vil_cached_image_resource.cxx

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// This is core/vil/vil_cached_image_resource.cxx

#include "vil_cached_image_resource.h"
#include <vil/vil_image_view_base.h>

// Get a view that is the size of a block.
// Uses the cache to retrieve frequently used blocks
vil_image_view_base_sptr
vil_cached_image_resource::get_block( unsigned  block_index_i,
                                      unsigned  block_index_j ) const
{
  // check if the block is already in the buffer
   vil_image_view_base_sptr blk;
  if (cache_.get_block(block_index_i, block_index_j, blk))
    return blk;
  // no - so get the block from the resource
  blk = bir_->get_block(block_index_i, block_index_j);
  if (!blk)
    return blk; // get block failed
  // put the block in the cache (cast away const since we are just caching)
  auto* non_const = (vil_cached_image_resource*)this;
  non_const->cache_.add_block(block_index_i, block_index_j, blk);
  return blk;
}