Developing web sites for portable devices
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Developing web sites for portable devices

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An introductory lecture to creating web pages for portable devices.

An introductory lecture to creating web pages for portable devices.
Don't expect rocket science here, it covers just the main ideas.

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Developing web sites for portable devices Developing web sites for portable devices Presentation Transcript

  • Developing web sites forportable devicesKrišs RauhvargersWeb Technologies I, 2013,University of Latvia
  • The changing internet• The internet is constantly changing, let‟sface it.Meme of 1996Sent in email,using a desktopcomputerMeme of 2011Shared on web socialnetworks …using mobile phones whileresting on a couch2013not sure yet
  • The changing internet (2)• Devices– Significance of desktop computers is falling– While portable devices (phones, tablets) are thehot marketing segment• Network coverage– Internet is available nearly everywhere– And for a reasonable price• Ogooglebar? http://www.bbc.com/future/story/20130328-who-owns-the-meaning-of-words– Google has indexed “everything”– Search is fast and people know how to use it
  • Result• Result: someone may need theinformation on your site… at night... from a device that has 3x4cm screen… and an “Edge” 56Kbps connection• Prepare!
  • PORTABLE DEVICESPECIFICS
  • Screen size• Problem: small viewport sizes– 360x640* (Samsung Galaxy S3)– 320x480px (iPhone 4)• When rendering page at full size, would see left top corneronly.– Thank God they invented the “zoom” feature.• Another problem: large viewport sizes:– Some screens have small physical dimensions, but hugeresolution:• 800x1280 (Asus Transformer Pad)• 768x1025 (iPad)• Result: designing a web site version “for mobile devices” isuseless• Better idea: check capabilities at runtime!* http://i-skool.co.uk/mobile-development/web-design-for-mobiles-and-tablets-viewport-sizes/
  • HTML viewport directive forportable devices• The modern devices know their screen is small– They render the page on a virtual viewport (largerthan screen)– You zoom in the interesting part of viewport• “viewport” meta element allows setting theviewport size<meta name="viewport"content="width=device-width; initial-scale=1.0;maximum-scale=5.0; user-scalable=yes;">– Fun fact:• the tag is Apple proprietary attribute.• Well documented*, but still not a standard* https://developer.apple.com/safari/library/documentation/AppleApplications/Reference/SafariWebContent/UsingtheViewport/UsingtheViewport.html
  • Be careful with the “viewport”directive!• Don‟t mess with “user-scalable=0”– The users will effectively be unable to zoom– http://blog.javierusobiaga.com/stop-using-the-viewport-tag-until-you-know-ho• Do not set maximum-scale=1 unless thepage really may not be zoomed
  • What happens when you use the“viewport” directiveBefore AfterInitial view of thesame page beforeand after settingthe “viewport”directive
  • Input methods• User input is very limited on portabledevices– No or little keyboard– Finger taps instead of controlled mousegestures• Fingers are hulky, small items areuntappable– Apple UI guidelines state: 44x44px is theminimum size of a tappable item:– http://developer.apple.com/library/ios/#documentation/userexperience/conceptual/mobilehig/Characteristics/Characteristics.html
  • How the “44px” looks likeThe links with yellowbackground are 44px high.And they seem to be tappable.
  • Limitation resultsSmall device screen + inability to tap=do not put too much information on thescreen of a mobile deviceThe question is – how?
  • CSS MEDIA QUERIES
  • Targeting media• Since CSS2 it is possible to target stylesheets to aspecific media:• <link rel=stylesheettype=text/cssmedia=screen />– media=„print‟– media=„handheld‟– media=„braille‟• Such stylesheet is only applied if the devicecharacteristics match• It works, but modern devices ignore the“handheld” media
  • Targeting media in a singlestyle sheet/***** style.css *****/body {/*Works on all devices*/color:green;font-family: Arial, sans-serif;font-size:14px;}@media print {/*Let’s save the ink!*//*applied to printers only */body {color:black;font-size:12pt;}}
  • Effect of CSS2 media types• Easy to prepare a specific print version:– Remove unnecessary colored items– Hide things that are useless on paper• Navigation menus• Clickable buttons & icons– Change text sizes to more readable ones– Reset dimension limits
  • CSS3 media queries• CSS3 extends the query language by addingmultiple device properties:– device-width, device-height• Screen resolution– width, height• Browser window size– aspect-ratio• width:height ratio to recognize wide screen devices– Orientation• Portrait, landscape– … http://www.w3.org/TR/css3-mediaqueries/
  • Query language• min- and max- prefixes are used:– min-width:1024 means “window width is 1024or higher”– max-device-width:600 means “the devicescreen may not be wider than 600 pixels”• Example:@media (min-width:300px) and (max-width:600px){body {color:red;}}
  • Query language: and/or?• Combinations of requirements are createdby AND keyword• Alternatives are separated by a comma@media(min-width:300px) and (orientation:portrait),(min-height:300px) and (orientation:landscape){//smallest side is no less than 300px}
  • Query language: combining withCSS2 properties• Some printers may match also min-width,max-width parameters• Your queries are most likely targeted atscreens@media screen and (device-min-width:600px) {/**._.**/}
  • PUTTING MEDIA QUERIES TOWORK
  • Setting up• The query syntax is understood by mobilebrowsers and desktop browsers• Desktop browser can be used for initialdevelopment– Just use “min-width” instead of “min-device-width” and resize the window!– Most browsers have hard limit of how smallthe window can be
  • What can I do with it?• Of course, you can do art:– http://arleym.com• Or, you can show additional artifacts if spaceallows it:– http://css-tricks.com/css-media-queries/• Or, you can– hide stuff that requires more space– rearrange items on page to “fit”– .. etc.– make your page “responsive”
  • Responsive?• “Responsive web design”– A coined term to describe pages that adapt toscreen properties.• Good example:– http://microsoft.com first page
  • Navigation changes• Horizontal navigation bars may require toomuch space– At a certain screen size, make them vertical• At a certain size, make navigation linkslarger– They will be tapped, not clicked• On very small screens navigation may behidden and only shown upon click;
  • Navigation differencesVertical on a smaller screenHorizontal and not that high ona larger screen
  • Rearranging page content• Multi-column pages are typically“serialized”– Aside items shown after (or before) the maincontent block– Inessential aside items hidden• Good example: http://css-tricks.com first page• Explained: http://webdesignerwall.com/demo/responsive-design/index.html
  • Planning the contentrearrangement• Many page detailshave minimumreasonable width– Plan, what to dowhen the minimumis reachedMain text withcontent hereAsideblockwithaddit.infoNot usable ifnarrower than200pxScreen width – aside widthShould be at least twice the asidewidth.Here, the problem arrives at document width 600px.
  • Planning the contentrearrangement (2)• Is the aside reallynecessary?• If yes,– can you make it eventighter?– can you put it beforethe content?• There are some toolsto help you:– Adobe Edge ReflowMain text withcontent hereAsideblockwithaddit.infoMain text with content hereAside block with addit. info
  • Who is responsible for this?• Theory– A web site design is a work of art– Making the site look nice is web designer‟swork• Practice– Not all designers are aware of the responsiveweb design paradigm– You will have to help them
  • Dealing with layout breakers• Items that are wider than screen widthbreak the layout– Images in their native size– Tables• Use “max-width” and width to fit them• Tables do not bend to these rules– Hide them?
  • Mobile first?• Some say, “mobile first” is the way to go:– First design the site for small screens– Then you have a lot of space to fill on a largescreen• This approach improves usability– Just play with the mobile site for a while, tryclicking everything• “Mobile last” makes you– think portable devices are 2nd class passengers,– want to hide lots of content from them.
  • OTHER METHODS USED INMOBILE (AND NOT ONLY) PAGES
  • Animations and transitions• CSS3 animations are nice, but may beslow on portable devices– (because the CPU speeds are relatively low)• Use only GPU accelerated properties– http://blog.forecast.io/its-not-a-web-app-its-an-app-you-install-from-the-web/• When scripting, try to avoid attaching toomany event handlers;
  • Avoid too many resource calls• 3G traffic has relatively high latency• Each HTTP request is expensive• Use CSS sprites
  • What is a CSS sprite?• A sprite is an image combined of severalsmaller images.• Sprites are used to decrease number ofHTTP requests• Only a fragment of sprite is shown onpage• background-position is usedto position the sprite image36
  • Where CSS sprites are used?• Image buttons– Mouse-over and inactive images in one image– When user hovers over button, thebackground is shifted• Search boxes– When the search box is focused, backgroundimage changes37
  • Hiding or not giving?• When you hide items in a “responsive”page, they are still loaded from the server• An improvement idea: the server couldomit rendering elements that won‟t bedisplayed• Involves server-side programming withbrowser sniffing or use of cookies