kdu_precinct::get_valid_blocks

Returns false if the precinct does not belong to a resolution level which includes the band indicated by band_idx. Otherwise, configures the indices argument to identify the range of indices which may be used to access code-blocks beloning to this precinct within the indicated subband. If this range of indices is non-empty, the function returns true; otherwise, it returns false.

Upon return, indices.area yields the total number of code-blocks in the subband which belong to the present precinct and indices.pos identifies the coordinates of the first (top left) block in the precinct-band. As with all of the index manipulation functions, indices may well turn out to be negative as a result of geometric manipulations.

As for kdu_subband::get_valid_blocksthe interpretation of the band_idx argument is affected by the transpose argument supplied in any call to kdu_codestream::change_appearance.

It is important to understand two distinctions between this function and its namesake, kdu_subband::get_valid_blocks interface. Firstly, the range of returned code-block indices is restricted to those belonging to the precinct; and secondly, the range of indices includes all code-blocks belonging to the precinct, even if some of these do not lie within the current region of interest, as established by kdu_codestream::apply_input_restrictions function. This is important, because a precinct is not considered loaded until all of its code-blocks have been written, regardless of whether or not they lie within the current region of interest.

band_idx [int]

indices [kdu_dims &]