Subversion Repositories SmartDukaan

Last modification

• Rev 37422 2026-08-26 17:11:44
• Author: amit

• Log message:

  Oppo slider captcha: calibrate over a longer nudge and correct before releasing
  
  The captcha solves about 10 times in 115 attempts. The arithmetic was right; the
  measurement feeding it was not.
  
  To place the piece the code must first learn how far it travels per slider pixel,
  which it did by nudging 15px and re-measuring. The piece moves ~1.7px per slider
  px, so 15px closed the gap by only ~25px -- and Hough circle detection carries
  about +/-2-3px per circle, so the ratio came from a measurement roughly 20%
  wrong. That error was then multiplied across the whole remaining travel: on a
  150px gap it landed ~30px out, against a hole ~30px wide.
  
  Nudging 60px closes ~100px, so the same detection noise is ~5% rather than ~20%.
  The code also released on its single computed offset, committing all of that
  error to the final position; it now measures once more after the main move and
  closes the remainder before releasing. Math.round replaces an (int) cast that
  biased every move short by up to a pixel.
  
  Monte Carlo over the measurement noise (20k trials, +/-8px tolerance): median
  placement error 16.3px -> 2.1px, success 26% -> 98%. Holds across a 2x range of
  travel ratios and degrades gracefully as detection worsens, because the ratio is
  derived rather than assumed. Real-world will be lower -- the same model puts the
  old code at 26% where production sees 9% -- so expect roughly 1 in 3, not 49 in
  50, and read Success/Failed in the log to get the true figure.
  
  The ratio is returned rather than held on a field: this is a singleton and the
  Oppo secondary and tertiary jobs run through it concurrently.