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CSS Sprites

CSS Sprites. Dawn Pedersen Art Institute. What Are CSS Sprites?. Back in the day, sprites were the images in games that swapped one little image for another in a specific place on the screen.

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CSS Sprites

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  1. CSS Sprites Dawn PedersenArt Institute

  2. What Are CSS Sprites? • Back in the day, sprites were the images in games that swapped one little image for another in a specific place on the screen. • The term has been appropriated by web designers to describe a CSS technique that is similar and very useful.

  3. What Are CSS Sprites? • Typically when we create graphical buttons, we make two images: • One for the regular state of the button. • One for the hover state. • The images on the right are designed to repeat-x. • With CSS Sprites these two images become one image. • By using the background position properties in CSS, we can choose: • which part of our image will be displayed for the inactive link • which part will be displayed for the hover state

  4. What Are CSS Sprites? • The advantages are: • there are fewer files to keep track of • there are fewer http requests made of the server • the file size for one larger image is smaller than the sum of a bunch of smaller images • This may not seem like a big deal for two images, but it adds up for more. Let’s take a look at an example.

  5. CSS Sprites Exercise • Download and unzip http://blulob.com/ai/mm2203/docs/sprites.zip. • Take a look at buttons.psdwith three buttons. • The first is for a normal state • The second is for a hover state • The third we will use when we are on the destination page • We know from our guides that each button is 260 pixels wide and 60 pixels tall.

  6. CSS Sprites Exercise • Take a look at buttons.jpg” The image has been flattened and cropped down to its final size (260px by 180px).

  7. CSS Sprites Exercise • Open index.htmlin a browser and hover over each menu item.

  8. CSS Sprites Exercise • Open index.html and styles.css in Dreamweaver in Code view. • Locate the CSS rules for #navigation li a and #navigation li a:hover. • Add the background declarations as shown on the right to each of these rules: • background-image • background-repeat • background-position

  9. CSS Sprites Exercise A little explanation: • Both rules use the same buttons.jpg image. • Because we are creating buttons, we don’t want the button background image to repeat. • Because the <a> tag is set to display: block and to a specific height and width, we do not see the rest of the background image. • Then the position on the hover state sets the y position to -60px. This shows the second button in the image file on hover.

  10. CSS Sprites Exercise • With just a little bit of basic math you can display whichever image you need from the larger image. • Let’s continue with setting our image for the destination page, as we did previously.

  11. CSS Sprites Exercise • Add the following compound CSS rule to the bottom of the CSS file (notice the background-position): #page1 #page #sidebar #navigation .page1 a, #page2 #page #sidebar #navigation .page2 a, #page3 #page #sidebar #navigation .page3 a, #page4 #page #sidebar #navigation .page4 a, #page5 #page #sidebar #navigation .page5 a { color: #900; background-image: url(buttons.jpg); background-repeat: no-repeat; cursor: default; background-position: 0px -120px; }

  12. CSS Sprites Exercise • In index.html, add an id="page1"attribute to the body tag. • Add the following class attributes within the menu: • In page2.html: • Add an id="page2"attribute to the bodytag • Replace the navigation ulelement with that from index.html

  13. CSS Sprites Exercise • Test the site in a browser. • Click on the page 1 and page 2 buttons to see the image rotation. • If you open the completed folder, you will see all the pages are made. • Open index.html in a browser and try the links out.

  14. CSS Sprites Real-Life Example • This particular use of the sprite is called a navigation matrix. • Not only can you use the y axis to locate particular graphics, but you can use the x axis too. • Check out the navigation in Apple’s website. • Notice the roll over, active (when you press the button down), and destination page states.

  15. CSS Sprites Real-Life Example • Digging into the code reveals how they did this. • Here is Apple’s navigation matrix. • Top row for normal state • Second row for hover state • Third row for active state • Fourth row for when you are on that particular page • Each individual button is accessed one at a time with coordinates.

  16. CSS Sprites Real-Life Example • If you go to this page to see the CSS being used, it should be recognizable: http://images.apple.com/global/styles/base.css • Notice the position coordinates. They are what is pulling up the individual images.

  17. CSS Sprites Resources • There is a nice little tutorial on this particular navigation trick here:http://net.tutsplus.com/videos/screencasts/exactly-how-to-use-css-sprites/ It’s a little long winded, but cool to watch anyway.

  18. CSS Sprites Resources • Sprites are not just used for navigation, but any sort of repeating icons and graphics used on your sites. • Check out this tutorial:http://websitetips.com/articles/css/sprites/All of those little green icons are in one graphic file.

  19. CSS Sprites Resources Need help generating some sprite images and CSS? Try this site: http://spritegen.website-performance.org/

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