[OpenLayers-Users] IE6 performance
Paul Spencer
pagameba at gmail.com
Tue Nov 13 07:46:08 EST 2007
Chris,
On 12-Nov-07, at 10:36 AM, Christopher Schmidt wrote:
> ... however, since the alpha-png hack is *always* applied, you'd have
> to do some hacking to turn that off. (Actually,
> OpenLayers.Util.alphaHack = function() { return false; } would
> accomplish that for you.)
In ka-Map (and other projects), we've used a css class .png24 to apply
the alpha hack to only selected images. Would it be feasible to do
this with OpenLayers too?
The css class is defined as follows:
.png24 {
filter:expression(applyPNGFilter(this));
}
Only IE supports execution of javascript in css class, so this is
automatically safe from other browsers.
the javascript function is:
applyPNGFilter = function(o) {
var t=Jx.baseURL + "images/a_pixel.png";
if( o.src != t ) {
var s=o.src;
o.src = t;
o.runtimeStyle.filter =
"progid:DXImageTransform.Microsoft.AlphaImageLoader(src='"+s
+"',sizingMethod='scale')";
}
};
This only works when you first insert an image into the DOM with this
class, but it could be adapted to support changing a url on an
existing image and optionally testing to see if the image has a
className of png24 before applying it.
If you think this is the right way to go, then I will create a patch
based on this approach. If you think there is a better approach, I'm
willing to try something else too.
Cheers
Paul
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