Changes between Version 2 and Version 3 of rfc40_enhanced_rat_support


Ignore:
Timestamp:
May 6, 2013, 2:20:14 PM (11 years ago)
Author:
Sam Gillingham
Comment:

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  • rfc40_enhanced_rat_support

    v2 v3  
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    7 Raster Attrbute Tables from some applications (notably segmentation) can be very large and are slow to access with the current API due to the way only one element can get read or written at a time. Also, when an attribute table is requested by the application the whole table must be read - there is no way of delaying this so just the required subset is read off disk. These changes these limitations at proposed will bring the attribute table support more in line with the way raster data is accessed.
     7Raster Attrbute Tables from some applications (notably segmentation) can be very large and are slow to access with the current API due to the way only one element can get read or written at a time. Also, when an attribute table is requested by the application the whole table must be read - there is no way of delaying this so just the required subset is read off disk. These changes will bring the attribute table support more in line with the way raster data is accessed.
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    3131It is expected that the application will allocate the required space for reading in the same way as with the RasterIO() call.
    3232
    33 The char** type will be used for reading and writing strings. When reading strings, it is expected that the array is created of the correct size and ValuesIO will just create the individual strings for each row. The application should use CSLDestroy when finished to deallocate all the memory.
     33The char** type will be used for reading and writing strings. When reading strings, it is expected that the array is created of the correct size and ValuesIO will just create the individual strings for each row. The application should call CPLFree on each of the strings before de-allocating the array.
    3434
    3535These methods will be available from C as GDALRATValuesIOAsDouble, GDALRATValuesIOAsInteger, GDALRATValuesIOAsBoolean and GDALRATValuesIOAsString.