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+# 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/.
+
+// Simple gestures support
+//
+// As per bug #412486, web content must not be allowed to receive any
+// simple gesture events. Multi-touch gesture APIs are in their
+// infancy and we do NOT want to be forced into supporting an API that
+// will probably have to change in the future. (The current Mac OS X
+// API is undocumented and was reverse-engineered.) Until support is
+// implemented in the event dispatcher to keep these events as
+// chrome-only, we must listen for the simple gesture events during
+// the capturing phase and call stopPropagation on every event.
+
+let gGestureSupport = {
+ _currentRotation: 0,
+ _lastRotateDelta: 0,
+ _rotateMomentumThreshold: .75,
+
+ /**
+ * Add or remove mouse gesture event listeners
+ *
+ * @param aAddListener
+ * True to add/init listeners and false to remove/uninit
+ */
+ init: function GS_init(aAddListener) {
+ // Bug 863514 - Make gesture support work in electrolysis
+ if (gMultiProcessBrowser)
+ return;
+
+ const gestureEvents = ["SwipeGestureStart",
+ "SwipeGestureUpdate", "SwipeGestureEnd", "SwipeGesture",
+ "MagnifyGestureStart", "MagnifyGestureUpdate", "MagnifyGesture",
+ "RotateGestureStart", "RotateGestureUpdate", "RotateGesture",
+ "TapGesture", "PressTapGesture"];
+
+ let addRemove = aAddListener ? window.addEventListener :
+ window.removeEventListener;
+
+ gestureEvents.forEach(function (event) addRemove("Moz" + event, this, true),
+ this);
+ },
+
+ /**
+ * Dispatch events based on the type of mouse gesture event. For now, make
+ * sure to stop propagation of every gesture event so that web content cannot
+ * receive gesture events.
+ *
+ * @param aEvent
+ * The gesture event to handle
+ */
+ handleEvent: function GS_handleEvent(aEvent) {
+ if (!Services.prefs.getBoolPref(
+ "dom.debug.propagate_gesture_events_through_content")) {
+ aEvent.stopPropagation();
+ }
+
+ // Create a preference object with some defaults
+ let def = function(aThreshold, aLatched)
+ ({ threshold: aThreshold, latched: !!aLatched });
+
+ switch (aEvent.type) {
+ case "MozSwipeGestureStart":
+ aEvent.preventDefault();
+ this._setupSwipeGesture(aEvent);
+ break;
+ case "MozSwipeGestureUpdate":
+ aEvent.preventDefault();
+ this._doUpdate(aEvent);
+ break;
+ case "MozSwipeGestureEnd":
+ aEvent.preventDefault();
+ this._doEnd(aEvent);
+ break;
+ case "MozSwipeGesture":
+ aEvent.preventDefault();
+ this.onSwipe(aEvent);
+ break;
+ case "MozMagnifyGestureStart":
+ aEvent.preventDefault();
+#ifdef XP_WIN
+ this._setupGesture(aEvent, "pinch", def(25, 0), "out", "in");
+#else
+ this._setupGesture(aEvent, "pinch", def(150, 1), "out", "in");
+#endif
+ break;
+ case "MozRotateGestureStart":
+ aEvent.preventDefault();
+ this._setupGesture(aEvent, "twist", def(25, 0), "right", "left");
+ break;
+ case "MozMagnifyGestureUpdate":
+ case "MozRotateGestureUpdate":
+ aEvent.preventDefault();
+ this._doUpdate(aEvent);
+ break;
+ case "MozTapGesture":
+ aEvent.preventDefault();
+ this._doAction(aEvent, ["tap"]);
+ break;
+ case "MozRotateGesture":
+ aEvent.preventDefault();
+ this._doAction(aEvent, ["twist", "end"]);
+ break;
+ /* case "MozPressTapGesture":
+ break; */
+ }
+ },
+
+ /**
+ * Called at the start of "pinch" and "twist" gestures to setup all of the
+ * information needed to process the gesture
+ *
+ * @param aEvent
+ * The continual motion start event to handle
+ * @param aGesture
+ * Name of the gesture to handle
+ * @param aPref
+ * Preference object with the names of preferences and defaults
+ * @param aInc
+ * Command to trigger for increasing motion (without gesture name)
+ * @param aDec
+ * Command to trigger for decreasing motion (without gesture name)
+ */
+ _setupGesture: function GS__setupGesture(aEvent, aGesture, aPref, aInc, aDec) {
+ // Try to load user-set values from preferences
+ for (let [pref, def] in Iterator(aPref))
+ aPref[pref] = this._getPref(aGesture + "." + pref, def);
+
+ // Keep track of the total deltas and latching behavior
+ let offset = 0;
+ let latchDir = aEvent.delta > 0 ? 1 : -1;
+ let isLatched = false;
+
+ // Create the update function here to capture closure state
+ this._doUpdate = function GS__doUpdate(aEvent) {
+ // Update the offset with new event data
+ offset += aEvent.delta;
+
+ // Check if the cumulative deltas exceed the threshold
+ if (Math.abs(offset) > aPref["threshold"]) {
+ // Trigger the action if we don't care about latching; otherwise, make
+ // sure either we're not latched and going the same direction of the
+ // initial motion; or we're latched and going the opposite way
+ let sameDir = (latchDir ^ offset) >= 0;
+ if (!aPref["latched"] || (isLatched ^ sameDir)) {
+ this._doAction(aEvent, [aGesture, offset > 0 ? aInc : aDec]);
+
+ // We must be getting latched or leaving it, so just toggle
+ isLatched = !isLatched;
+ }
+
+ // Reset motion counter to prepare for more of the same gesture
+ offset = 0;
+ }
+ };
+
+ // The start event also contains deltas, so handle an update right away
+ this._doUpdate(aEvent);
+ },
+
+ /**
+ * Checks whether a swipe gesture event can navigate the browser history or
+ * not.
+ *
+ * @param aEvent
+ * The swipe gesture event.
+ * @return true if the swipe event may navigate the history, false othwerwise.
+ */
+ _swipeNavigatesHistory: function GS__swipeNavigatesHistory(aEvent) {
+ return this._getCommand(aEvent, ["swipe", "left"])
+ == "Browser:BackOrBackDuplicate" &&
+ this._getCommand(aEvent, ["swipe", "right"])
+ == "Browser:ForwardOrForwardDuplicate";
+ },
+
+ /**
+ * Sets up the history swipe animations for a swipe gesture event, if enabled.
+ *
+ * @param aEvent
+ * The swipe gesture start event.
+ */
+ _setupSwipeGesture: function GS__setupSwipeGesture(aEvent) {
+ if (!this._swipeNavigatesHistory(aEvent))
+ return;
+
+ let canGoBack = gHistorySwipeAnimation.canGoBack();
+ let canGoForward = gHistorySwipeAnimation.canGoForward();
+ let isLTR = gHistorySwipeAnimation.isLTR;
+
+ if (canGoBack)
+ aEvent.allowedDirections |= isLTR ? aEvent.DIRECTION_LEFT :
+ aEvent.DIRECTION_RIGHT;
+ if (canGoForward)
+ aEvent.allowedDirections |= isLTR ? aEvent.DIRECTION_RIGHT :
+ aEvent.DIRECTION_LEFT;
+
+ gHistorySwipeAnimation.startAnimation();
+
+ this._doUpdate = function GS__doUpdate(aEvent) {
+ gHistorySwipeAnimation.updateAnimation(aEvent.delta);
+ };
+
+ this._doEnd = function GS__doEnd(aEvent) {
+ gHistorySwipeAnimation.swipeEndEventReceived();
+
+ this._doUpdate = function (aEvent) {};
+ this._doEnd = function (aEvent) {};
+ }
+ },
+
+ /**
+ * Generator producing the powerset of the input array where the first result
+ * is the complete set and the last result (before StopIteration) is empty.
+ *
+ * @param aArray
+ * Source array containing any number of elements
+ * @yield Array that is a subset of the input array from full set to empty
+ */
+ _power: function GS__power(aArray) {
+ // Create a bitmask based on the length of the array
+ let num = 1 << aArray.length;
+ while (--num >= 0) {
+ // Only select array elements where the current bit is set
+ yield aArray.reduce(function (aPrev, aCurr, aIndex) {
+ if (num & 1 << aIndex)
+ aPrev.push(aCurr);
+ return aPrev;
+ }, []);
+ }
+ },
+
+ /**
+ * Determine what action to do for the gesture based on which keys are
+ * pressed and which commands are set, and execute the command.
+ *
+ * @param aEvent
+ * The original gesture event to convert into a fake click event
+ * @param aGesture
+ * Array of gesture name parts (to be joined by periods)
+ * @return Name of the executed command. Returns null if no command is
+ * found.
+ */
+ _doAction: function GS__doAction(aEvent, aGesture) {
+ let command = this._getCommand(aEvent, aGesture);
+ return command && this._doCommand(aEvent, command);
+ },
+
+ /**
+ * Determine what action to do for the gesture based on which keys are
+ * pressed and which commands are set
+ *
+ * @param aEvent
+ * The original gesture event to convert into a fake click event
+ * @param aGesture
+ * Array of gesture name parts (to be joined by periods)
+ */
+ _getCommand: function GS__getCommand(aEvent, aGesture) {
+ // Create an array of pressed keys in a fixed order so that a command for
+ // "meta" is preferred over "ctrl" when both buttons are pressed (and a
+ // command for both don't exist)
+ let keyCombos = [];
+ ["shift", "alt", "ctrl", "meta"].forEach(function (key) {
+ if (aEvent[key + "Key"])
+ keyCombos.push(key);
+ });
+
+ // Try each combination of key presses in decreasing order for commands
+ for (let subCombo of this._power(keyCombos)) {
+ // Convert a gesture and pressed keys into the corresponding command
+ // action where the preference has the gesture before "shift" before
+ // "alt" before "ctrl" before "meta" all separated by periods
+ let command;
+ try {
+ command = this._getPref(aGesture.concat(subCombo).join("."));
+ } catch (e) {}
+
+ if (command)
+ return command;
+ }
+ return null;
+ },
+
+ /**
+ * Execute the specified command.
+ *
+ * @param aEvent
+ * The original gesture event to convert into a fake click event
+ * @param aCommand
+ * Name of the command found for the event's keys and gesture.
+ */
+ _doCommand: function GS__doCommand(aEvent, aCommand) {
+ let node = document.getElementById(aCommand);
+ if (node) {
+ if (node.getAttribute("disabled") != "true") {
+ let cmdEvent = document.createEvent("xulcommandevent");
+ cmdEvent.initCommandEvent("command", true, true, window, 0,
+ aEvent.ctrlKey, aEvent.altKey,
+ aEvent.shiftKey, aEvent.metaKey, aEvent);
+ node.dispatchEvent(cmdEvent);
+ }
+
+ }
+ else {
+ goDoCommand(aCommand);
+ }
+ },
+
+ /**
+ * Handle continual motion events. This function will be set by
+ * _setupGesture or _setupSwipe.
+ *
+ * @param aEvent
+ * The continual motion update event to handle
+ */
+ _doUpdate: function(aEvent) {},
+
+ /**
+ * Handle gesture end events. This function will be set by _setupSwipe.
+ *
+ * @param aEvent
+ * The gesture end event to handle
+ */
+ _doEnd: function(aEvent) {},
+
+ /**
+ * Convert the swipe gesture into a browser action based on the direction.
+ *
+ * @param aEvent
+ * The swipe event to handle
+ */
+ onSwipe: function GS_onSwipe(aEvent) {
+ // Figure out which one (and only one) direction was triggered
+ for (let dir of ["UP", "RIGHT", "DOWN", "LEFT"]) {
+ if (aEvent.direction == aEvent["DIRECTION_" + dir]) {
+ this._coordinateSwipeEventWithAnimation(aEvent, dir);
+ 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
+ */
+ processSwipeEvent: function GS_processSwipeEvent(aEvent, aDir) {
+ this._doAction(aEvent, ["swipe", aDir.toLowerCase()]);
+ },
+
+ /**
+ * 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
+ * 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()) &&
+ (aDir == "RIGHT" || aDir == "LEFT")) {
+ gHistorySwipeAnimation.processSwipeEvent(aEvent, aDir);
+ }
+ else {
+ this.processSwipeEvent(aEvent, aDir);
+ }
+ },
+
+ /**
+ * 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
+ */
+ _getPref: function GS__getPref(aPref, aDef) {
+ // Preferences branch under which all gestures preferences are stored
+ const branch = "browser.gesture.";
+
+ try {
+ // Determine what type of data to load based on default value's type
+ let type = typeof aDef;
+ let getFunc = "get" + (type == "boolean" ? "Bool" :
+ type == "number" ? "Int" : "Char") + "Pref";
+ return gPrefService[getFunc](branch + aPref);
+ }
+ catch (e) {
+ return aDef;
+ }
+ },
+
+ /**
+ * Perform rotation for ImageDocuments
+ *
+ * @param aEvent
+ * The MozRotateGestureUpdate event triggering this call
+ */
+ rotate: function(aEvent) {
+ if (!(content.document instanceof ImageDocument))
+ return;
+
+ let contentElement = 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: function() {
+ if (!(content.document instanceof ImageDocument))
+ return;
+
+ let contentElement = 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: function() {
+ // Bug 863514 - Make gesture support work in electrolysis
+ if (gMultiProcessBrowser)
+ return;
+
+ if (!(content.document instanceof ImageDocument))
+ return;
+
+ let contentElement = content.document.body.firstElementChild;
+ let transformValue = content.window.getComputedStyle(contentElement, null)
+ .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: function() {
+ let contentElement = content.document &&
+ content.document instanceof ImageDocument &&
+ content.document.body &&
+ content.document.body.firstElementChild;
+ if (!contentElement)
+ return;
+ contentElement.classList.remove("completeRotation");
+ contentElement.removeEventListener("transitionend", this._clearCompleteRotation);
+ },
+};
+
+// History Swipe Animation Support (bug 678392)
+let 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.mozMatchesSelector(
+ ":-moz-locale-dir(ltr)");
+ this._trackedSnapshots = [];
+ this._historyIndex = -1;
+ this._boxWidth = -1;
+ this._maxSnapshots = this._getMaxSnapshots();
+ this._lastSwipeDir = "";
+
+ // 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, false);
+ gBrowser.addEventListener("pageshow", this, false);
+ gBrowser.addEventListener("popstate", this, false);
+ gBrowser.tabContainer.addEventListener("TabClose", this, false);
+ }
+ },
+
+ /**
+ * Uninitializes the support for history swipe animations.
+ */
+ uninit: function HSA_uninit() {
+ gBrowser.removeEventListener("pagehide", this, false);
+ gBrowser.removeEventListener("pageshow", this, false);
+ gBrowser.removeEventListener("popstate", this, false);
+ gBrowser.tabContainer.removeEventListener("TabClose", this, false);
+
+ 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).
+ */
+ startAnimation: function HSA_startAnimation() {
+ if (this.isAnimationRunning()) {
+ gBrowser.stop();
+ this._lastSwipeDir = "RELOAD"; // just ensure that != ""
+ this._canGoBack = this.canGoBack();
+ this._canGoForward = this.canGoForward();
+ this._handleFastSwiping();
+ }
+ else {
+ this._historyIndex = gBrowser.webNavigation.sessionHistory.index;
+ this._canGoBack = this.canGoBack();
+ this._canGoForward = this.canGoForward();
+ if (this.active) {
+ this._takeSnapshot();
+ this._installPrevAndNextSnapshots();
+ this._addBoxes();
+ this._lastSwipeDir = "";
+ }
+ }
+ this.updateAnimation(0);
+ },
+
+ /**
+ * Stops the swipe animation.
+ */
+ stopAnimation: function HSA_stopAnimation() {
+ gHistorySwipeAnimation._removeBoxes();
+ },
+
+ /**
+ * 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;
+
+ if ((aVal >= 0 && this.isLTR) ||
+ (aVal <= 0 && !this.isLTR)) {
+ if (aVal > 1)
+ aVal = 1; // Cap value to avoid sliding the page further than allowed.
+
+ if (this._canGoBack)
+ this._prevBox.collapsed = false;
+ else
+ 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);
+
+ // The forward page should be pushed offscreen all the way to the right.
+ this._positionBox(this._nextBox, 1);
+ }
+ else {
+ if (aVal < -1)
+ aVal = -1; // Cap value to avoid sliding the page further than allowed.
+
+ // 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).
+ if (this._canGoForward) {
+ let offset = this.isLTR ? 1 : -1;
+ this._positionBox(this._curBox, 0);
+ this._positionBox(this._nextBox, offset + aVal); // aVal is negative
+ }
+ else {
+ this._prevBox.collapsed = true;
+ this._positionBox(this._curBox, aVal);
+ }
+ }
+ },
+
+ /**
+ * Event handler for events relevant to the history swipe animation.
+ *
+ * @param aEvent
+ * An event to process.
+ */
+ handleEvent: function HSA_handleEvent(aEvent) {
+ switch (aEvent.type) {
+ case "TabClose":
+ let browser = gBrowser.getBrowserForTab(aEvent.target);
+ this._removeTrackedSnapshot(-1, browser);
+ break;
+ case "pageshow":
+ case "popstate":
+ if (this.isAnimationRunning()) {
+ if (aEvent.target != gBrowser.selectedBrowser.contentDocument)
+ break;
+ this.stopAnimation();
+ }
+ this._historyIndex = gBrowser.webNavigation.sessionHistory.index;
+ break;
+ case "pagehide":
+ if (aEvent.target == gBrowser.selectedBrowser.contentDocument) {
+ // Take a snapshot of a page whenever it's about to be navigated away
+ // from.
+ this._takeSnapshot();
+ }
+ 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() {
+ if (this._lastSwipeDir != "")
+ this._navigateToHistoryIndex();
+ else
+ this.stopAnimation();
+ },
+
+ /**
+ * 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 {
+ gBrowser.webNavigation.sessionHistory.getEntryAtIndex(aIndex, false);
+ }
+ catch(ex) {
+ return false;
+ }
+ return true;
+ },
+
+ /**
+ * 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);
+ }
+ },
+
+ /**
+ * 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);
+
+ this._boxWidth = this._curBox.getBoundingClientRect().width; // cache width
+ },
+
+ /**
+ * Removes the boxes.
+ */
+ _removeBoxes: function HSA__removeBoxes() {
+ this._curBox = null;
+ this._prevBox = null;
+ this._nextBox = null;
+ if (this._container)
+ this._container.parentNode.removeChild(this._container);
+ this._container = null;
+ this._boxWidth = -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) {
+ aBox.style.transform = "translateX(" + this._boxWidth * aPosition + "px)";
+ },
+
+ /**
+ * Takes a snapshot of the page the browser is currently on.
+ */
+ _takeSnapshot: function HSA__takeSnapshot() {
+ if ((this._maxSnapshots < 1) ||
+ (gBrowser.webNavigation.sessionHistory.index < 0))
+ return;
+
+ let browser = gBrowser.selectedBrowser;
+ let r = browser.getBoundingClientRect();
+ let canvas = document.createElementNS("http://www.w3.org/1999/xhtml",
+ "canvas");
+ canvas.mozOpaque = true;
+ canvas.width = r.width;
+ canvas.height = r.height;
+ let ctx = canvas.getContext("2d");
+ let zoom = browser.markupDocumentViewer.fullZoom;
+ ctx.scale(zoom, zoom);
+ ctx.drawWindow(browser.contentWindow, 0, 0, r.width, r.height, "white",
+ ctx.DRAWWINDOW_DO_NOT_FLUSH | ctx.DRAWWINDOW_DRAW_VIEW |
+ ctx.DRAWWINDOW_ASYNC_DECODE_IMAGES |
+ ctx.DRAWWINDOW_USE_WIDGET_LAYERS);
+
+ this._installCurrentPageSnapshot(canvas);
+ this._assignSnapshotToCurrentBrowser(canvas);
+ },
+
+ /**
+ * 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 = browser.webNavigation.sessionHistory.index;
+
+ 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] = aCanvas;
+
+ // Kick off snapshot compression.
+ aCanvas.toBlob(function(aBlob) {
+ snapshots[currIndex] = aBlob;
+ }, "image/png"
+ );
+ },
+
+ /**
+ * 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];
+ 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 = URL.createObjectURL(aBlob);
+ img.onload = function() {
+ URL.revokeObjectURL(url);
+ };
+ img.src = url;
+ return img;
+ },
+
+ /**
+ * 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;
+ if (!currSnapshot) {
+ let snapshots = gBrowser.selectedBrowser.snapshots || {};
+ let currIndex = this._historyIndex;
+ if (currIndex in snapshots)
+ currSnapshot = this._convertToImg(snapshots[currIndex]);
+ }
+ 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]);
+ document.mozSetImageElement("historySwipeAnimationPreviousPageSnapshot",
+ prevSnapshot);
+
+ let nextIndex = currIndex + 1;
+ let nextSnapshot = null;
+ if (nextIndex in snapshots)
+ nextSnapshot = this._convertToImg(snapshots[nextIndex]);
+ document.mozSetImageElement("historySwipeAnimationNextPageSnapshot",
+ nextSnapshot);
+ },
+};