEnabled = !gPref.getBoolPref("javascript.options.jit.chrome");
  gPref.setBoolPref("javascript.options.jit.chrome", jitEnabled)
  jitMenuItem.setAttribute("checked", jitEnabled? "true" : "false");
}

function updateAlgoMenu() {
  try {
    var currentAlgo = gPref.getCharPref("mandelbrot.use_algorithm");
  }
  catch(e) {
    var currentAlgo = '';
  }
  if (!currentAlgo.length) {
    currentAlgo = 'numeric';
    setAlgorithm(currentAlgo);
  }

  var popup = document.getElementById("menu_algoPopup");
  var item = popup.firstChild;
  while (item) {
    if (item.getAttribute("name") == "algorithm") {
      if (item.getAttribute("value") == currentAlgo)
        item.setAttribute("checked", "true");
      else
        item.removeAttribute("checked");
    }
    item = item.nextSibling;
  }
}

function setAlgorithm(algoID) {
  gPref.setCharPref("mandelbrot.use_algorithm", algoID);
}

function addonsManager(aPane) {
  var theEM = Components.classes["@mozilla.org/appshell/window-mediator;1"]
                        .getService(Components.interfaces.nsIWindowMediator)
                        .getMostRecentWindow("Extension:Manager");
  if (theEM) {
    theEM.focus();
    if (aPane)
      theEM.showView(aPane);
    return;
  }

  const EMURL = "chrome://mozapps/content/extensions/extensions.xul";
  const EMFEATURES = "all,dialog=no";
  if (aPane)
    window.openDialog(EMURL, "", EMFEATURES, aPane);
  else
    window.openDialog(EMURL, "", EMFEATURES);
}

function errorConsole() {
  toOpenWindowByType("global:console", "chrome://global/content/console.xul");
}

/***** helper functions from external sources *****/

// function below is based on http://developer.mozilla.org/en/docs/Code_snippets:Canvas
// custom modifications:
//   - use "a"-prefix on function arguments
//   - take an nsILocalFile as aDestFile argument
//   - always do silent download
function saveCanvas(aCanvas, aDestFile) {
  // create a data url from the canvas and then create URIs of the source and targets  
  var io = Components.classes["@mozilla.org/network/io-service;1"]
                     .getService(Components.interfaces.nsIIOService);
  var source = io.newURI(aCanvas.toDataURL("image/png", ""), "UTF8", null);

  // prepare to save the canvas data
  var persist = Components.classes["@mozilla.org/embedding/browser/nsWebBrowserPersist;1"]
                          .createInstance(Components.interfaces.nsIWebBrowserPersist);

  persist.persistFlags = Components.interfaces.nsIWebBrowserPersist.PERSIST_FLAGS_REPLACE_EXISTING_FILES;
  persist.persistFlags |= Components.interfaces.nsIWebBrowserPersist.PERSIST_FLAGS_AUTODETECT_APPLY_CONVERSION;

  // save the canvas data to the file
  persist.saveURI(source, null, null, null, null, aDestFile);
}

// function below is from http://developer.mozilla.org/en/docs/How_to_Quit_a_XUL_Application
function quitApp(aForceQuit) {
  var appStartup = Components.classes['@mozilla.org/toolkit/app-startup;1']
                             .getService(Components.interfaces.nsIAppStartup);

  // eAttemptQuit will try to close each XUL window, but the XUL window can cancel the quit
  // process if there is unsaved data. eForceQuit will quit no matter what.
  var quitSeverity = aForceQuit ? Components.interfaces.nsIAppStartup.eForceQuit :
                                  Components.interfaces.nsIAppStartup.eAttemptQuit;
  appStartup.quit(quitSeverity);
}

// functions below are from comm-central/suite/common/tasksOverlay.js
function toOpenWindow(aWindow) {
  try {
    // Try to focus the previously focused window e.g. message compose body
    aWindow.document.commandDispatcher.focusedWindow.focus();
  } catch (e) {
    // e.g. full-page plugin or non-XUL document; just raise the top window
    aWindow.focus();
  }
}

function toOpenWindowByType(inType, uri, features) {
  // don't do several loads in parallel
  if (uri in window)
    return;

  var topWindow = Components.classes["@mozilla.org/appshell/window-mediator;1"]
                            .getService(Components.interfaces.nsIWindowMediator)
                            .getMostRecentWindow(inType);
  if ( topWindow )
    toOpenWindow( topWindow );
  else {
    // open the requested window, but block it until it's fully loaded
    function newWindowLoaded(event) {
      // make sure that this handler is called only once
      window.removeEventListener("unload", newWindowLoaded, false);
      window[uri].removeEventListener("load", newWindowLoaded, false);
      delete window[uri];
    }
    // remember the newly loading window until it's fully loaded
    // or until the current window passes away
    window[uri] = window.openDialog(uri, "", features || "all,dialog=no");
    window[uri].addEventListener("load", newWindowLoaded, false);
    window.addEventListener("unload", newWindowLoaded, false);
  }
}