| // Copyright 2014 The Closure Library Authors. All Rights Reserved. |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS-IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| /** |
| * @fileoverview This class aims to smooth out inconsistencies between browser |
| * handling of wheel events by providing an event that is similar to that |
| * defined in the standard, but also easier to consume. |
| * |
| * It is based upon the WheelEvent, which allows for up to 3 dimensional |
| * scrolling events that come in units of either pixels, lines or pages. |
| * http://www.w3.org/TR/2014/WD-DOM-Level-3-Events-20140925/#interface-WheelEvent |
| * |
| * The significant difference here is that it also provides reasonable pixel |
| * deltas for clients that do not want to treat line and page scrolling events |
| * specially. |
| * |
| * Clients of this code should be aware that some input devices only fire a few |
| * discrete events (such as a mouse wheel without acceleration) whereas some can |
| * generate a large number of events for a single interaction (such as a |
| * touchpad with acceleration). There is no signal in the events to reliably |
| * distinguish between these. |
| * |
| * @see ../demos/wheelhandler.html |
| */ |
| |
| goog.provide('goog.events.WheelEvent'); |
| |
| goog.require('goog.asserts'); |
| goog.require('goog.events.BrowserEvent'); |
| |
| |
| |
| /** |
| * A common class for wheel events. This is used with the WheelHandler. |
| * |
| * @param {Event} browserEvent Browser event object. |
| * @param {goog.events.WheelEvent.DeltaMode} deltaMode The delta mode units of |
| * the wheel event. |
| * @param {number} deltaX The number of delta units the user in the X axis. |
| * @param {number} deltaY The number of delta units the user in the Y axis. |
| * @param {number} deltaZ The number of delta units the user in the Z axis. |
| * @constructor |
| * @extends {goog.events.BrowserEvent} |
| * @final |
| */ |
| goog.events.WheelEvent = function( |
| browserEvent, deltaMode, deltaX, deltaY, deltaZ) { |
| goog.events.WheelEvent.base(this, 'constructor', browserEvent); |
| goog.asserts.assert(browserEvent, 'Expecting a non-null browserEvent'); |
| |
| /** @type {goog.events.WheelEvent.EventType} */ |
| this.type = goog.events.WheelEvent.EventType.WHEEL; |
| |
| /** |
| * An enum corresponding to the units of this event. |
| * @type {goog.events.WheelEvent.DeltaMode} |
| */ |
| this.deltaMode = deltaMode; |
| |
| /** |
| * The number of delta units in the X axis. |
| * @type {number} |
| */ |
| this.deltaX = deltaX; |
| |
| /** |
| * The number of delta units in the Y axis. |
| * @type {number} |
| */ |
| this.deltaY = deltaY; |
| |
| /** |
| * The number of delta units in the Z axis. |
| * @type {number} |
| */ |
| this.deltaZ = deltaZ; |
| |
| // Ratio between delta and pixel values. |
| var pixelRatio = 1; // Value for DeltaMode.PIXEL |
| switch (deltaMode) { |
| case goog.events.WheelEvent.DeltaMode.PAGE: |
| pixelRatio *= goog.events.WheelEvent.PIXELS_PER_PAGE_; |
| break; |
| case goog.events.WheelEvent.DeltaMode.LINE: |
| pixelRatio *= goog.events.WheelEvent.PIXELS_PER_LINE_; |
| break; |
| } |
| |
| /** |
| * The number of delta pixels in the X axis. Code that doesn't want to handle |
| * different deltaMode units can just look here. |
| * @type {number} |
| */ |
| this.pixelDeltaX = this.deltaX * pixelRatio; |
| |
| /** |
| * The number of pixels in the Y axis. Code that doesn't want to |
| * handle different deltaMode units can just look here. |
| * @type {number} |
| */ |
| this.pixelDeltaY = this.deltaY * pixelRatio; |
| |
| /** |
| * The number of pixels scrolled in the Z axis. Code that doesn't want to |
| * handle different deltaMode units can just look here. |
| * @type {number} |
| */ |
| this.pixelDeltaZ = this.deltaZ * pixelRatio; |
| }; |
| goog.inherits(goog.events.WheelEvent, goog.events.BrowserEvent); |
| |
| |
| /** |
| * Enum type for the events fired by the wheel handler. |
| * @enum {string} |
| */ |
| goog.events.WheelEvent.EventType = { |
| /** The user has provided wheel-based input. */ |
| WHEEL: 'wheel' |
| }; |
| |
| |
| /** |
| * Units for the deltas in a WheelEvent. |
| * @enum {number} |
| */ |
| goog.events.WheelEvent.DeltaMode = { |
| /** The units are in pixels. From DOM_DELTA_PIXEL. */ |
| PIXEL: 0, |
| /** The units are in lines. From DOM_DELTA_LINE. */ |
| LINE: 1, |
| /** The units are in pages. From DOM_DELTA_PAGE. */ |
| PAGE: 2 |
| }; |
| |
| |
| /** |
| * A conversion number between line scroll units and pixel scroll units. The |
| * actual value per line can vary a lot between devices and font sizes. This |
| * number can not be perfect, but it should be reasonable for converting lines |
| * scroll events into pixels. |
| * @const {number} |
| * @private |
| */ |
| goog.events.WheelEvent.PIXELS_PER_LINE_ = 15; |
| |
| |
| /** |
| * A conversion number between page scroll units and pixel scroll units. The |
| * actual value per page can vary a lot as many different devices have different |
| * screen sizes, and the window might not be taking up the full screen. This |
| * number can not be perfect, but it should be reasonable for converting page |
| * scroll events into pixels. |
| * @const {number} |
| * @private |
| */ |
| goog.events.WheelEvent.PIXELS_PER_PAGE_ = 30 * |
| goog.events.WheelEvent.PIXELS_PER_LINE_; |