forked from mirrors/gecko-dev
		
	MozReview-Commit-ID: CRYxu7copKb --HG-- extra : rebase_source : bc176c5e6890ffc6a4e26cb9bc9d441d9486ce7b
		
			
				
	
	
		
			1238 lines
		
	
	
	
		
			41 KiB
		
	
	
	
		
			JavaScript
		
	
	
	
	
	
			
		
		
	
	
			1238 lines
		
	
	
	
		
			41 KiB
		
	
	
	
		
			JavaScript
		
	
	
	
	
	
/* This Source Code Form is subject to the terms of the Mozilla Public
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 * License, v. 2.0. If a copy of the MPL was not distributed with this
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 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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// Simple gestures support
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//
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// As per bug #412486, web content must not be allowed to receive any
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// simple gesture events.  Multi-touch gesture APIs are in their
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// infancy and we do NOT want to be forced into supporting an API that
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// will probably have to change in the future.  (The current Mac OS X
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// API is undocumented and was reverse-engineered.)  Until support is
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// implemented in the event dispatcher to keep these events as
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// chrome-only, we must listen for the simple gesture events during
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// the capturing phase and call stopPropagation on every event.
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var gGestureSupport = {
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  _currentRotation: 0,
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  _lastRotateDelta: 0,
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  _rotateMomentumThreshold: .75,
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  /**
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   * Add or remove mouse gesture event listeners
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   *
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   * @param aAddListener
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   *        True to add/init listeners and false to remove/uninit
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   */
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  init: function GS_init(aAddListener) {
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    const gestureEvents = ["SwipeGestureMayStart", "SwipeGestureStart",
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      "SwipeGestureUpdate", "SwipeGestureEnd", "SwipeGesture",
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      "MagnifyGestureStart", "MagnifyGestureUpdate", "MagnifyGesture",
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      "RotateGestureStart", "RotateGestureUpdate", "RotateGesture",
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      "TapGesture", "PressTapGesture"];
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    let addRemove = aAddListener ? window.addEventListener :
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      window.removeEventListener;
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    for (let event of gestureEvents) {
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      addRemove("Moz" + event, this, true);
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    }
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  },
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  /**
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   * Dispatch events based on the type of mouse gesture event. For now, make
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   * sure to stop propagation of every gesture event so that web content cannot
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   * receive gesture events.
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   *
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   * @param aEvent
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   *        The gesture event to handle
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   */
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  handleEvent: function GS_handleEvent(aEvent) {
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    if (!Services.prefs.getBoolPref(
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           "dom.debug.propagate_gesture_events_through_content")) {
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      aEvent.stopPropagation();
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    }
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    // Create a preference object with some defaults
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    let def = (aThreshold, aLatched) =>
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      ({ threshold: aThreshold, latched: !!aLatched });
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    switch (aEvent.type) {
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      case "MozSwipeGestureMayStart":
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        if (this._shouldDoSwipeGesture(aEvent)) {
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          aEvent.preventDefault();
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        }
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        break;
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      case "MozSwipeGestureStart":
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        aEvent.preventDefault();
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        this._setupSwipeGesture();
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        break;
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      case "MozSwipeGestureUpdate":
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        aEvent.preventDefault();
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        this._doUpdate(aEvent);
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        break;
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      case "MozSwipeGestureEnd":
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        aEvent.preventDefault();
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        this._doEnd(aEvent);
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        break;
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      case "MozSwipeGesture":
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        aEvent.preventDefault();
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        this.onSwipe(aEvent);
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        break;
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      case "MozMagnifyGestureStart":
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        aEvent.preventDefault();
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        let pinchPref = AppConstants.platform == "win"
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                        ? def(25, 0)
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                        : def(150, 1);
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        this._setupGesture(aEvent, "pinch", pinchPref, "out", "in");
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        break;
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      case "MozRotateGestureStart":
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        aEvent.preventDefault();
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        this._setupGesture(aEvent, "twist", def(25, 0), "right", "left");
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        break;
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      case "MozMagnifyGestureUpdate":
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      case "MozRotateGestureUpdate":
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        aEvent.preventDefault();
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        this._doUpdate(aEvent);
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        break;
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      case "MozTapGesture":
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        aEvent.preventDefault();
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        this._doAction(aEvent, ["tap"]);
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        break;
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      case "MozRotateGesture":
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        aEvent.preventDefault();
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        this._doAction(aEvent, ["twist", "end"]);
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        break;
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      /* case "MozPressTapGesture":
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        break; */
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    }
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  },
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  /**
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   * Called at the start of "pinch" and "twist" gestures to setup all of the
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   * information needed to process the gesture
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   *
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   * @param aEvent
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   *        The continual motion start event to handle
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   * @param aGesture
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   *        Name of the gesture to handle
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   * @param aPref
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   *        Preference object with the names of preferences and defaults
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   * @param aInc
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   *        Command to trigger for increasing motion (without gesture name)
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   * @param aDec
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   *        Command to trigger for decreasing motion (without gesture name)
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   */
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  _setupGesture: function GS__setupGesture(aEvent, aGesture, aPref, aInc, aDec) {
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    // Try to load user-set values from preferences
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    for (let [pref, def] of Object.entries(aPref))
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      aPref[pref] = this._getPref(aGesture + "." + pref, def);
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    // Keep track of the total deltas and latching behavior
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    let offset = 0;
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    let latchDir = aEvent.delta > 0 ? 1 : -1;
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    let isLatched = false;
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    // Create the update function here to capture closure state
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    this._doUpdate = function GS__doUpdate(updateEvent) {
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      // Update the offset with new event data
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      offset += updateEvent.delta;
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      // Check if the cumulative deltas exceed the threshold
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      if (Math.abs(offset) > aPref["threshold"]) {
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        // Trigger the action if we don't care about latching; otherwise, make
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        // sure either we're not latched and going the same direction of the
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        // initial motion; or we're latched and going the opposite way
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        let sameDir = (latchDir ^ offset) >= 0;
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        if (!aPref["latched"] || (isLatched ^ sameDir)) {
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          this._doAction(updateEvent, [aGesture, offset > 0 ? aInc : aDec]);
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          // We must be getting latched or leaving it, so just toggle
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          isLatched = !isLatched;
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        }
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        // Reset motion counter to prepare for more of the same gesture
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        offset = 0;
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      }
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    };
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    // The start event also contains deltas, so handle an update right away
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    this._doUpdate(aEvent);
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  },
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  /**
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   * Checks whether a swipe gesture event can navigate the browser history or
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   * not.
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   *
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   * @param aEvent
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   *        The swipe gesture event.
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   * @return true if the swipe event may navigate the history, false othwerwise.
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   */
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  _swipeNavigatesHistory: function GS__swipeNavigatesHistory(aEvent) {
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    return this._getCommand(aEvent, ["swipe", "left"])
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              == "Browser:BackOrBackDuplicate" &&
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           this._getCommand(aEvent, ["swipe", "right"])
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              == "Browser:ForwardOrForwardDuplicate";
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  },
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  /**
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   * Checks whether we want to start a swipe for aEvent and sets
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   * aEvent.allowedDirections to the right values.
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   *
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   * @param aEvent
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   *        The swipe gesture "MayStart" event.
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   * @return true if we're willing to start a swipe for this event, false
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   *         otherwise.
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   */
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  _shouldDoSwipeGesture: function GS__shouldDoSwipeGesture(aEvent) {
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    if (!this._swipeNavigatesHistory(aEvent)) {
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      return false;
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    }
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    let isVerticalSwipe = false;
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    if (aEvent.direction == aEvent.DIRECTION_UP) {
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      if (gMultiProcessBrowser || window.content.pageYOffset > 0) {
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        return false;
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      }
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      isVerticalSwipe = true;
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    } else if (aEvent.direction == aEvent.DIRECTION_DOWN) {
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      if (gMultiProcessBrowser || window.content.pageYOffset < window.content.scrollMaxY) {
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        return false;
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      }
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      isVerticalSwipe = true;
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    }
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    if (isVerticalSwipe) {
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      // Vertical overscroll has been temporarily disabled until bug 939480 is
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      // fixed.
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      return false;
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    }
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    let canGoBack = gHistorySwipeAnimation.canGoBack();
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    let canGoForward = gHistorySwipeAnimation.canGoForward();
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    let isLTR = gHistorySwipeAnimation.isLTR;
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    if (canGoBack) {
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      aEvent.allowedDirections |= isLTR ? aEvent.DIRECTION_LEFT :
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                                          aEvent.DIRECTION_RIGHT;
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    }
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    if (canGoForward) {
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      aEvent.allowedDirections |= isLTR ? aEvent.DIRECTION_RIGHT :
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                                          aEvent.DIRECTION_LEFT;
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    }
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    return true;
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  },
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  /**
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   * Sets up swipe gestures. This includes setting up swipe animations for the
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   * gesture, if enabled.
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   *
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   * @param aEvent
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   *        The swipe gesture start event.
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   * @return true if swipe gestures could successfully be set up, false
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   *         othwerwise.
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   */
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  _setupSwipeGesture: function GS__setupSwipeGesture() {
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    gHistorySwipeAnimation.startAnimation(false);
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    this._doUpdate = function GS__doUpdate(aEvent) {
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      gHistorySwipeAnimation.updateAnimation(aEvent.delta);
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    };
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    this._doEnd = function GS__doEnd(aEvent) {
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      gHistorySwipeAnimation.swipeEndEventReceived();
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      this._doUpdate = function() {};
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      this._doEnd = function() {};
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    }
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  },
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  /**
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   * Generator producing the powerset of the input array where the first result
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   * is the complete set and the last result (before StopIteration) is empty.
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   *
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   * @param aArray
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   *        Source array containing any number of elements
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   * @yield Array that is a subset of the input array from full set to empty
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   */
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  _power: function* GS__power(aArray) {
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    // Create a bitmask based on the length of the array
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    let num = 1 << aArray.length;
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    while (--num >= 0) {
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      // Only select array elements where the current bit is set
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      yield aArray.reduce(function(aPrev, aCurr, aIndex) {
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        if (num & 1 << aIndex)
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          aPrev.push(aCurr);
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        return aPrev;
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      }, []);
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    }
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  },
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  /**
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   * Determine what action to do for the gesture based on which keys are
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   * pressed and which commands are set, and execute the command.
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   *
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   * @param aEvent
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   *        The original gesture event to convert into a fake click event
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   * @param aGesture
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   *        Array of gesture name parts (to be joined by periods)
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   * @return Name of the executed command. Returns null if no command is
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   *         found.
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   */
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  _doAction: function GS__doAction(aEvent, aGesture) {
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    let command = this._getCommand(aEvent, aGesture);
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    return command && this._doCommand(aEvent, command);
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  },
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  /**
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   * Determine what action to do for the gesture based on which keys are
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   * pressed and which commands are set
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   *
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   * @param aEvent
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   *        The original gesture event to convert into a fake click event
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   * @param aGesture
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   *        Array of gesture name parts (to be joined by periods)
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   */
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  _getCommand: function GS__getCommand(aEvent, aGesture) {
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    // Create an array of pressed keys in a fixed order so that a command for
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    // "meta" is preferred over "ctrl" when both buttons are pressed (and a
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    // command for both don't exist)
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    let keyCombos = [];
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    for (let key of ["shift", "alt", "ctrl", "meta"]) {
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      if (aEvent[key + "Key"])
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        keyCombos.push(key);
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    }
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    // Try each combination of key presses in decreasing order for commands
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    for (let subCombo of this._power(keyCombos)) {
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      // Convert a gesture and pressed keys into the corresponding command
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      // action where the preference has the gesture before "shift" before
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      // "alt" before "ctrl" before "meta" all separated by periods
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      let command;
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      try {
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        command = this._getPref(aGesture.concat(subCombo).join("."));
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      } catch (e) {}
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      if (command)
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        return command;
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    }
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    return null;
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  },
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  /**
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   * Execute the specified command.
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   *
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   * @param aEvent
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   *        The original gesture event to convert into a fake click event
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   * @param aCommand
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   *        Name of the command found for the event's keys and gesture.
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   */
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  _doCommand: function GS__doCommand(aEvent, aCommand) {
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    let node = document.getElementById(aCommand);
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    if (node) {
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      if (node.getAttribute("disabled") != "true") {
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        let cmdEvent = document.createEvent("xulcommandevent");
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        cmdEvent.initCommandEvent("command", true, true, window, 0,
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                                  aEvent.ctrlKey, aEvent.altKey,
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                                  aEvent.shiftKey, aEvent.metaKey, aEvent);
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        node.dispatchEvent(cmdEvent);
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      }
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    } else {
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      goDoCommand(aCommand);
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    }
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  },
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  /**
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   * Handle continual motion events.  This function will be set by
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   * _setupGesture or _setupSwipe.
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   *
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   * @param aEvent
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   *        The continual motion update event to handle
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   */
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  _doUpdate(aEvent) {},
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 | 
						|
  /**
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   * Handle gesture end events.  This function will be set by _setupSwipe.
 | 
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   *
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   * @param aEvent
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   *        The gesture end event to handle
 | 
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   */
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  _doEnd(aEvent) {},
 | 
						|
 | 
						|
  /**
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   * Convert the swipe gesture into a browser action based on the direction.
 | 
						|
   *
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						|
   * @param aEvent
 | 
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   *        The swipe event to handle
 | 
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   */
 | 
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  onSwipe: function GS_onSwipe(aEvent) {
 | 
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    // Figure out which one (and only one) direction was triggered
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    for (let dir of ["UP", "RIGHT", "DOWN", "LEFT"]) {
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						|
      if (aEvent.direction == aEvent["DIRECTION_" + dir]) {
 | 
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        this._coordinateSwipeEventWithAnimation(aEvent, dir);
 | 
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        break;
 | 
						|
      }
 | 
						|
    }
 | 
						|
  },
 | 
						|
 | 
						|
  /**
 | 
						|
   * Process a swipe event based on the given direction.
 | 
						|
   *
 | 
						|
   * @param aEvent
 | 
						|
   *        The swipe event to handle
 | 
						|
   * @param aDir
 | 
						|
   *        The direction for the swipe event
 | 
						|
   */
 | 
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  processSwipeEvent: function GS_processSwipeEvent(aEvent, aDir) {
 | 
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    this._doAction(aEvent, ["swipe", aDir.toLowerCase()]);
 | 
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  },
 | 
						|
 | 
						|
  /**
 | 
						|
   * Coordinates the swipe event with the swipe animation, if any.
 | 
						|
   * If an animation is currently running, the swipe event will be
 | 
						|
   * processed once the animation stops. This will guarantee a fluid
 | 
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   * motion of the animation.
 | 
						|
   *
 | 
						|
   * @param aEvent
 | 
						|
   *        The swipe event to handle
 | 
						|
   * @param aDir
 | 
						|
   *        The direction for the swipe event
 | 
						|
   */
 | 
						|
  _coordinateSwipeEventWithAnimation:
 | 
						|
  function GS__coordinateSwipeEventWithAnimation(aEvent, aDir) {
 | 
						|
    if ((gHistorySwipeAnimation.isAnimationRunning()) &&
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        (aDir == "RIGHT" || aDir == "LEFT")) {
 | 
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      gHistorySwipeAnimation.processSwipeEvent(aEvent, aDir);
 | 
						|
    } else {
 | 
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      this.processSwipeEvent(aEvent, aDir);
 | 
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    }
 | 
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  },
 | 
						|
 | 
						|
  /**
 | 
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   * Get a gesture preference or use a default if it doesn't exist
 | 
						|
   *
 | 
						|
   * @param aPref
 | 
						|
   *        Name of the preference to load under the gesture branch
 | 
						|
   * @param aDef
 | 
						|
   *        Default value if the preference doesn't exist
 | 
						|
   */
 | 
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  _getPref: function GS__getPref(aPref, aDef) {
 | 
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    // Preferences branch under which all gestures preferences are stored
 | 
						|
    const branch = "browser.gesture.";
 | 
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 | 
						|
    try {
 | 
						|
      // Determine what type of data to load based on default value's type
 | 
						|
      let type = typeof aDef;
 | 
						|
      let getFunc = "Char";
 | 
						|
      if (type == "boolean")
 | 
						|
        getFunc = "Bool";
 | 
						|
      else if (type == "number")
 | 
						|
        getFunc = "Int";
 | 
						|
      return gPrefService["get" + getFunc + "Pref"](branch + aPref);
 | 
						|
    } catch (e) {
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						|
      return aDef;
 | 
						|
    }
 | 
						|
  },
 | 
						|
 | 
						|
  /**
 | 
						|
   * Perform rotation for ImageDocuments
 | 
						|
   *
 | 
						|
   * @param aEvent
 | 
						|
   *        The MozRotateGestureUpdate event triggering this call
 | 
						|
   */
 | 
						|
  rotate(aEvent) {
 | 
						|
    if (!(window.content.document instanceof ImageDocument))
 | 
						|
      return;
 | 
						|
 | 
						|
    let contentElement = window.content.document.body.firstElementChild;
 | 
						|
    if (!contentElement)
 | 
						|
      return;
 | 
						|
    // If we're currently snapping, cancel that snap
 | 
						|
    if (contentElement.classList.contains("completeRotation"))
 | 
						|
      this._clearCompleteRotation();
 | 
						|
 | 
						|
    this.rotation = Math.round(this.rotation + aEvent.delta);
 | 
						|
    contentElement.style.transform = "rotate(" + this.rotation + "deg)";
 | 
						|
    this._lastRotateDelta = aEvent.delta;
 | 
						|
  },
 | 
						|
 | 
						|
  /**
 | 
						|
   * Perform a rotation end for ImageDocuments
 | 
						|
   */
 | 
						|
  rotateEnd() {
 | 
						|
    if (!(window.content.document instanceof ImageDocument))
 | 
						|
      return;
 | 
						|
 | 
						|
    let contentElement = window.content.document.body.firstElementChild;
 | 
						|
    if (!contentElement)
 | 
						|
      return;
 | 
						|
 | 
						|
    let transitionRotation = 0;
 | 
						|
 | 
						|
    // The reason that 360 is allowed here is because when rotating between
 | 
						|
    // 315 and 360, setting rotate(0deg) will cause it to rotate the wrong
 | 
						|
    // direction around--spinning wildly.
 | 
						|
    if (this.rotation <= 45)
 | 
						|
      transitionRotation = 0;
 | 
						|
    else if (this.rotation > 45 && this.rotation <= 135)
 | 
						|
      transitionRotation = 90;
 | 
						|
    else if (this.rotation > 135 && this.rotation <= 225)
 | 
						|
      transitionRotation = 180;
 | 
						|
    else if (this.rotation > 225 && this.rotation <= 315)
 | 
						|
      transitionRotation = 270;
 | 
						|
    else
 | 
						|
      transitionRotation = 360;
 | 
						|
 | 
						|
    // If we're going fast enough, and we didn't already snap ahead of rotation,
 | 
						|
    // then snap ahead of rotation to simulate momentum
 | 
						|
    if (this._lastRotateDelta > this._rotateMomentumThreshold &&
 | 
						|
        this.rotation > transitionRotation)
 | 
						|
      transitionRotation += 90;
 | 
						|
    else if (this._lastRotateDelta < -1 * this._rotateMomentumThreshold &&
 | 
						|
             this.rotation < transitionRotation)
 | 
						|
      transitionRotation -= 90;
 | 
						|
 | 
						|
    // Only add the completeRotation class if it is is necessary
 | 
						|
    if (transitionRotation != this.rotation) {
 | 
						|
      contentElement.classList.add("completeRotation");
 | 
						|
      contentElement.addEventListener("transitionend", this._clearCompleteRotation);
 | 
						|
    }
 | 
						|
 | 
						|
    contentElement.style.transform = "rotate(" + transitionRotation + "deg)";
 | 
						|
    this.rotation = transitionRotation;
 | 
						|
  },
 | 
						|
 | 
						|
  /**
 | 
						|
   * Gets the current rotation for the ImageDocument
 | 
						|
   */
 | 
						|
  get rotation() {
 | 
						|
    return this._currentRotation;
 | 
						|
  },
 | 
						|
 | 
						|
  /**
 | 
						|
   * Sets the current rotation for the ImageDocument
 | 
						|
   *
 | 
						|
   * @param aVal
 | 
						|
   *        The new value to take.  Can be any value, but it will be bounded to
 | 
						|
   *        0 inclusive to 360 exclusive.
 | 
						|
   */
 | 
						|
  set rotation(aVal) {
 | 
						|
    this._currentRotation = aVal % 360;
 | 
						|
    if (this._currentRotation < 0)
 | 
						|
      this._currentRotation += 360;
 | 
						|
    return this._currentRotation;
 | 
						|
  },
 | 
						|
 | 
						|
  /**
 | 
						|
   * When the location/tab changes, need to reload the current rotation for the
 | 
						|
   * image
 | 
						|
   */
 | 
						|
  restoreRotationState() {
 | 
						|
    // Bug 863514 - Make gesture support work in electrolysis
 | 
						|
    if (gMultiProcessBrowser)
 | 
						|
      return;
 | 
						|
 | 
						|
    if (!(window.content.document instanceof ImageDocument))
 | 
						|
      return;
 | 
						|
 | 
						|
    let contentElement = window.content.document.body.firstElementChild;
 | 
						|
    let transformValue = window.content.window.getComputedStyle(contentElement)
 | 
						|
                                              .transform;
 | 
						|
 | 
						|
    if (transformValue == "none") {
 | 
						|
      this.rotation = 0;
 | 
						|
      return;
 | 
						|
    }
 | 
						|
 | 
						|
    // transformValue is a rotation matrix--split it and do mathemagic to
 | 
						|
    // obtain the real rotation value
 | 
						|
    transformValue = transformValue.split("(")[1]
 | 
						|
                                   .split(")")[0]
 | 
						|
                                   .split(",");
 | 
						|
    this.rotation = Math.round(Math.atan2(transformValue[1], transformValue[0]) *
 | 
						|
                               (180 / Math.PI));
 | 
						|
  },
 | 
						|
 | 
						|
  /**
 | 
						|
   * Removes the transition rule by removing the completeRotation class
 | 
						|
   */
 | 
						|
  _clearCompleteRotation() {
 | 
						|
    let contentElement = window.content.document &&
 | 
						|
                         window.content.document instanceof ImageDocument &&
 | 
						|
                         window.content.document.body &&
 | 
						|
                         window.content.document.body.firstElementChild;
 | 
						|
    if (!contentElement)
 | 
						|
      return;
 | 
						|
    contentElement.classList.remove("completeRotation");
 | 
						|
    contentElement.removeEventListener("transitionend", this._clearCompleteRotation);
 | 
						|
  },
 | 
						|
};
 | 
						|
 | 
						|
// History Swipe Animation Support (bug 678392)
 | 
						|
var gHistorySwipeAnimation = {
 | 
						|
 | 
						|
  active: false,
 | 
						|
  isLTR: false,
 | 
						|
 | 
						|
  /**
 | 
						|
   * Initializes the support for history swipe animations, if it is supported
 | 
						|
   * by the platform/configuration.
 | 
						|
   */
 | 
						|
  init: function HSA_init() {
 | 
						|
    if (!this._isSupported())
 | 
						|
      return;
 | 
						|
 | 
						|
    this.active = false;
 | 
						|
    this.isLTR = document.documentElement.matches(":-moz-locale-dir(ltr)");
 | 
						|
    this._trackedSnapshots = [];
 | 
						|
    this._startingIndex = -1;
 | 
						|
    this._historyIndex = -1;
 | 
						|
    this._boxWidth = -1;
 | 
						|
    this._boxHeight = -1;
 | 
						|
    this._maxSnapshots = this._getMaxSnapshots();
 | 
						|
    this._lastSwipeDir = "";
 | 
						|
    this._direction = "horizontal";
 | 
						|
 | 
						|
    // We only want to activate history swipe animations if we store snapshots.
 | 
						|
    // If we don't store any, we handle horizontal swipes without animations.
 | 
						|
    if (this._maxSnapshots > 0) {
 | 
						|
      this.active = true;
 | 
						|
      gBrowser.addEventListener("pagehide", this);
 | 
						|
      gBrowser.addEventListener("pageshow", this);
 | 
						|
      gBrowser.addEventListener("popstate", this);
 | 
						|
      gBrowser.addEventListener("DOMModalDialogClosed", this);
 | 
						|
      gBrowser.tabContainer.addEventListener("TabClose", this);
 | 
						|
    }
 | 
						|
  },
 | 
						|
 | 
						|
  /**
 | 
						|
   * Uninitializes the support for history swipe animations.
 | 
						|
   */
 | 
						|
  uninit: function HSA_uninit() {
 | 
						|
    gBrowser.removeEventListener("pagehide", this);
 | 
						|
    gBrowser.removeEventListener("pageshow", this);
 | 
						|
    gBrowser.removeEventListener("popstate", this);
 | 
						|
    gBrowser.removeEventListener("DOMModalDialogClosed", this);
 | 
						|
    gBrowser.tabContainer.removeEventListener("TabClose", this);
 | 
						|
 | 
						|
    this.active = false;
 | 
						|
    this.isLTR = false;
 | 
						|
  },
 | 
						|
 | 
						|
  /**
 | 
						|
   * Starts the swipe animation and handles fast swiping (i.e. a swipe animation
 | 
						|
   * is already in progress when a new one is initiated).
 | 
						|
   *
 | 
						|
   * @param aIsVerticalSwipe
 | 
						|
   *        Whether we're dealing with a vertical swipe or not.
 | 
						|
   */
 | 
						|
  startAnimation: function HSA_startAnimation(aIsVerticalSwipe) {
 | 
						|
    this._direction = aIsVerticalSwipe ? "vertical" : "horizontal";
 | 
						|
 | 
						|
    if (this.isAnimationRunning()) {
 | 
						|
      // If this is a horizontal scroll, or if this is a vertical scroll that
 | 
						|
      // was started while a horizontal scroll was still running, handle it as
 | 
						|
      // as a fast swipe. In the case of the latter scenario, this allows us to
 | 
						|
      // start the vertical animation without first loading the final page, or
 | 
						|
      // taking another snapshot. If vertical scrolls are initiated repeatedly
 | 
						|
      // without prior horizontal scroll we skip this and restart the animation
 | 
						|
      // from 0.
 | 
						|
      if (this._direction == "horizontal" || this._lastSwipeDir != "") {
 | 
						|
        gBrowser.stop();
 | 
						|
        this._lastSwipeDir = "RELOAD"; // just ensure that != ""
 | 
						|
        this._canGoBack = this.canGoBack();
 | 
						|
        this._canGoForward = this.canGoForward();
 | 
						|
        this._handleFastSwiping();
 | 
						|
      }
 | 
						|
      this.updateAnimation(0);
 | 
						|
    } else {
 | 
						|
      // Get the session history from SessionStore.
 | 
						|
      let updateSessionHistory = sessionHistory => {
 | 
						|
        this._startingIndex = sessionHistory.index;
 | 
						|
        this._historyIndex = this._startingIndex;
 | 
						|
        this._canGoBack = this.canGoBack();
 | 
						|
        this._canGoForward = this.canGoForward();
 | 
						|
        if (this.active) {
 | 
						|
          this._addBoxes();
 | 
						|
          this._takeSnapshot();
 | 
						|
          this._installPrevAndNextSnapshots();
 | 
						|
          this._lastSwipeDir = "";
 | 
						|
        }
 | 
						|
        this.updateAnimation(0);
 | 
						|
      }
 | 
						|
      SessionStore.getSessionHistory(gBrowser.selectedTab, updateSessionHistory);
 | 
						|
    }
 | 
						|
  },
 | 
						|
 | 
						|
  /**
 | 
						|
   * Stops the swipe animation.
 | 
						|
   */
 | 
						|
  stopAnimation: function HSA_stopAnimation() {
 | 
						|
    gHistorySwipeAnimation._removeBoxes();
 | 
						|
    this._historyIndex = this._getCurrentHistoryIndex();
 | 
						|
  },
 | 
						|
 | 
						|
  /**
 | 
						|
   * Updates the animation between two pages in history.
 | 
						|
   *
 | 
						|
   * @param aVal
 | 
						|
   *        A floating point value that represents the progress of the
 | 
						|
   *        swipe gesture.
 | 
						|
   */
 | 
						|
  updateAnimation: function HSA_updateAnimation(aVal) {
 | 
						|
    if (!this.isAnimationRunning()) {
 | 
						|
      return;
 | 
						|
    }
 | 
						|
 | 
						|
    // We use the following value to decrease the bounce effect when scrolling
 | 
						|
    // to the top or bottom of the page, or when swiping back/forward past the
 | 
						|
    // browsing history. This value was determined experimentally.
 | 
						|
    let dampValue = 4;
 | 
						|
    if (this._direction == "vertical") {
 | 
						|
      this._prevBox.collapsed = true;
 | 
						|
      this._nextBox.collapsed = true;
 | 
						|
      this._positionBox(this._curBox, -1 * aVal / dampValue);
 | 
						|
    } else if ((aVal >= 0 && this.isLTR) ||
 | 
						|
               (aVal <= 0 && !this.isLTR)) {
 | 
						|
      let tempDampValue = 1;
 | 
						|
      if (this._canGoBack) {
 | 
						|
        this._prevBox.collapsed = false;
 | 
						|
      } else {
 | 
						|
        tempDampValue = dampValue;
 | 
						|
        this._prevBox.collapsed = true;
 | 
						|
      }
 | 
						|
 | 
						|
      // The current page is pushed to the right (LTR) or left (RTL),
 | 
						|
      // the intention is to go back.
 | 
						|
      // If there is a page to go back to, it should show in the background.
 | 
						|
      this._positionBox(this._curBox, aVal / tempDampValue);
 | 
						|
 | 
						|
      // The forward page should be pushed offscreen all the way to the right.
 | 
						|
      this._positionBox(this._nextBox, 1);
 | 
						|
    } else if (this._canGoForward) {
 | 
						|
      // The intention is to go forward. If there is a page to go forward to,
 | 
						|
      // it should slide in from the right (LTR) or left (RTL).
 | 
						|
      // Otherwise, the current page should slide to the left (LTR) or
 | 
						|
      // right (RTL) and the backdrop should appear in the background.
 | 
						|
      // For the backdrop to be visible in that case, the previous page needs
 | 
						|
      // to be hidden (if it exists).
 | 
						|
      this._nextBox.collapsed = false;
 | 
						|
      let offset = this.isLTR ? 1 : -1;
 | 
						|
      this._positionBox(this._curBox, 0);
 | 
						|
      this._positionBox(this._nextBox, offset + aVal);
 | 
						|
    } else {
 | 
						|
      this._prevBox.collapsed = true;
 | 
						|
      this._positionBox(this._curBox, aVal / dampValue);
 | 
						|
    }
 | 
						|
  },
 | 
						|
 | 
						|
  _getCurrentHistoryIndex() {
 | 
						|
    return SessionStore.getSessionHistory(gBrowser.selectedTab).index;
 | 
						|
  },
 | 
						|
 | 
						|
  /**
 | 
						|
   * Event handler for events relevant to the history swipe animation.
 | 
						|
   *
 | 
						|
   * @param aEvent
 | 
						|
   *        An event to process.
 | 
						|
   */
 | 
						|
  handleEvent: function HSA_handleEvent(aEvent) {
 | 
						|
    let browser = gBrowser.selectedBrowser;
 | 
						|
    switch (aEvent.type) {
 | 
						|
      case "TabClose":
 | 
						|
        let browserForTab = gBrowser.getBrowserForTab(aEvent.target);
 | 
						|
        this._removeTrackedSnapshot(-1, browserForTab);
 | 
						|
        break;
 | 
						|
      case "DOMModalDialogClosed":
 | 
						|
        this.stopAnimation();
 | 
						|
        break;
 | 
						|
      case "pageshow":
 | 
						|
        if (aEvent.target == browser.contentDocument) {
 | 
						|
          this.stopAnimation();
 | 
						|
        }
 | 
						|
        break;
 | 
						|
      case "popstate":
 | 
						|
        if (aEvent.target == browser.contentDocument.defaultView) {
 | 
						|
          this.stopAnimation();
 | 
						|
        }
 | 
						|
        break;
 | 
						|
      case "pagehide":
 | 
						|
        if (aEvent.target == browser.contentDocument) {
 | 
						|
          // Take and compress a snapshot of a page whenever it's about to be
 | 
						|
          // navigated away from. We already have a snapshot of the page if an
 | 
						|
          // animation is running, so we're left with compressing it.
 | 
						|
          if (!this.isAnimationRunning()) {
 | 
						|
            this._takeSnapshot();
 | 
						|
          }
 | 
						|
          this._compressSnapshotAtCurrentIndex();
 | 
						|
        }
 | 
						|
        break;
 | 
						|
    }
 | 
						|
  },
 | 
						|
 | 
						|
  /**
 | 
						|
   * Checks whether the history swipe animation is currently running or not.
 | 
						|
   *
 | 
						|
   * @return true if the animation is currently running, false otherwise.
 | 
						|
   */
 | 
						|
  isAnimationRunning: function HSA_isAnimationRunning() {
 | 
						|
    return !!this._container;
 | 
						|
  },
 | 
						|
 | 
						|
  /**
 | 
						|
   * Process a swipe event based on the given direction.
 | 
						|
   *
 | 
						|
   * @param aEvent
 | 
						|
   *        The swipe event to handle
 | 
						|
   * @param aDir
 | 
						|
   *        The direction for the swipe event
 | 
						|
   */
 | 
						|
  processSwipeEvent: function HSA_processSwipeEvent(aEvent, aDir) {
 | 
						|
    if (aDir == "RIGHT")
 | 
						|
      this._historyIndex += this.isLTR ? 1 : -1;
 | 
						|
    else if (aDir == "LEFT")
 | 
						|
      this._historyIndex += this.isLTR ? -1 : 1;
 | 
						|
    else
 | 
						|
      return;
 | 
						|
    this._lastSwipeDir = aDir;
 | 
						|
  },
 | 
						|
 | 
						|
  /**
 | 
						|
   * Checks if there is a page in the browser history to go back to.
 | 
						|
   *
 | 
						|
   * @return true if there is a previous page in history, false otherwise.
 | 
						|
   */
 | 
						|
  canGoBack: function HSA_canGoBack() {
 | 
						|
    if (this.isAnimationRunning())
 | 
						|
      return this._doesIndexExistInHistory(this._historyIndex - 1);
 | 
						|
    return gBrowser.webNavigation.canGoBack;
 | 
						|
  },
 | 
						|
 | 
						|
  /**
 | 
						|
   * Checks if there is a page in the browser history to go forward to.
 | 
						|
   *
 | 
						|
   * @return true if there is a next page in history, false otherwise.
 | 
						|
   */
 | 
						|
  canGoForward: function HSA_canGoForward() {
 | 
						|
    if (this.isAnimationRunning())
 | 
						|
      return this._doesIndexExistInHistory(this._historyIndex + 1);
 | 
						|
    return gBrowser.webNavigation.canGoForward;
 | 
						|
  },
 | 
						|
 | 
						|
  /**
 | 
						|
   * Used to notify the history swipe animation that the OS sent a swipe end
 | 
						|
   * event and that we should navigate to the page that the user swiped to, if
 | 
						|
   * any. This will also result in the animation overlay to be torn down.
 | 
						|
   */
 | 
						|
  swipeEndEventReceived: function HSA_swipeEndEventReceived() {
 | 
						|
    // Update the session history before continuing.
 | 
						|
    let updateSessionHistory = sessionHistory => {
 | 
						|
      if (this._lastSwipeDir != "" && this._historyIndex != this._startingIndex)
 | 
						|
        this._navigateToHistoryIndex();
 | 
						|
      else
 | 
						|
        this.stopAnimation();
 | 
						|
    }
 | 
						|
    SessionStore.getSessionHistory(gBrowser.selectedTab, updateSessionHistory);
 | 
						|
  },
 | 
						|
 | 
						|
  /**
 | 
						|
   * Checks whether a particular index exists in the browser history or not.
 | 
						|
   *
 | 
						|
   * @param aIndex
 | 
						|
   *        The index to check for availability for in the history.
 | 
						|
   * @return true if the index exists in the browser history, false otherwise.
 | 
						|
   */
 | 
						|
  _doesIndexExistInHistory: function HSA__doesIndexExistInHistory(aIndex) {
 | 
						|
    try {
 | 
						|
      return SessionStore.getSessionHistory(gBrowser.selectedTab).entries[aIndex] != null;
 | 
						|
    } catch (ex) {
 | 
						|
      return false;
 | 
						|
    }
 | 
						|
  },
 | 
						|
 | 
						|
  /**
 | 
						|
   * Navigates to the index in history that is currently being tracked by
 | 
						|
   * |this|.
 | 
						|
   */
 | 
						|
  _navigateToHistoryIndex: function HSA__navigateToHistoryIndex() {
 | 
						|
    if (this._doesIndexExistInHistory(this._historyIndex))
 | 
						|
      gBrowser.webNavigation.gotoIndex(this._historyIndex);
 | 
						|
    else
 | 
						|
      this.stopAnimation();
 | 
						|
  },
 | 
						|
 | 
						|
  /**
 | 
						|
   * Checks to see if history swipe animations are supported by this
 | 
						|
   * platform/configuration.
 | 
						|
   *
 | 
						|
   * return true if supported, false otherwise.
 | 
						|
   */
 | 
						|
  _isSupported: function HSA__isSupported() {
 | 
						|
    return window.matchMedia("(-moz-swipe-animation-enabled)").matches;
 | 
						|
  },
 | 
						|
 | 
						|
  /**
 | 
						|
   * Handle fast swiping (i.e. a swipe animation is already in
 | 
						|
   * progress when a new one is initiated). This will swap out the snapshots
 | 
						|
   * used in the previous animation with the appropriate new ones.
 | 
						|
   */
 | 
						|
  _handleFastSwiping: function HSA__handleFastSwiping() {
 | 
						|
    this._installCurrentPageSnapshot(null);
 | 
						|
    this._installPrevAndNextSnapshots();
 | 
						|
  },
 | 
						|
 | 
						|
  /**
 | 
						|
   * Adds the boxes that contain the snapshots used during the swipe animation.
 | 
						|
   */
 | 
						|
  _addBoxes: function HSA__addBoxes() {
 | 
						|
    let browserStack =
 | 
						|
      document.getAnonymousElementByAttribute(gBrowser.getNotificationBox(),
 | 
						|
                                              "class", "browserStack");
 | 
						|
    this._container = this._createElement("historySwipeAnimationContainer",
 | 
						|
                                          "stack");
 | 
						|
    browserStack.appendChild(this._container);
 | 
						|
 | 
						|
    this._prevBox = this._createElement("historySwipeAnimationPreviousPage",
 | 
						|
                                        "box");
 | 
						|
    this._container.appendChild(this._prevBox);
 | 
						|
 | 
						|
    this._curBox = this._createElement("historySwipeAnimationCurrentPage",
 | 
						|
                                       "box");
 | 
						|
    this._container.appendChild(this._curBox);
 | 
						|
 | 
						|
    this._nextBox = this._createElement("historySwipeAnimationNextPage",
 | 
						|
                                        "box");
 | 
						|
    this._container.appendChild(this._nextBox);
 | 
						|
 | 
						|
    // Cache width and height.
 | 
						|
    this._boxWidth = this._curBox.getBoundingClientRect().width;
 | 
						|
    this._boxHeight = this._curBox.getBoundingClientRect().height;
 | 
						|
  },
 | 
						|
 | 
						|
  /**
 | 
						|
   * Removes the boxes.
 | 
						|
   */
 | 
						|
  _removeBoxes: function HSA__removeBoxes() {
 | 
						|
    this._curBox = null;
 | 
						|
    this._prevBox = null;
 | 
						|
    this._nextBox = null;
 | 
						|
    if (this._container)
 | 
						|
      this._container.remove();
 | 
						|
    this._container = null;
 | 
						|
    this._boxWidth = -1;
 | 
						|
    this._boxHeight = -1;
 | 
						|
  },
 | 
						|
 | 
						|
  /**
 | 
						|
   * Creates an element with a given identifier and tag name.
 | 
						|
   *
 | 
						|
   * @param aID
 | 
						|
   *        An identifier to create the element with.
 | 
						|
   * @param aTagName
 | 
						|
   *        The name of the tag to create the element for.
 | 
						|
   * @return the newly created element.
 | 
						|
   */
 | 
						|
  _createElement: function HSA__createElement(aID, aTagName) {
 | 
						|
    let XULNS = "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul";
 | 
						|
    let element = document.createElementNS(XULNS, aTagName);
 | 
						|
    element.id = aID;
 | 
						|
    return element;
 | 
						|
  },
 | 
						|
 | 
						|
  /**
 | 
						|
   * Moves a given box to a given X coordinate position.
 | 
						|
   *
 | 
						|
   * @param aBox
 | 
						|
   *        The box element to position.
 | 
						|
   * @param aPosition
 | 
						|
   *        The position (in X coordinates) to move the box element to.
 | 
						|
   */
 | 
						|
  _positionBox: function HSA__positionBox(aBox, aPosition) {
 | 
						|
    let transform = "";
 | 
						|
 | 
						|
    if (this._direction == "vertical")
 | 
						|
      transform = "translateY(" + this._boxHeight * aPosition + "px)";
 | 
						|
    else
 | 
						|
      transform = "translateX(" + this._boxWidth * aPosition + "px)";
 | 
						|
 | 
						|
    aBox.style.transform = transform;
 | 
						|
  },
 | 
						|
 | 
						|
  /**
 | 
						|
   * Verifies that we're ready to take snapshots based on the global pref and
 | 
						|
   * the current index in history.
 | 
						|
   *
 | 
						|
   * @return true if we're ready to take snapshots, false otherwise.
 | 
						|
   */
 | 
						|
  _readyToTakeSnapshots: function HSA__readyToTakeSnapshots() {
 | 
						|
    return (this._maxSnapshots >= 1 && this._getCurrentHistoryIndex() >= 0);
 | 
						|
  },
 | 
						|
 | 
						|
  /**
 | 
						|
   * Takes a snapshot of the page the browser is currently on.
 | 
						|
   */
 | 
						|
  _takeSnapshot: function HSA__takeSnapshot() {
 | 
						|
    if (!this._readyToTakeSnapshots()) {
 | 
						|
      return;
 | 
						|
    }
 | 
						|
 | 
						|
    let canvas = null;
 | 
						|
 | 
						|
    let browser = gBrowser.selectedBrowser;
 | 
						|
    let r = browser.getBoundingClientRect();
 | 
						|
    canvas = document.createElementNS("http://www.w3.org/1999/xhtml",
 | 
						|
                                      "canvas");
 | 
						|
    canvas.mozOpaque = true;
 | 
						|
    let scale = window.devicePixelRatio;
 | 
						|
    canvas.width = r.width * scale;
 | 
						|
    canvas.height = r.height * scale;
 | 
						|
    let ctx = canvas.getContext("2d");
 | 
						|
    let zoom = browser.markupDocumentViewer.fullZoom * scale;
 | 
						|
    ctx.scale(zoom, zoom);
 | 
						|
    ctx.drawWindow(browser.contentWindow,
 | 
						|
                   0, 0, canvas.width / zoom, canvas.height / zoom, "white",
 | 
						|
                   ctx.DRAWWINDOW_DO_NOT_FLUSH | ctx.DRAWWINDOW_DRAW_VIEW |
 | 
						|
                   ctx.DRAWWINDOW_ASYNC_DECODE_IMAGES |
 | 
						|
                   ctx.DRAWWINDOW_USE_WIDGET_LAYERS);
 | 
						|
 | 
						|
    TelemetryStopwatch.start("FX_GESTURE_INSTALL_SNAPSHOT_OF_PAGE");
 | 
						|
    try {
 | 
						|
      this._installCurrentPageSnapshot(canvas);
 | 
						|
      this._assignSnapshotToCurrentBrowser(canvas);
 | 
						|
    } finally {
 | 
						|
      TelemetryStopwatch.finish("FX_GESTURE_INSTALL_SNAPSHOT_OF_PAGE");
 | 
						|
    }
 | 
						|
  },
 | 
						|
 | 
						|
  /**
 | 
						|
   * Retrieves the maximum number of snapshots that should be kept in memory.
 | 
						|
   * This limit is a global limit and is valid across all open tabs.
 | 
						|
   */
 | 
						|
  _getMaxSnapshots: function HSA__getMaxSnapshots() {
 | 
						|
    return gPrefService.getIntPref("browser.snapshots.limit");
 | 
						|
  },
 | 
						|
 | 
						|
  /**
 | 
						|
   * Adds a snapshot to the list and initiates the compression of said snapshot.
 | 
						|
   * Once the compression is completed, it will replace the uncompressed
 | 
						|
   * snapshot in the list.
 | 
						|
   *
 | 
						|
   * @param aCanvas
 | 
						|
   *        The snapshot to add to the list and compress.
 | 
						|
   */
 | 
						|
  _assignSnapshotToCurrentBrowser:
 | 
						|
  function HSA__assignSnapshotToCurrentBrowser(aCanvas) {
 | 
						|
    let browser = gBrowser.selectedBrowser;
 | 
						|
    let currIndex = this._getCurrentHistoryIndex();
 | 
						|
 | 
						|
    this._removeTrackedSnapshot(currIndex, browser);
 | 
						|
    this._addSnapshotRefToArray(currIndex, browser);
 | 
						|
 | 
						|
    if (!("snapshots" in browser))
 | 
						|
      browser.snapshots = [];
 | 
						|
    let snapshots = browser.snapshots;
 | 
						|
    // Temporarily store the canvas as the compressed snapshot.
 | 
						|
    // This avoids a blank page if the user swipes quickly
 | 
						|
    // between pages before the compression could complete.
 | 
						|
    snapshots[currIndex] = {
 | 
						|
      image: aCanvas,
 | 
						|
      scale: window.devicePixelRatio
 | 
						|
    };
 | 
						|
  },
 | 
						|
 | 
						|
  /**
 | 
						|
   * Compresses the HTMLCanvasElement that's stored at the current history
 | 
						|
   * index in the snapshot array and stores the compressed image in its place.
 | 
						|
   */
 | 
						|
  _compressSnapshotAtCurrentIndex:
 | 
						|
  function HSA__compressSnapshotAtCurrentIndex() {
 | 
						|
    if (!this._readyToTakeSnapshots()) {
 | 
						|
      // We didn't take a snapshot earlier because we weren't ready to, so
 | 
						|
      // there's nothing to compress.
 | 
						|
      return;
 | 
						|
    }
 | 
						|
 | 
						|
    TelemetryStopwatch.start("FX_GESTURE_COMPRESS_SNAPSHOT_OF_PAGE");
 | 
						|
    try {
 | 
						|
      let browser = gBrowser.selectedBrowser;
 | 
						|
      let snapshots = browser.snapshots;
 | 
						|
      let currIndex = this._getCurrentHistoryIndex();
 | 
						|
 | 
						|
      // Kick off snapshot compression.
 | 
						|
      let canvas = snapshots[currIndex].image;
 | 
						|
      canvas.toBlob(function(aBlob) {
 | 
						|
          if (snapshots[currIndex]) {
 | 
						|
            snapshots[currIndex].image = aBlob;
 | 
						|
          }
 | 
						|
        }, "image/png"
 | 
						|
      );
 | 
						|
    } finally {
 | 
						|
      TelemetryStopwatch.finish("FX_GESTURE_COMPRESS_SNAPSHOT_OF_PAGE");
 | 
						|
    }
 | 
						|
  },
 | 
						|
 | 
						|
  /**
 | 
						|
   * Removes a snapshot identified by the browser and index in the array of
 | 
						|
   * snapshots for that browser, if present. If no snapshot could be identified
 | 
						|
   * the method simply returns without taking any action. If aIndex is negative,
 | 
						|
   * all snapshots for a particular browser will be removed.
 | 
						|
   *
 | 
						|
   * @param aIndex
 | 
						|
   *        The index in history of the new snapshot, or negative value if all
 | 
						|
   *        snapshots for a browser should be removed.
 | 
						|
   * @param aBrowser
 | 
						|
   *        The browser the new snapshot was taken in.
 | 
						|
   */
 | 
						|
  _removeTrackedSnapshot: function HSA__removeTrackedSnapshot(aIndex, aBrowser) {
 | 
						|
    let arr = this._trackedSnapshots;
 | 
						|
    let requiresExactIndexMatch = aIndex >= 0;
 | 
						|
    for (let i = 0; i < arr.length; i++) {
 | 
						|
      if ((arr[i].browser == aBrowser) &&
 | 
						|
          (aIndex < 0 || aIndex == arr[i].index)) {
 | 
						|
        delete aBrowser.snapshots[arr[i].index];
 | 
						|
        arr.splice(i, 1);
 | 
						|
        if (requiresExactIndexMatch)
 | 
						|
          return; // Found and removed the only element.
 | 
						|
        i--; // Make sure to revisit the index that we just removed an
 | 
						|
             // element at.
 | 
						|
      }
 | 
						|
    }
 | 
						|
  },
 | 
						|
 | 
						|
  /**
 | 
						|
   * Adds a new snapshot reference for a given index and browser to the array
 | 
						|
   * of references to tracked snapshots.
 | 
						|
   *
 | 
						|
   * @param aIndex
 | 
						|
   *        The index in history of the new snapshot.
 | 
						|
   * @param aBrowser
 | 
						|
   *        The browser the new snapshot was taken in.
 | 
						|
   */
 | 
						|
  _addSnapshotRefToArray:
 | 
						|
  function HSA__addSnapshotRefToArray(aIndex, aBrowser) {
 | 
						|
    let id = { index: aIndex,
 | 
						|
               browser: aBrowser };
 | 
						|
    let arr = this._trackedSnapshots;
 | 
						|
    arr.unshift(id);
 | 
						|
 | 
						|
    while (arr.length > this._maxSnapshots) {
 | 
						|
      let lastElem = arr[arr.length - 1];
 | 
						|
      delete lastElem.browser.snapshots[lastElem.index].image;
 | 
						|
      delete lastElem.browser.snapshots[lastElem.index];
 | 
						|
      arr.splice(-1, 1);
 | 
						|
    }
 | 
						|
  },
 | 
						|
 | 
						|
  /**
 | 
						|
   * Converts a compressed blob to an Image object. In some situations
 | 
						|
   * (especially during fast swiping) aBlob may still be a canvas, not a
 | 
						|
   * compressed blob. In this case, we simply return the canvas.
 | 
						|
   *
 | 
						|
   * @param aBlob
 | 
						|
   *        The compressed blob to convert, or a canvas if a blob compression
 | 
						|
   *        couldn't complete before this method was called.
 | 
						|
   * @return A new Image object representing the converted blob.
 | 
						|
   */
 | 
						|
  _convertToImg: function HSA__convertToImg(aBlob) {
 | 
						|
    if (!aBlob)
 | 
						|
      return null;
 | 
						|
 | 
						|
    // Return aBlob if it's still a canvas and not a compressed blob yet.
 | 
						|
    if (aBlob instanceof HTMLCanvasElement)
 | 
						|
      return aBlob;
 | 
						|
 | 
						|
    let img = new Image();
 | 
						|
    let url = "";
 | 
						|
    try {
 | 
						|
      url = URL.createObjectURL(aBlob);
 | 
						|
      img.onload = function() {
 | 
						|
        URL.revokeObjectURL(url);
 | 
						|
      };
 | 
						|
    } finally {
 | 
						|
      img.src = url;
 | 
						|
    }
 | 
						|
    return img;
 | 
						|
  },
 | 
						|
 | 
						|
  /**
 | 
						|
   * Scales the background of a given box element (which uses a given snapshot
 | 
						|
   * as background) based on a given scale factor.
 | 
						|
   * @param aSnapshot
 | 
						|
   *        The snapshot that is used as background of aBox.
 | 
						|
   * @param aScale
 | 
						|
   *        The scale factor to use.
 | 
						|
   * @param aBox
 | 
						|
   *        The box element that uses aSnapshot as background.
 | 
						|
   */
 | 
						|
  _scaleSnapshot: function HSA__scaleSnapshot(aSnapshot, aScale, aBox) {
 | 
						|
    if (aSnapshot && aScale != 1 && aBox) {
 | 
						|
      if (aSnapshot instanceof HTMLCanvasElement) {
 | 
						|
        aBox.style.backgroundSize =
 | 
						|
          aSnapshot.width / aScale + "px " + aSnapshot.height / aScale + "px";
 | 
						|
      } else {
 | 
						|
        // snapshot is instanceof HTMLImageElement
 | 
						|
        aSnapshot.addEventListener("load", function() {
 | 
						|
          aBox.style.backgroundSize =
 | 
						|
            aSnapshot.width / aScale + "px " + aSnapshot.height / aScale + "px";
 | 
						|
        });
 | 
						|
      }
 | 
						|
    }
 | 
						|
  },
 | 
						|
 | 
						|
  /**
 | 
						|
   * Sets the snapshot of the current page to the snapshot passed as parameter,
 | 
						|
   * or to the one previously stored for the current index in history if the
 | 
						|
   * parameter is null.
 | 
						|
   *
 | 
						|
   * @param aCanvas
 | 
						|
   *        The snapshot to set the current page to. If this parameter is null,
 | 
						|
   *        the previously stored snapshot for this index (if any) will be used.
 | 
						|
   */
 | 
						|
  _installCurrentPageSnapshot:
 | 
						|
  function HSA__installCurrentPageSnapshot(aCanvas) {
 | 
						|
    let currSnapshot = aCanvas;
 | 
						|
    let scale = window.devicePixelRatio;
 | 
						|
    if (!currSnapshot) {
 | 
						|
      let snapshots = gBrowser.selectedBrowser.snapshots || {};
 | 
						|
      let currIndex = this._historyIndex;
 | 
						|
      if (currIndex in snapshots) {
 | 
						|
        currSnapshot = this._convertToImg(snapshots[currIndex].image);
 | 
						|
        scale = snapshots[currIndex].scale;
 | 
						|
      }
 | 
						|
    }
 | 
						|
    this._scaleSnapshot(currSnapshot, scale, this._curBox ? this._curBox :
 | 
						|
                                                            null);
 | 
						|
    document.mozSetImageElement("historySwipeAnimationCurrentPageSnapshot",
 | 
						|
                                currSnapshot);
 | 
						|
  },
 | 
						|
 | 
						|
  /**
 | 
						|
   * Sets the snapshots of the previous and next pages to the snapshots
 | 
						|
   * previously stored for their respective indeces.
 | 
						|
   */
 | 
						|
  _installPrevAndNextSnapshots:
 | 
						|
  function HSA__installPrevAndNextSnapshots() {
 | 
						|
    let snapshots = gBrowser.selectedBrowser.snapshots || [];
 | 
						|
    let currIndex = this._historyIndex;
 | 
						|
    let prevIndex = currIndex - 1;
 | 
						|
    let prevSnapshot = null;
 | 
						|
    if (prevIndex in snapshots) {
 | 
						|
      prevSnapshot = this._convertToImg(snapshots[prevIndex].image);
 | 
						|
      this._scaleSnapshot(prevSnapshot, snapshots[prevIndex].scale,
 | 
						|
                          this._prevBox);
 | 
						|
    }
 | 
						|
    document.mozSetImageElement("historySwipeAnimationPreviousPageSnapshot",
 | 
						|
                                prevSnapshot);
 | 
						|
 | 
						|
    let nextIndex = currIndex + 1;
 | 
						|
    let nextSnapshot = null;
 | 
						|
    if (nextIndex in snapshots) {
 | 
						|
      nextSnapshot = this._convertToImg(snapshots[nextIndex].image);
 | 
						|
      this._scaleSnapshot(nextSnapshot, snapshots[nextIndex].scale,
 | 
						|
                          this._nextBox);
 | 
						|
    }
 | 
						|
    document.mozSetImageElement("historySwipeAnimationNextPageSnapshot",
 | 
						|
                                nextSnapshot);
 | 
						|
  },
 | 
						|
};
 |