Css sprite best practices

css sprite best practices Richard Huang Twitter: @flyerhzm Github: http://github.com/flyerhzm www.ekohe.com Web Development & Graphic Design China Ruby on Rails Development - Rails Consulting - Rails Services - Merb - Offshore Web Development

What is css sprite?
Combine a lot of small images
into one big image
www.ekohe.com Web Development & Graphic Design China Ruby on Rails Development - Rails Consulting - Rails Services - Merb - Offshore Web Development

Why use css sprite?
It reduces a large number of http requests
www.ekohe.com Web Development & Graphic Design China Ruby on Rails Development - Rails Consulting - Rails Services - Merb - Offshore Web Development 5% to 38% download HTML document 62% to 95% make http requests to fetch all the components in HTML document (images, javascripts and stylesheets)

Why use css sprite? www.ekohe.com Web Development & Graphic Design China Ruby on Rails Development - Rails Consulting - Rails Services - Merb - Offshore Web Development #nav li a {background:none no-repeat left center} #nav li a.item1 {background-image:url('../img/image1.gif')} #nav li a:hover.item1 {background-image:url('../img/image1_over.gif')} #nav li a.item2 {background-image:url('../img/image2.gif')} #nav li a:hover.item2 {background-image:url('../img/image2_over.gif')} ...

Why use css sprite? www.ekohe.com Web Development & Graphic Design China Ruby on Rails Development - Rails Consulting - Rails Services - Merb - Offshore Web Development #nav li a {background-image:url('../img/image_nav.gif')} #nav li a.item1 {background-position:0px 0px} #nav li a:hover.item1 {background-position:0px -72px} #nav li a.item2 {background-position:0px -143px;} #nav li a:hover.item2 {background-position:0px -215px;} ...

How to use css sprite?
Use Photoshop (or other tool) to combine all the images
Define css (background image, position and size)

Problems in practices www.ekohe.com Web Development & Graphic Design China Ruby on Rails Development - Rails Consulting - Rails Services - Merb - Offshore Web Development
Not easy to maintain
Put small images together
Calculate the position and size for each small images (x, y, width, height)
x=-20px, y=0px
width=18px, height=18px

Problems in practices www.ekohe.com Web Development & Graphic Design China Ruby on Rails Development - Rails Consulting - Rails Services - Merb - Offshore Web Development
Always conflict when using version control system
Check out by bob Check out by joe Commit by bob Commit by joe

Solution
Make css sprite automatically
www.ekohe.com Web Development & Graphic Design China Ruby on Rails Development - Rails Consulting - Rails Services - Merb - Offshore Web Development Put images into one directory Automatically generate css sprite image Automatically generate css sprite css .facebook_icon { background:url(/images/css_sprite.png); no repeat 0 -20px; width: 16px; height: 16px; } Use .facebook_icon to display facebook icon

Solution www.ekohe.com Web Development & Graphic Design China Ruby on Rails Development - Rails Consulting - Rails Services - Merb - Offshore Web Development The blue parts on the above image are the css_sprite directories according to convention css_sprite directories according to convention. That means the directory whose name is css_sprite or css_sprite suffixed (e.g. another_css_sprite) needs to do the css sprite.

Solution www.ekohe.com Web Development & Graphic Design China Ruby on Rails Development - Rails Consulting - Rails Services - Merb - Offshore Web Development The green parts are images that need to be tranformed into the css sprite. Once you add images to the css_sprite directory or remove images, the css sprite operation will be automatically executed.

Solution www.ekohe.com Web Development & Graphic Design China Ruby on Rails Development - Rails Consulting - Rails Services - Merb - Offshore Web Development The red parts are automatically generated files. For each css_sprite directory, there is a css sprite image generated, combined by all the images under the css_sprite directory, and there is also a css or sass file generated according to the css_sprite image.

Advantage
Developers only need to know what images are under css_sprite directory, then they can use the corresponding class names to display these images on the html page.
They don’t care about css sprite image and css.

Name Convention www.ekohe.com Web Development & Graphic Design China Ruby on Rails Development - Rails Consulting - Rails Services - Merb - Offshore Web Development .logos.active .gmail-logo logos-active/gmail-logo.png .logos.active .gmail_logo logos_active/gmail_logo.png .gmail-logo.active gmail-logo-active.png .gmail_logo.active gmail_logo_active.png .logos:hover .gmail-logo logos-hover/gmail-logo.png .logos:hover .gmail_logo logos_hover/gmail_logo.png .twitter-icon:hover twitter-icon-hover.png .twitter_icon:hover twitter_icon_hover.png .widget .icons .twitter_icon widget/icons/twitter_icon.png .icons .twitter_icon icons/twitter_icon.png .gmail-logo gmail-logo.png .hotmail-logo hotmail-logo.png .facebook_icon facebook_icon.png .twitter_icon twitter_icon.png class name in css_sprite css images under css_sprite directory

Implementation
http://github.com/flyerhzm/css_sprite (Ruby/Rails)
More feature:
Image Optimization
Customization Styles
www.ekohe.com Web Development & Graphic Design China Ruby on Rails Development - Rails Consulting - Rails Services - Merb - Offshore Web Development suffix: button: | text-indent: -9999px; display: inline-block; cursor: pointer; font-size: 0; line-height: 15px; border: 0; outline: 0; icon: | text-indent: -9999px; bg: | display: block;

Articles
English version:
http://www.huangzhimin.com/entries/190-css-sprite-best-practices
Chinese version:
http://www.huangzhimin.com/entries/189-css-sprite-best-practices
Portuguese version:
http://blog.riopro.com.br/2010/04/22/acabaram-as-desculpas-para-nao-usar-css-sprite-na-sua-aplicacao/

Q&A Thank you www.ekohe.com Web Development & Graphic Design China Ruby on Rails Development - Rails Consulting - Rails Services - Merb - Offshore Web Development

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Css sprite best practices

by Richard Huang on Jun 12, 2010

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