Two faults on one picture. A block after a float keeps its box over
the float — only its lines move — so the caption on top swallowed
every click meant for the picture; the frame is lifted above the
in-flow boxes. And a caption can only sit under a side-wrapped frame
if it is boxed to it, so its span in the column is measured and
becomes the caption's indent, which also drops it clear of the float.
Measured at 100% and 150%: caption under the picture, its width, in
all four wrap modes.
A picture with "above and below" wrap is a frame centred in the
column while its paragraph carries no alignment at all, so the
caption still went to the left margin. framePlacement reads the
place off the frame: centred, the side it is set against, or its
offset as the caption's indent. The debug dump gains a frames
section — every other one measures the flow downwards, and this
is a sideways question.
It was inserted as a plain paragraph, so a centred or right-aligned
picture got its caption at the left edge of the text column.
LibreOffice frames picture and caption together; a loose paragraph
carries that over as the alignment of the block it captions.
Measured in the live editor: a centred 240px picture at 520…760
now has its caption text at 580…700.
A caption is a paragraph in the Caption style holding a sequence field —
one counter per category, in document order, renumbered as the document is
edited and on load (a file's cached numbers are unreadable wherever the
format is not arabic). Round-trips as an ODF text:sequence with
LibreOffice's own ooow:Illustration+1 formula and a Word SEQ field.
Caption style values probed off LibreOffice: 10pt italic, 0.212cm around.
Steffen Becker