Fix scrollLeft resetting while scrolling in 1up on Chrome/Firefox - #1575
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Calling getBoundingClientRect() during text layer rendering was forcing a synchronous reflow of the whole document -- for some reason resetting the scroll. So now we create a temporary iframe where we call getBoundingClientRect, which does not! Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## master #1575 +/- ##
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+ Coverage 63.64% 63.70% +0.05%
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Files 68 68
Lines 6206 6216 +10
Branches 1378 1378
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+ Hits 3950 3960 +10
Misses 2217 2217
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cdrini
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nsharma123
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Jul 28, 2026
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Reviewed the iframe-based measurement fix. The core idea (measuring in a detached, non-scrolling iframe instead of the live document) looks solid and I confirmed it builds, lints, and passes the existing Jest suite. Left two inline comments: one is a confirmed regression (repro'd locally), the other is a resource-leak concern worth considering.
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Calling getBoundingClientRect() during text layer rendering was forcing a synchronous reflow of the whole document -- for some reason resetting the scroll. So now we create a temporary iframe where we call getBoundingClientRect, which does not!
QA: https://deploy-preview-1575--ia-bookreader.netlify.app/bookreaderdemo/demo-internetarchive?ocaid=theworksofplato01platiala
To reproduce:
Expected behaviour: Your scroll left position should stay the same
Actual behaviour: It resets to the edge after a page or so
Recording.2026-07-24.145908.mp4