| 1 | /**
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| 2 | * Mouse wheel (and 2-finger trackpad) support on the web sucks. It is
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| 3 | * complicated, thus this doc is long and (hopefully) detailed enough to answer
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| 4 | * your questions.
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| 5 | *
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| 6 | * If you need to react to the mouse wheel in a predictable way, this code is
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| 7 | * like your bestest friend. * hugs *
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| 8 | *
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| 9 | * As of today, there are 4 DOM event types you can listen to:
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| 10 | *
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| 11 | * 'wheel' -- Chrome(31+), FF(17+), IE(9+)
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| 12 | * 'mousewheel' -- Chrome, IE(6+), Opera, Safari
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| 13 | * 'MozMousePixelScroll' -- FF(3.5 only!) (2010-2013) -- don't bother!
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| 14 | * 'DOMMouseScroll' -- FF(0.9.7+) since 2003
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| 15 | *
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| 16 | * So what to do? The is the best:
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| 17 | *
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| 18 | * normalizeWheel.getEventType();
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| 19 | *
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| 20 | * In your event callback, use this code to get sane interpretation of the
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| 21 | * deltas. This code will return an object with properties:
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| 22 | *
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| 23 | * spinX -- normalized spin speed (use for zoom) - x plane
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| 24 | * spinY -- " - y plane
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| 25 | * pixelX -- normalized distance (to pixels) - x plane
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| 26 | * pixelY -- " - y plane
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| 27 | *
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| 28 | * Wheel values are provided by the browser assuming you are using the wheel to
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| 29 | * scroll a web page by a number of lines or pixels (or pages). Values can vary
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| 30 | * significantly on different platforms and browsers, forgetting that you can
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| 31 | * scroll at different speeds. Some devices (like trackpads) emit more events
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| 32 | * at smaller increments with fine granularity, and some emit massive jumps with
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| 33 | * linear speed or acceleration.
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| 34 | *
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| 35 | * This code does its best to normalize the deltas for you:
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| 36 | *
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| 37 | * - spin is trying to normalize how far the wheel was spun (or trackpad
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| 38 | * dragged). This is super useful for zoom support where you want to
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| 39 | * throw away the chunky scroll steps on the PC and make those equal to
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| 40 | * the slow and smooth tiny steps on the Mac. Key data: This code tries to
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| 41 | * resolve a single slow step on a wheel to 1.
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| 42 | *
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| 43 | * - pixel is normalizing the desired scroll delta in pixel units. You'll
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| 44 | * get the crazy differences between browsers, but at least it'll be in
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| 45 | * pixels!
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| 46 | *
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| 47 | * - positive value indicates scrolling DOWN/RIGHT, negative UP/LEFT. This
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| 48 | * should translate to positive value zooming IN, negative zooming OUT.
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| 49 | * This matches the newer 'wheel' event.
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| 50 | *
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| 51 | * Why are there spinX, spinY (or pixels)?
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| 52 | *
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| 53 | * - spinX is a 2-finger side drag on the trackpad, and a shift + wheel turn
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| 54 | * with a mouse. It results in side-scrolling in the browser by default.
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| 55 | *
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| 56 | * - spinY is what you expect -- it's the classic axis of a mouse wheel.
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| 57 | *
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| 58 | * - I dropped spinZ/pixelZ. It is supported by the DOM 3 'wheel' event and
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| 59 | * probably is by browsers in conjunction with fancy 3D controllers .. but
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| 60 | * you know.
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| 61 | *
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| 62 | * Implementation info:
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| 63 | *
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| 64 | * Examples of 'wheel' event if you scroll slowly (down) by one step with an
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| 65 | * average mouse:
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| 66 | *
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| 67 | * OS X + Chrome (mouse) - 4 pixel delta (wheelDelta -120)
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| 68 | * OS X + Safari (mouse) - N/A pixel delta (wheelDelta -12)
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| 69 | * OS X + Firefox (mouse) - 0.1 line delta (wheelDelta N/A)
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| 70 | * Win8 + Chrome (mouse) - 100 pixel delta (wheelDelta -120)
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| 71 | * Win8 + Firefox (mouse) - 3 line delta (wheelDelta -120)
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| 72 | *
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| 73 | * On the trackpad:
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| 74 | *
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| 75 | * OS X + Chrome (trackpad) - 2 pixel delta (wheelDelta -6)
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| 76 | * OS X + Firefox (trackpad) - 1 pixel delta (wheelDelta N/A)
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| 77 | *
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| 78 | * On other/older browsers.. it's more complicated as there can be multiple and
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| 79 | * also missing delta values.
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| 80 | *
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| 81 | * The 'wheel' event is more standard:
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| 82 | *
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| 83 | * http://www.w3.org/TR/DOM-Level-3-Events/#events-wheelevents
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| 84 | *
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| 85 | * The basics is that it includes a unit, deltaMode (pixels, lines, pages), and
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| 86 | * deltaX, deltaY and deltaZ. Some browsers provide other values to maintain
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| 87 | * backward compatibility with older events. Those other values help us
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| 88 | * better normalize spin speed. Example of what the browsers provide:
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| 89 | *
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| 90 | * | event.wheelDelta | event.detail
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| 91 | * ------------------+------------------+--------------
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| 92 | * Safari v5/OS X | -120 | 0
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| 93 | * Safari v5/Win7 | -120 | 0
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| 94 | * Chrome v17/OS X | -120 | 0
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| 95 | * Chrome v17/Win7 | -120 | 0
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| 96 | * IE9/Win7 | -120 | undefined
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| 97 | * Firefox v4/OS X | undefined | 1
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| 98 | * Firefox v4/Win7 | undefined | 3
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| 99 | */
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| 100 | declare function normalizeWheel(event: any): { spinX: number; spinY: number; pixelX: number; pixelY: number };
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| 101 |
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| 102 | declare namespace normalizeWheel {
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| 103 | function getEventType(): "wheel" | "mousewheel" | "DOMMouseScroll";
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| 104 | }
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| 105 |
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| 106 | export = normalizeWheel;
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