Question

Load background image depending on dynamic variable

Asked by: Dada44

Hi all,

I'm receiving an id using $_REQUEST["id"]; in a page called page.php
This id will be used to change the background image of page.php depending on its value.  To do so I'm using the code below.

The id changes every now and then  and in all cases it is stored in $num = $_REQUEST["id"]; with no problem, works great, I've been testing it.
The issue is that once the background is loaded it does not change even if $num equals to 63.
Cache?? Should I preload the images? What can I do??

Thanks a ton!! 

$num = $_REQUEST["id"];
 
echo"
<body  style='background-image: url(/images/";
if ($num == 63){
echo"background1.jpg";
}else{
echo"background2.jpg";
}
echo");width:100%;height:100%;text-align:center;margin:0 auto;'>....

                                  
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Asked On
2009-03-23 at 05:39:48ID24255234
Tags

php

,

image

,

background

,

change

,

cache

,

load

Topics

PHP Scripting Language

,

JavaScript

,

Asynchronous Javascript and XML (AJAX)

Participating Experts
2
Points
500
Comments
6

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Answers

 

by: theoaksPosted on 2009-03-23 at 05:48:49ID: 23957062

I presume you've tried modifying your syntax as below to eliminate any potential formatting errors? Tried echoing out the result to ensure it's formatted right? Preloading the images won't do anything because you're modifying the HTML the client browser sees and displays, the client can't tell you're choosing the wallpaper at exec time, remember.

$num = $_REQUEST["id"];
 
if ($num == 63){
echo("<body style='background-image: url(/images/background1.jpg;width:100%;height:100%;text-align:center;margin:0 auto;'>")
}else{
echo("<body style='background-image: url(/images/background2.jpg;width:100%;height:100%;text-align:center;margin:0 auto;'>")
}

                                              
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by: babuno5Posted on 2009-03-23 at 05:50:25ID: 23957078

Yes the problem might be of cache try using a random number so that the image is never cached.

$num = $_REQUEST["id"];
 
echo"
<body  style='background-image: url(/images/";
if ($num == 63){
echo"background1.jpg?".rand();
}else{
echo"background2.jpg?".rand();
}

 

by: theoaksPosted on 2009-03-23 at 06:20:53ID: 23957315

babuno5, I have to disagree. The HTML will read <body style='background-image: url(/images/background1.jpg;width:100%;height:100%;text-align:center;margin:0 auto;'> OR <body style='background-image: url(/images/background2.jpg;width:100%;height:100%;text-align:center;margin:0 auto;'>.

If the browser has not cached background1.jpg, it will load it. It is not the image on the server that is changing, just the URI the HTML is pointing to.

http://server/images/background1.jpg is always http://server/images/background1.jpg
http://server/images/background2.jpg is always http://server/images/background2.jpg

However the page your browser is downloading will point to either of the images, thus I do not believe cache to be a possible cause.

 

by: Dada44Posted on 2009-03-23 at 08:46:03ID: 23958932

Thanks to both for answering.
In both solutions I get the first background but when the id changes it does not change to the second background :(

Hope the following may give you a clue:
In  Firebug's console:
The id is posted. The Post tab shows the id and its value correctly every time a new id is posted. Then in the Response tab for each id I have the correct html. If I copy and paste this html code into a new html document, it shows perfectly in the browser.
But that's in the Response Tab for each id posted.

Back in page.php, if I echo $num it shows in the Response tab and also changes  every time to its  new value coming from the newly posted id.  But the echo does not show in page.php just in the Response Tab ... what's going on???
Happens using $_REQUEST["id"]; and using $_POST["id"]; (and also using echo or print)

Thanks once again!

 

by: theoaksPosted on 2009-03-23 at 23:10:01ID: 23965157

If you do a Ctrl+F5 after the page has loaded, do you see any change?

 

by: Dada44Posted on 2009-03-24 at 01:53:38ID: 23965707

No, no changes :(

Here's the page:
http://www.vivocom.es/test/aa/page.php

And a screenshot so you can see how myid it is echoed in the Response tab (also in the post tab shows myid and the value) but not in page.php:
http://www.vivocom.es/test/aa/screenshot_page.gif

If you click in another video, you'll see that myid changes but not the background..
Below  page.php source code. As you'll see it's got an iframe .. could it be that myid is staying inside of the iframe .. and that's the reason why I cannot see it in the parent page (page.php)??
If so how can I catch myide from the iframe and echo it in the parent page???


Thanks everyone once again! 

<?
 
$num = $_REQUEST['myid'];
 
echo"<!DOCTYPE HTML PUBLIC '-//W3C//DTD HTML 4.01 Transitional//EN'><html><head><title>Test</title></head>";
echo"
<body  style='background-image: url(";
if ($num == 246220){
echo"background1.jpg";
}else{
echo"background2.jpg";
}
echo");width:100%;height:100%;text-align:center;margin:0 auto;'>
 
<iframe width='1024' height='650px'src='http://player27.narrowstep.tv/nsp.aspx?player=pru' frameborder='0' allowtransparency='yes' scrolling='no'>"; echo $num; echo"</iframe>
</html>";
?>

                                              
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