Changes between Version 4 and Version 5 of rfc15_nodatabitmask

Timestamp:

Aug 21, 2007, 7:37:27 AM (17 years ago)

Author:

warmerdam

Comment:

switch to mask flags.

rfc15_nodatabitmask

@@ -17 +17 @@
 {{{
     GDALRasterBand *GetNullMask();
-    GDALNullMaskType GetNullMaskType();
+    int             GetNullMaskFlags();
 }}}
 
-Note that the !GetNullMask() should always return a GDALRasterBand mask, even if it is only an all 255 mask with thetype 
+Note that the !GetNullMask() should always return a GDALRasterBand mask, even if it is only an all 255 mask with the type indicating "all valid".
 
-The GDALNullMaskType enumeration has the following values:
+The !GetNullMaskFlags() method returns an ORed set of status flags with the following available definitions that may be extended in the future:
 
- * GDALNMTAllValid: There are no invalid pixels, all mask values will be 255. 
- * GDALNMTPerBand: The mask band is meaningful and is unique to this band (other bands may have masks with different areas of validity)
- * GDALNMTPerDataset: The mask band is meaningful and is shared between all bands on this dataset. 
+ * GNMF_ALL_VALID(0x01): There are no invalid pixels, all mask values will be 255.  When used this will normally be the only flag set. 
+ * GNMF_PER_DATASET(0x02): The mask band is shared between all bands on the dataset.
+ * GNMF_ALPHA(0x04): The mask band is actually an alpha band and may have values other than 0 and 255.
 
-Note that the !GetNullMask() should always return a GDALRasterBand mask, even if it is only an all 255 mask with the type set to GDALNMTAllValid. 
+Note that the !GetNullMask() should always return a GDALRasterBand mask, even if it is only an all 255 mask with the flag GNMF_ALL_VALID set. 
 
 == Default Implementation ==
 
-The GDALRasterBand class will include a default implementation of !GetNullMask() that returns one of two default implementations.  The first default implement is a GDALNMTAllValid band that returns all 255.  The second default implementation would return a mask computed by reading the imagery data and comparing it to the nodata value.  The nodata based one would be used when the base band has a nodata value.   
+The GDALRasterBand class will include a default implementation of !GetNullMask() that returns one of two default implementations.  The first default implement is a GNMF_ALL_VALID band that returns all 255.  The second default implementation would return a mask computed by reading the imagery data and comparing it to the nodata value.  The nodata based one would be used when the base band has a nodata value set.
 
 == Drivers Updated ==
@@ -51 +51 @@
 == SWIG Implications ==
  
-The !GetNullMask() and !GetNullMaskType() methods (and corrsponding defines) will need to be added.  The bitmask should work like a normal raster band for swig purposes so minimal special work should be required. 
+The !GetNullMask() and !GetNullMaskFlags() methods (and corrsponding defines) will need to be added.  The bitmask should work like a normal raster band for swig purposes so minimal special work should be required. 
 
 == Testing ==