kdu_precinct::open_block

This function plays the same role as its namesakes, kdu_subband::open_block, except that the block_idx coordinates lie within the range returned by kdu_precinct::get_valid_blocks, rather than that returned by kdu_subband::get_valid_blocks. As mentioned in the description of kdu_precinct::get_valid_blocks above, this range may actually be larger than the range of block indices which are admissible for the kdu_subband::open_block function. This is because the range includes all code-blocks in the precinct-band, even though only some of the precinct's code-blocks contribute to the region of interest.

After opening a code-block using this function, the caller fills in its contents with compressed code bytes and other summary information, exactly as described in connection with the kdu_subband::open_block function. The block must then be closed using close_block (preferably), or kdu_subband::close_block, before another can be opened.

For interchange codestreams, the open_block and close_block functions defined here are recommended for opening and closing code-blocks instead of those provided by kdu_subband, both because they allow all of the precinct's blocks to be opened and also because they are somewhat more efficient in their implementation. Nevertheless, the kdu_subband::open_block and kdu_subband::close_block functions may be used. In fact, it is permissible to open a block using kdu_precinct::open_block and close it using kdu_subband::close_block or to open it using kdu_subband::open_block and close it using kdu_precinct::close_block.

band_idx [int]

block_idx [kdu_coords]