Reported from the floor: some assets showed their hover mini-map marker way off
to the left, outside the map, while the SAME asset sat correctly on the main
map. The data was right; the preview was drawing it wrong.
The preview is a fixed 390x300 box and the drawing was painted into it with
object-fit: contain, which letterboxes or pillarboxes to keep the drawing's own
aspect ratio. The marker, though, was positioned at a percentage of the BOX. So
the marker and the drawing were measured in two different coordinate spaces, and
they only agreed when the level's aspect ratio happened to be 390:300.
A level near that ratio looked perfect - 3300x2550 is 1.294 against the box's
1.300 - which is why this read as "some devices" rather than "the feature is
broken". A taller drawing pillarboxes, every marker's x shifts, and one near the
left edge lands in the grey gutter beside the map.
The image now SIZES the frame instead of filling it: the transform box
shrink-wraps the image and the image scales down to fit. A percentage of the
frame is therefore a percentage of the drawing by construction, at any aspect
ratio, and the letterboxing moves out to the preview around it where it does no
harm. dimensionsFor still converts the stored pixels to percentages - that part
was always right.
NOT visually confirmed against a live instance. The reasoning is traced and the
build is clean, but the shape of this bug is that it looks correct on any level
close to the old box ratio, so it wants a look at an asset that was landing left
and one that was already fine.
Related and NOT addressed: the wheel zoom applies translate percentages that
resolve against the element and are then multiplied by scale, so a zoomed
preview may still drift. At rest, which is the reported case, it is exact.
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