app/assets/javascripts/scrollme.js
// ----------------------------------------------------------------------------------------------------
// ScrollMe
// A jQuery plugin for adding simple scrolling effects to web pages
// http://scrollme.nckprsn.com
// ----------------------------------------------------------------------------------------------------
var scrollme = ( function( $ )
{
// ----------------------------------------------------------------------------------------------------
// ScrollMe object
var _this = {};
// ----------------------------------------------------------------------------------------------------
// Properties
var $document = $( document );
var $window = $( window );
_this.body_height = 0;
_this.viewport_height = 0;
_this.viewport_top = 0;
_this.viewport_bottom = 0;
_this.viewport_top_previous = -1;
_this.elements = [];
_this.elements_in_view = [];
_this.property_defaults =
{
'opacity' : 1,
'translatex' : 0,
'translatey' : 0,
'translatez' : 0,
'rotatex' : 0,
'rotatey' : 0,
'rotatez' : 0,
'scale' : 1,
'scalex' : 1,
'scaley' : 1,
'scalez' : 1
};
_this.scrollme_selector = '.scrollme';
_this.animateme_selector = '.animateme';
_this.update_interval = 10;
// Easing functions
_this.easing_functions =
{
'linear' : function( x )
{
return x;
},
'easeout' : function( x )
{
return x * x * x;
},
'easein' : function( x )
{
x = 1 - x;
return 1 - ( x * x * x );
},
'easeinout' : function( x )
{
if( x < 0.5 )
{
return ( 4 * x * x * x );
}
else
{
x = 1 - x;
return 1 - ( 4 * x * x * x ) ;
}
}
};
// Document events to bind initialisation to
_this.init_events =
[
'ready',
'page:load', // Turbolinks
'page:change' // Turbolinks
];
// ----------------------------------------------------------------------------------------------------
// Initialisation conditions
_this.init_if = function() { return true; }
// ----------------------------------------------------------------------------------------------------
// Initialisation
_this.init = function()
{
// Cancel if initialisation conditions not met
if( !_this.init_if() ) return false;
// Load all elements to animate
_this.init_elements();
// Get element & viewport sizes
_this.on_resize();
// Recalculate heights & positions on resize and rotate
$window.on( 'resize orientationchange' , function(){ _this.on_resize(); } );
// Recalculate heights & positions when page is fully loaded + a bit just in case
$window.load( function(){ setTimeout( function(){ _this.on_resize(); } , 100 ) });
// Start animating
setInterval( _this.update , _this.update_interval );
return true;
}
// ----------------------------------------------------------------------------------------------------
// Get list and pre-load animated elements
_this.init_elements = function()
{
// For each reference element
$( _this.scrollme_selector ).each( function()
{
var element = {};
element.element = $( this );
var effects = [];
// For each animated element
$( this ).find( _this.animateme_selector ).addBack( _this.animateme_selector ).each( function()
{
// Get effect details
var effect = {};
effect.element = $( this );
effect.when = effect.element.data( 'when' );
effect.from = effect.element.data( 'from' );
effect.to = effect.element.data( 'to' );
if( effect.element.is( '[data-crop]' ) )
{
effect.crop = effect.element.data( 'crop' );
}
else
{
effect.crop = true;
}
if( effect.element.is( '[data-easing]' ) )
{
effect.easing = _this.easing_functions[ effect.element.data( 'easing' ) ]
}
else
{
effect.easing = _this.easing_functions[ 'easeout' ];
}
// Get animated properties
var properties = {};
if( effect.element.is( '[data-opacity]' ) ) properties.opacity = effect.element.data( 'opacity' );
if( effect.element.is( '[data-translatex]' ) ) properties.translatex = effect.element.data( 'translatex' );
if( effect.element.is( '[data-translatey]' ) ) properties.translatey = effect.element.data( 'translatey' );
if( effect.element.is( '[data-translatez]' ) ) properties.translatez = effect.element.data( 'translatez' );
if( effect.element.is( '[data-rotatex]' ) ) properties.rotatex = effect.element.data( 'rotatex' );
if( effect.element.is( '[data-rotatey]' ) ) properties.rotatey = effect.element.data( 'rotatey' );
if( effect.element.is( '[data-rotatez]' ) ) properties.rotatez = effect.element.data( 'rotatez' );
if( effect.element.is( '[data-scale]' ) ) properties.scale = effect.element.data( 'scale' );
if( effect.element.is( '[data-scalex]' ) ) properties.scalex = effect.element.data( 'scalex' );
if( effect.element.is( '[data-scaley]' ) ) properties.scaley = effect.element.data( 'scaley' );
if( effect.element.is( '[data-scalez]' ) ) properties.scalez = effect.element.data( 'scalez' );
effect.properties = properties;
effects.push( effect );
});
element.effects = effects;
_this.elements.push( element );
});
}
// ----------------------------------------------------------------------------------------------------
// Update elements
_this.update = function()
{
window.requestAnimationFrame( function()
{
_this.update_viewport_position();
if( _this.viewport_top_previous != _this.viewport_top )
{
_this.update_elements_in_view();
_this.animate();
}
_this.viewport_top_previous = _this.viewport_top;
});
}
// ----------------------------------------------------------------------------------------------------
// Animate stuff
_this.animate = function()
{
// For each element in viewport
var elements_in_view_length = _this.elements_in_view.length;
for( var i=0 ; i<elements_in_view_length ; i++ )
{
var element = _this.elements_in_view[i];
// For each effect
var effects_length = element.effects.length;
for( var e=0 ; e<effects_length ; e++ )
{
var effect = element.effects[e];
// Get effect animation boundaries
switch( effect.when )
{
case 'view' : // Maintained for backwards compatibility
case 'span' :
var start = element.top - _this.viewport_height;
var end = element.bottom;
break;
case 'exit' :
var start = element.bottom - _this.viewport_height;
var end = element.bottom;
break;
default :
var start = element.top - _this.viewport_height;
var end = element.top;
break;
}
// Crop boundaries
if( effect.crop )
{
if( start < 0 ) start = 0;
if( end > ( _this.body_height - _this.viewport_height ) ) end = _this.body_height - _this.viewport_height;
}
// Get scroll position of reference selector
var scroll = ( _this.viewport_top - start ) / ( end - start );
// Get relative scroll position for effect
var from = effect[ 'from' ];
var to = effect[ 'to' ];
var length = to - from;
var scroll_relative = ( scroll - from ) / length;
// Apply easing
var scroll_eased = effect.easing( scroll_relative );
// Get new value for each property
var opacity = _this.animate_value( scroll , scroll_eased , from , to , effect , 'opacity' );
var translatey = _this.animate_value( scroll , scroll_eased , from , to , effect , 'translatey' );
var translatex = _this.animate_value( scroll , scroll_eased , from , to , effect , 'translatex' );
var translatez = _this.animate_value( scroll , scroll_eased , from , to , effect , 'translatez' );
var rotatex = _this.animate_value( scroll , scroll_eased , from , to , effect , 'rotatex' );
var rotatey = _this.animate_value( scroll , scroll_eased , from , to , effect , 'rotatey' );
var rotatez = _this.animate_value( scroll , scroll_eased , from , to , effect , 'rotatez' );
var scale = _this.animate_value( scroll , scroll_eased , from , to , effect , 'scale' );
var scalex = _this.animate_value( scroll , scroll_eased , from , to , effect , 'scalex' );
var scaley = _this.animate_value( scroll , scroll_eased , from , to , effect , 'scaley' );
var scalez = _this.animate_value( scroll , scroll_eased , from , to , effect , 'scalez' );
// Override scale values
if( 'scale' in effect.properties )
{
scalex = scale;
scaley = scale;
scalez = scale;
}
// Update properties
effect.element.css(
{
'opacity' : opacity,
'transform' : 'translate3d( '+translatex+'px , '+translatey+'px , '+translatez+'px ) rotateX( '+rotatex+'deg ) rotateY( '+rotatey+'deg ) rotateZ( '+rotatez+'deg ) scale3d( '+scalex+' , '+scaley+' , '+scalez+' )'
} );
}
}
}
// ----------------------------------------------------------------------------------------------------
// Calculate property values
_this.animate_value = function( scroll , scroll_eased , from , to , effect , property )
{
var value_default = _this.property_defaults[ property ];
// Return default value if property is not animated
if( !( property in effect.properties ) ) return value_default;
var value_target = effect.properties[ property ];
var forwards = ( to > from ) ? true : false;
// Return boundary value if outside effect boundaries
if( scroll < from && forwards ) { return value_default; }
if( scroll > to && forwards ) { return value_target; }
if( scroll > from && !forwards ) { return value_default; }
if( scroll < to && !forwards ) { return value_target; }
// Calculate new property value
var new_value = value_default + ( scroll_eased * ( value_target - value_default ) );
// Round as required
switch( property )
{
case 'opacity' : new_value = new_value.toFixed(2); break;
case 'translatex' : new_value = new_value.toFixed(0); break;
case 'translatey' : new_value = new_value.toFixed(0); break;
case 'translatez' : new_value = new_value.toFixed(0); break;
case 'rotatex' : new_value = new_value.toFixed(1); break;
case 'rotatey' : new_value = new_value.toFixed(1); break;
case 'rotatez' : new_value = new_value.toFixed(1); break;
case 'scale' : new_value = new_value.toFixed(3); break;
default : break;
}
// Done
return new_value;
}
// ----------------------------------------------------------------------------------------------------
// Update viewport position
_this.update_viewport_position = function()
{
_this.viewport_top = $window.scrollTop();
_this.viewport_bottom = _this.viewport_top + _this.viewport_height;
}
// ----------------------------------------------------------------------------------------------------
// Update list of elements in view
_this.update_elements_in_view = function()
{
_this.elements_in_view = [];
var elements_length = _this.elements.length;
for( var i=0 ; i<elements_length ; i++ )
{
if ( ( _this.elements[i].top < _this.viewport_bottom ) && ( _this.elements[i].bottom > _this.viewport_top ) )
{
_this.elements_in_view.push( _this.elements[i] );
}
}
}
// ----------------------------------------------------------------------------------------------------
// Stuff to do on resize
_this.on_resize = function()
{
// Update viewport/element data
_this.update_viewport();
_this.update_element_heights();
// Update display
_this.update_viewport_position();
_this.update_elements_in_view();
_this.animate();
}
// ----------------------------------------------------------------------------------------------------
// Update viewport parameters
_this.update_viewport = function()
{
_this.body_height = $document.height();
_this.viewport_height = $window.height();
}
// ----------------------------------------------------------------------------------------------------
// Update height of animated elements
_this.update_element_heights = function()
{
var elements_length = _this.elements.length;
for( var i=0 ; i<elements_length ; i++ )
{
var element_height = _this.elements[i].element.outerHeight();
var position = _this.elements[i].element.offset();
_this.elements[i].height = element_height;
_this.elements[i].top = position.top;
_this.elements[i].bottom = position.top + element_height;
}
}
// ----------------------------------------------------------------------------------------------------
// Bind initialisation
$document.on( _this.init_events.join( ' ' ) , function(){ _this.init(); } );
// ----------------------------------------------------------------------------------------------------
return _this;
// ----------------------------------------------------------------------------------------------------
})( jQuery );