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Internet / Intranet CIS-536

Internet / Intranet CIS-536. Class 3 More HTML Cascading Style Sheets. Class 3 Agenda. Recap Last Week Homepage Discussion More HTML Cascading Style Sheets Style Discussion Discuss Homework/Project. Internet / Intranet / Extranet. The Main Difference is in the Target Audience

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Internet / Intranet CIS-536

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  1. Internet / IntranetCIS-536 Class 3 More HTML Cascading Style Sheets

  2. Class 3 Agenda • Recap Last Week • Homepage Discussion • More HTML • Cascading Style Sheets • Style Discussion • Discuss Homework/Project

  3. Internet / Intranet / Extranet • The Main Difference is in the Target Audience • Internet • All Potential Users • Those With GUIs • Those With Current Browsers, Fast Connections • Those With Netscape or Internet Explorer • Intranet • Within a Specific User Community • Microsoft: Users of Microsoft O/S, Browsers • Usually Means Within a Company • Extranet • An Intranet With Some Features Available to a Broader User Community • E.g. Customers, Suppliers • Typically Means Different Levels of Access to Different Users • Two Levels of Accessibility • The Ability to View the Pages as Intended • The Ability to Access the Page

  4. HTML Tips / Compatibility • Quotes in Attributes • Double Quotes are Necessary if a Space Exists in Value • E.g. <FONT FACE = “Times Roman”> • Optional Otherwise • E.g. <FONT COLOR=“blue”> <FONT COLOR=blue> • Safe Tags • Results are Reasonable Even if Tag is Not Recognized • E.g. It was a <B>great</B> day! • Confusing Tags • Result is Confusing, But No Serious Harm Results • The following text is <b>bold</b> • Bad Tags • Result May Be Opposite of What You Expect • <DEL>If this text appears, we have a deal</DEL> • Page May Be Unreadable • E.g. White Text on Dark Background will be unreadable if Browser does not recognize background color.

  5. Using Color/Fonts in Web Pages • Originally Netscape Extensions to HTML • Now “de-facto” Standards • (Netscape and IE Support Them) • Many Not Officially Part of HTML Standard • Video Displays Vary • Many PCs Configured to Only Support 256 Colors at Once • Other Colors Often Dithered • Colors, Fonts Will Likely Look Different on Different Systems

  6. Specifying Color • By Name • Browsers Support Some Common Color Names • By RGB Value: #RRGGBB (Hexadecimal) • #000000 – Black • #FFFFFF - White • In Order of Portability • 16 Color Safety Palette • Colors are Same on Macs, PCs • 216 Color Palette • Netscape, IE “Map” Them to Common Colors • RGB–00,33,66,99,CC,FF • 65,536 Colors • Colors Will Vary Somewhat on Macs, PCs • 16.7 million Colors • Expect Dithering on Many Displays • Example

  7. Color Attributes • Body Background (defaults): • <BODY BGCOLOR=“white” TEXT=“black” LINK=“blue” VLINK=“maroon” ALINK=“red”> • BGCOLOR – Background Color • TEXT – Text Color • LINK – Color of Unvisited Links • VLINK – Color of Visited Links • ALINK (Netscape Only) – Color of Link During “MouseDown”

  8. Fonts • <BASEFONT SIZE=“2”> • Sets the Default Size of Text • 1 – Smallest, 7 – Largest, Default = 3 • <FONT FACE=“arial” COLOR=“blue” SIZE=“+2”> • FACE – The Font Face • Must Be Resident on the System • “Portable” Font Faces: (Windows, Mac, Unix) • Arial • Times Roman • Courier • Sans Serif • WingDings • SIZE – Absolute or Relative to BASEFONT • Standard: Size = 3

  9. Other Text Manipulation Tags • <BLINK>Flashing Text </BLINK> • Flashes Text On and Off, Netscape Only • <MARQUEE BEHAVIOR=“scroll” BGCOLOR=“red” DIRECTION=“left” LOOP=“7”> • Scrolls Text Across Page, Microsoft IE Only • BEHAVIOR – scroll, slide, alternate • LOOP – Number of Times to Scroll (Default-Infinite) • <STRIKE> StrikeThroughText </STRIKE> • <SUB>Subscript Text </SUB> • <SUP>Superscript Text </SUP> • <B>Bold Text </B> • <I>Italicized Text </I> • <U> Underlined Text </U> • <NOBR>Text Between Tags Will Be on One Line </NOBR> • <WBR>Identifies Where Hyphen Will Go If Word is Split • Example

  10. Image Formats • GIF Files – Graphics Interchange Format • Allows Transparent Backgrounds • 256 Color Palette • Supports Interlaced GIFs • Supports Animations • Four Sequential Images • May Distract Users • JPG Files (JPEG) • Better Compression • 16.7m Color Palette • Optimized For Color – Not as Good as GIF for Black & White • Better For Photos • Requires More Decompression by Browser • Progressive JPGs • Smoother Version of Interlaced GIFs • Not Supported by All Browsers (Blank Image Results)

  11. Image Formats (2) • PNG – Portable Network Graphics • GIF Successor • Don’t See it Much in Practice • BMP • No Compression • Display Issues • Larger Graphic Size Means Slower Page Display • Caching • Most Browsers Cache Graphics • If You Use the Same Graphic in Multiple Places on Site, Cached Image Will Produce Faster Dispays

  12. Using Images • <IMG SRC=“image.gif” ALIGN=“top” HEIGHT=“100” WIDTH=“200” BORDER=“5”> • ALIGN – Where Image is Displayed in Regards to Text • HEIGHT,WIDTH – If Specified, the Image is Scaled to This Size. (Pixels, or Percentages) • Use Judiciously. Scaling Can Cause Picture Degradation • BORDER – Size in Pixels of a Border Around the Image • Page Background • <BODY BACKGROUND=“image.gif” BGPROPERTIES=“fixed”> • BACKGROUND – Image File to Show As Background • Backgrounds are Tiled • BGPROPERTIES=fixed – (IE Only) Don’t Scroll Background As Page Scrolls • IMG May Appear Within an Anchor: Acts as a “Button” • <A HREF=“link.htm”><IMG SRC=“clickme.gif”></A>

  13. HTML Tables (1) • As Tables of Data • <TABLE BORDER=“2” CELLSPACING = “5” CELLPADDING=“3”> • BORDER – Displays A Visible Border Around Cells • CELLSPACING – Amount of Space Between Cells • CELLPADDING – Amount of Space Between Data and Border • As a Text Formatting Feature • Used to Create Tabs, Left, Right Margins • Tables Within Tables Allows Additional Positioning • <TABLE WIDTH=“80%”> • WIDTH – Percentage of Browser Window • <TR COLSPAN=“2” ROWSPAN=“2”> • Allows Information to Span Multiple Rows/Columns

  14. HTML Tables (2) • Can Do Amazingly Creative Things With Tables • Easy to Get Tags/Hierarchy Messed Up • Debugging Can Be Pretty Difficult • Make Sure to Try Complex Tables on Multiple Browsers • Run Through a Tag Validation Utility • Many Browser Specific Extensions • Easy to Get Into Habit of Using Them Without Realizing That They are Browser Specific Example

  15. Frames (1) • Method to Display Multiple HTML Files on the Same Page • Requires Netscape Navigator / Internet Explorer 3.0 or Above • Requires a “Master Layout Page” • Divides the Page Into Sections (Frames) • Identifies the HTML Files To Be Displayed in each Frame • <FRAMESET> • Replaces the <BODY> Tags • Hierarchical – Can Subdivide Sections Further • <NOFRAME> • “Conditional Code” If Browser Supports Frames Then Display What is Between <FRAMESET> </FRAMESET> Else Display What is Between <NOFRAME> </NOFRAME> • By Putting <BODY> Tags Within <NOFRAME> Section • Cleverly Allow This to Work on Older Browsers • I.e. Browser Doesn’t Have to Recognize <FRAME> Tags

  16. Frames (2) • <FRAME NAME=“leftframe” SRC=“info.htm” SCROLLING =“Yes”> • SRC – The URL to Display in This Frame • NAME – An Internal Reference Name of The Frame • SCROLLING – (Default) Allow Scrolling When Page is Larger Than Frame • Links Within Frames • Straight Link Replaces the Entire Page • Targeted Links – Allows a Link to Replace a Frame • <A HREF=“newpage.htm” TARGET=“left”> • TARGET = The Internal Frame Reference Name • Use Frames Judiciously • Often Same Effect Can Be Achieved Through a Single Page • Example

  17. Multimedia • Sound • <BGSOUND SRC=“noise.wav” LOOP=“Infinite”> • IE Only • Plays Sound in Background • SRC – URL of the Sound File • .WAV, .MID Formats are Common • LOOP – Number of Times to Repeat Sound (Default = Once) • Alternatives: • Plug-In • OBJECT= (HTML 4.0) • Video – MPG, AVI • Client-Pull • <META HTTP-EQUIV=“refresh” CONTENT=5; URL=“newpage.htm”> • Document Will Reload Every 5 Seconds • If URL Specified: This Page Will Display For 5 Seconds and Load New Page • Example

  18. Client-Side Image Maps • Allow a Graphic to Be Used as a Segmented Button • When User Clicks on the Region In Map • The Appropriate URL is Invoked • <IMG SRC=“pic.gif” USEMAP=“#mapname”> • <MAP name=“mapname”> • <AREA SHAPE=“rect” COORDS=“0,0,100,100” HREF=“thisone.htm” ALT=“lower left”> • <AREA SHAPE=“circle” COORDS=“200,200,20” HREF=“circlepage.htm” ALT=“middle”> • </MAP> • SHAPE – Circle, Rect, Polygon • COORDS – • Rectangle - Lower Left, Upper Right Corners • Circle: Center Coords and Radius • Polygon – Polygon Edges • ALT – Text to Be Displayed For Text-Only Browsers • Coords Start at Upper Left Corner Example

  19. Meta Tags • Information About the Data • Information Passed to Browser, Server • Information Passed as Name, Value Pairs • <META NAME=“keyword” CONTENT =“value”> • Information for Browser • <META HTTP-EQUIV=“keyword” CONTENT=“value”> • Information for Server • Meta Tags are Not Strictly Part of HTML • Standard Tags By Convention • No Guarantee That Browser / Server Will Understand Tags • No Guarantee That Browser / Server Will Obey Tags

  20. Meta Tags(2) • Browser Keyword/Values: • “Author” – Author’s Name • “Review”– Page Should Be Reviewed After Specified Date • “Keywords” - Search Engine Should Index This Page on Specified Keywords • PICS-Label – Content Ratings • Server Keyword/Values: • “Refresh” / Time Period – Reload Page Periodically • “Expires” / Time Period – Server Shouldn’t Cache Page After This Date • Content-Type – Character Set Used in Document • Page-Enter – Visual Transition Effect Upon Page Entry • Page-Exit - Visual Transition Effect Upon Page Exit Example

  21. Cascading Style Sheets (CSS) • Similar to Word-Processing Styles • Controls Layout, Not Content • Change in Web Page Design Philosophy • The Reality: Web Page Authors Were Using “Tricks” to Control Layout • The Response: Give in to the Inevitable • Develop a Reasonable Standard: Cascading Style Sheets • CSS is Now the Preferred Method For Portability • Allows Users to Change Styles for Readability • CSS “Requires” Upgraded Browser • Browser/User Now Have More Options for Making it Readable • Older Browsers Won’t “Crash”, Just Won’t Show Formatting • Underlying Text is More Human Readable • Proliferation of Font, Table, etc. Tags Made HTML “Unreadable” in Many Cases • Styles Allow Control of: • Fonts, Colors, Spacing, Margins

  22. The Philosophy of Style Sheets • All Text Belongs to a “Style” • Style Information Kept Together in Dictionary • Style Information Defined in: • Within the HTML Text Itself (Inline) • Uses Style Sheets Purely For Enhanced Formatting • HTML Header • A Linked CSS File • Can Be Easily Changed to Produce a Different Document Style • A User Defined CSS File (Defaults For the Document) • Allows Better Access For People With Disabilities • A Useful Goal: • A Generic Set of Styles Used By Many • The Reality: • May Help Consistency Among Similar Documents • Unlikely to Happen Across Companies • Designers Will Want to Create Own Unique Look and Feel

  23. Basic Example of Global Style in Header • <HEAD> • <STYLE>H1 {color: blue} </STYLE> • </HEAD> • All Text Within an H1 Tag is Blue • Equvalent of: • <H1><FONT color=“blue”>xxx </FONT></H1> For ALL H1 Tags in the Document • Saves “Code” • Makes it Easier on Designers • Easier to Make a Global Change • Resulting HTML Body is Easier to Read

  24. Same Example Using Inline Style • <H1 STYLE=“color: blue”>xxx </H1> • In This H1 Instance, the Text is Blue • Subsequent H1 Tags Revert to Default • The “Cascading” in Cascading Style Sheets • Defines How “Conflicts” are Resolved • i.e. What if There’s Both a Global and Inline Style? • Common Sense Hierarchy: • Inline Rules Override Global Rules • Document Styles Override User Style Sheets • EXCEPTION: Can Override Others Through !important Tag

  25. Global Style Sheets • <HEAD> • <LINK REL=STYLESHEET HREF=“mystyle.css TYPE=text/css”> • </HEAD> • Style Sheet “Libraries” • W3C Core Styles • http://www.w3.org/StyleSheets/Core/stylename • Eight Core Styles • For demo: http://www.w3.org/StyleSheets/Core/preview.html

  26. Style Sheet Grouping • H1 {color: green} H2 {color:green} H3 {color:green} Can Be Written: H1 H2 H3 {color: green}

  27. Style Sheet Classes • User Defined Classes • <HTML><HEAD> • <STYLE> • P.stoptext {color: red; font: 16 pt} • P.gotext {color: green; font: 18 pt} • </STYLE> </HEAD> <BODY> • <P Class=stoptext>This text appears in red</P> • <P Class=gotext>This text appears in green </P> • </BODY></HTML> • C-Style Comments • H2 {color: blue} /* All Headers Displayed in Blue */

  28. CSS Properties • Background: color – The Background Color • Color: color – The Text Color • Font-family: “font name” – The Font to Be Used • Font-size : size/units (e.g. 12pt or 1in) • Font-style: italic • Font-weight: bold, demi-bold, demi-light, extra-bold, extra-light, light, medium • Line-height – distance between lines • Margin-left • Margin-right • Margin-top • Text-align: left, center, right • Text-decoration: italic, line-through, none, underline • Text-indent

  29. More CSS Properties • List Styles • List-style-image:URL (newbullet.gif)} • List-style-type: disc,circle,square,decimal,upper-alpha,lower-alpha,upper-roman,none. • <STYLE> • UL {list-style-image:URL(newbullet.gif)} • </STYLE> • Cursor: auto, crosshair, default,hand,text,help,wait • Downloadable Fonts • Give the URL Where Font Can Be Found • Layers • CSS is the Foundation for Dynamic HTML • Allows Script to Reference an HTML Property • E.g. ButtonClick Changes Text Color

  30. Other Useful Tags / Information • <DIV STYLE=“font-size:10pt; color:blue”> • Allows an Arbitrary Division of an HTML Document • Attributes Only Apply Within the <DIV> Tags • <SPAN class=“xxx”> • Allows “Custom Tags” • ID, NAME Attributes • Give a Tag Instance a Unique Name, ID • Allow a Specific Tag To be Referenced Through Dynamic HTML • All HTML Tags Now Have the STYLE Attribute Example1 Example2

  31. Future HTML • Deprecated Tags • May Not Be Supported in Future Versions of HTML • CSS Alternative Recommended • Basefont • Center • Font • Strike • Underline • XHTML 1.0 • Requires Strict Conformance • Must Conform to One of 3 DTDS • Strict, Transitional, Frameset • Must Be Well-Formed • Elements, Attributes in Lower Case • Attribute Values Must Always Be Quoted • Empty Elements Require End-Tags • Or Short-Cut e.g. <HR/>

  32. In Class Exercise • Convert the index.htm File That You Created Last Class to Use Style Sheets • Insert the Following in the <HEAD> Section • <STYLE> • H1 {color:Blue} • H2 {color:Red} • </STYLE> • Publish it to your Web Site • Use an external W3C Style Sheet to Display the Same Page • Link These to Your Class Web Page

  33. Lab Work • HomeSite • HTML Validation

  34. For More Information • CSS • http://www.w3c.org/Style/CSS • http://stars.com/Authoring/Style/Sheets/ • http://www.westciv.com/style_master/house/tutorials/index.html

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