| // Copyright (c) 2011 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| /** |
| * @fileoverview Touch Handler. Class that handles all touch events and |
| * uses them to interpret higher level gestures and behaviors. TouchEvent is a |
| * built in mobile safari type: |
| * http://developer.apple.com/safari/library/documentation/UserExperience/Reference/TouchEventClassReference/TouchEvent/TouchEvent.html. |
| * This class is intended to work with all webkit browsers, tested on Chrome and |
| * iOS. |
| * |
| * The following types of gestures are currently supported. See the definition |
| * of TouchHandler.EventType for details. |
| * |
| * Single Touch: |
| * This provides simple single-touch events. Any secondary touch is |
| * ignored. |
| * |
| * Drag: |
| * A single touch followed by some movement. This behavior will handle all |
| * of the required events and report the properties of the drag to you |
| * while the touch is happening and at the end of the drag sequence. This |
| * behavior will NOT perform the actual dragging (redrawing the element) |
| * for you, this responsibility is left to the client code. |
| * |
| * Long press: |
| * When your element is touched and held without any drag occuring, the |
| * LONG_PRESS event will fire. |
| */ |
| |
| // Use an anonymous function to enable strict mode just for this file (which |
| // will be concatenated with other files when embedded in Chrome) |
| var TouchHandler = (function() { |
| 'use strict'; |
| |
| /** |
| * A TouchHandler attaches to an Element, listents for low-level touch (or |
| * mouse) events and dispatching higher-level events on the element. |
| * @param {!Element} element The element to listen on and fire events |
| * for. |
| * @constructor |
| */ |
| function TouchHandler(element) { |
| /** |
| * @type {!Element} |
| * @private |
| */ |
| this.element_ = element; |
| |
| /** |
| * The absolute sum of all touch y deltas. |
| * @type {number} |
| * @private |
| */ |
| this.totalMoveY_ = 0; |
| |
| /** |
| * The absolute sum of all touch x deltas. |
| * @type {number} |
| * @private |
| */ |
| this.totalMoveX_ = 0; |
| |
| /** |
| * An array of tuples where the first item is the horizontal component of a |
| * recent relevant touch and the second item is the touch's time stamp. Old |
| * touches are removed based on the max tracking time and when direction |
| * changes. |
| * @type {!Array.<number>} |
| * @private |
| */ |
| this.recentTouchesX_ = []; |
| |
| /** |
| * An array of tuples where the first item is the vertical component of a |
| * recent relevant touch and the second item is the touch's time stamp. Old |
| * touches are removed based on the max tracking time and when direction |
| * changes. |
| * @type {!Array.<number>} |
| * @private |
| */ |
| this.recentTouchesY_ = []; |
| |
| /** |
| * Used to keep track of all events we subscribe to so we can easily clean |
| * up |
| * @type {EventTracker} |
| * @private |
| */ |
| this.events_ = new EventTracker(); |
| } |
| |
| |
| /** |
| * DOM Events that may be fired by the TouchHandler at the element |
| */ |
| TouchHandler.EventType = { |
| // Fired whenever the element is touched as the only touch to the device. |
| // enableDrag defaults to false, set to true to permit dragging. |
| TOUCH_START: 'touchhandler:touch_start', |
| |
| // Fired when an element is held for a period of time. Prevents dragging |
| // from occuring (even if enableDrag was set to true). |
| LONG_PRESS: 'touchhandler:long_press', |
| |
| // If enableDrag was set to true at TOUCH_START, DRAG_START will fire when |
| // the touch first moves sufficient distance. enableDrag is set to true but |
| // can be reset to false to cancel the drag. |
| DRAG_START: 'touchhandler:drag_start', |
| |
| // If enableDrag was true after DRAG_START, DRAG_MOVE will fire whenever the |
| // touch is moved. |
| DRAG_MOVE: 'touchhandler:drag_move', |
| |
| // Fired just before TOUCH_END when a drag is released. Correlates 1:1 with |
| // a DRAG_START. |
| DRAG_END: 'touchhandler:drag_end', |
| |
| // Fired whenever a touch that is being tracked has been released. |
| // Correlates 1:1 with a TOUCH_START. |
| TOUCH_END: 'touchhandler:touch_end' |
| }; |
| |
| |
| /** |
| * The type of event sent by TouchHandler |
| * @constructor |
| * @param {string} type The type of event (one of Grabber.EventType). |
| * @param {boolean} bubbles Whether or not the event should bubble. |
| * @param {number} clientX The X location of the touch. |
| * @param {number} clientY The Y location of the touch. |
| * @param {!Element} touchedElement The element at the current location of the |
| * touch. |
| */ |
| TouchHandler.Event = function(type, bubbles, clientX, clientY, |
| touchedElement) { |
| var event = document.createEvent('Event'); |
| event.initEvent(type, bubbles, true); |
| event.__proto__ = TouchHandler.Event.prototype; |
| |
| /** |
| * The X location of the touch affected |
| * @type {number} |
| */ |
| event.clientX = clientX; |
| |
| /** |
| * The Y location of the touch affected |
| * @type {number} |
| */ |
| event.clientY = clientY; |
| |
| /** |
| * The element at the current location of the touch. |
| * @type {!Element} |
| */ |
| event.touchedElement = touchedElement; |
| |
| return event; |
| }; |
| |
| TouchHandler.Event.prototype = { |
| __proto__: Event.prototype, |
| |
| /** |
| * For TOUCH_START and DRAG START events, set to true to enable dragging or |
| * false to disable dragging. |
| * @type {boolean|undefined} |
| */ |
| enableDrag: undefined, |
| |
| /** |
| * For DRAG events, provides the horizontal component of the |
| * drag delta. Drag delta is defined as the delta of the start touch |
| * position and the current drag position. |
| * @type {number|undefined} |
| */ |
| dragDeltaX: undefined, |
| |
| /** |
| * For DRAG events, provides the vertical component of the |
| * drag delta. |
| * @type {number|undefined} |
| */ |
| dragDeltaY: undefined |
| }; |
| |
| /** |
| * Minimum movement of touch required to be considered a drag. |
| * @type {number} |
| * @private |
| */ |
| TouchHandler.MIN_TRACKING_FOR_DRAG_ = 8; |
| |
| |
| /** |
| * The maximum number of ms to track a touch event. After an event is older |
| * than this value, it will be ignored in velocity calculations. |
| * @type {number} |
| * @private |
| */ |
| TouchHandler.MAX_TRACKING_TIME_ = 250; |
| |
| |
| /** |
| * The maximum number of touches to track. |
| * @type {number} |
| * @private |
| */ |
| TouchHandler.MAX_TRACKING_TOUCHES_ = 5; |
| |
| |
| /** |
| * The maximum velocity to return, in pixels per millisecond, that is used |
| * to guard against errors in calculating end velocity of a drag. This is a |
| * very fast drag velocity. |
| * @type {number} |
| * @private |
| */ |
| TouchHandler.MAXIMUM_VELOCITY_ = 5; |
| |
| |
| /** |
| * The velocity to return, in pixel per millisecond, when the time stamps on |
| * the events are erroneous. The browser can return bad time stamps if the |
| * thread is blocked for the duration of the drag. This is a low velocity to |
| * prevent the content from moving quickly after a slow drag. It is less |
| * jarring if the content moves slowly after a fast drag. |
| * @type {number} |
| * @private |
| */ |
| TouchHandler.VELOCITY_FOR_INCORRECT_EVENTS_ = 1; |
| |
| /** |
| * The time, in milliseconds, that a touch must be held to be considered |
| * 'long'. |
| * @type {number} |
| * @private |
| */ |
| TouchHandler.TIME_FOR_LONG_PRESS_ = 500; |
| |
| TouchHandler.prototype = { |
| /** |
| * If defined, the identifer of the single touch that is active. Note that |
| * 0 is a valid touch identifier - it should not be treated equivalently to |
| * undefined. |
| * @type {number|undefined} |
| * @private |
| */ |
| activeTouch_: undefined, |
| |
| /** |
| * @type {boolean|undefined} |
| * @private |
| */ |
| tracking_: undefined, |
| |
| /** |
| * @type {number|undefined} |
| * @private |
| */ |
| startTouchX_: undefined, |
| |
| /** |
| * @type {number|undefined} |
| * @private |
| */ |
| startTouchY_: undefined, |
| |
| /** |
| * @type {number|undefined} |
| * @private |
| */ |
| endTouchX_: undefined, |
| |
| /** |
| * @type {number|undefined} |
| * @private |
| */ |
| endTouchY_: undefined, |
| |
| /** |
| * Time of the touchstart event. |
| * @type {number|undefined} |
| * @private |
| */ |
| startTime_: undefined, |
| |
| /** |
| * The time of the touchend event. |
| * @type {number|undefined} |
| * @private |
| */ |
| endTime_: undefined, |
| |
| /** |
| * @type {number|undefined} |
| * @private |
| */ |
| lastTouchX_: undefined, |
| |
| /** |
| * @type {number|undefined} |
| * @private |
| */ |
| lastTouchY_: undefined, |
| |
| /** |
| * @type {number|undefined} |
| * @private |
| */ |
| lastMoveX_: undefined, |
| |
| /** |
| * @type {number|undefined} |
| * @private |
| */ |
| lastMoveY_: undefined, |
| |
| /** |
| * @type {number|undefined} |
| * @private |
| */ |
| longPressTimeout_: undefined, |
| |
| /** |
| * If defined and true, the next click event should be swallowed |
| * @type {boolean|undefined} |
| * @private |
| */ |
| swallowNextClick_: undefined, |
| |
| /** |
| * Start listenting for events. |
| * @param {boolean=} opt_capture True if the TouchHandler should listen to |
| * during the capture phase. |
| */ |
| enable: function(opt_capture) { |
| var capture = !!opt_capture; |
| |
| // Just listen to start events for now. When a touch is occuring we'll |
| // want to be subscribed to move and end events on the document, but we |
| // don't want to incur the cost of lots of no-op handlers on the document. |
| this.events_.add(this.element_, 'touchstart', this.onStart_.bind(this), |
| capture); |
| this.events_.add(this.element_, 'mousedown', |
| this.mouseToTouchCallback_(this.onStart_.bind(this)), |
| capture); |
| |
| // If the element is long-pressed, we may need to swallow a click |
| this.events_.add(this.element_, 'click', this.onClick_.bind(this), true); |
| }, |
| |
| /** |
| * Stop listening to all events. |
| */ |
| disable: function() { |
| this.stopTouching_(); |
| this.events_.removeAll(); |
| }, |
| |
| /** |
| * Wraps a callback with translations of mouse events to touch events. |
| * NOTE: These types really should be function(Event) but then we couldn't |
| * use this with bind (which operates on any type of function). Doesn't |
| * JSDoc support some sort of polymorphic types? |
| * @param {Function} callback The event callback. |
| * @return {Function} The wrapping callback. |
| * @private |
| */ |
| mouseToTouchCallback_: function(callback) { |
| return function(e) { |
| // Note that there may be synthesizes mouse events caused by touch |
| // events (a mouseDown after a touch-click). We leave it up to the |
| // client to worry about this if it matters to them (typically a short |
| // mouseDown/mouseUp without a click is no big problem and it's not |
| // obvious how we identify such synthesized events in a general way). |
| var touch = { |
| // any fixed value will do for the identifier - there will only |
| // ever be a single active 'touch' when using the mouse. |
| identifier: 0, |
| clientX: e.clientX, |
| clientY: e.clientY, |
| target: e.target |
| }; |
| e.touches = []; |
| e.targetTouches = []; |
| e.changedTouches = [touch]; |
| if (e.type != 'mouseup') { |
| e.touches[0] = touch; |
| e.targetTouches[0] = touch; |
| } |
| callback(e); |
| }; |
| }, |
| |
| /** |
| * Begin tracking the touchable element, it is eligible for dragging. |
| * @private |
| */ |
| beginTracking_: function() { |
| this.tracking_ = true; |
| }, |
| |
| /** |
| * Stop tracking the touchable element, it is no longer dragging. |
| * @private |
| */ |
| endTracking_: function() { |
| this.tracking_ = false; |
| this.dragging_ = false; |
| this.totalMoveY_ = 0; |
| this.totalMoveX_ = 0; |
| }, |
| |
| /** |
| * Reset the touchable element as if we never saw the touchStart |
| * Doesn't dispatch any end events - be careful of existing listeners. |
| */ |
| cancelTouch: function() { |
| this.stopTouching_(); |
| this.endTracking_(); |
| // If clients needed to be aware of this, we could fire a cancel event |
| // here. |
| }, |
| |
| /** |
| * Record that touching has stopped |
| * @private |
| */ |
| stopTouching_: function() { |
| // Mark as no longer being touched |
| this.activeTouch_ = undefined; |
| |
| // If we're waiting for a long press, stop |
| window.clearTimeout(this.longPressTimeout_); |
| |
| // Stop listening for move/end events until there's another touch. |
| // We don't want to leave handlers piled up on the document. |
| // Note that there's no harm in removing handlers that weren't added, so |
| // rather than track whether we're using mouse or touch we do both. |
| this.events_.remove(document, 'touchmove'); |
| this.events_.remove(document, 'touchend'); |
| this.events_.remove(document, 'touchcancel'); |
| this.events_.remove(document, 'mousemove'); |
| this.events_.remove(document, 'mouseup'); |
| }, |
| |
| /** |
| * Touch start handler. |
| * @param {!TouchEvent} e The touchstart event. |
| * @private |
| */ |
| onStart_: function(e) { |
| // Only process single touches. If there is already a touch happening, or |
| // two simultaneous touches then just ignore them. |
| if (e.touches.length > 1) |
| // Note that we could cancel an active touch here. That would make |
| // simultaneous touch behave similar to near-simultaneous. However, if |
| // the user is dragging something, an accidental second touch could be |
| // quite disruptive if it cancelled their drag. Better to just ignore |
| // it. |
| return; |
| |
| // It's still possible there could be an active "touch" if the user is |
| // simultaneously using a mouse and a touch input. |
| if (this.activeTouch_ !== undefined) |
| return; |
| |
| var touch = e.targetTouches[0]; |
| this.activeTouch_ = touch.identifier; |
| |
| // We've just started touching so shouldn't swallow any upcoming click |
| if (this.swallowNextClick_) |
| this.swallowNextClick_ = false; |
| |
| // Sign up for end/cancel notifications for this touch. |
| // Note that we do this on the document so that even if the user drags |
| // their finger off the element, we'll still know what they're doing. |
| if (e.type == 'mousedown') { |
| this.events_.add(document, 'mouseup', |
| this.mouseToTouchCallback_(this.onEnd_.bind(this)), false); |
| } else { |
| this.events_.add(document, 'touchend', this.onEnd_.bind(this), false); |
| this.events_.add(document, 'touchcancel', this.onEnd_.bind(this), |
| false); |
| } |
| |
| // This timeout is cleared on touchEnd and onDrag |
| // If we invoke the function then we have a real long press |
| window.clearTimeout(this.longPressTimeout_); |
| this.longPressTimeout_ = window.setTimeout( |
| this.onLongPress_.bind(this), |
| TouchHandler.TIME_FOR_LONG_PRESS_); |
| |
| // Dispatch the TOUCH_START event |
| if (!this.dispatchEvent_(TouchHandler.EventType.TOUCH_START, touch)) |
| // Dragging was not enabled, nothing more to do |
| return; |
| |
| // We want dragging notifications |
| if (e.type == 'mousedown') { |
| this.events_.add(document, 'mousemove', |
| this.mouseToTouchCallback_(this.onMove_.bind(this)), false); |
| } else { |
| this.events_.add(document, 'touchmove', this.onMove_.bind(this), false); |
| } |
| |
| this.startTouchX_ = this.lastTouchX_ = touch.clientX; |
| this.startTouchY_ = this.lastTouchY_ = touch.clientY; |
| this.startTime_ = e.timeStamp; |
| |
| this.recentTouchesX_ = []; |
| this.recentTouchesY_ = []; |
| this.recentTouchesX_.push(touch.clientX, e.timeStamp); |
| this.recentTouchesY_.push(touch.clientY, e.timeStamp); |
| |
| this.beginTracking_(); |
| }, |
| |
| /** |
| * Given a list of Touches, find the one matching our activeTouch |
| * identifier. Note that Chrome currently always uses 0 as the identifier. |
| * In that case we'll end up always choosing the first element in the list. |
| * @param {TouchList} touches The list of Touch objects to search. |
| * @return {!Touch|undefined} The touch matching our active ID if any. |
| * @private |
| */ |
| findActiveTouch_: function(touches) { |
| assert(this.activeTouch_ !== undefined, 'Expecting an active touch'); |
| // A TouchList isn't actually an array, so we shouldn't use |
| // Array.prototype.filter/some, etc. |
| for (var i = 0; i < touches.length; i++) { |
| if (touches[i].identifier == this.activeTouch_) |
| return touches[i]; |
| } |
| return undefined; |
| }, |
| |
| /** |
| * Touch move handler. |
| * @param {!TouchEvent} e The touchmove event. |
| * @private |
| */ |
| onMove_: function(e) { |
| if (!this.tracking_) |
| return; |
| |
| // Our active touch should always be in the list of touches still active |
| assert(this.findActiveTouch_(e.touches), 'Missing touchEnd'); |
| |
| var that = this; |
| var touch = this.findActiveTouch_(e.changedTouches); |
| if (!touch) |
| return; |
| |
| var clientX = touch.clientX; |
| var clientY = touch.clientY; |
| |
| var moveX = this.lastTouchX_ - clientX; |
| var moveY = this.lastTouchY_ - clientY; |
| this.totalMoveX_ += Math.abs(moveX); |
| this.totalMoveY_ += Math.abs(moveY); |
| this.lastTouchX_ = clientX; |
| this.lastTouchY_ = clientY; |
| |
| if (!this.dragging_ && (this.totalMoveY_ > |
| TouchHandler.MIN_TRACKING_FOR_DRAG_ || |
| this.totalMoveX_ > |
| TouchHandler.MIN_TRACKING_FOR_DRAG_)) { |
| // If we're waiting for a long press, stop |
| window.clearTimeout(this.longPressTimeout_); |
| |
| // Dispatch the DRAG_START event and record whether dragging should be |
| // allowed or not. Note that this relies on the current value of |
| // startTouchX/Y - handlers may use the initial drag delta to determine |
| // if dragging should be permitted. |
| this.dragging_ = this.dispatchEvent_( |
| TouchHandler.EventType.DRAG_START, touch); |
| |
| if (this.dragging_) { |
| // Update the start position here so that drag deltas have better |
| // values but don't touch the recent positions so that velocity |
| // calculations can still use touchstart position in the time and |
| // distance delta. |
| this.startTouchX_ = clientX; |
| this.startTouchY_ = clientY; |
| this.startTime_ = e.timeStamp; |
| } else { |
| this.endTracking_(); |
| } |
| } |
| |
| if (this.dragging_) { |
| this.dispatchEvent_(TouchHandler.EventType.DRAG_MOVE, touch); |
| |
| this.removeTouchesInWrongDirection_(this.recentTouchesX_, |
| this.lastMoveX_, moveX); |
| this.removeTouchesInWrongDirection_(this.recentTouchesY_, |
| this.lastMoveY_, moveY); |
| this.removeOldTouches_(this.recentTouchesX_, e.timeStamp); |
| this.removeOldTouches_(this.recentTouchesY_, e.timeStamp); |
| this.recentTouchesX_.push(clientX, e.timeStamp); |
| this.recentTouchesY_.push(clientY, e.timeStamp); |
| } |
| |
| this.lastMoveX_ = moveX; |
| this.lastMoveY_ = moveY; |
| }, |
| |
| /** |
| * Filters the provided recent touches array to remove all touches except |
| * the last if the move direction has changed. |
| * @param {!Array.<number>} recentTouches An array of tuples where the first |
| * item is the x or y component of the recent touch and the second item |
| * is the touch time stamp. |
| * @param {number|undefined} lastMove The x or y component of the previous |
| * move. |
| * @param {number} recentMove The x or y component of the most recent move. |
| * @private |
| */ |
| removeTouchesInWrongDirection_: function(recentTouches, lastMove, |
| recentMove) { |
| if (lastMove && recentMove && recentTouches.length > 2 && |
| (lastMove > 0 ^ recentMove > 0)) { |
| recentTouches.splice(0, recentTouches.length - 2); |
| } |
| }, |
| |
| /** |
| * Filters the provided recent touches array to remove all touches older |
| * than the max tracking time or the 5th most recent touch. |
| * @param {!Array.<number>} recentTouches An array of tuples where the first |
| * item is the x or y component of the recent touch and the second item |
| * is the touch time stamp. |
| * @param {number} recentTime The time of the most recent event. |
| * @private |
| */ |
| removeOldTouches_: function(recentTouches, recentTime) { |
| while (recentTouches.length && recentTime - recentTouches[1] > |
| TouchHandler.MAX_TRACKING_TIME_ || |
| recentTouches.length > |
| TouchHandler.MAX_TRACKING_TOUCHES_ * 2) { |
| recentTouches.splice(0, 2); |
| } |
| }, |
| |
| /** |
| * Touch end handler. |
| * @param {!TouchEvent} e The touchend event. |
| * @private |
| */ |
| onEnd_: function(e) { |
| var that = this; |
| assert(this.activeTouch_ !== undefined, 'Expect to already be touching'); |
| |
| // If the touch we're tracking isn't changing here, ignore this touch end. |
| var touch = this.findActiveTouch_(e.changedTouches); |
| if (!touch) { |
| // In most cases, our active touch will be in the 'touches' collection, |
| // but we can't assert that because occasionally two touchend events can |
| // occur at almost the same time with both having empty 'touches' lists. |
| // I.e., 'touches' seems like it can be a bit more up-to-date than the |
| // current event. |
| return; |
| } |
| |
| // This is touchEnd for the touch we're monitoring |
| assert(!this.findActiveTouch_(e.touches), |
| 'Touch ended also still active'); |
| |
| // Indicate that touching has finished |
| this.stopTouching_(); |
| |
| if (this.tracking_) { |
| var clientX = touch.clientX; |
| var clientY = touch.clientY; |
| |
| if (this.dragging_) { |
| this.endTime_ = e.timeStamp; |
| this.endTouchX_ = clientX; |
| this.endTouchY_ = clientY; |
| |
| this.removeOldTouches_(this.recentTouchesX_, e.timeStamp); |
| this.removeOldTouches_(this.recentTouchesY_, e.timeStamp); |
| |
| this.dispatchEvent_(TouchHandler.EventType.DRAG_END, touch); |
| |
| // Note that in some situations we can get a click event here as well. |
| // For now this isn't a problem, but we may want to consider having |
| // some logic that hides clicks that appear to be caused by a touchEnd |
| // used for dragging. |
| } |
| |
| this.endTracking_(); |
| } |
| |
| // Note that we dispatch the touchEnd event last so that events at |
| // different levels of semantics nest nicely (similar to how DOM |
| // drag-and-drop events are nested inside of the mouse events that trigger |
| // them). |
| this.dispatchEvent_(TouchHandler.EventType.TOUCH_END, touch); |
| }, |
| |
| /** |
| * Get end velocity of the drag. This method is specific to drag behavior, |
| * so if touch behavior and drag behavior is split then this should go with |
| * drag behavior. End velocity is defined as deltaXY / deltaTime where |
| * deltaXY is the difference between endPosition and the oldest recent |
| * position, and deltaTime is the difference between endTime and the oldest |
| * recent time stamp. |
| * @return {Object} The x and y velocity. |
| */ |
| getEndVelocity: function() { |
| // Note that we could move velocity to just be an end-event parameter. |
| var velocityX = this.recentTouchesX_.length ? |
| (this.endTouchX_ - this.recentTouchesX_[0]) / |
| (this.endTime_ - this.recentTouchesX_[1]) : 0; |
| var velocityY = this.recentTouchesY_.length ? |
| (this.endTouchY_ - this.recentTouchesY_[0]) / |
| (this.endTime_ - this.recentTouchesY_[1]) : 0; |
| |
| velocityX = this.correctVelocity_(velocityX); |
| velocityY = this.correctVelocity_(velocityY); |
| |
| return { |
| x: velocityX, |
| y: velocityY |
| }; |
| }, |
| |
| /** |
| * Correct erroneous velocities by capping the velocity if we think it's too |
| * high, or setting it to a default velocity if know that the event data is |
| * bad. |
| * @param {number} velocity The x or y velocity component. |
| * @return {number} The corrected velocity. |
| * @private |
| */ |
| correctVelocity_: function(velocity) { |
| var absVelocity = Math.abs(velocity); |
| |
| // We add to recent touches for each touchstart and touchmove. If we have |
| // fewer than 3 touches (6 entries), we assume that the thread was blocked |
| // for the duration of the drag and we received events in quick succession |
| // with the wrong time stamps. |
| if (absVelocity > TouchHandler.MAXIMUM_VELOCITY_) { |
| absVelocity = this.recentTouchesY_.length < 3 ? |
| TouchHandler.VELOCITY_FOR_INCORRECT_EVENTS_ : |
| TouchHandler.MAXIMUM_VELOCITY_; |
| } |
| return absVelocity * (velocity < 0 ? -1 : 1); |
| }, |
| |
| /** |
| * Handler when an element has been pressed for a long time |
| * @private |
| */ |
| onLongPress_: function() { |
| // Swallow any click that occurs on this element without an intervening |
| // touch start event. This simple click-busting technique should be |
| // sufficient here since a real click should have a touchstart first. |
| this.swallowNextClick_ = true; |
| |
| // Dispatch to the LONG_PRESS |
| this.dispatchEventXY_(TouchHandler.EventType.LONG_PRESS, this.element_, |
| this.startTouchX_, this.startTouchY_); |
| }, |
| |
| /** |
| * Click handler - used to swallow clicks after a long-press |
| * @param {!Event} e The click event. |
| * @private |
| */ |
| onClick_: function(e) { |
| if (this.swallowNextClick_) { |
| e.preventDefault(); |
| e.stopPropagation(); |
| this.swallowNextClick_ = false; |
| } |
| }, |
| |
| /** |
| * Dispatch a TouchHandler event to the element |
| * @param {string} eventType The event to dispatch. |
| * @param {Touch} touch The touch triggering this event. |
| * @return {boolean|undefined} The value of enableDrag after dispatching |
| * the event. |
| * @private |
| */ |
| dispatchEvent_: function(eventType, touch) { |
| |
| // Determine which element was touched. For mouse events, this is always |
| // the event/touch target. But for touch events, the target is always the |
| // target of the touchstart (and it's unlikely we can change this |
| // since the common implementation of touch dragging relies on it). Since |
| // touch is our primary scenario (which we want to emulate with mouse), |
| // we'll treat both cases the same and not depend on the target. |
| var touchedElement; |
| if (eventType == TouchHandler.EventType.TOUCH_START) { |
| touchedElement = touch.target; |
| } else { |
| touchedElement = this.element_.ownerDocument. |
| elementFromPoint(touch.clientX, touch.clientY); |
| } |
| |
| return this.dispatchEventXY_(eventType, touchedElement, touch.clientX, |
| touch.clientY); |
| }, |
| |
| /** |
| * Dispatch a TouchHandler event to the element |
| * @param {string} eventType The event to dispatch. |
| @param {number} clientX The X location for the event. |
| @param {number} clientY The Y location for the event. |
| * @return {boolean|undefined} The value of enableDrag after dispatching |
| * the event. |
| * @private |
| */ |
| dispatchEventXY_: function(eventType, touchedElement, clientX, clientY) { |
| var isDrag = (eventType == TouchHandler.EventType.DRAG_START || |
| eventType == TouchHandler.EventType.DRAG_MOVE || |
| eventType == TouchHandler.EventType.DRAG_END); |
| |
| // Drag events don't bubble - we're really just dragging the element, |
| // not affecting its parent at all. |
| var bubbles = !isDrag; |
| |
| var event = new TouchHandler.Event(eventType, bubbles, clientX, clientY, |
| touchedElement); |
| |
| // Set enableDrag when it can be overridden |
| if (eventType == TouchHandler.EventType.TOUCH_START) |
| event.enableDrag = false; |
| else if (eventType == TouchHandler.EventType.DRAG_START) |
| event.enableDrag = true; |
| |
| if (isDrag) { |
| event.dragDeltaX = clientX - this.startTouchX_; |
| event.dragDeltaY = clientY - this.startTouchY_; |
| } |
| |
| this.element_.dispatchEvent(event); |
| return event.enableDrag; |
| } |
| }; |
| |
| return TouchHandler; |
| })(); |
