Pseudo Classes

Last day, we learned about class, generic, and id selectors in CSS.
These allow you to select which tags a given style applies to.
In contrast, pseudo selectors allow you to apply styles in the case that certain events happen.
Two pseudo-classes are supported by Firefox and IE7, but not 6 are: hover and focus.

An example of using these is:

input:hover {color:red} /* input tag will turn red when mouse over. */
input:focus {color:green} /* when click into 
   input field, it will turn green */

What values can a property have?

CSS1 supports over 60 properties for tags (the next few slides will discuss these).
First, though, the values one can assign a property can take one of several forms:
Predefined values:

For example, bold, red, disc. These are case insensitive

Signed Number values:

-17, 17em /*1 em =height of letter m */, 17ex, 17mm, 17px, 17cm, 17pt These may or may not have a unit after them.

Percentage values:
75%

URL values:

For example: url(mypic.jpg)

Color values:
These can be predefined as for example the keyword white Or you can specify rgb values in one of two formats:
```
  rgb(0, 0, 0) /*decimal */
  #C8C8C8 /*hex */
```

Color, Fonts, and Text Decoration

Colors

You should remember when specifying colors that they might look different on different machines / monitors. There is a list of 216 so called web-safe colors on Wikipedia.
To specify the foreground color of a tag you can set the color property. For example, div.changed {color: red} <div class="changed"><p>first paragraph that's new</p><p>2nd...</p></div>
To specify the background you use the background-color property

Fonts

There are several properties of font you use that you can control.

font-family (examples: Arial, Times, Courier)
font-size (examples: 20pt, 15px, xx-small, x-small, small, medium, large, smaller, larger, etc)
font-style (example: italic, oblique)
font-weight (example: bold, bolder)

Text-Decoration

The text-decoration property can be further used to control how text looks. Some values are line-through, overline, underline, and none.

List Properties

Here are some properties which can be used to control how ordered and unordered lists are displayed:
list-style-type:
For unordered lists one can have values disc, square, circle; for ordered lists one can have values decimal, upper-alpha, lower-alpha, upper-roman, lower-roman.

list-style-image:
Can be set to the url of an image to be used for the bullet. For example,
```
  <li style="list-style-image: url(mybullet.png)"> item </li> 
```

Alignment of Text

There are several properties which control the flow of text and images in a given set of tags.

text-indent
Usually used to control how much the first line of a paragraph is indented. Ex: p.indent {text-indent: 0.5in}

text-align
This controls how the text is aligned within margins. It can have the values: left, right, center, and justify.

float
This a property often used with images and tables to control how text flows around the element. possible values are left, right, and none. We showed in class that the float tag can be used to make a simple two column layout.

Box Model

Each element in XHTML has properties which control its border and the amount of white space around it
This model is also used when you use CSS with other kinds of XML documents

More on the Box Model

Controlling the border:

border-style:
This can be none, solid, dotted, dashed, double

border-width:
This can be a length in pixels or thin, medium, or thick. You can more finely control each side of the border by using the properties: border-top-width, border-bottom-width, border-left-width, bottom-right-width border-color: This sets the color of the border. This can also be more finely controlled with border-top-color, border-bottom-color, border-left-color, and border-right-color.
Controlling margins and padding: These can be controlled using the properties: margin-left, margin-right, margin-top, margin-bottom, padding-left, padding-right, padding-top, padding-bottom.

Background Images

The background-image property is used to place an image in the background of an element:
```
body {background-image: url(background.jpg);}
```
The way this image is displayed can be further controlled using the properties:

background-repeat:
this may have values: no-repeat, repeat-x, repeat-y

background-position:
this may have values which are space separated combinations of top, center, bottom, left, and right. You can also give an x and y value for the image offset in each direction. This is useful for sprites.

Position and Display Properties

The position property can have the value relative (says to place element relative to the last element) or absolute (says to place element at some offset from top left of display).

For example,

<style type="text/css"> 
   p.first {position: absolute; top:1in; left:2in;}
   p.second {position: relative; left:-1in;}
</style> 
<p class="first">displays one inch down 
two inches from left of top of screen</p>
<p class="second">displays 1inch to the left 
of where the first paragraph finished</p>

The display property can be one of block, inline, or none. block causes the box model to be used, inline makes the element data flow like text, and none does not render the element. You can also set the property "visibility: hidden" which renders the element in the background color
Other useful properties are width and height which set and control respectively the width and height of an element.

Keyboard Shortcuts

We are now done talking about CSS.
As a brief interlude before beginning our next major topic -- which is PHP-- I thought I would point out a useful way to make web pages more accessible.
This is to use the accesskey attribute of an element within the web page:
```
<input type="text" name="fname" accesskey="f" />
```
Now when ALT-f (maybe CTRL-f on a Mac) is typed the focus will go directly to this element.

Introduction

PHP was developed by Rasmus Lerdorf around 1994-1995.
PHP originally stood for Personal Home Page, later PHP became an acronym for PHP: Hypertext Processor.
It is one of the most common server-side programming languages.
According to Tiobe, it is ranked fourth in overall popularity amongst all languages for any use.
The Wikipedia article on PHP says over 20 million domains are hosted on servers with PHP enabled.
One oft-touted advantage of PHP is its shared nothing architecture: Each php request is distinct and does not directly share memory/data with other requests. Shared data is stored in filesystem/memory cache/database/etc.
This can make PHP easier to debug and easier to scale.

Overview

The web site for PHP is http://www.php.net/
The web server determines that a page is PHP usually by looking for one of the extensions .php, .php3, .phtml
When called from the web server on a PHP page, the PHP processor takes a PHP document and starts processing in one of two modes.
When it sees XHTML it simply copies it to the output. (Copy mode).
When it sees PHP code it executes the code and writes the result to the output.(Interpretive mode)
PHP is typically interpreted but it also can be precompiled.
The syntax of PHP is closely related to Perl and Javascript.

Configuring PHP

PHP should be installed and running as of HW1.
You can fine-tune how PHP runs by editing the file php.ini
A ';' is used to indicate a comment in this file.
The most common thing for people to change is to have a line:
```
short_open_tag = On
```
so that you can escape to a PHP script using <? rather than <?php
Unfortunately, using the short open tag can mean your script is not as portable so for this class we will leave this off.
Xampp sets things this way by default so for today we will not worry about this. -- Many open source projects prefer long tags for compatibility.
Another common thing to change is the amount of error reporting PHP gives.
By default, it is assumed we are in a production environment so none is given.
For today, we want error-reporting. So find the line:
```
;error_reporting = E_ALL & ~E_NOTICE
```
and uncomment it, restart Apache

General Syntax

PHP scripts are run on the server.
They can be run standalone, but typically, PHP code is embedded in an XHTML document.
A section of PHP code is delimited with <?php ... code here ...?>
The command include("filename.php"); can be used to include one document in another.
All variables in PHP begin with a $ sign. Names of variables are otherwise like in Perl or other common programming languages.
PHP can use either Perl, C++, or C comments: #, //, /* ... */

CSS and Intro to PHP

Outline