fix(canvas): eliminate screenChanged disconnect RuntimeWarning#116
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…connect warning
PR-J's DPR change handler called disconnect+connect on every showEvent,
which raised a RuntimeWarning ("Failed to disconnect from signal
screenChanged") on the first show and any re-show where the signal
was never actually connected. PySide6 6.11 emits a RuntimeWarning
(not an exception) for the "signal was never connected" case, so
contextlib.suppress(TypeError, RuntimeError) could not silence it.
Now showEvent tracks the previously-connected window in
_screen_signal_window and only disconnects when the window actually
changes (e.g., widget was reparented to a different top-level).
First show, same-window re-show, and reparent are all handled
without the warning.
Applied identically to _SelectCanvas (viewer) and PdfEditCanvas (editor).
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
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Summary
PR-J (R8/D1 DPR change handler) added a disconnect-then-connect pattern in
showEventfor both the viewer canvas and editor canvas. On PySide6 6.11, callingdisconnecton a signal that was never connected (first show, or re-show after teardown) emits:contextlib.suppress(TypeError, RuntimeError)doesn't silence a warning — Python warnings and exceptions are separate.Fix
Instead of blindly disconnecting on every show, both canvases now track the currently-connected window in
self._screen_signal_window:Applied identically in
_SelectCanvas.showEvent(app/viewer/canvas.py) andPdfEditCanvas.showEvent(app/editor/canvas.py). Kept inline (~10 lines each) rather than extracting a helper — factoring acrossviewer+editorpackages had marginal gain.Tests
tests/test_screen_changed_binding.py— 8 source-level regressions:__init__methodswin is prev_winAlso verified that the existing R8/D1 tests (
test_round8_fixes.py::test_{viewer,editor}_canvas_handles_screen_changed) still pass — no regression on the DPR change handling behaviour.Validation
APP_VERSIONbumpNot related to PR #115
PR #115 (presentation mode HUD icons) touches the same files but different lines. Merge order doesn't matter; either can go first.