From a4c51500ad9ca9478a6452b0296bd1581dad6827 Mon Sep 17 00:00:00 2001
From: Mina Almasry <almasry.mina@gmail.com>
Date: Sat, 12 Oct 2013 13:59:50 -0400
Subject: [PATCH] Bug 698437 - Allow spatial navigation with directional
 controller. r=kats

---
 .../forms/test_input_range_key_events.html    |   4 +
 .../test/forms/test_input_range_rounding.html |   4 +
 content/html/content/test/test_bug633058.html |   3 +
 content/html/content/test/test_bug674558.html |   5 +
 dom/tests/mochitest/bugs/test_bug265203.html  |   4 +
 .../libeditor/base/tests/test_bug795785.html  |   6 +
 layout/forms/test/test_bug345267.html         |   4 +
 layout/forms/test/test_bug365410.html         |   3 +
 layout/forms/test/test_bug563642.html         |   3 +
 .../test/test_select_prevent_default.html     |   5 +
 mobile/android/app/mobile.js                  |   2 +
 mobile/android/chrome/content/browser.js      |   4 +
 modules/libpref/src/init/all.js               |   3 +
 toolkit/modules/SpatialNavigation.jsm         | 505 ++++++++++++++++++
 toolkit/modules/moz.build                     |   1 +
 toolkit/modules/tests/mochitest/mochitest.ini |   1 +
 .../mochitest/test_spatial_navigation.html    |  78 +++
 toolkit/modules/tests/moz.build               |   2 +
 widget/android/nsWindow.cpp                   |   3 +
 19 files changed, 640 insertions(+)
 create mode 100644 toolkit/modules/SpatialNavigation.jsm
 create mode 100644 toolkit/modules/tests/mochitest/mochitest.ini
 create mode 100644 toolkit/modules/tests/mochitest/test_spatial_navigation.html

diff --git a/content/html/content/test/forms/test_input_range_key_events.html b/content/html/content/test/forms/test_input_range_key_events.html
index c8f8d182d4f0..b936c8e49246 100644
--- a/content/html/content/test/forms/test_input_range_key_events.html
+++ b/content/html/content/test/forms/test_input_range_key_events.html
@@ -24,6 +24,10 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=843725
  * various key events while it is in various states.
  **/
 SimpleTest.waitForExplicitFinish();
+
+// Turn off Spatial Navigation because it hijacks arrow keydown events:
+SpecialPowers.setBoolPref("snav.enabled", false);
+
 SimpleTest.waitForFocus(function() {
   test();
   SimpleTest.finish();
diff --git a/content/html/content/test/forms/test_input_range_rounding.html b/content/html/content/test/forms/test_input_range_rounding.html
index 535c1e931af7..abc0fa85c8c8 100644
--- a/content/html/content/test/forms/test_input_range_rounding.html
+++ b/content/html/content/test/forms/test_input_range_rounding.html
@@ -26,6 +26,10 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=853525
  * ugly rounding errors.
  **/
 SimpleTest.waitForExplicitFinish();
+
+// Turn off spatial navigation because it hijacks arrow keydown events:
+SpecialPowers.setBoolPref("snav.enabled", false);
+
 SimpleTest.waitForFocus(function() {
   test();
   SimpleTest.finish();
diff --git a/content/html/content/test/test_bug633058.html b/content/html/content/test/test_bug633058.html
index 0a6cf0faf1c0..a291eafd5d64 100644
--- a/content/html/content/test/test_bug633058.html
+++ b/content/html/content/test/test_bug633058.html
@@ -22,6 +22,9 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=633058
 
 SimpleTest.waitForExplicitFinish();
 
+// Turn off Spatial Navigation so that the 'keypress' event fires.
+SpecialPowers.setBoolPref('snav.enabled', false);
+
 SimpleTest.waitForFocus(function() {
   var nbExpectedKeyPress = 8;
   var inputGotKeyPress = 0;
diff --git a/content/html/content/test/test_bug674558.html b/content/html/content/test/test_bug674558.html
index cbf2f5149484..21d3ad60b515 100644
--- a/content/html/content/test/test_bug674558.html
+++ b/content/html/content/test/test_bug674558.html
@@ -19,6 +19,11 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=674558
 
 /** Test for Bug 674558 **/
 SimpleTest.waitForExplicitFinish();
+
+// Turn off spatial navigation because it hijacks VK_RIGHT and VK_LEFT keydown
+// events.
+SpecialPowers.setBoolPref("snav.enabled", false);
+
 SimpleTest.waitForFocus(function() {
   function textAreaCtor() {
     return document.createElement("textarea");
diff --git a/dom/tests/mochitest/bugs/test_bug265203.html b/dom/tests/mochitest/bugs/test_bug265203.html
index 0ac70f90b8f4..435ba683199f 100644
--- a/dom/tests/mochitest/bugs/test_bug265203.html
+++ b/dom/tests/mochitest/bugs/test_bug265203.html
@@ -41,6 +41,10 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=265203
 
 /** Test for Bug 265203 **/
 
+// Turn off spatial navigation because it hijacks VK_RIGHT and VK_LEFT keydown
+// events
+SpecialPowers.setBoolPref("snav.enabled", false);
+
 var gTestStarted = false;
 var expectedResult = [ null, 0, null ];
 var nextTest;
diff --git a/editor/libeditor/base/tests/test_bug795785.html b/editor/libeditor/base/tests/test_bug795785.html
index 4ee48f29796d..aedffa762781 100644
--- a/editor/libeditor/base/tests/test_bug795785.html
+++ b/editor/libeditor/base/tests/test_bug795785.html
@@ -23,7 +23,13 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=795785
 
 <script class="testbody" type="application/javascript">
 
+
 SimpleTest.waitForExplicitFinish();
+
+// Turn off spatial navigation because it hijacks arrow key events and VK_RETURN
+// events.
+SpecialPowers.setBoolPref("snav.enabled", false);
+
 SimpleTest.waitForFocus(runTests);
 
 var textarea = document.getElementById("textarea");
diff --git a/layout/forms/test/test_bug345267.html b/layout/forms/test/test_bug345267.html
index 0856b798abd9..96f8d6f9f1df 100644
--- a/layout/forms/test/test_bug345267.html
+++ b/layout/forms/test/test_bug345267.html
@@ -28,6 +28,10 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=345267
 <script class="testbody" type="text/javascript">
 
 /** Test for Bug 345267 **/
+
+// Turn off Spatial Navigation to stop if from hijacking "left" keypress event.
+SpecialPowers.setBoolPref('snav.enabled', false);
+
 is($("d1").value, "abcde",
    "Displayed initial value should not be truncated by maxlength");
 is($("u1").value, "abcdef",
diff --git a/layout/forms/test/test_bug365410.html b/layout/forms/test/test_bug365410.html
index 19c5fb68a2af..e9d9507f84c4 100644
--- a/layout/forms/test/test_bug365410.html
+++ b/layout/forms/test/test_bug365410.html
@@ -74,6 +74,9 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=365410
 
 /** Test for Bug 365410 **/
 
+// Turn off spatial nav so that it does not hijack the up and down events.
+SpecialPowers.setBoolPref("snav.enabled", false);
+
 function pageUpDownTest(id,index) {
   var elm = document.getElementById(id);
   elm.focus();
diff --git a/layout/forms/test/test_bug563642.html b/layout/forms/test/test_bug563642.html
index 916435c4ff56..75cce45ca747 100644
--- a/layout/forms/test/test_bug563642.html
+++ b/layout/forms/test/test_bug563642.html
@@ -37,6 +37,9 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=563642
 
 /** Test for Bug 563642 **/
 
+// Turn off Spatial Navigation because it hijacks down and up key events.
+SpecialPowers.setBoolPref("snav.enabled", false);
+
 function pageUpDownTest(id,index) {
   var elm = document.getElementById(id);
   elm.focus();
diff --git a/layout/forms/test/test_select_prevent_default.html b/layout/forms/test/test_select_prevent_default.html
index 06d5f5f7aa7d..da4a62f94e6b 100644
--- a/layout/forms/test/test_select_prevent_default.html
+++ b/layout/forms/test/test_select_prevent_default.html
@@ -11,6 +11,11 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=291082
 <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
 <script type="application/javascript">
   /** Test for Bug 291082 **/
+
+
+  // Turn off Spatial Navigation because it hijacks arrow keydown events.
+  SpecialPowers.setBoolPref("snav.enabled", false);
+
   SimpleTest.waitForExplicitFinish();
 
   function preventDefault(event) {
diff --git a/mobile/android/app/mobile.js b/mobile/android/app/mobile.js
index 24444f04a932..a7c7853b58af 100644
--- a/mobile/android/app/mobile.js
+++ b/mobile/android/app/mobile.js
@@ -787,3 +787,5 @@ pref("general.useragent.override.youtube.com", "Android; Tablet;#Android; Mobile
 // When true, phone number linkification is enabled.
 pref("browser.ui.linkify.phone", false);
 
+// Enables/disables Spatial Navigation
+pref("snav.enabled", true);
diff --git a/mobile/android/chrome/content/browser.js b/mobile/android/chrome/content/browser.js
index 6f069f81fa4b..9cd65d525629 100644
--- a/mobile/android/chrome/content/browser.js
+++ b/mobile/android/chrome/content/browser.js
@@ -18,6 +18,7 @@ Cu.import("resource://gre/modules/JNI.jsm");
 Cu.import('resource://gre/modules/Payment.jsm');
 Cu.import("resource://gre/modules/PermissionPromptHelper.jsm");
 Cu.import("resource://gre/modules/ContactService.jsm");
+Cu.import("resource://gre/modules/SpatialNavigation.jsm");
 
 #ifdef ACCESSIBILITY
 Cu.import("resource://gre/modules/accessibility/AccessFu.jsm");
@@ -4111,6 +4112,9 @@ var BrowserEventHandler = {
     BrowserApp.deck.addEventListener("touchstart", this, true);
     BrowserApp.deck.addEventListener("click", InputWidgetHelper, true);
     BrowserApp.deck.addEventListener("click", SelectHelper, true);
+
+    SpatialNavigation.init(BrowserApp.deck, null);
+
     document.addEventListener("MozMagnifyGesture", this, true);
 
     Services.prefs.addObserver("browser.zoom.reflowOnZoom", this, false);
diff --git a/modules/libpref/src/init/all.js b/modules/libpref/src/init/all.js
index 9fbd6aafeceb..06b9494e3a3f 100644
--- a/modules/libpref/src/init/all.js
+++ b/modules/libpref/src/init/all.js
@@ -4464,3 +4464,6 @@ pref("urlclassifier.malware_table", "goog-malware-shavar");
 pref("urlclassifier.phish_table", "goog-phish-shavar");
 pref("urlclassifier.download_block_table", "goog-badbinurl-shavar");
 pref("urlclassifier.download_allow_table", "goog-downloadwhite-digest256");
+
+// Turn off Spatial navigation by default.
+pref("snav.enabled", false);
diff --git a/toolkit/modules/SpatialNavigation.jsm b/toolkit/modules/SpatialNavigation.jsm
new file mode 100644
index 000000000000..4d64d52ebb74
--- /dev/null
+++ b/toolkit/modules/SpatialNavigation.jsm
@@ -0,0 +1,505 @@
+// -*- Mode: js2; tab-width: 2; indent-tabs-mode: nil; js2-basic-offset: 2; js2-skip-preprocessor-directives: t; -*-
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * Import this module through
+ *
+ * Components.utils.import("resource://gre/modules/SpatialNavigation.jsm");
+ *
+ * Usage: (Literal class)
+ *
+ * SpatialNavigation.init(browser_element, optional_callback);
+ *
+ * optional_callback will be called when a new element is focused.
+ *
+ *    function optional_callback(element) {}
+ */
+
+"use strict";
+
+this.EXPORTED_SYMBOLS = ["SpatialNavigation"];
+
+var SpatialNavigation = {
+  init: function(browser, callback) {
+          browser.addEventListener("keydown", function (event) {
+            _onInputKeyPress(event, callback);
+          }, true);
+  }
+};
+
+// Private stuff
+
+const Cc = Components.classes;
+const Ci = Components.interfaces;
+const Cu = Components.utils;
+
+Cu["import"]("resource://gre/modules/Services.jsm", this);
+
+let eventListenerService = Cc["@mozilla.org/eventlistenerservice;1"]
+                             .getService(Ci.nsIEventListenerService);
+let focusManager         = Cc["@mozilla.org/focus-manager;1"]
+                             .getService(Ci.nsIFocusManager);
+let windowMediator       = Cc['@mozilla.org/appshell/window-mediator;1']
+                             .getService(Ci.nsIWindowMediator);
+
+// Debug helpers:
+function dump(a) {
+  Services.console.logStringMessage("SpatialNavigation: " + a);
+}
+
+function dumpRect(desc, rect) {
+  dump(desc + " " + Math.round(rect.left) + " " + Math.round(rect.top) + " " +
+       Math.round(rect.right) + " " + Math.round(rect.bottom) + " width:" +
+       Math.round(rect.width) + " height:" + Math.round(rect.height));
+}
+
+function dumpNodeCoord(desc, node) {
+  let rect = node.getBoundingClientRect();
+  dump(desc + " " + node.tagName + " x:" + Math.round(rect.left + rect.width/2) +
+       " y:" + Math.round(rect.top + rect.height / 2));
+}
+
+// modifier values
+
+const kAlt   = "alt";
+const kShift = "shift";
+const kCtrl  = "ctrl";
+const kNone  = "none";
+
+function _onInputKeyPress (event, callback) {
+  //If Spatial Navigation isn't enabled, return.
+  if (!PrefObserver['enabled']) {
+    return;
+  }
+
+  // Use whatever key value is available (either keyCode or charCode).
+  // It might be useful for addons or whoever wants to set different
+  // key to be used here (e.g. "a", "F1", "arrowUp", ...).
+  var key = event.which || event.keyCode;
+
+  if (key != PrefObserver['keyCodeDown']  &&
+      key != PrefObserver['keyCodeRight'] &&
+      key != PrefObserver['keyCodeUp'] &&
+      key != PrefObserver['keyCodeLeft'] &&
+      key != PrefObserver['keyCodeReturn']) {
+    return;
+  }
+
+  if (key == PrefObserver['keyCodeReturn']) {
+    // We report presses of the action button on a gamepad "A" as the return
+    // key to the DOM. The behaviour of hitting the return key and clicking an
+    // element is the same for some elements, but not all, so we handle the
+    // ones we want (like the Select element) here:
+    if (event.target instanceof Ci.nsIDOMHTMLSelectElement &&
+        event.target.click) {
+      event.target.click();
+      event.stopPropagation();
+      event.preventDefault();
+      return;
+    } else {
+      // Leave the action key press to get reported to the DOM as a return
+      // keypress.
+      return;
+    }
+  }
+
+  // If it is not using the modifiers it should, return.
+  if (!event.altKey && PrefObserver['modifierAlt'] ||
+      !event.shiftKey && PrefObserver['modifierShift'] ||
+      !event.crtlKey && PrefObserver['modifierCtrl']) {
+    return;
+  }
+
+  let currentlyFocused = event.target;
+  let currentlyFocusedWindow = currentlyFocused.ownerDocument.defaultView;
+  let bestElementToFocus = null;
+
+  // If currentlyFocused is an nsIDOMHTMLBodyElement then the page has just been
+  // loaded, and this is the first keypress in the page.
+  if (currentlyFocused instanceof Ci.nsIDOMHTMLBodyElement) {
+    focusManager.moveFocus(currentlyFocusedWindow, null, focusManager.MOVEFOCUS_FIRST, 0);
+    event.stopPropagation();
+    event.preventDefault();
+    return;
+  }
+
+  let windowUtils = currentlyFocusedWindow.QueryInterface(Ci.nsIInterfaceRequestor)
+                                          .getInterface(Ci.nsIDOMWindowUtils);
+  let cssPageRect = _getRootBounds(windowUtils);
+  let searchRect = _getSearchRect(currentlyFocused, key, cssPageRect);
+
+  let nodes = {};
+  nodes.length = 0;
+
+  let searchRectOverflows = false;
+
+  while (!bestElementToFocus && !searchRectOverflows) {
+    switch (key) {
+      case PrefObserver['keyCodeLeft']:
+      case PrefObserver['keyCodeRight']: {
+        if (searchRect.top < cssPageRect.top &&
+            searchRect.bottom > cssPageRect.bottom) {
+          searchRectOverflows = true;
+        }
+        break;
+      }
+      case PrefObserver['keyCodeUp']:
+      case PrefObserver['keyCodeDown']: {
+        if (searchRect.left < cssPageRect.left &&
+            searchRect.right > cssPageRect.right) {
+          searchRectOverflows = true;
+        }
+        break;
+      }
+    }
+
+    nodes = windowUtils.nodesFromRect(searchRect.left, searchRect.top,
+                                      0, searchRect.width, searchRect.height, 0,
+                                      true, false);
+    // Make the search rectangle "wider": double it's size in the direction
+    // that is not the keypress.
+    switch (key) {
+      case PrefObserver['keyCodeLeft']:
+      case PrefObserver['keyCodeRight']: {
+        searchRect.top = searchRect.top - (searchRect.height / 2);
+        searchRect.bottom = searchRect.top + (searchRect.height * 2);
+        searchRect.height = searchRect.height * 2;
+        break;
+      }
+      case PrefObserver['keyCodeUp']:
+      case PrefObserver['keyCodeDown']: {
+        searchRect.left = searchRect.left - (searchRect.width / 2);
+        searchRect.right = searchRect.left + (searchRect.width * 2);
+        searchRect.width = searchRect.width * 2;
+        break;
+      }
+    }
+    bestElementToFocus = _getBestToFocus(nodes, key, currentlyFocused);
+  }
+
+
+  if (bestElementToFocus === null) {
+    // Couldn't find an element to focus.
+    return;
+  }
+
+  focusManager.setFocus(bestElementToFocus, focusManager.FLAG_SHOWRING);
+
+  //if it is a text element, select all.
+  if ((bestElementToFocus instanceof Ci.nsIDOMHTMLInputElement &&
+       bestElementToFocus.mozIsTextField(false)) ||
+      bestElementToFocus instanceof Ci.nsIDOMHTMLTextAreaElement) {
+    bestElementToFocus.selectionStart = 0;
+    bestElementToFocus.selectionEnd = bestElementToFocus.textLength;
+  }
+
+  if (callback != undefined) {
+    callback(bestElementToFocus);
+  }
+
+  event.preventDefault();
+  event.stopPropagation();
+}
+
+// Returns the bounds of the page relative to the viewport.
+function _getRootBounds(windowUtils) {
+  let cssPageRect = windowUtils.getRootBounds();
+
+  let scrollX = {};
+  let scrollY = {};
+  windowUtils.getScrollXY(false, scrollX, scrollY);
+
+  let cssPageRectCopy = {};
+
+  cssPageRectCopy.right = cssPageRect.right - scrollX.value;
+  cssPageRectCopy.left = cssPageRect.left - scrollX.value;
+  cssPageRectCopy.top = cssPageRect.top - scrollY.value;
+  cssPageRectCopy.bottom = cssPageRect.bottom - scrollY.value;
+  cssPageRectCopy.width = cssPageRect.width;
+  cssPageRectCopy.height = cssPageRect.height;
+
+  return cssPageRectCopy;
+}
+
+// Returns the best node to focus from the list of nodes returned by the hit
+// test.
+function _getBestToFocus(nodes, key, currentlyFocused) {
+  let best = null;
+  let bestDist;
+  let bestMid;
+  let nodeMid;
+  let currentlyFocusedMid = _getMidpoint(currentlyFocused);
+  let currentlyFocusedRect = currentlyFocused.getBoundingClientRect();
+
+  for (let i = 0; i < nodes.length; i++) {
+    // Reject the currentlyFocused, and all node types we can't focus
+    if (!_canFocus(nodes[i]) || nodes[i] === currentlyFocused) {
+      continue;
+    }
+
+    // Reject all nodes that aren't "far enough" in the direction of the
+    // keypress
+    nodeMid = _getMidpoint(nodes[i]);
+    switch (key) {
+      case PrefObserver['keyCodeLeft']:
+        if (nodeMid.x >= (currentlyFocusedMid.x - currentlyFocusedRect.width / 2)) {
+          continue;
+        }
+        break;
+      case PrefObserver['keyCodeRight']:
+        if (nodeMid.x <= (currentlyFocusedMid.x + currentlyFocusedRect.width / 2)) {
+          continue;
+        }
+        break;
+
+      case PrefObserver['keyCodeUp']:
+        if (nodeMid.y >= (currentlyFocusedMid.y - currentlyFocusedRect.height / 2)) {
+          continue;
+        }
+        break;
+      case PrefObserver['keyCodeDown']:
+        if (nodeMid.y <= (currentlyFocusedMid.y + currentlyFocusedRect.height / 2)) {
+          continue;
+        }
+        break;
+    }
+
+    // Initialize best to the first viable value:
+    if (!best) {
+      best = nodes[i];
+      bestDist = _spatialDistance(best, currentlyFocused);
+      continue;
+    }
+
+    // Of the remaining nodes, pick the one closest to the currently focused
+    // node.
+    let curDist = _spatialDistance(nodes[i], currentlyFocused);
+    if (curDist > bestDist) {
+      continue;
+    }
+
+    bestMid = _getMidpoint(best);
+    switch (key) {
+      case PrefObserver['keyCodeLeft']:
+        if (nodeMid.x > bestMid.x) {
+          best = nodes[i];
+          bestDist = curDist;
+        }
+        break;
+      case PrefObserver['keyCodeRight']:
+        if (nodeMid.x < bestMid.x) {
+          best = nodes[i];
+          bestDist = curDist;
+        }
+        break;
+      case PrefObserver['keyCodeUp']:
+        if (nodeMid.y > bestMid.y) {
+          best = nodes[i];
+          bestDist = curDist;
+        }
+        break;
+      case PrefObserver['keyCodeDown']:
+        if (nodeMid.y < bestMid.y) {
+          best = nodes[i];
+          bestDist = curDist;
+        }
+        break;
+    }
+  }
+  return best;
+}
+
+// Returns the midpoint of a node.
+function _getMidpoint(node) {
+  let mid = {};
+  let box = node.getBoundingClientRect();
+  mid.x = box.left + (box.width / 2);
+  mid.y = box.top + (box.height / 2);
+
+  return mid;
+}
+
+// Returns true if the node is a type that we want to focus, false otherwise.
+function _canFocus(node) {
+  if (node instanceof Ci.nsIDOMHTMLLinkElement ||
+      node instanceof Ci.nsIDOMHTMLAnchorElement) {
+    return true;
+  }
+  if ((node instanceof Ci.nsIDOMHTMLButtonElement ||
+        node instanceof Ci.nsIDOMHTMLInputElement ||
+        node instanceof Ci.nsIDOMHTMLLinkElement ||
+        node instanceof Ci.nsIDOMHTMLOptGroupElement ||
+        node instanceof Ci.nsIDOMHTMLSelectElement ||
+        node instanceof Ci.nsIDOMHTMLTextAreaElement) &&
+      node.disabled === false) {
+    return true;
+  }
+  return false;
+}
+
+// Returns a rectangle that extends to the end of the screen in the direction that
+// the key is pressed.
+function _getSearchRect(currentlyFocused, key, cssPageRect) {
+  let currentlyFocusedRect = currentlyFocused.getBoundingClientRect();
+
+  let newRect = {};
+  newRect.left   = currentlyFocusedRect.left;
+  newRect.top    = currentlyFocusedRect.top;
+  newRect.right  = currentlyFocusedRect.right;
+  newRect.bottom = currentlyFocusedRect.bottom;
+  newRect.width  = currentlyFocusedRect.width;
+  newRect.height = currentlyFocusedRect.height;
+
+  switch (key) {
+    case PrefObserver['keyCodeLeft']:
+      newRect.left = cssPageRect.left;
+      newRect.width = newRect.right - newRect.left;
+      break;
+
+    case PrefObserver['keyCodeRight']:
+      newRect.right = cssPageRect.right;
+      newRect.width = newRect.right - newRect.left;
+      break;
+
+    case PrefObserver['keyCodeUp']:
+      newRect.top = cssPageRect.top;
+      newRect.height = newRect.bottom - newRect.top;
+      break;
+
+    case PrefObserver['keyCodeDown']:
+      newRect.bottom = cssPageRect.bottom;
+      newRect.height = newRect.bottom - newRect.top;
+      break;
+  }
+  return newRect;
+}
+
+// Gets the distance between two points a and b.
+function _spatialDistance(a, b) {
+  let mida = _getMidpoint(a);
+  let midb = _getMidpoint(b);
+
+  return Math.round(Math.pow(mida.x - midb.x, 2) +
+                    Math.pow(mida.y - midb.y, 2));
+}
+
+// Snav preference observer
+var PrefObserver = {
+  register: function() {
+    this.prefService = Cc["@mozilla.org/preferences-service;1"]
+                          .getService(Ci.nsIPrefService);
+
+    this._branch = this.prefService.getBranch("snav.");
+    this._branch.QueryInterface(Ci.nsIPrefBranch2);
+    this._branch.addObserver("", this, false);
+
+    // set current or default pref values
+    this.observe(null, "nsPref:changed", "enabled");
+    this.observe(null, "nsPref:changed", "xulContentEnabled");
+    this.observe(null, "nsPref:changed", "keyCode.modifier");
+    this.observe(null, "nsPref:changed", "keyCode.right");
+    this.observe(null, "nsPref:changed", "keyCode.up");
+    this.observe(null, "nsPref:changed", "keyCode.down");
+    this.observe(null, "nsPref:changed", "keyCode.left");
+    this.observe(null, "nsPref:changed", "keyCode.return");
+  },
+
+  observe: function(aSubject, aTopic, aData) {
+    if (aTopic != "nsPref:changed") {
+      return;
+    }
+
+    // aSubject is the nsIPrefBranch we're observing (after appropriate QI)
+    // aData is the name of the pref that's been changed (relative to aSubject)
+    switch (aData) {
+      case "enabled":
+        try {
+          this.enabled = this._branch.getBoolPref("enabled");
+        } catch(e) {
+          this.enabled = false;
+        }
+        break;
+
+      case "xulContentEnabled":
+        try {
+          this.xulContentEnabled = this._branch.getBoolPref("xulContentEnabled");
+        } catch(e) {
+          this.xulContentEnabled = false;
+        }
+        break;
+
+      case "keyCode.modifier": {
+        let keyCodeModifier;
+        try {
+          keyCodeModifier = this._branch.getCharPref("keyCode.modifier");
+
+          // resetting modifiers
+          this.modifierAlt = false;
+          this.modifierShift = false;
+          this.modifierCtrl = false;
+
+          if (keyCodeModifier != this.kNone) {
+            // we are using '+' as a separator in about:config.
+            let mods = keyCodeModifier.split(/\++/);
+            for (let i = 0; i < mods.length; i++) {
+              let mod = mods[i].toLowerCase();
+              if (mod === "")
+                continue;
+              else if (mod == kAlt)
+                this.modifierAlt = true;
+              else if (mod == kShift)
+                this.modifierShift = true;
+              else if (mod == kCtrl)
+                this.modifierCtrl = true;
+              else {
+                keyCodeModifier = kNone;
+                break;
+              }
+            }
+          }
+        } catch(e) { }
+        break;
+      }
+
+      case "keyCode.up":
+        try {
+          this.keyCodeUp = this._branch.getIntPref("keyCode.up");
+        } catch(e) {
+          this.keyCodeUp = Ci.nsIDOMKeyEvent.DOM_VK_UP;
+        }
+        break;
+      case "keyCode.down":
+        try {
+          this.keyCodeDown = this._branch.getIntPref("keyCode.down");
+        } catch(e) {
+          this.keyCodeDown = Ci.nsIDOMKeyEvent.DOM_VK_DOWN;
+        }
+        break;
+      case "keyCode.left":
+        try {
+          this.keyCodeLeft = this._branch.getIntPref("keyCode.left");
+        } catch(e) {
+          this.keyCodeLeft = Ci.nsIDOMKeyEvent.DOM_VK_LEFT;
+        }
+        break;
+      case "keyCode.right":
+        try {
+          this.keyCodeRight = this._branch.getIntPref("keyCode.right");
+        } catch(e) {
+          this.keyCodeRight = Ci.nsIDOMKeyEvent.DOM_VK_RIGHT;
+        }
+        break;
+      case "keyCode.return":
+        try {
+          this.keyCodeReturn = this._branch.getIntPref("keyCode.return");
+        } catch(e) {
+          this.keyCodeReturn = Ci.nsIDOMKeyEvent.DOM_VK_RETURN;
+        }
+        break;
+    }
+  }
+};
+
+PrefObserver.register();
diff --git a/toolkit/modules/moz.build b/toolkit/modules/moz.build
index 4e1d9d5edd73..211bf8559213 100644
--- a/toolkit/modules/moz.build
+++ b/toolkit/modules/moz.build
@@ -35,6 +35,7 @@ EXTRA_JS_MODULES += [
     'SelectContentHelper.jsm',
     'SelectParentHelper.jsm',
     'Sntp.jsm',
+    'SpatialNavigation.jsm',
     'Sqlite.jsm',
     'Task.jsm',
     'TelemetryTimestamps.jsm',
diff --git a/toolkit/modules/tests/mochitest/mochitest.ini b/toolkit/modules/tests/mochitest/mochitest.ini
new file mode 100644
index 000000000000..dd281bf82433
--- /dev/null
+++ b/toolkit/modules/tests/mochitest/mochitest.ini
@@ -0,0 +1 @@
+[test_spatial_navigation.html]
diff --git a/toolkit/modules/tests/mochitest/test_spatial_navigation.html b/toolkit/modules/tests/mochitest/test_spatial_navigation.html
new file mode 100644
index 000000000000..7fc227b1fd49
--- /dev/null
+++ b/toolkit/modules/tests/mochitest/test_spatial_navigation.html
@@ -0,0 +1,78 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=698437
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for Bug 698437</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="/tests/SimpleTest/EventUtils.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+  <script type="application/javascript">
+
+  /** Test for Bug 698437 **/
+
+  SimpleTest.waitForExplicitFinish();
+
+  function Test() {
+    if (!SpecialPowers.getBoolPref("snav.enabled")) {
+      todo(false, "Enable spatial navigiation on this platform.");
+      SimpleTest.finish();
+      return;
+    }
+
+    var center = document.getElementById("center");
+    var right = document.getElementById("right");
+    var left = document.getElementById("left");
+    var top = document.getElementById("top");
+    var bottom = document.getElementById("bottom");
+
+    console.log(top);
+    console.log(bottom);
+    console.log(center);
+    console.log(left);
+    console.log(right);
+
+    center.focus();
+    is(center.id, document.activeElement.id, "How did we call focus on center and it did" +
+                                             " not become the active element?");
+
+    synthesizeKey("VK_UP", { });
+    is(top.id, document.activeElement.id,
+       "Spatial navigation up key is not handled correctly.");
+
+    center.focus();
+    synthesizeKey("VK_DOWN", { });
+    is(bottom.id, document.activeElement.id,
+       "Spatial navigation down key is not handled correctly.");
+
+    center.focus();
+    synthesizeKey("VK_RIGHT", { });
+    is(right.id, document.activeElement.id,
+       "Spatial navigation right key is not handled correctly.");
+
+    center.focus();
+    synthesizeKey("VK_LEFT", { });
+    is(left.id, document.activeElement.id,
+       "Spatial navigation left key is not handled correctly.");
+
+    SimpleTest.finish();
+  }
+
+  </script>
+</head>
+<body onload="Test();">
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=698437">Mozilla Bug 698437</a>
+<p id="display"></p>
+<div id="content">
+  <p> This is a <a id="top" href="#">really</a> long sentence </p>
+  <p> <a id="left" href="#">This</a> is a
+      <a id="center" href="#">really</a> long
+      <a id="right" href="#">sentence</a> </p>
+  <p> This is a <a id="bottom" href="#">really</a> long sentence </p>
+</div>
+<pre id="test">
+</pre>
+</body>
+</html>
diff --git a/toolkit/modules/tests/moz.build b/toolkit/modules/tests/moz.build
index 798b6ff93346..f0262b20701f 100644
--- a/toolkit/modules/tests/moz.build
+++ b/toolkit/modules/tests/moz.build
@@ -9,3 +9,5 @@ DIRS += ['browser']
 MODULE = 'test_toolkit_general'
 
 XPCSHELL_TESTS_MANIFESTS += ['xpcshell/xpcshell.ini']
+
+MOCHITEST_MANIFESTS += ['mochitest/mochitest.ini']
diff --git a/widget/android/nsWindow.cpp b/widget/android/nsWindow.cpp
index a2143dfdc213..e8f8c5027c7c 100644
--- a/widget/android/nsWindow.cpp
+++ b/widget/android/nsWindow.cpp
@@ -1438,6 +1438,9 @@ static unsigned int ConvertAndroidKeyCodeToDOMKeyCode(int androidKeyCode)
         case AKEYCODE_KANA:               return NS_VK_KANA;
         case AKEYCODE_ASSIST:             return NS_VK_HELP;
 
+        // the A key is the action key for gamepad devices.
+        case AKEYCODE_BUTTON_A:          return NS_VK_RETURN;
+
         default:
             ALOG("ConvertAndroidKeyCodeToDOMKeyCode: "
                  "No DOM keycode for Android keycode %d", androidKeyCode);