javascript - Jerky parallaxing with scrollwheel in WebKit -


i'm having issues parallaxing backgrounds. i've made little website event organized friends of mine, , on site have bunch of background images alternating in between content sections. i've added logic offset these background images when scrolling, create parallaxing effect.

it's working enough , haven't noticed performance issues, when using scrollwheel, parallaxing seems lagging behind in webkit browsers.

here's link website:

http://eventyrfestival.info/

the effect i've tried mimic, @ least background images, 1 seen on spotify website:

https://www.spotify.com/

from looking @ source code, seem doing more or less same thing: have parallaxing function calculates background transform based on scrolltop value of document, , function throttled 16 ms , bound window's scroll event. still, background transformation on spotify site instant, while mine visually lags behind content. it's not "broken" in works in firefox/ie , works in webkit browsers when sliding scrollbar manually... it's annoying.

does have tips on causing jerkiness?

here's code parallaxing functionality (i'm using prototype sorry this spam):

    parallaxbackground: function () {         var viewporttop = this.elements.$document.scrolltop();         var viewportbottom = viewporttop + this.elements.$window.height();         var scrolldelta = this.slideheight + this.elements.$window.height();          $.each( this.backgroundslides, function ( index, slide ) {             var slidetop = slide.$container.offset().top;             var slidebottom = slidetop + this.slideheight;             if ( slidebottom < viewporttop || slidetop > viewportbottom )                 return true;             var factor = 1 - ( slidebottom - viewporttop ) / scrolldelta;             this.transformbackground( slide.$image, this.slidelength * ( factor - 1 ) );         }.bind( ) );     },      transformbackground: modernizr.csstransforms ? function ( $backgroundelement, distance ) {         $backgroundelement.css( {             '-ms-transform': 'translate(0px, ' + distance + 'px)',             '-webkit-transform': 'translate(0px, ' + distance + 'px)',             'transform': 'translate(0px, ' + distance + 'px)'         } );     } : function ( $backgroundelement, distance ) {         $backgroundelement.css( 'top', distance );     }

and here's how gets bound (using underscore throttling):

this.elements.$window.on( 'scroll',     _.throttle( this.parallaxbackground.bind( ), 16 ) );

i recreated own parallax effect based on spotify's website , ran across many of issues mention here.

while cannot rid of stutter on safari specifically, i've managed smooth 60fps on chrome , firefox.

i've published jquery plugin here, adapt use framework of choice:

http://pixelcog.com/parallax.js/

there several tips helped me optimize it:

  1. avoid triggering layout whenever possible

  2. don't attach lot of logic scroll event directly, defer settimeout or requestanimationframe call instead

  3. utilize position:fixed; on background elements. on browsers lag bit, stutter minimal.

  4. enforce browser layering null transforms, sparingly.

  5. explore chrome devtools diagnose bottlenecks

these helped me rid of of stutter seeing in own implementation.


Comments

Post a Comment

Popular posts from this blog

commonjs - How to write a typescript definition file for a node module that exports a function? -

consider, toml node module can use: // toml.d.ts declare module toml { export function parse(value:string):any; } declare module "toml" { export = toml; } then: /// <reference path="../../../../../defs/toml/toml.d.ts"/> import toml = require('toml'); toml.parse(...); however, node module export single function, such 'glob' ( https://github.com/isaacs/node-glob ). the node usage of module be: var glob = require("glob") glob("*.js", {}, callback(err, files) { ... }); you'd naively expect this: // glob.d.ts declare function globs(paths:string, options:any, callback:{(err:any, files:string[]):void; ...but because typescripts 'import' semantics bit strange, seems can use 'import .. = require()' statement alias modules . trying call: /// <reference path="../../../../../defs/glob/glob.d.ts"/> import blog = require('glob'); results in: error ts2072: mod
Read more

openid - Okta: Failed to get authorization code through API call -

i'm integrating okta own idp server using okta's api. i'm implementing authorization code flow following steps below: in own server, use /api/v1/authn endpoint sessiontoken. use sessiontoken obtain authorization calling endpoint: /oauth2/v1/authorize?client_id=" + clientid + "&sessiontoken=" + sessiontoken + "&response_type=code&response_mode=query&scope=openid&redirect_uri=" + redirecturl + "&state=evanyang&nonce=" it's supposed return response status code 302 , location header containing redirect url code value. however, keep getting response status code 200 , without location header, html body saying "you using unsupported browser." , "javascript disabled on browser." according api documentation: http://developer.okta.com/docs/api/resources/oidc.html#authentication-request , sessiontoken parameter sufficient this: an okta one-time sessiontoken. allows api-based
Read more

thorough guide for profiling racket code -

did googling ("racket profiling", "racket measure performance"), didn't find , there no examples in docs. did google "profile" search on htdp - no luck. (profile (f ...)) output isn't obvious other small snippets. ideally want python's python -m cprofile usage examples. when search "python profiling", both duckduckgo , google give top result: 26.4. python profilers . (although scanned quickly, seems more of reference "thorough usage guide" examples. if had else in mind, perhaps please link that?) the equivalent racket documentation be: profile: statistical profiler . a usage example: #lang racket (require profile) (profile-thunk (thunk (function-to-profile arg0 arg1) )) here (thunk e) convenience (lambda () e) . bigger example: #lang racket (module mod racket (provide f) (define (f) (for/list ([i 10000]) i))) (require (prefix-in mod: 'mod)) (define (f) (for ([i 10000
Read more