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J661 Maps management

    1  Design−time
    2  Runtime
       2.1  MapItems screen coordinates updates
    3  Notes

As defined in the article about map widgets, the relationships between Map widgets is the following:

The coordinate system is managed by the MapSource widget and is not modifiable at runtime, but the other characteristics of the Map[1] are modifiable at runtime:


The separation of the Map elements between the 3 widgets means that:


There are two "events" which can modify the coordinates of MapItems: These two "events" are completely unrelated (they even can be sent by different User Applications).
Without taking any particular care, the Server could be completely swamped by the updates sent by the UA. For example in a use case where the reference for a MapHorz is the position of the aircraft, this position can for example change every 10 ms, which would mean that the Server would have to compute the position of all the MapItems for this mapHorz every 10 ms.

To avoid this kind of problem, the server.projectionUpdateCap property allows to specify at which rate the MapItems coordinates will be updated: This is the minimum time between two projection characteristics changes in Maps. The default is 160 ms, and 0 means that there is no cap at all. If two MapItemList buffers or MapHorz characteristics are received in less than his value, the Server will wait until this time has elapsed to compute the change.
Also, if updates to the MapItems are received before this time are elapsed, the Server will store the associated MapItems characteristics in the received Buffers and perform the compute after the time has elapsed.

MapItems screen coordinates updates

Contrary to "regular" widgets, updating the screen coordinates of MapItems involves two phases:


  1. In the following of this article, we will use the example of the MapHorz architecture, but the MapVert architecture is exactly the same except that the ranges in the X and Y axis are different
  2. Because the same MapItemList can be presented more than once (see map widgets usage in Connectors), there is a list of screen coordinates for each target where the MapItemList is presented

See Also

Category: server Category: dev Category: archi

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