Page pre-fetching for meteograms generation

[GoogleCodeExporter]

Whenever the gadget detects the new image has to be shown (because of time
change), it tries to fetch it from ICM server. However, in case the page
that shall contain the image has never been shown, the image doesn't exist
on the ICM server. It appears that the image is generated when the first
call for the page is generated.

The gadget shall pre-fetch the page from the ICM server, to ensure, the
image has been generated. It may store information about the last
prefetched site it the hidden user-preferences field, so each site will be
fetched only once.

Original issue reported on code.google.com by pkryger on 19 Aug 2007 at 8:46

[GoogleCodeExporter]

It appears, that the date/time generation depends on the language used.
Needs more investigation (source code of english version of the page).

It would be also nice to poll the page with meteogram image and check whether it
contains the new image. In such a case method for generating the image URL may 
be
useful to determining if page fetching is needed.

Original comment by pkryger on 29 Aug 2007 at 12:38

[GoogleCodeExporter]

Another approach:
1. try to get cached image as described in comment #1
(http://code.google.com/p/meteo-icm-gadget/issues/detail?id=9#c1)
2. if 1. didn't work try to get cached image as in original algorithm
3. if 2. didn't work try to get previously successfully cached image (as per 
gadget
instance)

1. & 2. shall update the cached image name

Cache shall be longer (like +6h or even more) 

Original comment by pkryger on 29 May 2008 at 11:34

[GoogleCodeExporter]

The following code extracts values used by meteo-script:
function response(obj) {
var sStartTime = obj.substr(obj.indexOf("var Start_time=") + 15, 2);
document.writeln("StartTime = " + sStartTime);
var sDay = obj.substr(obj.indexOf("var Day=") + 8, 2);
document.writeln("Day = " + sDay);
var sMonth = obj.substr(obj.indexOf("var Month=") + 10, 2);
document.writeln("Month = " + sMonth);
var sYear = obj.substr(obj.indexOf("var Year=") + 9, 4);
document.writeln("Year = " + sYear);
}
var url = 'http://umold.meteo.pl/java/mgram.php?x=17&y=8&lang=0&ver=&ikonka=1';
_IG_FetchContent(url, response);

Values are used in the following way in meteo-script:
if (st<10) st="0"+st;
if (Day<10) dd="0"+Day; else dd=Day;
nazwa = 
Year+mm2ang[Month]+dd+"_"+st+"_row"+mgy_i+"_col"+mgx_i+"_"+language+".png";
wyn = "/gpp/data/"+nazwa;

Original comment by pkryger on 1 Jun 2008 at 2:44

[GoogleCodeExporter]

The following code works with Google caching mechanizm:
<div id="main"></div>
<script>
var url = "http://umold.meteo.pl/gpp/data/2008Jun01_06_row35_col17_pl.png";
var img = _IG_GetImage(url, {refreshInterval:1000});
var mainDiv = _gel("main");
if (true == img.complete) {
mainDiv.innerHTML = "";
mainDiv.appendChild(img);
} else {
mainDiv.innerHTML = "Cannot load image!";
} 
</script>

Original comment by pkryger on 1 Jun 2008 at 2:57

[GoogleCodeExporter]

First create a flag that is set to true when your callback function is
called. Next, create a timer with setTimeout that checks the status of
the flag after a few seconds (10 should work well). If the callback
was successful, the flag will be set to true. If it failed, the flag
will still be false and you will know you had an error.

Original comment by pkryger on 1 Jun 2008 at 3:30

[GoogleCodeExporter]

Progress bar implementation as in GMail:
<style type="text/css">
.lpb{margin: 2px 0;border:1px solid #949dad;width:200px;height:0.5em}
#lpt{background:#d4e4ff;width:0;height:100%}
</style>
<div class="lpb">
<div id="lpt" style=""></div>
</div>
<script>
var progress = 0;
function increment() {
if (progress < 100) {
progress += 5;
_gel("lpt").setAttribute("style", "width:" + progress + "%");
setTimeout("increment()", 1000);
}
}
setTimeout("increment()", 1000);
</script>

Original comment by pkryger on 2 Jun 2008 at 7:48

[GoogleCodeExporter]

Original comment by pkryger on 7 Jun 2008 at 2:21

• Changed state: Verified