Fix screenCurtain/Fullscreen conflict#20342
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| """ | ||
| if not (screenCurtain.screenCurtain and screenCurtain.screenCurtain.enabled): | ||
| return False | ||
| from NVDAState import _TrackNVDAInitialization |
| log.debug("Full-screen Magnifier gain focus event") | ||
| nextHandler() | ||
|
|
||
| def _isBlockedByScreenCurtain(self) -> bool: |
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won't these functions need to be more generic than just the full screen magnifier?
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Link to issue number:
Fixes #20289
Summary of the issue:
Two bugs occur when both the fullscreen magnifier and screen curtain are enabled and NVDA is restarted:
(Privacy/critical) The magnifier's initialization calls MagUninitialize() on the screen curtain's active API session, briefly exposing the screen.
After restart, disabling the screen curtain then enabling the magnifier fails on the first attempt due to stale Windows API state left by the screen curtain's MagSetFullscreenColorEffect(TRANSFORM_BLACK) call.
Description of user facing changes:
On restart, the screen curtain remains active during magnifier initialization, the screen is no longer exposed.
Enabling the screen curtain while the magnifier is active stops the magnifier (with a spoken message) and re-enables it automatically when the screen curtain is disabled.
Trying to enable the magnifier while the screen curtain is active speaks an error message.
Description of developer facing changes:
FullScreenMagnifier gains onScreenCurtainEnabled(), onScreenCurtainDisabled(), _isBlockedByScreenCurtain(), and _clearStaleApiState().
screenCurtain now calls the two onScreenCurtain methods, guarded by _MAGNIFIED_VIEW == MagnifiedView.FULLSCREEN.
All screen curtain logic removed from the base Magnifier class into fullscreen
Description of development approach:
Bug 1 is fixed by checking the screen curtain at the start of _startMagnifier() and returning immediately without touching the API if it is active.
Bug 2 : after MagSetFullscreenColorEffect(TRANSFORM_BLACK) + MagUninitialize(), the next MagSetFullscreenTransform silently fails. _clearStaleApiState() runs a dummy MagInitialize / MagSetFullscreenColorEffect(NORMAL) / MagUninitialize cycle before every real MagInitialize to clear this state.
All screen curtain handling is confined to FullScreenMagnifier since it is the only magnifier type that drives the Windows Magnification API.
Testing strategy:
manual/unit
Known issues with pull request:
Code Review Checklist: