Onyx Boox: strokes become strange after refresh

[Iey4iej3]

Before submitting an issue, please check the following

• [x] I have searched for similar issues (both open and closed) and cannot find a duplicate
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Describe the bug

Strokes become strange after refresh (i.e. about 1s later)

To reproduce

1. Write something;
2. Wait for some seconds to refresh.

Expected behavior

Strokes are normal.

Saber version

v0.25.4 Google Play (25040)

Device

• Device: Onyx Boox Note Air 3C
• OS: Android 12

Anything else?

A sample: _whiteboard.sba.zip

[Iey4iej3]

Also reproducible on Go 10.3.

[Iey4iej3]

The issue is still here after having upgraded to onyxsdk-device:1.2.32 and onyxsdk-pen:1.4.12.

[Iey4iej3]

This issue seems to be fixed by the PR #1452

[cben]

Partial mitigation: This seems to depend on zoom level.
(I'm running v0.26.10 Google Play, on NoteAir3C android firmware 2025-08-28_17-13_4.1-rel_0827_fc8adf71a.)

• At zoom levels smaller than ~1.0x, pen drawing seems to rely on the Onyx integration: no perceptible latency 👍, thin (1 pixel?) and black ignoring selected style & color; and as OP says after a brief delay it gets redrawn by Saber with correct style & color 👍 but alas the coordinates get ruined 🤕 — it seems the line gets downsampled to a few straight segments, plus the endpoints of the segments seem to shift around(?). The resulting quality varies between tests, but is pretty unreadable; the most reproducible effect is drawing a smooth o or zero ellipse closing neatly on itself; after downsampling it becomes angular and will not close on itself, but tends to become like a 6 or 9 etc. Whole parts of letter can get skipped, e.g. m can become n etc.

  This is with settings "Auto straighten lines"=OFF, Shape recognition delay=Never.
  Both with pencil tool, and with fountain pen tool (pressure dependent mode, NOT shape mode).

• Zooming in to 1.0x, or sometimes need higher e.g. 1.2x, it seems to skip the integration, with Saber itself doing the drawing(?).
  There is perceptible latency of like half a letter ⏳, but as soon as it appears it's with right style & color 👍 but most importantly with great fidelity to the path I drew with the stylus 💯.

Behavior at exactly 1.0x (fit to width) varies, so it's more like "correlates with zoom"? 🥴
It perhaps also depends on portrait/landscape? Landscape works better. So perhaps it's like absolute scale on screen and not just the N.Nx factor?

gonna try to test that PR...