Frames - Part 1 from Chapter 11 of HTML & XHTML: The Definitive Guide (2/4)
HTML & XHTML: The Definitive Guide, Chapter 11: Frames
Frame layout is similar to table layout. Using the
<frameset> tag, you can arrange frames into rows and columns while defining their relative or absolute sizes.
The <frameset> Tag
<frameset> tag to define a collection of frames and other framesets and control their spacing and borders. Framesets also may be nested, allowing for a richer set of layout capabilities.
- Defines a collection of frames
- class onUnload
- cols rows
- End tag:
</frameset>; never omitted
- Used in:
<frameset> tag in lieu of a
<body> tag in the frame document. You may not include any other content except valid
<frameset> content in a frame document. Combining frames with a conventional document containing a
<body> section may result in unpredictable browser behavior.
The rows and cols attributes
<frameset> tag has one required attribute: either
rows-your choice. They define the size and number of columns or rows of either frames or nested framesets for the document window. Both attributes accept a quote-enclosed, comma-separated list of values that specifies either the absolute (pixels) or relative (percentage or remaining space) width (for columns) or height (for rows) for the frames. The number of attribute values determines how many rows or columns of frames the browser displays in the document window.
As with tables, the browser matches the size you give a frameset as closely as possible. The browser does not, however, extend the boundaries of the main document window to accommodate framesets that would otherwise exceed those boundaries or fill the window with empty space if the specified frames don't fill the window. Rather, browsers allocate space to a particular frame relative to all other frames in the row and column and resolutely fill the entire document window. (Did you notice that the main frame window does not have scrollbars?)
creates three rows of frames, each extending across the entire document window. The first and last frames are set to 150 pixels tall, and the second is set to 300 pixels. In reality, unless the browser window is exactly 600 pixels tall, the browser automatically and proportionately stretches or compresses the first and last frames so that each occupies one quarter of the window space. The center row occupies the remaining half of the window space.
Frame row- and column-size values expressed as percentages of the window dimensions are more sensible. For instance, the following example is effectively identical to the previous one:
Of course, if the percentages don't add up to 100%, the browser automatically and proportionally resizes each row to make up the difference.
If you are like us, making things add up is not a strength. Perhaps some of the frame designers suffer the same difficulty, which would explain why they included the very nifty asterisk option for
cols values. It tells the browser to size the respective column or row to whatever space is left over after putting adjacent frames into the frameset.
For example, when the browser encounters the following frame tag:
it makes a fixed-sized column 100 pixels wide and then creates another frame column that occupies all of the remaining space in the frameset.
Here's a fancier layout example:
This one creates two very thin columns down the edges of the frameset and gives the remaining center portion to the middle column.
You may also use the asterisk for more than one row- or column-attribute value. In that case, the corresponding rows or columns equally divide the available space. For example:
creates a 100-pixel tall row in the middle of the frameset and equal-sized rows above and below it.
If you precede the asterisk with an integer value, the corresponding row or column gets proportionally more of the available space. For example:
creates four columns: the first column occupies 10% of the overall width of the frameset. The browser then gives the second frame three-fifths of the remaining space, and the third and the fourth are each given one-fifth of the remaining space.
Using asterisks (especially with the numeric prefix) makes it easy to divide up the remaining space in a frameset.
Be aware, too, that unless you explicitly tell it not to, the browser lets users manually resize the individual frame document's columns and rows and hence change the relative proportions each frame occupies in the frames display. To prevent this, use the
noresize attribute for the
<frame> tag, which we describe later.
Created: November 6, 2002
Revised: November 6, 2002