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As I understand Christopher's answer, this is not built into OpenLayers.<br>
So, you must modify the source code yourself to get this behavior.<br>
<br>
"Nothing you can do" then translates to, "There is no option you can
switch on".<br>
<br>
You can start up by looking into Layer\Image.js and the function
"setUrl" <br>
which calls Tile\Image.js "draw", which in turn invokses .\Tile.js
"draw".<br>
<br>
You can see here that it calls "clear", which is implemented in
Tile\Image.js.<br>
I suppose you can simply comment out line 188 in Tile\Image.js:<br>
clear: function() {<br>
if(this.imgDiv) {<br>
//this.hide(); --> Commented out<br>
if (OpenLayers.Tile.Image.useBlankTile) { <br>
this.imgDiv.src = OpenLayers.Util.getImagesLocation() +
"blank.gif";<br>
} <br>
}<br>
},<br>
<br>
I have not tested it, so i probably has some sideeffects.<br>
You may also want to turn on Smooth transition, as that prevents the
original<br>
image from hiding before the new one is visible.<br>
<br>
And it is fairly annoying to maintain a modified version of OpenLayers,
so if at all possible,<br>
you should consider adding this as a selectable option, and submitting
the change as a patch.<br>
<br>
Another option is to replace the function at runtime, but that is bound
to break when<br>
OpenLayers is updated.<br>
<pre class="moz-signature" cols="72">Regards, Kenneth Skovhede, GEOGRAF A/S
</pre>
<br>
<br>
Jesper Larsen skrev:
<blockquote
cite="mid:fa493d130807142058h13af61d6see0e8fc1dc2aa60e@mail.gmail.com"
type="cite">
<pre wrap="">Hi Christopher, realjax and others,
As I understand your answer Christopher there is nothing I can do to
avoid the blinking. Is that a correct understanding? In case that is
not how I should understand your answer I have setup a minimal demo of
the problem on:
<a class="moz-txt-link-freetext" href="http://jlar.webfactional.com/static/">http://jlar.webfactional.com/static/</a>
When you press the switch button (with most of the browsers I have
tested) the OpenLayers map blinks but the ordinary html img attribute
does not. Any help on this issue is still very welcome.
Regards,
Jesper
2008/7/11 Christopher Schmidt <a class="moz-txt-link-rfc2396E" href="mailto:crschmidt@metacarta.com"><crschmidt@metacarta.com></a>:
</pre>
<blockquote type="cite">
<pre wrap="">On Fri, Jul 11, 2008 at 12:37:05AM -0700, realjax wrote:
</pre>
<blockquote type="cite">
<pre wrap="">Jesper-5 wrote:
</pre>
<blockquote type="cite">
<pre wrap="">Is the solution to this to use Tween to create a smooth transition
between to Layers? I tried it but I haven't been able to understand
how to do it. I hope someone can help me out. What I tried is simply:
</pre>
</blockquote>
<pre wrap="">OpenLayers.Tween is not likely going to suit your needs.
I think you need to search for an external solution that has one layer fade
out while the other fades in. You could (with a bit of hacking) prolly get
this working in combination with a lightweight framework like Mootools for
example.
</pre>
</blockquote>
<pre wrap="">I don't think this will do what he wants. The proble is that OpenLayers
intentionally hides images before they're loaded -- look at delayDisplay
in OpenLayers.Util.createImage.
In general, we have put no effort into changing this behavior.
Regards,
--
Christopher Schmidt
MetaCarta
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