Squash Odysseus development history

static/js/platform.js

@@ -0,0 +1,47 @@
+// ============================================
+// Platform detection + AltGr-keystroke helper
+// ============================================
+// Shared by the keybind code: root keyboard-shortcuts.js, the editor's
+// keyboard-shortcuts.js, and settings.js. Single source of truth so the three
+// guards can't drift.
+
+// AltGr (right Alt on AZERTY/QWERTZ and most non-US layouts, used to type
+// @ # { } [ ] | \ and €) is reported by browsers as Ctrl+Alt. macOS is the
+// exception: there the Option key — a normal part of Mac shortcuts — also sets
+// the AltGraph modifier state, so it must NOT be treated as AltGr.
+//
+// IS_MAC covers all Apple platforms, iPad/iPhone included: a Magic Keyboard's
+// Option key sets AltGraph exactly like a Mac's, so they need the same carve-out
+// — narrowing to macOS-only would re-break them. The name and the
+// /Mac|iPhone|iPad/ test deliberately mirror the existing isMac checks in
+// calendar.js and sessions.js; this is their single shared source of truth.
+export const IS_MAC =
+  /Mac|iPhone|iPad/.test((typeof navigator !== 'undefined' && navigator.platform) || '') ||
+  /Mac/.test((typeof navigator !== 'undefined' && navigator.userAgent) || '');
+
+// True when `e` is an AltGr keystroke we should ignore for Ctrl+Alt shortcut
+// purposes. getModifierState('AltGraph') is true for AltGr but false for a
+// genuine left Ctrl+Alt, so real shortcuts still work. Always false on macOS,
+// where Option legitimately sets AltGraph.
+//
+// We also require ctrlKey+altKey: the collision we defend against is precisely
+// "AltGr reported AS Ctrl+Alt", so an event that asserts AltGraph WITHOUT
+// presenting as Ctrl+Alt (a Linux ISO_Level3_Shift layout, a stray modifier
+// state) is left alone instead of being swallowed.
+//
+// Trade-off: on Windows AltGr *is* Ctrl+right-Alt, so a deliberate
+// Ctrl+Alt+<char> shortcut typed via AltGr is unreachable too — accepted; use
+// the left Ctrl+Alt.
+//
+// NOTE: the AltGr -> AltGraph mapping is taken from the UI Events spec / MDN,
+// not proven by our tests. Older Firefox and some Linux setups historically did
+// not report AltGraph; where a browser sets ctrlKey+altKey without it this
+// guard is simply a no-op (the pre-fix behaviour) rather than a regression.
+export function isAltGrEvent(e, isMac = IS_MAC) {
+  return (
+    !isMac &&
+    !!e.ctrlKey &&
+    !!e.altKey &&
+    !!(e.getModifierState && e.getModifierState('AltGraph'))
+  );
+}