site/js/elevator.js

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2015-04-22 21:50:42 +00:00
/*!
* Elevator.js
*
* MIT licensed
* Copyright (C) 2015 Tim Holman, http://tholman.com
*/
/*********************************************
* Elevator.js
*********************************************/
var Elevator = (function() {
'use strict';
// Elements
var body = null;
// Scroll vars
var animation = null;
var duration = null; // ms
var customDuration = false;
var startTime = null;
var startPosition = null;
var mainAudio;
var endAudio;
var elevating = false;
/**
* Utils
*/
// Soft object augmentation
function extend( target, source ) {
for ( var key in source ) {
if ( !( key in target ) ) {
target[ key ] = source[ key ];
}
}
return target;
};
// Thanks Mr Penner - http://robertpenner.com/easing/
function easeInOutQuad( t, b, c, d ) {
t /= d/2;
if (t < 1) return c/2*t*t + b;
t--;
return -c/2 * (t*(t-2) - 1) + b;
};
/**
* Main
*/
// Time is passed through requestAnimationFrame, what a world!
function animateLoop( time ) {
if (!startTime) {
startTime = time;
}
var timeSoFar = time - startTime;
var easedPosition = easeInOutQuad(timeSoFar, startPosition, -startPosition, duration);
window.scrollTo(0, easedPosition);
if( timeSoFar < duration ) {
animation = requestAnimationFrame(animateLoop);
} else {
animationFinished();
}
};
// ELEVATE!
// /
// ____
// .' '=====<0
// |======|
// |======|
// [IIIIII[\--()
// |_______|
// C O O O D
// C O O O D
// C O O O D
// C__O__O__O__D
// [_____________]
function elevate() {
if( elevating ) {
return;
}
elevating = true;
startPosition = (document.documentElement.scrollTop || body.scrollTop);
// No custom duration set, so we travel at pixels per millisecond. (0.75px per ms)
if( !customDuration ) {
duration = (startPosition * 1.5);
}
requestAnimationFrame( animateLoop );
// Start music!
if( mainAudio ) {
mainAudio.play();
}
}
function resetPositions() {
startTime = null;
startPosition = null;
elevating = false;
}
function animationFinished() {
resetPositions();
// Stop music!
if( mainAudio ) {
mainAudio.pause();
mainAudio.currentTime = 0;
}
if( endAudio ) {
endAudio.play();
}
}
function onWindowBlur() {
// If animating, go straight to the top. And play no more music.
if( elevating ) {
cancelAnimationFrame( animation );
resetPositions();
if( mainAudio ) {
mainAudio.pause();
mainAudio.currentTime = 0;
}
window.scrollTo(0, 0);
}
}
//@TODO: Does this need tap bindings too?
function bindElevateToElement( element ) {
element.addEventListener('click', elevate, false);
}
function main( options ) {
// Bind to element click event, if need be.
body = document.body;
if( options.element ) {
bindElevateToElement( options.element );
}
if( options.duration ) {
customDuration = true;
duration = options.duration;
}
if( options.mainAudio ) {
mainAudio = new Audio( options.mainAudio );
mainAudio.setAttribute( 'preload', 'true' ); //@TODO: Option to not preload audio.
mainAudio.setAttribute( 'loop', 'true' );
}
if( options.endAudio ) {
endAudio = new Audio( options.endAudio );
endAudio.setAttribute( 'preload', 'true' );
}
window.addEventListener('blur', onWindowBlur, false);
}
return extend(main, {
elevate: elevate
});
})();