The Tor Browser: browser/metro/base/content/helperui/SelectionHelperUI.js@6474c204b198 (annotated)

browser/metro/base/content/helperui/SelectionHelperUI.js@6474c204b198 (annotated)

browser/metro/base/content/helperui/SelectionHelperUI.js

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 /* 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/. */
 /*
  * selection management
  */
 /*
  * Current monocle image:
  *  dimensions: 32 x 24
  *  circle center: 16 x 14
  *  padding top: 6
  */
 // Y axis scroll distance that will disable this module and cancel selection
 const kDisableOnScrollDistance = 25;
 // Drag hysteresis programmed into monocle drag moves
 const kDragHysteresisDistance = 10;
 // selection layer id returned from SelectionHandlerUI's layerMode.
 const kChromeLayer = 1;
 const kContentLayer = 2;
 /*
  * Markers
  */
 function MarkerDragger(aMarker) {
   this._marker = aMarker;
 }
 MarkerDragger.prototype = {
   _selectionHelperUI: null,
   _marker: null,
   _shutdown: false,
   _dragging: false,
   get marker() {
     return this._marker;
   },
   set shutdown(aVal) {
     this._shutdown = aVal;
   },
   get shutdown() {
     return this._shutdown;
   },
   get dragging() {
     return this._dragging;
   },
   freeDrag: function freeDrag() {
     return true;
   },
   isDraggable: function isDraggable(aTarget, aContent) {
     return { x: true, y: true };
   },
   dragStart: function dragStart(aX, aY, aTarget, aScroller) {
     if (this._shutdown)
       return false;
     this._dragging = true;
     this.marker.dragStart(aX, aY);
     return true;
   },
   dragStop: function dragStop(aDx, aDy, aScroller) {
     if (this._shutdown)
       return false;
     this._dragging = false;
     this.marker.dragStop(aDx, aDy);
     return true;
   },
   dragMove: function dragMove(aDx, aDy, aScroller, aIsKenetic, aClientX, aClientY) {
     // Note if aIsKenetic is true this is synthetic movement,
     // we don't want that so return false.
     if (this._shutdown || aIsKenetic)
       return false;
     this.marker.moveBy(aDx, aDy, aClientX, aClientY);
     // return true if we moved, false otherwise. The result
     // is used in deciding if we should repaint between drags.
     return true;
   }
 }
 function Marker(aParent, aTag, aElementId, xPos, yPos) {
   this._xPos = xPos;
   this._yPos = yPos;
   this._selectionHelperUI = aParent;
   this._element = aParent.overlay.getMarker(aElementId);
   this._elementId = aElementId;
   // These get picked in input.js and receives drag input
   this._element.customDragger = new MarkerDragger(this);
   this.tag = aTag;
 }
 Marker.prototype = {
   _element: null,
   _elementId: "",
   _selectionHelperUI: null,
   _xPos: 0,
   _yPos: 0,
   _xDrag: 0,
   _yDrag: 0,
   _tag: "",
   _hPlane: 0,
   _vPlane: 0,
   _restrictedToBounds: false,
   // Tweak me if the monocle graphics change in any way
   _monocleRadius: 8,
   _monocleXHitTextAdjust: -2,
   _monocleYHitTextAdjust: -10,
   get xPos() {
     return this._xPos;
   },
   get yPos() {
     return this._yPos;
   },
   get tag() {
     return this._tag;
   },
   set tag(aVal) {
     this._tag = aVal;
   },
   get dragging() {
     return this._element.customDragger.dragging;
   },
   // Indicates that marker's position doesn't reflect real selection boundary
   // but rather boundary of input control while actual selection boundaries are
   // not visible (ex. due scrolled content).
   get restrictedToBounds() {
     return this._restrictedToBounds;
   },
   shutdown: function shutdown() {
     this._element.hidden = true;
     this._element.customDragger.shutdown = true;
     delete this._element.customDragger;
     this._selectionHelperUI = null;
     this._element = null;
   },
   setTrackBounds: function setTrackBounds(aVerticalPlane, aHorizontalPlane) {
     // monocle boundaries
     this._hPlane = aHorizontalPlane;
     this._vPlane = aVerticalPlane;
   },
   show: function show() {
     this._element.hidden = false;
   },
   hide: function hide() {
     this._element.hidden = true;
   },
   get visible() {
     return this._element.hidden == false;
   },
   position: function position(aX, aY, aRestrictedToBounds) {
     this._xPos = aX;
     this._yPos = aY;
     this._restrictedToBounds = !!aRestrictedToBounds;
     this._setPosition();
   },
   _setPosition: function _setPosition() {
     this._element.left = this._xPos + "px";
     this._element.top = this._yPos + "px";
   },
   dragStart: function dragStart(aX, aY) {
     this._xDrag = 0;
     this._yDrag = 0;
     this._selectionHelperUI.markerDragStart(this);
   },
   dragStop: function dragStop(aDx, aDy) {
     this._selectionHelperUI.markerDragStop(this);
   },
   moveBy: function moveBy(aDx, aDy, aClientX, aClientY) {
     this._xPos -= aDx;
     this._yPos -= aDy;
     this._xDrag -= aDx;
     this._yDrag -= aDy;
     // Add a bit of hysteresis to our directional detection so "big fingers"
     // are detected accurately.
     let direction = "tbd";
     if (Math.abs(this._xDrag) > kDragHysteresisDistance ||
         Math.abs(this._yDrag) > kDragHysteresisDistance) {
       direction = (this._xDrag <= 0 && this._yDrag <= 0 ? "start" : "end");
     }
     // We may swap markers in markerDragMove. If markerDragMove
     // returns true keep processing, otherwise get out of here.
     if (this._selectionHelperUI.markerDragMove(this, direction)) {
       this._setPosition();
     }
   },
   hitTest: function hitTest(aX, aY) {
     // Gets the pointer of the arrow right in the middle of the
     // monocle.
     aY += this._monocleYHitTextAdjust;
     aX += this._monocleXHitTextAdjust;
     if (aX >= (this._xPos - this._monocleRadius) &&
         aX <= (this._xPos + this._monocleRadius) &&
         aY >= (this._yPos - this._monocleRadius) &&
         aY <= (this._yPos + this._monocleRadius))
       return true;
     return false;
   },
   swapMonocle: function swapMonocle(aCaret) {
     let targetElement = aCaret._element;
     let targetElementId = aCaret._elementId;
     aCaret._element = this._element;
     aCaret._element.customDragger._marker = aCaret;
     aCaret._elementId = this._elementId;
     this._xPos = aCaret._xPos;
     this._yPos = aCaret._yPos;
     this._element = targetElement;
     this._element.customDragger._marker = this;
     this._elementId = targetElementId;
     this._element.visible = true;
   },
 };
 /*
  * SelectionHelperUI
  */
 var SelectionHelperUI = {
   _debugEvents: false,
   _msgTarget: null,
   _startMark: null,
   _endMark: null,
   _caretMark: null,
   _target: null,
   _showAfterUpdate: false,
   _activeSelectionRect: null,
   _selectionMarkIds: [],
   _targetIsEditable: false,
   /*
    * Properties
    */
   get startMark() {
     if (this._startMark == null) {
       this._startMark = new Marker(this, "start", this._selectionMarkIds.pop(), 0, 0);
     }
     return this._startMark;
   },
   get endMark() {
     if (this._endMark == null) {
       this._endMark = new Marker(this, "end", this._selectionMarkIds.pop(), 0, 0);
     }
     return this._endMark;
   },
   get caretMark() {
     if (this._caretMark == null) {
       this._caretMark = new Marker(this, "caret", this._selectionMarkIds.pop(), 0, 0);
     }
     return this._caretMark;
   },
   get overlay() {
     return document.getElementById(this.layerMode == kChromeLayer ?
       "chrome-selection-overlay" : "content-selection-overlay");
   },
   get layerMode() {
     if (this._msgTarget && this._msgTarget instanceof SelectionPrototype)
       return kChromeLayer;
     return kContentLayer;
   },
   /*
    * isActive (prop)
    *
    * Determines if a selection edit session is currently active.
    */
   get isActive() {
     return this._msgTarget ? true : false;
   },
   /*
    * isSelectionUIVisible (prop)
    *
    * Determines if edit session monocles are visible. Useful
    * in checking if selection handler is setup for tests.
    */
   get isSelectionUIVisible() {
     if (!this._msgTarget || !this._startMark)
       return false;
     return this._startMark.visible;
   },
   /*
    * isCaretUIVisible (prop)
    *
    * Determines if caret browsing monocle is visible. Useful
    * in checking if selection handler is setup for tests.
    */
   get isCaretUIVisible() {
     if (!this._msgTarget || !this._caretMark)
       return false;
     return this._caretMark.visible;
   },
   /*
    * hasActiveDrag (prop)
    *
    * Determines if a marker is actively being dragged (missing call
    * to markerDragStop). Useful in checking if selection handler is
    * setup for tests.
    */
   get hasActiveDrag() {
     if (!this._msgTarget)
       return false;
     if ((this._caretMark && this._caretMark.dragging) ||
         (this._startMark && this._startMark.dragging) ||
         (this._endMark && this._endMark.dragging))
       return true;
     return false;
   },
   /*
    * Observers
    */
   observe: function (aSubject, aTopic, aData) {
     switch (aTopic) {
       case "attach_edit_session_to_content":
         // We receive this from text input bindings when this module
         // isn't accessible.
         this.chromeTextboxClick(aSubject);
         break;
       case "apzc-transform-begin":
         if (this.isActive && this.layerMode == kContentLayer) {
           this._hideMonocles();
         }
         break;
       case "apzc-transform-end":
         // The selection range callback will check to see if the new
         // position is off the screen, in which case it shuts down and
         // clears the selection.
         if (this.isActive && this.layerMode == kContentLayer) {
           this._showAfterUpdate = true;
           this._sendAsyncMessage("Browser:SelectionUpdate", {
             isInitiatedByAPZC: true
           });
         }
         break;
       }
   },
   /*
    * Public apis
    */
   /*
    * pingSelectionHandler
    *
    * Ping the SelectionHandler and wait for the right response. Insures
    * all previous messages have been received. Useful in checking if
    * selection handler is setup for tests.
    *
    * @return a promise
    */
   pingSelectionHandler: function pingSelectionHandler() {
     if (!this.isActive)
       return null;
     if (this._pingCount == undefined) {
       this._pingCount = 0;
       this._pingArray = [];
     }
     this._pingCount++;
     let deferred = Promise.defer();
     this._pingArray.push({
       id: this._pingCount,
       deferred: deferred
     });
     this._sendAsyncMessage("Browser:SelectionHandlerPing", { id: this._pingCount });
     return deferred.promise;
   },
   /*
    * openEditSession
    *
    * Attempts to select underlying text at a point and begins editing
    * the section.
    *
    * @param aMsgTarget - Browser or chrome message target
    * @param aX, aY - Browser relative client coordinates.
    * @param aSetFocus - (optional) For form inputs, requests that the focus
    * be set to the element.
    */
   openEditSession: function openEditSession(aMsgTarget, aX, aY, aSetFocus) {
     if (!aMsgTarget || this.isActive)
       return;
     this._init(aMsgTarget);
     this._setupDebugOptions();
     let setFocus = aSetFocus || false;
     // Send this over to SelectionHandler in content, they'll message us
     // back with information on the current selection. SelectionStart
     // takes client coordinates.
     this._sendAsyncMessage("Browser:SelectionStart", {
       setFocus: setFocus,
       xPos: aX,
       yPos: aY
     });
   },
   /*
    * attachEditSession
    *
    * Attaches to existing selection and begins editing.
    *
    * @param aMsgTarget - Browser or chrome message target.
    * @param aX Tap browser relative client X coordinate.
    * @param aY Tap browser relative client Y coordinate.
    * @param aTarget Actual tap target (optional).
    */
   attachEditSession: function attachEditSession(aMsgTarget, aX, aY, aTarget) {
     if (!aMsgTarget || this.isActive)
       return;
     this._init(aMsgTarget);
     this._setupDebugOptions();
     // Send this over to SelectionHandler in content, they'll message us
     // back with information on the current selection. SelectionAttach
     // takes client coordinates.
     this._sendAsyncMessage("Browser:SelectionAttach", {
       target: aTarget,
       xPos: aX,
       yPos: aY
     });
   },
   /*
    * attachToCaret
    *
    * Initiates a touch caret selection session for a text input.
    * Can be called multiple times to move the caret marker around.
    *
    * Note the caret marker is pretty limited in functionality. The
    * only thing is can do is be displayed at the caret position.
    * Once the user starts a drag, the caret marker is hidden, and
    * the start and end markers take over.
    *
    * @param aMsgTarget - Browser or chrome message target.
    * @param aX Tap browser relative client X coordinate.
    * @param aY Tap browser relative client Y coordinate.
    * @param aTarget Actual tap target (optional).
    */
   attachToCaret: function attachToCaret(aMsgTarget, aX, aY, aTarget) {
     if (!this.isActive) {
       this._init(aMsgTarget);
       this._setupDebugOptions();
     } else {
       this._hideMonocles();
     }
     this._lastCaretAttachment = {
       target: aTarget,
       xPos: aX,
       yPos: aY
     };
     this._sendAsyncMessage("Browser:CaretAttach", {
       target: aTarget,
       xPos: aX,
       yPos: aY
     });
   },
   /*
    * canHandleContextMenuMsg
    *
    * Determines if we can handle a ContextMenuHandler message.
    */
   canHandleContextMenuMsg: function canHandleContextMenuMsg(aMessage) {
     if (aMessage.json.types.indexOf("content-text") != -1)
       return true;
     return false;
   },
   /*
    * closeEditSession(aClearSelection)
    *
    * Closes an active edit session and shuts down. Does not clear existing
    * selection regions if they exist.
    *
    * @param aClearSelection bool indicating if the selection handler should also
    * clear any selection. optional, the default is false.
    */
   closeEditSession: function closeEditSession(aClearSelection) {
     if (!this.isActive) {
       return;
     }
     // This will callback in _selectionHandlerShutdown in
     // which we will call _shutdown().
     let clearSelection = aClearSelection || false;
     this._sendAsyncMessage("Browser:SelectionClose", {
       clearSelection: clearSelection
     });
   },
   /*
    * Click handler for chrome pages loaded into the browser (about:config).
    * Called from the text input bindings via the attach_edit_session_to_content
    * observer.
    */
   chromeTextboxClick: function (aEvent) {
     this.attachEditSession(Browser.selectedTab.browser, aEvent.clientX,
         aEvent.clientY, aEvent.target);
   },
   /*
    * Handy debug routines that work independent of selection. They
    * make use of the selection overlay for drawing points.
    */
   debugDisplayDebugPoint: function (aLeft, aTop, aSize, aCssColorStr, aFill) {
     this.overlay.enabled = true;
     this.overlay.displayDebugLayer = true;
     this.overlay.addDebugRect(aLeft, aTop, aLeft + aSize, aTop + aSize,
                               aCssColorStr, aFill);
   },
   debugClearDebugPoints: function () {
     this.overlay.displayDebugLayer = false;
     if (!this._msgTarget) {
       this.overlay.enabled = false;
     }
   },
   /*
    * Init and shutdown
    */
   init: function () {
     let os = Services.obs;
     os.addObserver(this, "attach_edit_session_to_content", false);
     os.addObserver(this, "apzc-transform-begin", false);
     os.addObserver(this, "apzc-transform-end", false);
   },
   _init: function _init(aMsgTarget) {
     // store the target message manager
     this._msgTarget = aMsgTarget;
     // Init our list of available monocle ids
     this._setupMonocleIdArray();
     // Init selection rect info
     this._activeSelectionRect = Util.getCleanRect();
     this._targetElementRect = Util.getCleanRect();
     // SelectionHandler messages
     messageManager.addMessageListener("Content:SelectionRange", this);
     messageManager.addMessageListener("Content:SelectionCopied", this);
     messageManager.addMessageListener("Content:SelectionFail", this);
     messageManager.addMessageListener("Content:SelectionDebugRect", this);
     messageManager.addMessageListener("Content:HandlerShutdown", this);
     messageManager.addMessageListener("Content:SelectionHandlerPong", this);
     messageManager.addMessageListener("Content:SelectionSwap", this);
     // capture phase
     window.addEventListener("keypress", this, true);
     window.addEventListener("MozPrecisePointer", this, true);
     window.addEventListener("MozDeckOffsetChanging", this, true);
     window.addEventListener("MozDeckOffsetChanged", this, true);
     window.addEventListener("KeyboardChanged", this, true);
     // bubble phase
     window.addEventListener("click", this, false);
     window.addEventListener("touchstart", this, false);
     Elements.browsers.addEventListener("URLChanged", this, true);
     Elements.browsers.addEventListener("SizeChanged", this, true);
     Elements.tabList.addEventListener("TabSelect", this, true);
     Elements.navbar.addEventListener("transitionend", this, true);
     this.overlay.enabled = true;
   },
   _shutdown: function _shutdown() {
     messageManager.removeMessageListener("Content:SelectionRange", this);
     messageManager.removeMessageListener("Content:SelectionCopied", this);
     messageManager.removeMessageListener("Content:SelectionFail", this);
     messageManager.removeMessageListener("Content:SelectionDebugRect", this);
     messageManager.removeMessageListener("Content:HandlerShutdown", this);
     messageManager.removeMessageListener("Content:SelectionHandlerPong", this);
     messageManager.removeMessageListener("Content:SelectionSwap", this);
     window.removeEventListener("keypress", this, true);
     window.removeEventListener("MozPrecisePointer", this, true);
     window.removeEventListener("MozDeckOffsetChanging", this, true);
     window.removeEventListener("MozDeckOffsetChanged", this, true);
     window.removeEventListener("KeyboardChanged", this, true);
     window.removeEventListener("click", this, false);
     window.removeEventListener("touchstart", this, false);
     Elements.browsers.removeEventListener("URLChanged", this, true);
     Elements.browsers.removeEventListener("SizeChanged", this, true);
     Elements.tabList.removeEventListener("TabSelect", this, true);
     Elements.navbar.removeEventListener("transitionend", this, true);
     this._shutdownAllMarkers();
     this._selectionMarkIds = [];
     this._msgTarget = null;
     this._activeSelectionRect = null;
     this.overlay.displayDebugLayer = false;
     this.overlay.enabled = false;
   },
   /*
    * Utilities
    */
   /*
    * _swapCaretMarker
    *
    * Swap two drag markers - used when transitioning from caret mode
    * to selection mode. We take the current caret marker (which is in a
    * drag state) and swap it out with one of the selection markers.
    */
   _swapCaretMarker: function _swapCaretMarker(aDirection) {
     let targetMark = null;
     if (aDirection == "start")
       targetMark = this.startMark;
     else
       targetMark = this.endMark;
     let caret = this.caretMark;
     targetMark.swapMonocle(caret);
     let id = caret._elementId;
     caret.shutdown();
     this._caretMark = null;
     this._selectionMarkIds.push(id);
   },
   /*
    * _transitionFromCaretToSelection
    *
    * Transitions from caret mode to text selection mode.
    */
   _transitionFromCaretToSelection: function _transitionFromCaretToSelection(aDirection) {
     // Get selection markers initialized if they aren't already
     { let mark = this.startMark; mark = this.endMark; }
     // Swap the caret marker out for the start or end marker depending
     // on direction.
     this._swapCaretMarker(aDirection);
     let targetMark = null;
     if (aDirection == "start")
       targetMark = this.startMark;
     else
       targetMark = this.endMark;
     // Position both in the same starting location.
     this.startMark.position(targetMark.xPos, targetMark.yPos);
     this.endMark.position(targetMark.xPos, targetMark.yPos);
     // We delay transitioning until we know which direction the user is dragging
     // based on a hysteresis value in the drag marker code. Down in our caller, we
     // cache the first drag position in _cachedCaretPos so we can select from the
     // initial caret drag position. Use those values if we have them. (Note
     // _cachedCaretPos has already been translated in _getMarkerBaseMessage.)
     let xpos = this._cachedCaretPos ? this._cachedCaretPos.xPos :
       this._msgTarget.ctobx(targetMark.xPos, true);
     let ypos = this._cachedCaretPos ? this._cachedCaretPos.yPos :
       this._msgTarget.ctoby(targetMark.yPos, true);
     // Start the selection monocle drag. SelectionHandler relies on this
     // for getting initialized. This will also trigger a message back for
     // monocle positioning. Note, markerDragMove is still on the stack in
     // this call!
     this._sendAsyncMessage("Browser:SelectionSwitchMode", {
       newMode: "selection",
       change: targetMark.tag,
       xPos: xpos,
       yPos: ypos,
     });
   },
   /*
    * _setupDebugOptions
    *
    * Sends a message over to content instructing it to
    * turn on various debug features.
    */
   _setupDebugOptions: function _setupDebugOptions() {
     // Debug options for selection
     let debugOpts = { dumpRanges: false, displayRanges: false, dumpEvents: false };
     try {
       if (Services.prefs.getBoolPref(kDebugSelectionDumpPref))
         debugOpts.displayRanges = true;
     } catch (ex) {}
     try {
       if (Services.prefs.getBoolPref(kDebugSelectionDisplayPref))
         debugOpts.displayRanges = true;
     } catch (ex) {}
     try {
       if (Services.prefs.getBoolPref(kDebugSelectionDumpEvents)) {
         debugOpts.dumpEvents = true;
         this._debugEvents = true;
       }
     } catch (ex) {}
     if (debugOpts.displayRanges || debugOpts.dumpRanges || debugOpts.dumpEvents) {
       // Turn on the debug layer
       this.overlay.displayDebugLayer = true;
       // Tell SelectionHandler what to do
       this._sendAsyncMessage("Browser:SelectionDebug", debugOpts);
     }
   },
   /*
    * _sendAsyncMessage
    *
    * Helper for sending a message to SelectionHandler.
    */
   _sendAsyncMessage: function _sendAsyncMessage(aMsg, aJson) {
     if (!this._msgTarget) {
       if (this._debugEvents)
         Util.dumpLn("SelectionHelperUI sendAsyncMessage could not send", aMsg);
       return;
     }
     if (this._msgTarget && this._msgTarget instanceof SelectionPrototype) {
       this._msgTarget.msgHandler(aMsg, aJson);
     } else {
       this._msgTarget.messageManager.sendAsyncMessage(aMsg, aJson);
     }
   },
   _checkForActiveDrag: function _checkForActiveDrag() {
     return (this.startMark.dragging || this.endMark.dragging ||
             this.caretMark.dragging);
   },
   _hitTestSelection: function _hitTestSelection(aEvent) {
     // Ignore if the double tap isn't on our active selection rect.
     if (this._activeSelectionRect &&
         Util.pointWithinRect(aEvent.clientX, aEvent.clientY, this._activeSelectionRect)) {
       return true;
     }
     return false;
   },
   /*
    * _setCaretPositionAtPoint - sets the current caret position.
    *
    * @param aX, aY - browser relative client coordinates
    */
   _setCaretPositionAtPoint: function _setCaretPositionAtPoint(aX, aY) {
     let json = this._getMarkerBaseMessage("caret");
     json.caret.xPos = aX;
     json.caret.yPos = aY;
     this._sendAsyncMessage("Browser:CaretUpdate", json);
   },
   /*
    * _shutdownAllMarkers
    *
    * Helper for shutting down all markers and
    * freeing the objects associated with them.
    */
   _shutdownAllMarkers: function _shutdownAllMarkers() {
     if (this._startMark)
       this._startMark.shutdown();
     if (this._endMark)
       this._endMark.shutdown();
     if (this._caretMark)
       this._caretMark.shutdown();
     this._startMark = null;
     this._endMark = null;
     this._caretMark = null;
   },
   /*
    * _setupMonocleIdArray
    *
    * Helper for initing the array of monocle anon ids.
    */
   _setupMonocleIdArray: function _setupMonocleIdArray() {
     this._selectionMarkIds = ["selectionhandle-mark1",
                               "selectionhandle-mark2",
                               "selectionhandle-mark3"];
   },
   _hideMonocles: function _hideMonocles() {
     if (this._startMark) {
       this.startMark.hide();
     }
     if (this._endMark) {
       this.endMark.hide();
     }
     if (this._caretMark) {
       this.caretMark.hide();
     }
   },
   _showMonocles: function _showMonocles(aSelection) {
     if (!aSelection) {
       if (this._checkMonocleVisibility(this.caretMark.xPos, this.caretMark.yPos)) {
         this.caretMark.show();
       }
     } else {
       if (this._checkMonocleVisibility(this.endMark.xPos, this.endMark.yPos)) {
         this.endMark.show();
       }
       if (this._checkMonocleVisibility(this.startMark.xPos, this.startMark.yPos)) {
         this.startMark.show();
       }
     }
   },
   _checkMonocleVisibility: function(aX, aY) {
     let viewport = Browser.selectedBrowser.contentViewportBounds;
     aX = this._msgTarget.ctobx(aX);
     aY = this._msgTarget.ctoby(aY);
     if (aX < viewport.x || aY < viewport.y ||
         aX > (viewport.x + viewport.width) ||
         aY > (viewport.y + viewport.height)) {
       return false;
     }
     return true;
   },
   /*
    * Event handlers for document events
    */
   /*
    * Handles taps that move the current caret around in text edits,
    * clear active selection and focus when necessary, or change
    * modes. Only active after SelectionHandlerUI is initialized.
    */
   _onClick: function(aEvent) {
     if (this.layerMode == kChromeLayer && this._targetIsEditable) {
       this.attachToCaret(this._msgTarget, aEvent.clientX, aEvent.clientY,
           aEvent.target);
     }
   },
   _onKeypress: function _onKeypress() {
     this.closeEditSession();
   },
   _onResize: function _onResize() {
     this._sendAsyncMessage("Browser:SelectionUpdate", {});
   },
   /*
    * _onDeckOffsetChanging - fired by ContentAreaObserver before the browser
    * deck is shifted for form input access in response to a soft keyboard
    * display.
    */
   _onDeckOffsetChanging: function _onDeckOffsetChanging(aEvent) {
     // Hide the monocles temporarily
     this._hideMonocles();
   },
   /*
    * _onDeckOffsetChanged - fired by ContentAreaObserver after the browser
    * deck is shifted for form input access in response to a soft keyboard
    * display.
    */
   _onDeckOffsetChanged: function _onDeckOffsetChanged(aEvent) {
     // Update the monocle position and display
     this.attachToCaret(null, this._lastCaretAttachment.xPos,
         this._lastCaretAttachment.yPos, this._lastCaretAttachment.target);
   },
   /*
    * Detects when the nav bar transitions, so we can enable selection at the
    * appropriate location once the transition is complete, or shutdown
    * selection down when the nav bar is hidden.
    */
   _onNavBarTransitionEvent: function _onNavBarTransitionEvent(aEvent) {
     // Ignore when selection is in content
     if (this.layerMode == kContentLayer) {
       return;
     }
     // After tansitioning up, show the monocles
     if (Elements.navbar.isShowing) {
       this._showAfterUpdate = true;
       this._sendAsyncMessage("Browser:SelectionUpdate", {});
     }
   },
   _onKeyboardChangedEvent: function _onKeyboardChangedEvent() {
     if (!this.isActive || this.layerMode == kContentLayer) {
       return;
     }
     this._sendAsyncMessage("Browser:SelectionUpdate", {});
   },
   /*
    * Event handlers for message manager
    */
   _onDebugRectRequest: function _onDebugRectRequest(aMsg) {
     this.overlay.addDebugRect(aMsg.left, aMsg.top, aMsg.right, aMsg.bottom,
                               aMsg.color, aMsg.fill, aMsg.id);
   },
   _selectionHandlerShutdown: function _selectionHandlerShutdown() {
     this._shutdown();
   },
   _selectionSwap: function _selectionSwap() {
     [this.startMark.tag, this.endMark.tag] = [this.endMark.tag,
         this.startMark.tag];
     [this._startMark, this._endMark] = [this.endMark, this.startMark];
   },
   /*
    * Message handlers
    */
   _onSelectionCopied: function _onSelectionCopied(json) {
     this.closeEditSession(true);
   },
   _onSelectionRangeChange: function _onSelectionRangeChange(json) {
     let haveSelectionRect = true;
     if (json.updateStart) {
       let x = this._msgTarget.btocx(json.start.xPos, true);
       let y = this._msgTarget.btocy(json.start.yPos, true);
       this.startMark.position(x, y, json.start.restrictedToBounds);
     }
     if (json.updateEnd) {
       let x = this._msgTarget.btocx(json.end.xPos, true);
       let y = this._msgTarget.btocy(json.end.yPos, true);
       this.endMark.position(x, y, json.end.restrictedToBounds);
     }
     if (json.updateCaret) {
       let x = this._msgTarget.btocx(json.caret.xPos, true);
       let y = this._msgTarget.btocy(json.caret.yPos, true);
       // If selectionRangeFound is set SelectionHelper found a range we can
       // attach to. If not, there's no text in the control, and hence no caret
       // position information we can use.
       haveSelectionRect = json.selectionRangeFound;
       if (json.selectionRangeFound) {
         this.caretMark.position(x, y);
         this._showMonocles(false);
       }
     }
     if (this._showAfterUpdate) {
       this._showAfterUpdate = false;
       this._showMonocles(!json.updateCaret);
     }
     this._targetIsEditable = json.targetIsEditable;
     this._activeSelectionRect = haveSelectionRect ?
       this._msgTarget.rectBrowserToClient(json.selection, true) :
       this._activeSelectionRect = Util.getCleanRect();
     this._targetElementRect =
       this._msgTarget.rectBrowserToClient(json.element, true);
     // If this is the end of a selection move show the appropriate
     // monocle images. src=(start, update, end, caret)
     if (json.src == "start" || json.src == "end") {
       this._showMonocles(true);
     }
   },
   _onSelectionFail: function _onSelectionFail() {
     Util.dumpLn("failed to get a selection.");
     this.closeEditSession();
   },
   /*
    * _onPong
    *
    * Handles the closure of promise we return when we send a ping
    * to SelectionHandler in pingSelectionHandler. Testing use.
    */
   _onPong: function _onPong(aId) {
     let ping = this._pingArray.pop();
     if (ping.id != aId) {
       ping.deferred.reject(
         new Error("Selection module's pong doesn't match our last ping."));
     }
     ping.deferred.resolve();
    },
   /*
    * Events
    */
   handleEvent: function handleEvent(aEvent) {
     if (this._debugEvents && aEvent.type != "touchmove") {
       Util.dumpLn("SelectionHelperUI:", aEvent.type);
     }
     switch (aEvent.type) {
       case "click":
         this._onClick(aEvent);
         break;
       case "touchstart": {
         if (aEvent.touches.length != 1)
           break;
         // Only prevent default if we're dragging so that
         // APZC doesn't scroll.
         if (this._checkForActiveDrag()) {
           aEvent.preventDefault();
         }
         break;
       }
       case "keypress":
         this._onKeypress(aEvent);
         break;
       case "SizeChanged":
         this._onResize(aEvent);
         break;
       case "URLChanged":
       case "TabSelect":
         this._shutdown();
         break;
       case "MozPrecisePointer":
         this.closeEditSession(true);
         break;
       case "MozDeckOffsetChanging":
         this._onDeckOffsetChanging(aEvent);
         break;
       case "MozDeckOffsetChanged":
         this._onDeckOffsetChanged(aEvent);
         break;
       case "transitionend":
         this._onNavBarTransitionEvent(aEvent);
         break;
       case "KeyboardChanged":
         this._onKeyboardChangedEvent();
         break;
     }
   },
   receiveMessage: function sh_receiveMessage(aMessage) {
     if (this._debugEvents) Util.dumpLn("SelectionHelperUI:", aMessage.name);
     let json = aMessage.json;
     switch (aMessage.name) {
       case "Content:SelectionFail":
         this._onSelectionFail();
         break;
       case "Content:SelectionRange":
         this._onSelectionRangeChange(json);
         break;
       case "Content:SelectionCopied":
         this._onSelectionCopied(json);
         break;
       case "Content:SelectionDebugRect":
         this._onDebugRectRequest(json);
         break;
       case "Content:HandlerShutdown":
         this._selectionHandlerShutdown();
         break;
       case "Content:SelectionSwap":
         this._selectionSwap();
         break;
       case "Content:SelectionHandlerPong":
         this._onPong(json.id);
         break;
     }
   },
   /*
    * Callbacks from markers
    */
   _getMarkerBaseMessage: function _getMarkerBaseMessage(aMarkerTag) {
     return {
       change: aMarkerTag,
       start: {
         xPos: this._msgTarget.ctobx(this.startMark.xPos, true),
         yPos: this._msgTarget.ctoby(this.startMark.yPos, true),
         restrictedToBounds: this.startMark.restrictedToBounds
       },
       end: {
         xPos: this._msgTarget.ctobx(this.endMark.xPos, true),
         yPos: this._msgTarget.ctoby(this.endMark.yPos, true),
         restrictedToBounds: this.endMark.restrictedToBounds
       },
       caret: {
         xPos: this._msgTarget.ctobx(this.caretMark.xPos, true),
         yPos: this._msgTarget.ctoby(this.caretMark.yPos, true)
       },
     };
   },
   markerDragStart: function markerDragStart(aMarker) {
     let json = this._getMarkerBaseMessage(aMarker.tag);
     if (aMarker.tag == "caret") {
       // Cache for when we start the drag in _transitionFromCaretToSelection.
       if (!this._cachedCaretPos) {
         this._cachedCaretPos = this._getMarkerBaseMessage(aMarker.tag).caret;
       }
       return;
     }
     this._sendAsyncMessage("Browser:SelectionMoveStart", json);
   },
   markerDragStop: function markerDragStop(aMarker) {
     let json = this._getMarkerBaseMessage(aMarker.tag);
     if (aMarker.tag == "caret") {
       this._cachedCaretPos = null;
       return;
     }
     this._sendAsyncMessage("Browser:SelectionMoveEnd", json);
   },
   markerDragMove: function markerDragMove(aMarker, aDirection) {
     if (aMarker.tag == "caret") {
       // If direction is "tbd" the drag monocle hasn't determined which
       // direction the user is dragging.
       if (aDirection != "tbd") {
         // We are going to transition from caret browsing mode to selection
         // mode on drag. So swap the caret monocle for a start or end monocle
         // depending on the direction of the drag, and start selecting text.
         this._transitionFromCaretToSelection(aDirection);
         return false;
       }
       return true;
     }
     this._cachedCaretPos = null;
     // We'll re-display these after the drag is complete.
     this._hideMonocles();
     let json = this._getMarkerBaseMessage(aMarker.tag);
     this._sendAsyncMessage("Browser:SelectionMove", json);
     return true;
   },
 };