This is a utility for RISC OS which displays documentation as if it were a ring-bound file open on the desk.
It presents a view of the open document, allowing pages to be turned. Ind index tabs allow quick movement to the start of a new Section. The document type it recognises is 'Bound' (&1EB). A utility to convert PDF files to 'Bound' files is included with full instructions.
Opening the 'Bound' file '528Guide' results in this view. Clicking over a page corner with ADJUST shows an animated view of the page turning. Clicking with SELECT causes the page to move instantly without the animation.
The whole 'Bound' file is only loaded into memory if there is sufficient memory available. Otherwise only four of the available pages are loaded into memory as required. The slider bar gives access to any point in the file with a single clcik. The Chapter/Section/Sub-section arrows, shown below the display, move forward or backward to the start of end of the section, sub-section or chapter. Large 'Bound' files can be used on VRPC (or with Aemulor running) provided there is space to fit four pages in memory. An appropriate error message is given if not.
During animation two screen banks are used if memory is available to be allocated - if insufficient, the icon bar icon will show yellow or red and screen updating will be visible as flickering. Where dual screen banks are in use the invisible bank is updated and then the banks are swopped, which reduces flickering. A mode change with dual banks in use (e.g. f12, Enter) will terminate the animation. Pages which contain JPEGs would cause an error if plot with a skew - this error is trapped and plotting proceeds with no skew. The icon bar icon turns green or red to indicate this. During animation, the invisible screen bank is completely redrawn each time in case any windows are moved - if this were not done, one bank would show them in their original position.