A second drag while the first was settling showed the new image briefly
at the wrong size: the commit copied the preview's src into vimg (an
async paint — one frame of old content in the new box) and openViewer
then reset vScale=1, so the promoted image rendered at thumb scale
until full-res landed.
Commit now swaps the ELEMENTS' roles instead of copying pixels: the
preview element already shows the incoming image at its own size and
scale, so finishCommit promotes it in place (geometry adopted from
the loaded preview, moved to 0, brought to front, old primary hidden
immediately). No src copy, no async paint, no re-layout — the settled
frame is the drag frame. P/S role variables replace the fixed
vimg/vimg2 references throughout the viewer.
openViewer(keepVisible) no longer resets the view state (the commit
already set it), and a full-res landing while a slide owns
base/vScale is deferred to the safety timer instead of jumping the
animation.
Verified on the emulator: mid second-drag the promoted image holds
its exact fit size (1081 px) in every captured frame (the bug showed
~288), both images visible on the strip, and the chained landing is
pixel-identical to two deliberate swipes.
Greg Pomerantz
347b6825cc