RustDesk/flutter/lib/models/input_modifier_utils.dart

import 'package:flutter/services.dart';

/// Returns true when a stale mobile one-shot Shift state should be released
/// by replaying a tracked Shift key-down as a synthesized key-up.
///
/// This is only valid on mobile when Flutter's cached Shift state is still on
/// (`cachedShiftPressed == true`) but the current hardware/raw event reports
/// Shift as off (`actualShiftPressed == false`).
///
/// A tracked Shift key-down is required so the caller can safely synthesize the
/// matching key-up. Both `shiftLeft` and `shiftRight` are excluded because the
/// Shift key event itself must be processed first; otherwise we could release
/// the tracked key while still handling the original Shift press/release.
/// Callers should evaluate this only after their cached modifier state has been
/// updated for the current event.
///
/// When this returns true, the caller logs a line like:
/// `input: releasing stale mobile Shift before replaying tracked raw key-up`
/// immediately before calling `_releaseTrackedRawShiftKeyEventIfNeeded()`.
bool shouldReleaseStaleMobileShift({
  required bool isMobile,
  required bool cachedShiftPressed,
  required bool actualShiftPressed,
  required LogicalKeyboardKey logicalKey,
  required bool hasTrackedShiftKeyDown,
}) {
  if (!isMobile || !cachedShiftPressed || actualShiftPressed) {
    return false;
  }
  if (!hasTrackedShiftKeyDown) {
    return false;
  }
  if (logicalKey == LogicalKeyboardKey.shiftLeft ||
      logicalKey == LogicalKeyboardKey.shiftRight) {
    return false;
  }
  return true;
}