Slice a page's geometry from buf, whose byte base corresponds to the page's toc.byteOffset (base = toc.byteOffset for the whole file, or 0 for a Range fetch of just this page).
buf
base
toc.byteOffset
base = toc.byteOffset
0
Slice a page's geometry from
buf, whose bytebasecorresponds to the page'stoc.byteOffset(base = toc.byteOffsetfor the whole file, or0for a Range fetch of just this page).