lisn.js
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Simply handle user gestures and actions. Includes widgets.
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JavaScript
/**
* @module
* @ignore
* @internal
*
* FULL CREDIT FOR THIS GOES TO
* https://github.com/facebookarchive/fixed-data-table/blob/master/src/vendor_upstream/dom/normalizeWheel.js
*
* ADAPTED FROM THE ABOVE SOURCE
*
* ORIGINAL COPYRIGHT IN FILE PRESERVED:
*
* Copyright (c) 2015, Facebook, Inc.
* All rights reserved.
*
* This source code is licensed under the BSD-style license found in the
* LICENSE file in the root directory of this source tree. An additional grant
* of patent rights can be found in the PATENTS file in the same directory.
*
* ORIGINAL LICENSE
*
* BSD License
*
* For FixedDataTable software
*
* Copyright (c) 2015, Facebook, Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification,
* are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* * Neither the name Facebook nor the names of its contributors may be used to
* endorse or promote products derived from this software without specific
* prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
* ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
import { settings } from "../globals/settings.js";
/**
* ORIGINAL DEVELOPER COMMENT PRESERVED
*
* Mouse wheel (and 2-finger trackpad) support on the web sucks. It is
* complicated, thus this doc is long and (hopefully) detailed enough to answer
* your questions.
*
* If you need to react to the mouse wheel in a predictable way, this code is
* like your bestest friend. * hugs *
*
* As of today, there are 4 DOM event types you can listen to:
*
* 'wheel' -- Chrome(31+), FF(17+), IE(9+)
* 'mousewheel' -- Chrome, IE(6+), Opera, Safari
* 'MozMousePixelScroll' -- FF(3.5 only!) (2010-2013) -- don't bother!
* 'DOMMouseScroll' -- FF(0.9.7+) since 2003
*
* So what to do? The is the best:
*
* normalizeWheel.getEventType();
*
* In your event callback, use this code to get sane interpretation of the
* deltas. This code will return an object with properties:
*
* spinX -- normalized spin speed (use for zoom) - x plane
* spinY -- " - y plane
* pixelX -- normalized distance (to pixels) - x plane
* pixelY -- " - y plane
*
* Wheel values are provided by the browser assuming you are using the wheel to
* scroll a web page by a number of lines or pixels (or pages). Values can vary
* significantly on different platforms and browsers, forgetting that you can
* scroll at different speeds. Some devices (like trackpads) emit more events
* at smaller increments with fine granularity, and some emit massive jumps with
* linear speed or acceleration.
*
* This code does its best to normalize the deltas for you:
*
* - spin is trying to normalize how far the wheel was spun (or trackpad
* dragged). This is super useful for zoom support where you want to
* throw away the chunky scroll steps on the PC and make those equal to
* the slow and smooth tiny steps on the Mac. Key data: This code tries to
* resolve a single slow step on a wheel to 1.
*
* - pixel is normalizing the desired scroll delta in pixel units. You'll
* get the crazy differences between browsers, but at least it'll be in
* pixels!
*
* - positive value indicates scrolling DOWN/RIGHT, negative UP/LEFT. This
* should translate to positive value zooming IN, negative zooming OUT.
* This matches the newer 'wheel' event.
*
* Why are there spinX, spinY (or pixels)?
*
* - spinX is a 2-finger side drag on the trackpad, and a shift + wheel turn
* with a mouse. It results in side-scrolling in the browser by default.
*
* - spinY is what you expect -- it's the classic axis of a mouse wheel.
*
* - I dropped spinZ/pixelZ. It is supported by the DOM 3 'wheel' event and
* probably is by browsers in conjunction with fancy 3D controllers .. but
* you know.
*
* Implementation info:
*
* Examples of 'wheel' event if you scroll slowly (down) by one step with an
* average mouse:
*
* OS X + Chrome (mouse) - 4 pixel delta (wheelDelta -120)
* OS X + Safari (mouse) - N/A pixel delta (wheelDelta -12)
* OS X + Firefox (mouse) - 0.1 line delta (wheelDelta N/A)
* Win8 + Chrome (mouse) - 100 pixel delta (wheelDelta -120)
* Win8 + Firefox (mouse) - 3 line delta (wheelDelta -120)
*
* On the trackpad:
*
* OS X + Chrome (trackpad) - 2 pixel delta (wheelDelta -6)
* OS X + Firefox (trackpad) - 1 pixel delta (wheelDelta N/A)
*
* On other/older browsers.. it's more complicated as there can be multiple and
* also missing delta values.
*
* The 'wheel' event is more standard:
*
* http://www.w3.org/TR/DOM-Level-3-Events/#events-wheelevents
*
* The basics is that it includes a unit, deltaMode (pixels, lines, pages), and
* deltaX, deltaY and deltaZ. Some browsers provide other values to maintain
* backward compatibility with older events. Those other values help us
* better normalize spin speed. Example of what the browsers provide:
*
* | event.wheelDelta | event.detail
* ------------------+------------------+--------------
* Safari v5/OS X | -120 | 0
* Safari v5/Win7 | -120 | 0
* Chrome v17/OS X | -120 | 0
* Chrome v17/Win7 | -120 | 0
* IE9/Win7 | -120 | undefined
* Firefox v4/OS X | undefined | 1
* Firefox v4/Win7 | undefined | 3
*/
export const normalizeWheel = event => {
let spinX = 0,
spinY = 0,
pixelX = event.deltaX,
pixelY = event.deltaY;
const LINE = settings.deltaLineHeight;
// Legacy
if (event.detail !== undefined) {
spinY = event.detail;
}
if (event.wheelDelta !== undefined) {
spinY = -event.wheelDelta / 120;
}
if (event.wheelDeltaY !== undefined) {
spinY = -event.wheelDeltaY / 120;
}
if (event.wheelDeltaX !== undefined) {
spinX = -event.wheelDeltaX / 120;
}
if ((pixelX || pixelY) && event.deltaMode) {
if (event.deltaMode === 1) {
// delta in LINE units
pixelX *= LINE;
pixelY *= LINE;
} else {
// delta in PAGE units
pixelX *= settings.deltaPageWidth;
pixelY *= settings.deltaPageHeight;
}
}
// Fall-back if spin cannot be determined
if (pixelX && !spinX) {
spinX = pixelX < 1 ? -1 : 1;
}
if (pixelY && !spinY) {
spinY = pixelY < 1 ? -1 : 1;
}
return {
spinX,
spinY,
pixelX,
pixelY
};
};
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