FA-79745 / Barcode symbology encoding / Member archive

Bar edges drift because the module width is rounded first · case 05

Symbols printed at fractional pixel pitches grow or shrink across their width and fail verification.

Member previewVariant 5 · 3 implementations · 8 checks per implementation

Case contract

Render a module string ("1" bar, "0" space) at xn/xd device pixels per module after `quiet` leading quiet-zone modules. Module boundary k lies at round-half-up((quiet + k) * X), computed from the exact fraction so errors do not accumulate. Adjacent bar modules merge into one bar [start, end); bar width reduction shaves `bwr` pixels from the right edge of each bar, but a bar is never narrower than 1 pixel.

Why this case matters

Retail, logistics, pharmacy and document workflows depend on encoders that produce exactly the module pattern, code-set switches, separators and quiet zones scanners expect; one misplaced module or separator makes a label unreadable or, worse, scan as different data.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
regression: module boundary rounding 0	`[[22, 32], [36, 38], [40, 42], [44, 46]]`	`[[26, 37], [42, 44], [47, 49], [51, 54]]`	Failed

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This record includes three runnable implementations, regression fixtures, execution results, and source hashes.

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