[jira] [Assigned] (SIS-327) Defer loading of datum shift grid files

["Martin Desruisseaux (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/SIS-327?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Martin Desruisseaux reassigned SIS-327:
---------------------------------------

    Assignee: Martin Desruisseaux

> Defer loading of datum shift grid files
> ---------------------------------------
>
>                 Key: SIS-327
>                 URL: https://issues.apache.org/jira/browse/SIS-327
>             Project: Spatial Information Systems
>          Issue Type: Improvement
>          Components: Referencing
>    Affects Versions: 0.7
>            Reporter: Martin Desruisseaux
>            Assignee: Martin Desruisseaux
>            Priority: Minor
>             Fix For: 0.8
>
>
> When a {{CoordinateOperation}} is created, its {{MathTransform}} is created immediately. This is usually not so costly, except in the case of datum shift based on a grid files where the grid files is loaded immediately. This is a waste of resources when the caller needs create many such operations, compare their {{domainOfValidity}} and retain only one operation at the end.
> The proposal is to load the datum shift grid files only the first time that {{getMathTransform()}} is invoked. In addition to reduce the amount of resources to load, another effect of this would be to reduce the amount of warnings emitted because of grid files not present.
> *How to reproduce:* the snippet below produces a lot of warnings if the grid files are not present. After this issue is fixed, we should have at most 1 warning.
> {code:java}
> CoordinateReferenceSystem sourceCRS = CRS.forCode("EPSG:4267");
> CoordinateReferenceSystem targetCRS = CRS.forCode("EPSG:4326");
> CoordinateOperation op = CRS.findOperation(sourceCRS, targetCRS, null);
> {code}
> *Note:* we could defer the creation of all {{MathTransform}} objects, but this is advantageous only for the cases where many operations exist between the same pair of CRS. This is the case of datum shift mostly.



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