This document is a work in progress and is subject to change.
Summary
- Firefox allows you to use coding to manipulate the opacity of an image.
- "Opacity" refers to transparency; the lesser the opacity of an image, the more transparent it is.
| Initial Value: | 1(opaque) |
| Applies to | all elements |
| Inherited: | No |
Syntax
Opacity:1.0 shows you all of the image; Without any filters applied the opacity of an image is 1.0 (fully opaque).
We use CSS to define the initial degree of opacity in Firefox:
<IMG style="-moz-opacity:0.5" src="test.gif">
Valid range of values for -moz.opacity is from 0 to 1, where lesser equates to more transparency.
Usage
- Quick opacity change onMouseover:
<IMG style="-moz-opacity:0.6" src="alta.gif" onMouseover="this.style.MozOpacity=1" onMouseout="this.style.MozOpacity=0.6">
- For CSS opacity to work in the browser it must have some placement specified. Mozilla recommends that we use float:left; and position:relative; to work in Mozilla Firefox. The opacity code for simply displaying an image is more straightforward.
<span style="float:left;filter:alpha(opacity=25);-moz-opacity:.25;opacity:.25;"><img src="v90.gif" width="50" height="50"></span>
Fun with -moz-opacity
<div style="color:black;width:150px;background:white;filter:alpha(opacity=50);-moz-opacity:.50;opacity:.50;float:right;margin-top:10px;margin-bottom:10px;margin-left:10px;font-family:Verdana, Arial, Helvetica,Georgia;font-size: 28px;line-height:26px; text-align: right;"> ...this will look like some of the <b>pullquotes or subtitles we see</b> in <span style="width:150px;padding-bottom:10px;float:right;text-align:left;color:black;background:white;filter:alpha(opacity=25);-moz-opacity:.25;opacity:.25;">magazine<b>layout...</b></span> </div> <p> <b>DIV</b><br> The text to the right is a <code>div</code> defined as <code>black</code> with a background color of <code>white</code>. The opacity on the <code>div</code> is <code>50</code>. </p> <p> <b>SPAN</b><br> The <code>span</code> inside of the <code>div</code> is defined with an opacity of <code>25</code>. The edges should not be jagged. The padding of 10 pixels on the span is simply so that we don't lose the bottom of the text <span style="font-weight:bold;">magazinelayout</span>. </p> <div style="clear:both;"></div>
Mozilla Recommended Values
Notes
The World Wide Web Consortium (W3C) provides a free online CSS validation service.
Browser Compatibility
- Internet Explorer
- Firefox
- Opera