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Building Apps in the World of TV and Mobile



N Screens problem: W3C Conference Redmond, Nov 15,2011 – Presentation Transcript

  1. THE N-SCREENS PROBLEM Building Apps in the world of TV & Mobile Rajesh Lal Senior Engineer
  2. Agenda 7 Key Challenges WebApp Develop Design N-Screens
  3. The N-Screens
  4. Mobile PCTablet TV
  5. 1. Design Problem: N Screens
  6. On the Go MobileScreen size 2-4”Distance 1’Connection 3GNot reliableHighly InterruptibleFinger Input
  7. Screen 7-14” TabletCasual EnvironmentDistance 1’Wi-Fi Loosely connectedInterruptibleInput Touch
  8. Screen size 14-27” Computer Desk Distance 2’ Reliable LAN PC Focused Keyboard Mouse
  9. Screen size 25-65” Couch Distance 10’ LAN Fast TV connection Total Emersion D-Pad Remote
  10. 2. Developing Apps for N Screens Native vs. WebApp
  11. Native: Developing Apps for N-Screens Pros • Each “Screen” with an SDK • Great for THAT device • Robust • Device APIs
  12. Native: Developing for N-Screens Cons Objective C • Learning curve for each SDK Java • Multiple Programing Languages C# C++ • Time and Effort for every device Qt, QML XAML • Maintenance • Versions
  13. 3. The WebApp Solution Web Application 1.0
  14. WebApp: Developing for N-Screens A WebApp is an application created using HTML, CSS and JavaScript. • App in the Web browser (Full screen) • WebApp in a native container (Hybrid)
  15. History“Old” HTML Web RIAs HTML5 WebApp Applications Basic Server Script Media Advanced Touch Table, Img Client-Server Players Canvas Camera Cookies Thin Client Plug-ins Media Contacts Sandbox Validation Extensions Storage Calendar CSS Object Tag Web db Notification JavaScript Pvt. Storage Geo location Battery Audio video Offline Orientation XPCOM Drag Drop Acceleromet Threads CSS3
  16. WebApp: Developing Apps for N-Screens Pros • One “SDK” • Easy to Develop • Powerful HTML5 APIs • CSS3
  17. WebApp: Developing for N-Screens Cons • Work in Progress • Challenging when porting to many Screens
  18. 4. Seven Key Challenges And How to Work Around Them
  19. 1/7 Feature Detection Which Feature Your Screen Support ?
  20. Feature Detection Feature Browser Detection Detection Old method New method
  21. Feature DetectionIn the code
  22. Feature Detection Use libraries • Modernizr • jQuery.support
  23. Feature Detection code <script src=”modernizr-1.7.js“/> Modernizr.canvas ? “Canvas” : “No canvas”; <script src=”jquery-latest.js“/> jQuery.support.ajax ? “Ajax” : “No Ajax”;
  24. Feature DetectionModernizrCanvas SVG Cross Window MsgAudio InlineSVG Web WorkersVideo WebGL Web SQL databaseAnimation Websockets TouchTransformation GeolocationDrag and Drop Local Storage
  25. Feature Detection jQuery.Support Ajax Cross Domain Resource Sharing (CORS) Fixed Position CSS Opacity CSS Float htmlNormalize
  26. 2/7 Layout Detection How to adapt the layout to the device form factor?
  27. Layout Detection Media Orientati Queries Viewport on JavaScript
  28. Layout Detection Media-queries enable style sheets tailored for different ’width’, ‘height’ and ‘color’
  29. Media Queries: Layout Detection <link rel=”stylesheet” href=”handheld.css” media=”only screen and (max-width: 480px), handheld” /> <link rel=”stylesheet” href=”default.css” media=”screen” /> <link rel=”stylesheet” href=”wider.css” media=”only screen and (min-width: 1200px)” />
  30. Media Queries: Layout Detectionhandheld Default screen Wider screen http://www.lancs.ac.uk/
  31. Media Queries: Layout Detection jQuery.mediaqueriesThe script adds basic Media Query-Support (min-width and max-width in px units ) to all browsers <script src=”jquery.mediaqueries.js“></script>
  32. LayoutMedia Query for device-aspect-ratio@media screen and (device-aspect-ratio: 16/9)@media screen and (device-aspect-ratio: 32/18)@media screen and (device-aspect-ratio: 1280/720)@media screen and (device-aspect-ratio: 2560/1440)
  33. Orientation Media Query for Orientation*@media screen and (orientation:portrait) { /* Portrait styles */}@media screen and (orientation:landscape) { /* Landscape styles */} *DeviceOrientation Events specification at W3C
  34. ViewportViewable area on the screen<meta name=”viewport” content=”width=device-width,initial-scale=1, maximum-scale=1″>
  35. 3/7 Advanced Styles How to utilize CSS3 for Advanced Graphics ?
  36. Advanced Styles with CSS3 • Background • Border Radius • Drag and Drop • Opacity • Transformation • …
  37. Challenge: Advanced Styles with CSS3 Prefix • -moz- • -ms- • -o- • -webkit-
  38. Workaround: Advanced Styles with CSS3 .style { -moz-border-radius: 1em; -ms-border-radius: 1em; -o-border-radius: 1em; -webkit-border-radius: 1em; border-radius: 1em; }
  39. 4/7 Animation When to Use SVG, Canvas, CSS3 and WebGL Animation?
  40. Animation: Challenge WebGL CSS3 Canvas & Animation SVG & JavaScript JavaScript
  41. Animation: SVG • 2D vector graphics using XML • Object retained in the memory • Full DOM support • SVG elements can be styled • Check Modernizr.svg / Modernizr.inlinesvg Perform better when smaller number of elements and large surface
  42. Animation: SVG <svg id=”svgElement” width=”800px” height=”600px” viewBox=”0 0 800 600″> <rect x=”0″ y=”0″ width=”100%” height=”100%” rx=”10″ ry=”10″ style=”fill: white; stroke: black;” /> <circle id=”circle0″ cx=”40″ cy=”40″ r=”40″ style=”fill: orange; stroke: black; stroke-width: 1;” /> </svg>
  43. Animation: Canvas: Context 2D • Bitmap drawing area • Rectangles, lines, arcs, paths • Stateless • No DOM support, single element • Check Modernizr.canvas Perform better when large number of objects and surface is small
  44. Animation: CSS3 • Styles for Individual elements • Use CSS3 animation if available • Better than JavaScript based animation • Check Modernizr.csstransitions Can perform better with GPU acceleration
  45. Animation: CSS3 var elem = document.getElementById(transelem); elem.addEventListener(click, function loop() { elem.style.left = „100px;}, false); #transelement { … -xxx-transition: opacity 1s ease; transition: opacity 1s ease; }
  46. Animation: WebGL (Canvas Context: webgl) • Canvas based 3D implementation • Use GPU acceleration • Supported only in a few browsers • Check Modernizr.webgl
  47. 5/7 Media How to use Audio-Video?
  48. Audio: Big Challenge Open AL Audio Web RIA Audio Data – Audio – Firefox Webkit HTML5 Flash/ Audio Silverlight Not suitable for Sfx
  49. 6/7 Ajax How to use Ajax and do Cross Domain call?
  50. Ajax: XMLHttpRequest CORS Write a Cross JSONP Proxy Origin Resource Hybrid Not sharing App Standard
  51. Ajax: XMLHttpRequest • Cors Server code self.response.headers.add_header (“Access-Control-Allow-Origin”, “*”) • Check jQuery.Support.Ajax jQuery.Support.cors
  52. 7/7 HTML5 APIs How to use HTML5 advanced APIs in all Screens? & What are PolyFills and Shims?
  53. HTML5 API: Challenge HTML5 API Polyfills and Shims JavaScript Code
  54. HTML5 API: Polyfills and Shims? Provide support for missing features. • Polyfills: Replicate standard feature API • Shims: Own API with useful features
  55. W3C Working Groups And other resources
  56. Where to look for more information W3C Working Groups http://www.w3.org/Mobile/ http://www.w3.org/TR/css3-mediaqueries/ http://www.w3.org/2011/audio/ http://www.w3.org/testing/browser/ http://www.w3.org/Graphics/SVG/WG/wiki/Main_Page http://www.w3.org/TR/cors/ http://dev.w3.org/geo/api/spec-source-orientation.html Other Resources http://www.modernizr.com/ http://api.jquery.com/jQuery.support/ http://Html5rocks.com http://mediaqueri.es/
  57. The future is already here—it’s just not veryevenly distributed. – William Gibson Thank You @rajeshlalnokia [email protected]


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