jp2_input_box::open

Opens the box as a sub-box of the indicated super_box. You may think of the present box and the super-box as sharing a common "read pointer" so that once the present box is closed, reading may continue within the super-box from the point where we left off. The super-box is "locked" so long as any sub-box is open; an error will be generated if any attempt is made to read from a super-box which is locked in this way. While the sub-box is being read, values returned by super_box→get_remaining_bytes or super_box→get_pos are unstable and cannot be trusted.

If this function fails to open a new box, the function returns false, leaving the box closed (the exists function will return false). This may happen if one of the following conditions occur:

• The super-box is exhausted, meaning that it has no remaining content bytes at all; or
• The super-box contains insufficient contents for the moment to open a new box, but it may contain sufficient bytes in the future as more data becomes available. This is only possible if the jp2_family_src object uses a cache for its information source, since the cache may be updated dynamically. This case may be distinguished from the former case by checking the super-box's get_remaining_bytes member, which will be 0 if and only if the super-box has actually been exhausted.

True if a new box was opened, else false.

super_box [jp2_input_box *]