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September 3, 2012 21:30
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jQuery.parallax.coffee
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| ### | |
| jQuery.parallax | |
| by ken210.com | |
| Based on homonymous plugin by Ian Lunn | |
| Author URL: http://www.ianlunn.co.uk/ | |
| Plugin URL: http://www.ianlunn.co.uk/plugins/jquery-parallax/ | |
| Dual licensed under the MIT and GPL licenses: | |
| http://www.opensource.org/licenses/mit-license.php | |
| http://www.gnu.org/licenses/gpl.html | |
| ### | |
| $.fn.parallax = (options) -> | |
| defaults = | |
| bgPosX: '50% ' | |
| bgPosY: '50%' | |
| adjuster: 0 | |
| inertia: 0.1 | |
| outerHeight: true | |
| mode: 'backgroundPosition' | |
| $.extend(defaults, options) | |
| @each -> | |
| self = $(this) | |
| top = self.position().top | |
| height = if defaults.outerHeight then self.outerHeight(true) else self.height() | |
| # caching usefull props | |
| mode = defaults.mode | |
| bgPosX = defaults.bgPosX | |
| adjuster = defaults.adjuster | |
| inertia = defaults.inertia | |
| getStyle = (now) -> | |
| output = '' | |
| expression = Math.round((adjuster - height - now) * inertia) | |
| if (mode == 'backgroundPosition') | |
| output = bgPosX + expression + 'px' | |
| else | |
| output = parseInt(top + (top - expression)) + 'px' | |
| return output | |
| onScrolled = () -> | |
| now = $(scrollContainer).scrollTop() | |
| self.css(mode, getStyle(now)) | |
| ### | |
| cssObj = {} | |
| cssObj[mode] = getStyle(now) | |
| self.stop().animate(cssObj, 300) | |
| ### | |
| $(scrollContainer).bind(scrollEvent, onScrolled) |
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