hi stephen, <br>it seems we're saying the same thing. the url i sent only redraws markers if current extents pass out of an expanded extent. <br>your way would definitely be a lot cleaner implemented as a core ka-map event as you suggest.
<br>-b<br><br><div><span class="gmail_quote">On 2/28/06, <b class="gmail_sendername">Stephen Woodbridge</b> <<a href="mailto:woodbri@swoodbridge.com">woodbri@swoodbridge.com</a>> wrote:</span><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
Hi Chris,<br><br>I think what needs to be done here it that you need to maintain extents<br>of the loaded tiles (the padded extents) which is like the viewport plus<br>the additional tiles surrounding it, call this the META_EXTENTS because
<br>the EXTENTS_CHANGED event will get triggered on every pan. Then in the<br>event you need to check if the viewport extents has moved outside of the<br>META_EXTENTS. If not then your done, if it has you need to reset the
<br>META_EXTENTS based on the current position and zoom scale and request<br>and update via Ajax.<br><br>This way panning within the META_EXTENTS will not request new data from<br>the server, but moving outside the META_EXTENTS or a zoom event will
<br>trigger a request for more data.<br><br>-Steve W.<br><br>Base Bloc wrote:<br>> Hi Brent,<br>><br>> This sounds like a good way to do this for me as the number of markers that<br>> would be displayed for my application would never be more than 50 within a
<br>> padded viewport at the required scale.<br>><br>> I apologize I haven't yet had the opportunity study the inner workings of<br>> ka-map so am not familiar with all the functions yet; what your suggesting<br>
> is building a new function that uses an existing function called<br>> getGeoExtents to find the extent of the current viewport (which can then be<br>> padded for optimum results) then sending these variables back to the server
<br>> to query the database via an Ajax call to return the relevant markers. This<br>> function will be set in motion if EXTENTS_CHANGED is true?<br>><br>> Thanks, this sounds like a solid yet simple solution, do you have any
<br>> working code that you can share with us, or a demo of this in action?<br>><br>> Thanks,<br>><br>> Chris<br>><br>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~<br>> Christopher Brown<br>> Head of Internet Development
<br>> Base Bloc Cambodia<br>> #33, 123, Phnom Penh, Cambodia.<br>> P.O. Box 2086<br>> <a href="http://www.basebloc.com">www.basebloc.com</a><br>> <a href="mailto:chris@basebloc.com">chris@basebloc.com</a><br>
> Tel (+885) 12 315 302<br>><br>> -----Original Message-----<br>> From: <a href="mailto:ka-map-users-bounces@lists.maptools.org">ka-map-users-bounces@lists.maptools.org</a><br>> [mailto:<a href="mailto:ka-map-users-bounces@lists.maptools.org">
ka-map-users-bounces@lists.maptools.org</a>] On Behalf Of<br>> <a href="mailto:ka-map-users-request@lists.maptools.org">ka-map-users-request@lists.maptools.org</a><br>> Sent: 01 March 2006 00:00<br>> To: <a href="mailto:ka-map-users@lists.maptools.org">
ka-map-users@lists.maptools.org</a><br>> Subject: ka-Map-users Digest, Vol 10, Issue 28<br>><br>> Send ka-Map-users mailing list submissions to<br>> <a href="mailto:ka-map-users@lists.maptools.org">ka-map-users@lists.maptools.org
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<br>><br>><br>> Today's Topics:<br>><br>> 1. Re: Controlling the number of points using addObjectGeo<br>> (Brent Pedersen)<br>><br>><br>> ----------------------------------------------------------------------
<br>><br>> Message: 1<br>> Date: Tue, 28 Feb 2006 07:48:51 -0800<br>> From: "Brent Pedersen" <<a href="mailto:bpederse@gmail.com">bpederse@gmail.com</a>><br>> Subject: Re: [ka-Map-users] Controlling the number of points using
<br>> addObjectGeo<br>> To: <a href="mailto:ka-map-users@lists.maptools.org">ka-map-users@lists.maptools.org</a><br>> Message-ID:<br>> <<a href="mailto:e183a99d0602280748y7bb7c176k6fbf1f1d42de5599@mail.gmail.com">
e183a99d0602280748y7bb7c176k6fbf1f1d42de5599@mail.gmail.com</a>><br>> Content-Type: text/plain; charset="iso-8859-1"<br>><br>> hi, a super simple version of this has been useful to me. just via calling
<br>> kaMap.getGeoExtents, then pad that (so it adds ~1/2 length of the viewport<br>> on each side) and fetch<br>> all of the markers in that expanded extent. then register for an event of<br>> EXTENTS_CHANGED and check
<br>> if the new getGeoExtents results fall with the expanded extents. if so, do<br>> nothing. otherwise, fetch new markers.<br>><br>> base, most of the slowness will come from having 500+ images attached to<br>
> your div. but you can assign an AJAX (call()) to each div to fetch the meat<br>> of the information instead of sending it with the inital marker import. if<br>> you have the div id correspond to database id, that keeps it simple.
<br>> -brent<br>><br>> On 2/28/06, Stephen Woodbridge <<a href="mailto:woodbri@swoodbridge.com">woodbri@swoodbridge.com</a>> wrote:<br>><br>>>Paul Spencer wrote:<br>>><br>>>>Ok, then the event could be triggered as a result of the call to
<br>>>>checkWrap and if any wrapping has occurred you would get an event<br>>>>indicating the new extents of the meta viewport. You could then make<br>>>>your overlay image the size of the meta viewport (in pixels) and pin it
<br>>>>to the top/left image in the meta viewport. When this event is<br>>>>triggered, you would reposition the image and change its source so it<br>>>>would load a new overlay from the server.
<br>>>><br>>>>Are you going to implement this and contribute?<br>>><br>>>Matt has been working on this, but I think he is currently pinning an<br>>>image just the size of the viewport so we have to request a new one for
<br>>>every pan. I think the plan is to contribute some of the stuff he has<br>>>been working on, but I don't know any of the details.<br>>><br>>>-Steve<br>>><br>>><br>>>>Cheers
<br>>>><br>>>>Paul<br>>>><br>>>>On 28-Feb-06, at 9:23 AM, Stephen Woodbridge wrote:<br>>>><br>>>><br>>>>>Hi Paul,<br>>>>><br>>>>>These get called for every tile load request if I understand your
<br>>>>>description, if I pan diagonally then I would expect to get rows<br>>>>>+cols-1 (or more) events triggered as you add new rows and columns to<br>>>>>the meta_viewport.<br>>>>>
<br>>>>>I think this a little too granular, but we might be able to roll up<br>>>>>these events. What I was thinking about was to consider the<br>>>>>additional tiles around the viewport as a meta_viewport that has
<br>>>>>extents. Then when the viewport moves outside the meta_viewport a<br>>>>>single event is triggered and the new extents of the meta_viewport<br>>>>>are made available.<br>>>>>
<br>>>>>If it is easy to get this from what you suggested below then that<br>>>>>would be great other you might consider add this type of event as I<br>>>>>think anyone trying to track an overlay with a server side image will
<br>>>>>be able to use this.<br>>>>><br>>>>>-Steve<br>>>>><br>>>>>Paul Spencer wrote:<br>>>>><br>>>>><br>>>>>>Steve,<br>>>>>>I think that we should expose two events:
<br>>>>>>KAMAP_TILE_CHANGING<br>>>>>>KAMAP_TILE_CHANGED<br>>>>>>this would potentially allow the interface to expose the number of<br>>>>>>tiles that are 'in the queue' and could be used for other purposes
<br>>>>>>to, like fixing overlays etc<br>>>>>>KAMAP_TILE_CHANGING would be triggered in the setTile method of<br>>>>>>_layer (and affliates).<br>>>>>>KAMAP_TILE_CHANGED would be triggered in the kaMap_imgOnLoad function
<br>>>>>>One thing to consider is that images do fail to load for various<br>>>>>>reasons and we need to be aware of the difference between an image<br>>>>>>that is loaded the first time and an image that is loaded because
<br>>>>>>of an error, otherwise tile counts could be seriously impacted.<br>>>>>>Would this meet your needs?<br>>>>>>Cheers<br>>>>>>Paul<br>>>>>>On 28-Feb-06, at 7:58 AM, Stephen Woodbridge wrote:
<br>>>>>><br>>>>>><br>>>>>>>This is an excellent question as we have been doing something<br>>>>>>>similar with router overlays. We currently overlay an image just
<br>>>>>>>the size of the viewport, but it would make sense to ask for a<br>>>>>>>larger image say the size of the preloaded tile extents and then<br>>>>>>>only update that when additional tiles are requested because the
<br>>>>>>>preloaded tile extent needs to change because of panning or<br>>>>>>>zooming. Could this be made an ka-map event that can be<br>>><br>>>easily hooked?<br>>>
<br>>>>>>>-Steve<br>>>>>>><br>>>>>>>Base Bloc wrote:<br>>>>>>><br>>>>>>><br>>>>>>>>Dear all,<br>>>>>>>> First off I would like to say that ka-map
0.2 is a fantastic<br>>>>>>>>piece of kit and thanks for all the work that people have put in<br>>>>>>>>to this.<br>>>>>>>> I am currently building an application using
0.2 and I am using<br>>>>>>>>the addObjectGeo function to add markers along with mouseover<br>>>>>>>>events (pop-up windows) to the map. All is working as it should<br>>>>>>>>and is looking good. My concern now is the number of markers; the
<br>>>>>>>>application is covering most of Southeast Asia and the number of<br>>>>>>>>markers is going to be high. I am looking to use Ajax to connect<br>>>>>>>>to a MySQL database to retrieve the point data relevant to the
<br>>>>>>>>area of the map being viewed, as if all of the points were to be<br>>>>>>>>retrieved in one go it would result in a serious performance hit<br>>>>>>>>for the user.
<br>>>>>>>> I'm no ka-map expert, but I was wondering how ka-map does this<br>>>>>>>>efficiently with the tiles; as in it gets x number of tiles<br>>>>>>>>closest to the area being viewed then moves outwards, is there
<br>>>>>>>>anyway to use the variable(s) that are being sent to the server<br>>>>>>>>to request the tiles to also query the database and return the<br>>>>>>>>point data in an equally efficient manor?
<br>>>>>>>> Thanks in advance for your thoughts.<br>>>>>>>> Chris<br>>>>>>>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~<br>>>>>>>>Christopher Brown<br>
>>>>>>>Head of Internet Development<br>>>>>>>>Base Bloc Cambodia<br>>>>>>>>#33, 123, Phnom Penh, Cambodia.<br>>>>>>>>P.O. Box 2086<br>>>>>>>>
<a href="http://www.basebloc.com">www.basebloc.com</a><br>>>>>>>>Tel (+885) 12 315 302<br>>>>>>>><br>>>>>>>>-------------------------------------------------------------------
<br>>>>>>>>-- ---<br>>>>>>>>_______________________________________________<br>>>>>>>>ka-Map-users mailing list<br>>>>>>>><a href="mailto:ka-Map-users@lists.maptools.org">
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<br>>>>>>|Paul Spencer <a href="mailto:pspencer@dmsolutions.ca">pspencer@dmsolutions.ca</a> |<br>>>>>>+-----------------------------------------------------------------+
<br>>>>>>|Applications & Software Development |<br>>>>>>|DM Solutions Group Inc <a href="http://www.dmsolutions.ca/|">http://www.dmsolutions.ca/|
</a><br>>>>>>+-----------------------------------------------------------------+<br>>>>><br>>>>><br>>>>+-----------------------------------------------------------------+<br>
>>>|Paul Spencer <a href="mailto:pspencer@dmsolutions.ca">pspencer@dmsolutions.ca</a> |<br>>>>+-----------------------------------------------------------------+<br>>>>|Applications & Software Development |
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