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Web-based Application Development

Web-based Application Development. Lecture 5 January 24, 2006 Anita Raja. Agenda. Cascading Style Sheets PTW Chapter 3 Attributes, Lists, and Tables PTW Chapter 4. Programming the Web using XHTML and JavaScript. Chapter 3 Cascading Style Sheets. I’ll bet red headings would look nice.

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Web-based Application Development

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  1. Web-based Application Development Lecture 5 January 24, 2006 Anita Raja

  2. Agenda • Cascading Style Sheets • PTW Chapter 3 • Attributes, Lists, and Tables • PTW Chapter 4

  3. Programming the Web using XHTML and JavaScript Chapter 3 Cascading Style Sheets

  4. I’ll bet red headings would look nice

  5. Internal Style Sheets • Redefines the presentation rule (style) for certain elements • “Internal” because contained within the HTML source document itself • Styles may be defined using different style sheet languages so … • … the language used must be specified

  6. The style sheet instructions in this element are: • Written in plain text format • Using the cascading style sheet language Internal Style Sheets • <style> element in <head> section <style type=“text/css”> … </style>

  7. Internal Style Sheets • Also specify default style sheet language for entire HTML document: <meta http-equiv=“Content-Style-Type” content=“text/css” /> • <meta> elements go in the <head> section

  8. Style definition Name of tag Property Value Internal Style Sheets h2 { color:red }

  9. Internal Style Sheets h2 { color:#D61130 }

  10. Internal Style Sheets • Alignment • Options are: left, center, right, justify <style type=“text/css”> </style> h2 {color:red; text-align:center}

  11. Uh, oh. I need bigger section headings

  12. Formatting Fonts Using Styles • Could find & replace all <h2> with <h1> • Why not? • What if some <h2> had been used for other things?

  13. Formatting Fonts Using Styles • Use font-size property: <style type=“text/css”> </style> h2 {color:red; text-align:center;font-size:24pt}

  14. Formatting Fonts Using Styles • Other choices for font-size value: • 150% • smaller • small, x-small, xx-small • larger • large, x-large, xx-large

  15. Formatting Fonts Using Styles • Use font-style property: <style type=“text/css”> </style> h2 {… font-style:italic …}

  16. Also normal, oblique

  17. Formatting Fonts Using Styles • Other properties • text-decoration • underline, overline, line-through, blink, none • text-transform • capitalize, uppercase, lowercase, none • font-variant • small-caps, none • background-color • transparent, one of the color names or numbers

  18. Formatting Fonts Using Styles • Paragraph styles • Only works for content enclosed within <p> elements <style type=“text/css”> p {font-size:14pt} </style>

  19. Formatting Fonts Using Styles • Indent and line spacing: <style type=“text/css”> p {text-indent:25pt; line-height:24pt} </style> <style type=“text/css”> p {text-indent:12%; line-height:150%} </style>

  20. Formatting Fonts Using Styles • Font Families • What if not installed on user’s browser? <style type=“text/css”> p {font-family:”Lucida”} </style>

  21. Formatting Fonts Using Styles • Include more than one font families: <style type=“text/css”> p {font-family:”Lucida”,”Arial”} </style>

  22. Formatting Fonts Using Styles • Warning: multiple fonts may not have the impact you intend • User’s display may not include the fonts you specified • Common fonts may be the best choice overall

  23. Formatting Fonts Using Styles • Can compress definition <style type=“text/css”> p {font-style:italic; font-weight:500; font-variant:small-caps; font-size:14pt; line-height:24pt; font-family:”Lucida”,”Arial”} </style> <style type=“text/css”> p {font: italic 500 small-caps 14pt/24pt ”Lucida”,”Arial”} </style>

  24. Do all paragraphs have to be the same?

  25. Tags with Multiple Styles • The same type of element can have multiple definitions called “classes” <style type=“text/css”> p {text-align:justify; font-weight:bold} </style> p.intro {text-align:center; color:red}

  26. Tags with Multiple Styles • The p.intro class includes the styles of the p class but changes those styles • How is this class invoked? • Explains why “none” is an option • text-transform; font-variant <p class=“intro”> … </p>

  27. Local Styles • Local styles take precedence over other style definitions <p>The text in this paragraph won’t be red</p> <p style=“color:red”>The text in this paragraph will</p>

  28. No existing tag is quite right. Now what?

  29. Custom Tags • Can create entirely new elements • Generic tags: • <div> (block level) • <span> (inline)

  30. Custom Tags <style type=“text/css”> span {font-size:18pt} </style> Let me make something <span>perfectly</span> clear.

  31. Custom Tags • Classes may be defined for custom tags <style type=“text/css”> span.red {color:red} </style>

  32. I’m going to get tired of entering style definitions into all my web pages.

  33. External Style Sheets • Text-only file • Contains style definitions only h2 {color:red} h1 {font-size:24pt p {text-align:center} p.small {font-size:10pt} • No <style> tags needed

  34. External Style Sheets • Save in a file with a .css extension • css = cascading style sheets • Local, internal and external may be present in the same document • Local overrides internal • Internal overrides external

  35. External Style Sheets • How to specify external style sheets? • Add <link> tag in <head> section <link rel=“stylesheet” type=“text/css” href=“my_styles.css”>

  36. External Style Sheets • Problem: older versions of browsers might not recognize style definitions • Could use comments: <style type=“text/css”> <!-- p {text-indent:25pt; line-height:24pt} --> </style>

  37. External Style Sheets • MORE problems: XHTML may not recognize this use of comments • Solution: use <link> method • If older version of browser does not recognize this tag it will ignore it

  38. Assignment • Debugging Exercise, p. 81 • Correct errors • Post corrected document to your Web space as “Lagerstrom-Ch-3.html” • Grade based on: • Appearance • Technical correctness of code

  39. Programming the Web using XHTML and JavaScript Chapter 4 Attributes, Lists, and Tables

  40. Extensions and Deprecations • Extensions – features not found in “standard” HTML • Too often, NN’s extensions don’t work in IE and vice versa • Therefore, be careful about non-standard features • Official features listed at www.w3c.org

  41. Extensions and Deprecations • Deprecation – feature being phased out • May work in older browser versions but eventually will cease to be supported • Obsolete – features that are not supported by browsers in strict compliance with W3C standards

  42. Extensions and Deprecations • At www.w3c.org … Site Index H HTML 4.01 Specification A. Changes 3.1 Deprecated Elements

  43. Extensions and Deprecations • Forms of XHTML (see p. 85) • Strict • Does not recognize deprecated elements • Transitional • Which should you use? • Transitional • Otherwise older browsers won’t display your pages well

  44. Extensions and Deprecations • <font> vs. <style> • <font> is deprecated • <style> isn’t • Which would be preferable for making changes to an entire document?

  45. No quotation marks Quotation marks Tags and Attributes • Styles have properties <style type=“text/css”> h2 {text-align:center} </style> • Attributes have values <font align=“center”> … </font>

  46. Tags and Attributes • <font> • size= “1” to “7” (smallest to largest) • color= “red”, “blue”, etc. • face= “Arial”, “Courier”, etc. <font size=“5” color=“red” face=“Arial”>

  47. Tags and Attributes • Alignment = “left”, “center”, “right” • Using tags: <h2 align=“center”> <p align=“right”> • Centering <center>this text is centered</center>

  48. Tags and Attributes • Preferred method using styles: <style type=“text/css”> h2 {text-align:center} p {text-align:center} </style>

  49. Tags and Attributes • Background colors • <body> tag • bgcolor and text attributes • Using tags: <body bgcolor=“yellow” text=“blue”>

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