mirror of
https://github.com/flynx/ImageGrid.git
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522 lines
15 KiB
JavaScript
Executable File
522 lines
15 KiB
JavaScript
Executable File
/**********************************************************************
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*
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* General Swipe/Scroll handler lib
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*
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* TODO a demo page to show/test the features...
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*
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**********************************************************************/
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//var DEBUG = DEBUG != null ? DEBUG : true
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// click threshold in pixels, if the distance between start and end is
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// less than this, the whole event is considered a click and not a
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// drag/swipe...
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var CLICK_THRESHOLD = 10
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// if the amount of time to wait bteween start and end is greater than
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// this the event is considered a long click.
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// NOTE: this will not auto-fire the event, the user MUST release first.
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var LONG_CLICK_THRESHOLD = 400
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// the maximum amount of time between clicks to count them together.
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// NOTE: if multi-clicks are disabled this has no effect.
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// NOTE: this is reset by the timeout explicitly set in the handler...
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// NOTE: this is the timeout between two consecutive clicks and not the
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// total.
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// NOTE: if multiple clicks are enabled this will introduce a lag after
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// each click (while we wait for the next), so keep this as small
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// as possible, but not too small as to rush the user too much.
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var MULTI_CLICK_TIMEOUT = 200
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// the amount of time between finger releases.
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// NOTE: when this is passed all the fingers released before are ignored.
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var MULTITOUCH_RELEASE_THRESHOLD = 100
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/*********************************************************************/
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// Scroll handler
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//
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// This will take two elements a root (container) and a scrolled (first
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// child of the container) and implement drag-scrolling of the scrolled
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// within the root.
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//
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// This calls the following callbacks if they are defined.
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// - preCallback (unset)
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// - scrollCallback (unset)
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// - postCallback (set to postScrollCallback)
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//
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// See scroller.options for configuration.
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//
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//
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// XXX add a resonable cancel scheme...
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// ... something similar to touch threshold but bigger...
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// XXX setup basic styles for the contained element...
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// XXX revise...
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// XXX test on other devices...
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function makeScrollHandler(root, config){
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root = $(root)
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// local data...
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var ignoring = false
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// XXX this and scroller.state are redundent...
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var scrolling = false
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var touch = false
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var touches = 0
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var max_dx = 0
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var max_dy = 0
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var cancelThreshold, scrolled
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// initial state...
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, start_x, start_y, start_t
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// previous state...
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, prev_x, prev_y, prev_t
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// current state...
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, x, y, t
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// state delta...
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, dx, dy, dt
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, shift
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, scale
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//, bounds
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function startMoveHandler(evt){
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var options = scroller.options
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// ignore...
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if(options.ignoreElements
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&& $(evt.target).closest(options.ignoreElements).length > 0
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|| scroller.state == 'paused'){
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ignoring = true
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return
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} else {
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ignoring = false
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}
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if(event.touches != null){
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touch = true
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}
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cancelThreshold = options.scrollCancelThreshold
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touches = touch ? event.touches.length : 1
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// if we are already touching then just skip on this...
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// XXX test this...
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if(touches > 1){
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return false
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}
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prev_t = event.timeStamp || Date.now();
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start_t = prev_t
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/*
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if(options.autoCancelEvents){
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bounds = {
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left: options.eventBounds,
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right: root.width() - options.eventBounds,
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top: options.eventBounds,
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bottom: root.height() - options.eventBounds
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}
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}
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*/
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//scrolled = $(root.children()[0])
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scrolled = root.children().first()
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setTransitionDuration(scrolled, 0)
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// XXX these two are redundant...
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scrolling = true
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scroller.state = 'scrolling'
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// XXX do we need to pass something to this?
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options.preCallback && options.preCallback()
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shift = getElementShift(scrolled)
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scale = getElementScale(scrolled)
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// get the user coords...
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prev_x = touch ? event.touches[0].pageX : evt.clientX
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start_x = prev_x
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prev_y = touch ? event.touches[0].pageY : evt.clientY
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start_y = prev_y
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return false
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}
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// XXX try and make this adaptive to stay ahead of the lags...
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// NOTE: this does not support limiting the scroll, might be done in
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// the future though.
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// The way to go about this is to track scrolled size in the
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// callback...
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function moveHandler(evt){
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if(ignoring){
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return
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}
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var options = scroller.options
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evt.preventDefault()
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t = event.timeStamp || Date.now();
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// get the user coords...
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x = touch ? event.touches[0].pageX : evt.clientX
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y = touch ? event.touches[0].pageY : evt.clientY
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touches = touch ? event.touches.length : 1
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/*
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// XXX needs testing...
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// XXX do we need to account for scrollDisabled here???
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// check scroll bounds...
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if(bounds != null){
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if(options.hScroll && (x <= bounds.left || x >= bounds.right)
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|| options.vScroll && (y <= bounds.top || y >= bounds.bottom)){
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// XXX cancel the touch event and trigger the end handler...
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return endMoveHandler(evt)
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}
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}
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*/
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// do the actual scroll...
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if(!options.scrollDisabled && scrolling){
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if(options.hScroll){
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shift.left += x - prev_x
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}
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if(options.vScroll){
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shift.top += y - prev_y
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}
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setElementTransform(scrolled, shift, scale)
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// XXX these should be done every time the event is caught or
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// just while scrolling?
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dx = x - prev_x
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dy = y - prev_y
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max_dx += Math.abs(dx)
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max_dy += Math.abs(dy)
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dt = t - prev_t
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prev_x = x
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prev_y = y
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prev_t = t
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// XXX do we need to pass something to this?
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options.scrollCallback && options.scrollCallback()
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}
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return false
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}
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function endMoveHandler(evt){
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t = event.timeStamp || Date.now();
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touches = touch ? event.touches.length : 0
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if(ignoring){
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if(touches == 0){
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ignoring = false
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}
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return
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}
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var options = scroller.options
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// XXX get real transition duration...
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scroller.resetTransitions()
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x = touch ? event.changedTouches[0].pageX : evt.clientX
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y = touch ? event.changedTouches[0].pageY : evt.clientY
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// check if we are canceling...
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if(cancelThreshold
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&& Math.abs(start_x-x) < cancelThreshold
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&& Math.abs(start_y-y) < cancelThreshold
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&& (max_dx > cancelThreshold
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|| max_dy > cancelThreshold)){
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scroller.state = 'canceling'
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}
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var data = {
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orig_event: evt,
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scroller: scroller,
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speed: {
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x: dx/dt,
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y: dy/dt
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},
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distance: {
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x: start_x-x,
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y: start_y-y
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},
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duration: t-start_t,
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// current touches...
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touches: touches,
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clicks: null,
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}
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// XXX stop only if no fingers are touching or let the callback decide...
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if(options.postCallback
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// XXX revise this....
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&& options.postCallback(data) === false
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|| touches == 0){
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// cleanup and stop...
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touch = false
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scrolling = false
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scroller.state = 'waiting'
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scrolled = null
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//bounds = null
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max_dx = 0
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max_dy = 0
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}
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return false
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}
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var scroller = {
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options: {
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// if one of these is false, it will restrict scrolling in
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// that direction. hScroll for horizontal and vScroll for
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// vertical.
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// NOTE: to disable scroll completely use scrollDisabled, see
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// below for details.
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hScroll: true,
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vScroll: true,
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// this will disable scroll.
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// NOTE: this is the same as setting both vScroll and hScroll
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// to false, but can be set and reset without affecting
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// the actual settings individually...
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// NOTE: this takes priority over hScroll/vScroll.
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scrollDisabled: false,
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// sets the default transition settings while not scrolling...
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transitionDuration: 200,
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transitionEasing: 'ease',
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// items to be ignored by the scroller...
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// this is a jQuery compatible selector.
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ignoreElements: '.noScroll',
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// this is the side of the rectangle in px, if the user moves
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// out of it, and then returns back, the action will get cancelled.
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// i.e. the callback will get called with the "cancelling" state.
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scrollCancelThreshold: 100,
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/*
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// XXX padding within the target element moving out of which
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// will cancell the action...
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// XXX needs testing...
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autoCancelEvents: false,
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eventBounds: 5,
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*/
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// callback to be called when the user first touches the screen...
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preCallback: null,
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// callback to be called when a scroll step is done...
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scrollCallback: null,
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// callback to be called when the user lifts a finger/mouse.
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// NOTE: this may happen before the scroll is done, for instance
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// when one of several fingers participating in the action
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// gets lifted.
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// NOTE: if this returns false explicitly, this will stop scrolling.
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postCallback: postScrollCallback,
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// These are used by the default callback...
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//
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// if true then doubleClick and multiClick events will get
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// triggered.
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// NOTE: this will introduce a lag needed to wait for next
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// clicks in a group.
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// NOTE: when this is false, shortClick is triggered for every
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// single click separately.
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enableMultiClicks: false,
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// NOTE: if these are null, respective values from the env will
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// be used.
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clickThreshold: null,
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longClickThreshold: null,
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multiClickTimeout: null,
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multitouchTimeout: null,
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},
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state: 'stopped',
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root: root,
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start: function(){
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if(this.state == 'paused'){
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this.state = 'waiting'
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} else {
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this.state = 'waiting'
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// NOTE: if we bind both touch and mouse events, on touch devices they
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// might start interfering with each other...
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if('ontouchmove' in window){
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root
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.on('touchstart', startMoveHandler)
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.on('touchmove', moveHandler)
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.on('touchend', endMoveHandler)
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.on('touchcancel', endMoveHandler)
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} else {
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root
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.on('mousedown', startMoveHandler)
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.on('mousemove', moveHandler)
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.on('mouseup', endMoveHandler)
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}
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}
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// setup transitions...
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this.resetTransitions()
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return this
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},
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// XXX test...
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pause: function(){
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this.state = 'paused'
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return this
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},
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stop: function(){
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if('ontouchmove' in window){
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root
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.off('touchstart', startMoveHandler)
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.off('touchmove', moveHandler)
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.off('touchend', endMoveHandler)
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.off('touchcancel', endMoveHandler)
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} else {
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root
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.off('mousedown', startMoveHandler)
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.off('mousemove', moveHandler)
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.off('mouseup', endMoveHandler)
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}
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this.state = 'stopped'
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return this
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},
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resetTransitions: function(){
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var scrolled = this.root.children().first()
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setTransitionDuration(scrolled, this.options.transitionDuration)
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setTransitionEasing(scrolled, this.options.transitionEasing)
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return this
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}
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}
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// merge the config with the defaults...
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if(config != null){
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$.extend(scroller.options, config)
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}
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return scroller
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}
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// default callback...
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//
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// This will provide support for the following events on the scroll root
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// element:
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// - scrollCancelled
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//
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// - shortClick
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// - doubleClick
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// - multiClick
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// this will store the number of clicks in data.clicks
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// - longClick
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//
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// - swipeLeft
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// - swipeRight
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// - swipeUp
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// - swipeDown
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//
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// - screenReleased
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//
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// NOTE: data.touches passed to the event is the number of touches
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// released within the multitouchTimeout.
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// this differs from what postScrollCallback actually gets in the
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// same field when it receives the scroll data object.
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// XXX add generic snap
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// XXX add generic inertial scroll
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// ...see jli.js/animateElementTo for a rough implementation
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// XXX test multiple touches...
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function postScrollCallback(data){
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var scroller = data.scroller
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var options = scroller.options
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var root = scroller.root
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var clickThreshold = options.clickThreshold || CLICK_THRESHOLD
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var longClickThreshold = options.longClickThreshold || LONG_CLICK_THRESHOLD
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var multitouchTimeout = options.multitouchTimeout || MULTITOUCH_RELEASE_THRESHOLD
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var enableMultiClicks = options.enableMultiClicks
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var multiClickTimeout = options.multiClickTimeout || MULTI_CLICK_TIMEOUT
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var now = Date.now();
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// cancel event...
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if(scroller.state == 'canceling'){
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return root.trigger('scrollCancelled', data)
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}
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// handle multiple touches...
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if(data.touches > 0){
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var then = scroller._last_touch_release
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if(then == null || now - then < multitouchTimeout){
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if(scroller._touches == null){
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scroller._touches = 1
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} else {
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scroller._touches += 1
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}
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} else {
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scroller._touches = null
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}
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// wait for the next touch release...
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scroller._last_touch_release = now
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return
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// calculate how many touches did participate...
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} else {
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data.touches = scroller._touches ? scroller._touches + 1 : 1
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scroller._last_touch_release = null
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scroller._touches = null
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}
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// clicks, double-clicks, multi-clicks and long-clicks...
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if(Math.max(
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Math.abs(data.distance.x),
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Math.abs(data.distance.y)) < clickThreshold){
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if(data.duration > longClickThreshold){
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return root.trigger('longClick', data)
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}
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if(!enableMultiClicks){
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return root.trigger('shortClick', data)
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} else {
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// count the clicks so far...
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if(scroller._clicks == null){
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scroller._clicks = 1
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} else {
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scroller._clicks += 1
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}
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// kill any previous waits...
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if(scroller._click_timeout_id != null){
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clearTimeout(scroller._click_timeout_id)
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}
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// wait for the next click...
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scroller._click_timeout_id = setTimeout(function(){
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var clicks = scroller._clicks
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data.clicks = clicks
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if(clicks == 1){
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root.trigger('shortClick', data)
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} else if(clicks == 2){
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root.trigger('doubleClick', data)
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} else {
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root.trigger('multiClick', data)
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}
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scroller._clicks = null
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scroller._click_timeout_id = null
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}, multiClickTimeout)
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return
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}
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}
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// swipes...
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// XXX might be a good idea to chain these with swipe and screenReleased
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if(Math.abs(data.distance.x) > Math.abs(data.distance.y)){
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if(data.distance.x <= -clickThreshold && root.data('events').swipeLeft){
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return root.trigger('swipeLeft', data)
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} else if(data.distance.x >= clickThreshold && root.data('events').swipeRight){
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return root.trigger('swipeRight', data)
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}
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} else {
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if(data.distance.y <= -clickThreshold && root.data('events').swipeUp){
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return root.trigger('swipeUp', data)
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} else if(data.distance.y >= clickThreshold && root.data('events').swipeDown){
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return root.trigger('swipeDown', data)
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}
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}
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// this is triggered if no swipes were handled...
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return root.trigger('screenReleased', data)
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}
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/**********************************************************************
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* vim:set ts=4 sw=4 : */
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