Chapter 3 - Part 1 - Lecture Notes:
Color Sites for Reference
The Color HEX Code
The six-digit number and letter combinations represent
colors by giving their RGB (red, green, blue) value. RGB triplet RRGGBB
where RR= Red GG= Green and BB= Blue. The six digits are actually three
two-digit numbers in sequence, representing the amount of red, green, or
blue as a hexadecimal value in the range 00-FF. For example, 000000 is
black (no color at all), FF0000 is bright red, 0000FF is bright blue, and
FFFFFF is white (fully saturated with all three colors).
The Background Attribute
CONTROLLING DOCUMENT BACKGROUNDS
Some of the following information was taken from the
Netscape Page at http://home.netscape.com/assist/net_sites/bg/
HTML 3.0 spec. have added a BACKGROUND attribute
to the BODY tag. The purpose of this attribute is to specify a URL pointing
to an image that is to be used as a background for the document. In Netscape
1.1, this background image is used to tile the full background of the document-viewing
area. Thus specifying:
<BODY BACKGROUND="metal/brushed_aluminum.gif">Document
here</BODY>
would cause whatever text, images, etc. appeared
in that document to be placed on a background similar to this one.
THE BGCOLOR ATTRIBUTE
To change the color of the background without having
to specify a separate image that requires another network access to load.
This attribute allows just that. Coded as below:
<BODY BGCOLOR="#rrggbb">Document here</BODY>
Where "#rrggbb" is a hexadecimal red-green-blue triplet
used to specify the background color.
HOW TO CONTROL THE DOCUMENT'S FOREGROUND
Once you have the background color or image set, you
are going to need to control the foreground to establish the proper contrasts.
The following attributes are also recognized as part of the BODY tag.
THE TEXT ATTRIBUTE
This attribute is used to control the color of all the
normal text in the document. This basically consists of all text that is
not specially colored to indicate a link. The format of TEXT is the same
as that of BGCOLOR.
<BODY TEXT="#rrggbb">Document here</BODY>
THE LINK, VLINK, AND ALINK ATTRIBUTE
These attributes control the coloring of link text.
VLINK stands for visited link, and ALINK stands for active link. The default
coloring of these is: LINK=blue, VLINK=purple, and ALINK=red. Remember
you can use the hex code for the color as well as word colors. Again the
format for these attributes is the same as that for BGCOLOR and TEXT.
<BODY LINK="#rrggbb" VLINK="#rrggbb" ALINK="#rrggbb">Document
here</BODY>
COMPLETE EXAMPLE
<HTML>
<HEAD>
<TITLE>Color Control Example</TITLE>
</HEAD>
<BODY BGCOLOR="#000000" TEXT="#F0F0F0"
LINK="#FFFF00" VLINK="#22AA22" ALINK="#0077FF">
This is an example document. Text is light-gray on
black, and
<a href="nowhere.html">anchors</a> are yellow
at first,
flashing blue-green when activated, and pale green
if already visited.
</P>
</BODY>
</HTML>
Images
http://www.ncsa.uiuc.edu/General/Internet/WWW/HTMLPrimerAll.html
Inline Images
Most Web browsers can display inline images (that
is, images next to text) that are in X Bitmap (XBM), GIF, or JPEG format.
Other image formats are also being incorporated into Web browsers [e.g.,
the Portable Network Graphic (PNG) format]. Each image takes additional
time to download and slows down the initial display of a document. Carefully
select your images and the number of images in a document.
To include an inline image, enter:
<IMG SRC=ImageName>
where ImageName is the URL of the image file.
The syntax for <IMG SRC> URLs is identical to
that used in an anchor HREF. If the image file is a GIF file, then the
filename part of ImageName must end with .gif. Filenames of X Bitmap images
must end with .xbm; JPEG image files must end with .jpg or .jpeg; and Portable
Network Graphic files must end with .png.
Image Size Attributes
You should include two other attributes on <IMG>
tags to tell your browser the size of the images it is downloading with
the text. The HEIGHT and WIDTH attributes let your browser set aside the
appropriate space (in pixels) for the images as it downloads the rest of
the file. (You can get the pixel size from your image-processing software,
such as Adobe Photoshop. Some browsers will
also display the dimensions of an image file in the
title bar if the image is viewed by itself without an enclosing HTML document.)
For example, to include a self portrait image in
a file along with the portrait's dimensions, enter:
<IMG SRC=SelfPortrait.gif HEIGHT=100 WIDTH=65>
NOTE: Some browsers use the HEIGHT and WIDTH attributes
to stretch or shrink an image to fit into the allotted space when the image
does not exactly match the attribute numbers. Not all browser developers
think stretching/shrinking is a good idea, so don't plan on your readers
having access
to this feature. Check your dimensions and use the
correct ones.
Aligning Images
You have some flexibility when displaying images.
You can have images separated from text and aligned to the left or right
or centered. Or you can have an image aligned with text. Try several possibilities
to see how your information looks best.
Aligning Text with an Image
By default the bottom of an image is aligned with
the following text, as shown in this paragraph. You can align images to
the top or center of a paragraph using the ALIGN= attributes TOP and CENTER.
Alternate Text for Images
Some World Wide Web browsers -- primarily the text-only
browsers such as Lynx -- cannot display images. Some users turn off image
loading even if their software can display images (especially if they are
using a modem or have a slow connection). HTML provides a mechanism to
tell readers what they are missing on your pages if they can't load images.
The ALT attribute lets you specify text to be displayed
instead of an image. For example:
<IMG SRC="UpArrow.gif" ALT="Up">
where UpArrow.gif is the picture of an upward pointing
arrow. With graphics-capable viewers that have image-loading turned on,
you see the up arrow graphic. With a text-only browser or if image-loading
is turned off, the word Up is shown in your window in place of the image.
You should try to include alternate text for each
image you use in your document, which is a courtesy for your readers --
or, for users who might be visually impaired, a necessity.
Images as Hyperlinks
Inline images can be used as hyperlinks just like
plain text. The following HTML code:
<A HREF="hotlist.html"><IMG SRC="BarHotlist.gif"
ALT="[HOTLIST]"></A>
(Note that this link doesn't actually go anywhere.)
The blue border that surrounds the image indicates that it's a clickable
hyperlink. You may not always want this border to be displayed, though.
In this case you can use the BORDER attribute of the IMG tag to make the
image appear as normal. Adding the BORDER attribute and setting it to zero:
<A HREF="hotlist.html"><IMG SRC="BarHotlist.gif"
BORDER=0 ALT="[HOTLIST]"></A>
Borders
The BORDER attribute can also be set to non-zero
values, whether or not the image is used as a hyperlink. In this case,
the border will appear using the default text color for the web page. For
instance, if you wanted to give your image a plain black border to help
it stand out on the page, you might try this:
<IMG SRC="BarHotlist.gif" BORDER=6 ALT="[HOTLIST]">
|
Code
|
Results
|
| <a href=under.html><img
border=3 src=coffeecup.jpg></a> |
 |
| <a href=under.html><img
border=0 src=coffeecup.jpg></a>A link to somewhere (no border) |
A link to somewhere
(no border) |
|
<a href=under.html><img border=5 src=coffeecup.jpg>
</a>A link to somewhere else (border 5) |
A link to somewhere
else (border 5) |
![[HOTLIST]](http://www.cerritos.edu/hohly/online75/coffeecup.jpg)
This is an example of
text which can be aligned with your image.