[ka-Map-users] Controlling the number of points using addObjectGeo

[Stephen Woodbridge]

Paul Spencer wrote:
> Ok, then the event could be triggered as a result of the call to  
> checkWrap and if any wrapping has occurred you would get an event  
> indicating the new extents of the meta viewport.  You could then make  
> your overlay image the size of the meta viewport (in pixels) and pin  it 
> to the top/left image in the meta viewport.  When this event is  
> triggered, you would reposition the image and change its source so it  
> would load a new overlay from the server.
> 
> Are you going to implement this and contribute?

Matt has been working on this, but I think he is currently pinning an 
image just the size of the viewport so we have to request a new one for 
every pan. I think the plan is to contribute some of the stuff he has 
been working on, but I don't know any of the details.

-Steve

> Cheers
> 
> Paul
> 
> On 28-Feb-06, at 9:23 AM, Stephen Woodbridge wrote:
> 
>> Hi Paul,
>>
>> These get called for every tile load request if I understand your  
>> description, if I pan diagonally then I would expect to get rows 
>> +cols-1 (or more) events triggered as you add new rows and columns  to 
>> the meta_viewport.
>>
>> I think this a little too granular, but we might be able to roll up  
>> these events. What I was thinking about was to consider the  
>> additional tiles around the viewport as a meta_viewport that has  
>> extents. Then when the viewport moves outside the meta_viewport a  
>> single event is triggered and the new extents of the meta_viewport  
>> are made available.
>>
>> If it is easy to get this from what you suggested below then that  
>> would be great other you might consider add this type of event as I  
>> think anyone trying to track an overlay with a server side image  will 
>> be able to use this.
>>
>> -Steve
>>
>> Paul Spencer wrote:
>>
>>> Steve,
>>> I think that we should expose two events:
>>> KAMAP_TILE_CHANGING
>>> KAMAP_TILE_CHANGED
>>> this would potentially allow the interface to expose the number  of  
>>> tiles that are 'in the queue' and could be used for other  purposes  
>>> to, like fixing overlays etc
>>> KAMAP_TILE_CHANGING would be triggered in the setTile method of   
>>> _layer (and affliates).
>>> KAMAP_TILE_CHANGED would be triggered in the kaMap_imgOnLoad function
>>> One thing to consider is that images do fail to load for various   
>>> reasons and we need to be aware of the difference between an  image  
>>> that is loaded the first time and an image that is loaded  because 
>>> of  an error, otherwise tile counts could be seriously  impacted.
>>> Would this meet your needs?
>>> Cheers
>>> Paul
>>> On 28-Feb-06, at 7:58 AM, Stephen Woodbridge wrote:
>>>
>>>> This is an excellent question as we have been doing something   
>>>> similar with router overlays. We currently overlay an image just   
>>>> the size of the viewport, but it would make sense to ask for a   
>>>> larger image say the size of the preloaded tile extents and then   
>>>> only update that when additional tiles are requested because the   
>>>> preloaded tile extent needs to change because of panning or   
>>>> zooming. Could this be made an ka-map event that can be easily  hooked?
>>>>
>>>> -Steve
>>>>
>>>> Base Bloc wrote:
>>>>
>>>>> Dear all,
>>>>>  First off I would like to say that ka-map 0.2 is a fantastic   
>>>>> piece of kit and thanks for all the work that people have put  in  
>>>>> to this.
>>>>>  I am currently building an application using 0.2 and I am  using  
>>>>> the addObjectGeo function to add markers along with  mouseover  
>>>>> events (pop-up windows) to the map. All is working as  it should  
>>>>> and is looking good. My concern now is the number of  markers; the  
>>>>> application is covering most of Southeast Asia and  the number of  
>>>>> markers is going to be high. I am looking to use  Ajax to connect  
>>>>> to a MySQL database to retrieve the point data  relevant to the  
>>>>> area of the map being viewed, as if all of the  points were to be  
>>>>> retrieved in one go it would result in a  serious performance hit  
>>>>> for the user.
>>>>>  I’m no ka-map expert, but I was wondering how ka-map does this   
>>>>> efficiently with the tiles; as in it gets x number of tiles   
>>>>> closest to the area being viewed then moves outwards, is there   
>>>>> anyway to use the variable(s) that are being sent to the server  
>>>>> to  request the tiles to also query the database and return the  
>>>>> point  data in an equally efficient manor?
>>>>>  Thanks in advance for your thoughts.
>>>>>  Chris
>>>>>   ~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>>>> Christopher Brown
>>>>> Head of Internet Development
>>>>> Base Bloc Cambodia
>>>>> #33, 123, Phnom Penh, Cambodia.
>>>>> P.O. Box 2086
>>>>> www.basebloc.com
>>>>> Tel (+885) 12 315 302
>>>>>    
>>>>> ------------------------------------------------------------------- 
>>>>> -- ---
>>>>> _______________________________________________
>>>>> ka-Map-users mailing list
>>>>> ka-Map-users at lists.maptools.org
>>>>> http://lists.maptools.org/mailman/listinfo/ka-map-users
>>>>
>>>>
>>>>
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>>>
>>> +-----------------------------------------------------------------+
>>> |Paul Spencer                           pspencer at dmsolutions.ca   |
>>> +-----------------------------------------------------------------+
>>> |Applications & Software Development                              |
>>> |DM Solutions Group Inc                 http://www.dmsolutions.ca/|
>>> +-----------------------------------------------------------------+
>>
>>
> 
> +-----------------------------------------------------------------+
> |Paul Spencer                           pspencer at dmsolutions.ca   |
> +-----------------------------------------------------------------+
> |Applications & Software Development                              |
> |DM Solutions Group Inc                 http://www.dmsolutions.ca/|
> +-----------------------------------------------------------------+
> 
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