What did we learn so far?

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What did we learn so far?. Computer hardware and software Computer block diagram HTML (hyper text markup language) <tag> </tag> Parts of a HTML document: doc identification, head, body HTML file has contents Content of HTML file specified between tags Notebook editor Firefox browser
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What did we learn so far?
  • Computer hardware and software
  • Computer block diagram
  • HTML (hyper text markup language) <tag> </tag>
  • Parts of a HTML document: doc identification, head, body
  • HTML file has contents
  • Content of HTML file specified between tags
  • Notebook editor
  • Firefox browser
  • CSS files for specifying styles (red color etc.)
  • Image and music tags
  • Basic Elements of a web pagewebpageWeb browserFirefox, Safari.cssfile.html filedisplaysinterpretsimage and audio files Prepare/edit filesReferences: href tag
  • You can refer to a document/item by using path names/links.
  • Path names can be absolute or relative
  • Lets look at examples from your lab 1.
  • Example of an absolute pathname or link:
  • <http://www.acsu.buffalo.edu/~bfhaag/webhamster.wav" type="audio/wav">>
  • For the absolute pathname file references can be any machines on the internet
  • Example of relative path /link:
  • <link rel="stylesheet" type="text/css" href="lab1.css">
  • For relative path names the file should be on your computer
  • Relative Pathnames
  • Often links refer to other Web pages on the same site
  • These pages are all be stored in the same or nearby folders
  • These anchor tags use relative pathnames
  • A relative pathname describes how to find the referenced file relative to the file in which the anchor tag appears
  • Structure of the Image Tag
  • An image tag specifies a file that contains an image:<img src="filename" alt="description"/>
  • src is the abbreviation for “source”
  • filename uses the same rules for absolute and relative pathnames as anchor tags
  • alt value specifies an alternative form for the image, usually a textual description
  • Structure of the Image Tag: Accessibility
  • The alt tag was introduced to assist persons who are visually impaired
  • Screen readers don’t know what the image is, but they can read the description of the alt tag
  • HTML requires alt tags
  • When an image is not available or loads slow, browsers display the alt information
  • GIF and JPG Images
  • Images can come in several formats
  • Web pages tend to use two of them:
  • GIF(pronounced is jif ) (Graphics Interchange Format) best suited for cartoons and simple drawings
  • JPEG(pronounced JAY·peg)Joint Photographic Experts Groupappropriate for high-resolution photographs and complex artwork
  • GIF and JPG Images
  • PNG are newer forms of GIF and can also be used on Web pages
  • PNG stands for Portable Network Graphics format
  • To tell the browser which format the image is in, the file name should include one of these extensions: .gif, .png, .jpg, or .jpeg
  • Making an Image Link
  • We do not have to use text as the anchor
  • Images can be used as well
  • Combine an anchor tag with an image tag:<a href="history_red_square.html"><img src="red.gif" alt="Red Box“></a>
  • When the page displays, the usual highlighting that links receive will be used to mark the .gif as a link
  • Attributes
  • Attributes
  • An additional specification included inside a tag
  • The abbreviations href, src, and alt are attributes
  • Attributes have the form name="value”
  • the name, such as href, is the attribute
  • the text in quotes, such as, biographies/russellbio.html, is the value
  • Values are always enclosed in quotes
  • The Style Attribute
  • The style attribute is the most useful attribute
  • Used to control a huge list of properties for every feature of a Web page
  • Properties are characteristics of page components, such as color, size, or position.
  • The value of the style has a standard form:style = "property_name : specification”
  • The Style Attributestyle = "property_name : specification"
  • The colon (:) separates the property name from its specification
  • The spaces on each side of the colon are optional<body style="background-color : black; color : green">
  • Notice that when more than one property is set with style, the name/specification pairs are separated by a semicolon (;)
  • Attributes for Image Tags
  • The attributes width and height of the image tag can be used to specify the size of an image<img src="puffer.jpg" width="200" height="200" alt="origami puffer fish"/>
  • The photo puffer.jpg will appear as 200 × 200 pixels, even if the actual size of the photo is 2000 × 2000
  • Specify only the width or the height of an image
  • Cascading Style Sheets (CSS)
  • Cascading Style Sheets (CSS)are responsible for much of the design of Web pages
  • It is a general styling system for documents that simplifies the task of creating complex page designs
  • Setting Global Style
  • Repeating style information wherever it is needed can be time-consuming and tedious
  • It can be placed in one global location inside the <head>
  • It then applies to the whole page
  • Place the style information inside a pair of <style> and </style> tags
  • Setting Global Style
  • The <style> tag contains a type attribute specifying the form of the style
  • Within the <style> and </style> are specifications for each tag that should have its properties adjusted
  • The general syntax iselem_name { prop_name1 : value1 ; prop_nameN : valueN}
  • Setting Global Style
  • The text between the tag’s angle brackets, known as the tag element, is given by the element name
  • When styling a particular tag, use the name only, we are not allowed to use the brackets here
  • After the element name and inside curly braces ({}) is the list of property—value pairs separated by semicolons
  • Setting Global Style
  • For each value pair, the property is separated from its value by a colon
  • Now, all occurrences of the tag will be styled with these properties
  • A document can be now given a consistent look without having to repeat the styling information every time a style tag is used
  • In Styling, Closest Wins
  • What if you want an exception to the rule?
  • What if you want the <h2> to look different for one heading?
  • Just style that specific tags with the style attribute
  • The basic style is given globally, a specific style is given locally or at that point in the Web page
  • Adding Class to Style
  • If a tag should be styled in several different ways, then there are several different classes of styling
  • A classis a family of styling specifications with a common name
  • The class is given in two places:
  • In the style definition inside the style tags in the <head>
  • At the site in the HTML code when thecode is used
  • Adding Class to Style<h2 class="scientist"> . . . </h2>
  • For the style definition, we append the class name (scientist) to the tag with a dot:h2.scientist
  • Plain <h2> tags are styled with those features that apply to all <h2> tags
  • Each separate class gives additional styling specifications
  • Style from Files
  • To reuse the style information for multiple works, all of the style information is placed inside a separate file
  • The browser is told where the style information is by using a <link> tag in the <head>:<link rel="stylesheet" type="text/css" href="AWAstyle.css">
  • This ensures that a whole site is styled consistently
  • Moving Style to a File<link rel="stylesheet" type="text/css" href="AWAstyle.css">
  • Place the global style specification into a file as a sequence of elements and their property/specification pairs
  • Don’t include the <style> tags!
  • The style file should be plain ASCII text
  • The file extension should be .css
  • Moving the style out shortens the <head> section of the HTML
  • Cascading the Style Sheets
  • CSS uses the rule “closest style wins”
  • There are 5 levels of styling information:
  • Default, given by browser settings
  • External, given in a file
  • Global, given in the <head> section
  • Range, given in an enclosing tag
  • Site, given by the style attribute
  • Cascading the Style Sheets
  • Each level is broader and more general than the level below it
  • However, there’s a rule:the closest style wins!
  • This idea of progressively becoming more site specific is the “cascading” behind Cascading Style Sheet
  • It allows general styles to be adopted at various and overridden later
  • Lists Tags
  • The easiest type of list is the unordered list
  • Unordered list tags <ul> and </ul> surround the items of the list
  • The items are enclosed in list item tags, <li> and </li>
  • Lists Tags
  • Another list is the ordered list
  • It uses the tags <ol> and </ol>
  • Bullets are replaced with numbers
  • The ordered list behaves just like the unnumbered list
  • Lists Tags
  • You can also have a list within a list
  • Make a sublist within the main list
  • Notice that sublists use a different bullet symbol
  • Lists Tags
  • The definitional list
  • Indicated by the <dl> and </dl> tags
  • Definitional lists are made of:
  • Definitional terms surrounded by <dt> and </dt>
  • Definitional data surrounded by <dd> and </dd>
  • Handling Tables
  • A table is a good way to present information.
  • It’s like defining a list of lists
  • The main list items, called rows, has one or more items, called cells
  • The browser aligns cells to form columns
  • Handling Tables
  • The table is enclosed in <table> and </table>
  • The table can have a border, if you use the border attribute
  • Each row is enclosed in <tr> and </tr>
  • Cells are surrounded by table data tags, <td> and </td>
  • Handling Tables
  • You can give tables captions and column headings:
  • Place caption tags within the table tags around the table’s caption
  • caption tags are <caption> and </caption>
  • Captions are centered at the top of the table
  • Handling Tables
  • Column headings are the first row of the table
  • In the “heading” row, replace the table data tags with table heading tags<th> and </th>
  • Column headings display in bold
  • Summary
  • Recall the idea of using tags for formatting:
  • A working set of HTML tags, giving you the ability to create a Web page.
  • An explanation of how links are marked with anchor tags.
  • Absolute and relative pathnames. Relative pathnames refer to files deeper or higher in the directory hierarchy.
  • The two most popular image formatting schemes and how to place them in a page.
  • Cascading Style Sheets, a general system for styling Web documents.
  • Lists and tables.
  • Related Search
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