Transcript HTML5
HTML5 (HYPER TEXT MARKUP LANGUAGE) Lab 223 潘建廷 [email protected] 何偉聖 [email protected] INTRODUCE Today, some elements in HTML 4.01 (1999)are obsolete, never used, or not used the way they were intended to. These elements are deleted or re-written in HTML5. HTML5 is the next generation of HTML. HTML5 will be the new standard for HTML, XHTML, and the HTML DOM. HTML5 is still a work in progress. However, most modern browsers have some HTML5 support. GOALS Document real-world browser behaviour Document and standardise useful extensions Develop practical new features Ensure backwards compatibility Define robust error handling DESIGN PRINCIPLES Foundation of Design and Development Organised into 3 Categories Compatibility Utility Interoperability DESIGN PRINCIPLES: COMPATIBILITY Support Existing Content Degrade Gracefully Don't Reinvent the Wheel Pave the Cow paths Evolution, not Revolution DESIGN PRINCIPLES: UTILITY Solve Real Problems Priority of Constituencies Media Independence Universal Access Support World Languages Secure By Design Separation of Concerns DESIGN PRINCIPLES: INTEROPERABILITY Well-Defined Behaviour Avoid Needless Complexity Handle Errors BENEFITS OF HTML Backwards compatible with legacy UAs Author familiarity Lenient and forgiving syntax Convenient shorthand syntax Can omit some tags and attribute values BENEFITS OF XHTML Strict XML Syntax Integrate directly with other XML vocabularies SVG, MathML Use XML Processing DOCUMENT REPRESENTATIONS HTML5 will be the new standard for HTML, XHTML, and the HTML DOM. HTML5 WERE ESTABLISHED New features should be based on HTML, CSS, DOM, and JavaScript Reduce the need for external plugins (like Flash) Better error handling More markup to replace scripting HTML5 should be device independent The development process should be visible to the public VIDEO •Ogg = Ogg files with Theora video codec and Vorbis audio codec •WebM = WebM files with VP8 video codec and Vorbis audio codec •MPEG4 = MPEG 4 files with H.264 video codec and AAC audio codec VIDEO H.264 SUPPORT IN THE “BIG-5” VIDEO --VIA HTML5 Example •The video element allows multiple source elements. Source elements can link to different video files. • The browser will use the first recognized format VIDEO – UI CONTROLS AUDIO • Until now, there has never been a standard for playing audio on a web page. • Today, most audio are played through a plugin (like flash). However, not all browsers have the same plugins. • HTML5 specifies a standard way to include audio, with the audio element. • The audio element can play sound files, or an audio stream. WEB STORAGE HTML5 offers two new objects for storing data on the client: localStorage - stores data with no time limit sessionStorage - stores data for one session