Changes between Version 15 and Version 16 of rfc15_nodatabitmask
- Timestamp:
- Dec 19, 2016, 4:36:43 AM (7 years ago)
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rfc15_nodatabitmask
v15 v16 50 50 The GDALRasterBand will include a protected poMask instance variable and a bOwnMask flag. The first call to the default !GetMaskBand() will result in creation of the GDALNodataMaskRasterBand, GDALAllValidMaskRasterBand and their assignment to poMask with bOwnMask set TRUE. If an alpha band is identified for use, it will be assigned to poMask and bOwnMask set to FALSE. The GDALRasterBand class will take care of deleting the poMask if set and bOwnMask is true in the destructor. Derived band classes may safely use the poMask and bOwnMask flag similarly as long as the semantics are maintained. 51 51 52 For an external .msk file to be recognized by GDAL, it must be a valid GDAL 53 dataset, with the same name as the main dataset and suffixed with .msk, 54 with either one band (in the GMF_PER_DATASET case), or as many bands as the 55 main dataset. 56 It must have INTERNAL_MASK_FLAGS_xx metadata items set at the dataset 57 level, where xx matches the band number of a band of the main dataset. The 58 value of those items is a combination of the flags GMF_ALL_VALID, 59 GMF_PER_DATASET, GMF_ALPHA and GMF_NODATA. If a metadata item is missing for 60 a band, then the other rules explained above will be used to generate a 61 on-the-fly mask band. 62 52 63 == Default !CreateMaskBand() == 53 64