Function exr::block::enumerate_ordered_header_block_indices

pub fn enumerate_ordered_header_block_indices(
    headers: &[Header]
) -> impl '_ + Iterator<Item = (usize, BlockIndex)>

This iterator tells you the block indices of all blocks that must be in the image. The order of the blocks depends on the LineOrder attribute (unspecified line order is treated the same as increasing line order). The blocks written to the file must be exactly in this order, except for when the LineOrder is unspecified. The index represents the block index, in increasing line order, within the header.