rinkhals-community/Rinkhals untagged-ab91d864bc478734410c

Rinkhals 20260530_03_feature-z-offset-ui

on GitHub

What this build adds

Restores the live Z-offset adjust button on the K3SysUi print page. Anycubic
removed the button widget from their UI but left the popup, the dispatcher
case-10 handler, the embedded SVG icon, and the underlying device RPC
machinery intact in the K3SysUi binary. This build injects a replacement
button at runtime via an LD_PRELOAD shim that hooks
QButtonGroup::addButton, constructs a fresh QPushButton, sets the
Anycubic Z-offset icon, and wires its clicked() signal directly to the
popup's show() slot via Qt's string-based connect.

The shim does its own dynamic discovery of the popup widget's offset inside
MainWindow by parsing the K3SysUi ELF symbol table and disassembling the
dispatcher lambda. Discovery is scoped to the lambda(int)#12 inside
MainWindow::AcFilePrintPageUiInit by mangled-name pattern match, then to
the bl AcDeviceLeviqGetZoffset call site inside that lambda, then to the
ldr r3, [r3, #N]; mov r0, r3; bl <show> triple that loads and displays the
popup. The discovered N is the popup offset.

Visibility mirrors the print page via a global event filter on qApp,
matching QEvent::Show/Hide against an ancestor chain registered for each
captured template button. The filter object is a bare QObject with its
per-instance vtable patched at the eventFilter slot, so we avoid Qt's moc
metadata requirement entirely.

Where it's wired in

• New build stage build-shim-zoffset in the root Dockerfile
  cross-compiles libzoffset.so via the existing ghcr.io/jbatonnet/armv7-uclibc:rinkhals
  image (same image as the Moonraker ARMv7 build). Output ships in the SWU
  bundle under /opt/rinkhals/shims/k3sysui-zoffset/.
• files/3-rinkhals/start.sh launches K3SysUi with
  LD_PRELOAD=$ZOFFSET_SHIM and RINKHALS_ZOFFSET_INJECT=1 after the
  per-firmware binary patches have run. The shim is loaded into the
  patched K3SysUi process.
• The shim is inert without RINKHALS_ZOFFSET_INJECT=1. To disable
  without removing the file, edit start.sh to drop the env var.

Verified targets

KS1 firmware 2.7.2.1 on Qt 5.14.2. Other supported models
(K3, K3M, K3V2, KS1M, K2P) are not yet verified. The dynamic offset
discovery should adapt to per-build differences, but the assumption that
case 10 = Z-offset and the icon resource path are still binary-bound and
need spot-checking per model. Falls back gracefully (SIGSEGV trap, then
shim does nothing further on that group) if the assumptions don't hold.

Known caveats

• The shim wraps every Qt construction call in a SIGSEGV/sigsetjmp
  trap. Worst case is the affected injection is abandoned and K3SysUi
  continues without the button. It should not crash K3SysUi.
• appCheck.sh (the Anycubic watchdog) respawns K3SysUi without
  LD_PRELOAD if it dies. If K3SysUi crashes, the restarted process
  won't have the shim until the printer reboots. Not a problem in
  practice unless K3SysUi is unstable.
• RINKHALS_ZOFFSET_LOG=1 adds startup diagnostics to
  /tmp/rinkhals/K3SysUi.log. Off by default; enable by editing
  start.sh if you're debugging.

How to test

1. Flash this SWU on a KS1 running stock firmware 2.7.2.1.
2. Boot, go to the print page.
3. Tap the Z-offset icon at top-left.
4. Z-offset popup should appear, with current value pre-filled.
5. Navigate to another page — icon should hide. Navigate back —
   icon should reappear.
6. Report results in the relevant developer discussion, not as
   a general issue (this is not yet a feature anyone should be using
   unless they're testing it on purpose).

Build/source

Branch: feature/K3SysUi_z_offset_UI
Tag: 20260530_03_feature-z-offset-ui
Source: files/3-rinkhals/opt/rinkhals/shims/k3sysui-zoffset/zoffset.cpp