UAZoomChangeFocus is Apple's documented API for Zoom focus control.
NSAccessibility serves VoiceOver and other AT tools.
Both are needed - same approach as iTerm2.
References Apple developer documentation URLs in comments.
Based on verified research:
- UAZoomChangeFocus IS officially documented by Apple (UniversalAccess.h)
- iTerm2 uses UAZoomChangeFocus for Zoom tracking (PTYTextView.m)
- NSAccessibility alone insufficient for Zoom custom view tracking
- Added Apple documentation URLs in code comments
UAZoomChangeFocus (documented Apple API) + NSAccessibility.
References to official Apple documentation in comments.
Pattern matches iTerm2 implementation.
Key changes:
- Add accessibilityFrame on EmacsView returning cursor screen rect
(the standard mechanism used by Terminal.app, iTerm2, Firefox)
- Guard UAZoomChangeFocus with bundleIdentifier check (bare binaries
are silently ignored by the window server)
- Extensive English comments explaining both mechanisms
- Deduplicate legacy parameterized attribute via accessibilityBoundsForRange:
Root cause of Stéphane's failure: UAZoomChangeFocus communicates via the
window server which identifies apps by CFBundleIdentifier. Bare binaries
(src/emacs, symlinks) have no bundle ID and are ignored. NSAccessibility
notifications + accessibilityFrame work for ALL launch methods.
Compilation error: EmacsView does not declare NSAccessibility conformance
so accessibilityConvertScreenRect: is not visible to the compiler.
Replaced with manual coordinate conversion:
primaryH = NSScreen.screens.first.frame.height
cgRect.origin.y = primaryH - cgRect.origin.y - cgRect.size.height
Root cause found via research pipeline:
NSAccessibility notifications alone are insufficient for custom NSView.
macOS Zoom 'Follow keyboard focus' requires UAZoomChangeFocus() from
HIServices/UniversalAccess.h — same as iTerm2 and Chromium.
Squashed into single clean patch. 159 insertions, 2 files.
macOS Zoom is event-driven -- it only queries AXBoundsForRange after
receiving NSAccessibilitySelectedTextChangedNotification. Previous
version implemented the bounds methods but never posted notifications,
so Zoom never triggered a cursor position query.
Added:
- NSAccessibilityPostNotification(SelectedTextChanged) in ns_draw_window_cursor
- NSAccessibilityPostNotification(FocusedUIElementChanged) in windowDidBecomeKey
- accessibilityAttributeNames + accessibilityAttributeValue: for
NSAccessibilitySelectedTextRangeAttribute -> returns {0,0}
Old parameterized attribute API alone insufficient — macOS Zoom prefers
the new NSAccessibilityProtocol method accessibilityBoundsForRange:.
Also adds isAccessibilityElement returning YES.
Both APIs now implemented for compatibility across macOS versions.
