FocusZoneViewManager-macOS.mm

// (c) Facebook, Inc. and its affiliates. Confidential and proprietary.

#import "FocusZoneViewManager-macOS.h"

#import <React/RCTView.h>

@interface FocusZoneView : RCTView

@end

@implementation FocusZoneView

- (NSView*)firstViewInKeyViewLoop {
  NSView* nextValidKeyView = self.nextValidKeyView;
  return [nextValidKeyView isDescendantOf:self] ? nextValidKeyView : nil;
}

- (NSView*)lastViewInKeyViewLoop {
  NSView* view = self.nextValidKeyView;
  NSView* previousView = self.nextValidKeyView;
  while ([view isDescendantOf:self]) {
    previousView = view;
    view = view.nextValidKeyView;
  }
  return previousView;
}

- (BOOL)isFirstControlSelected {
  return self.window.firstResponder == [self firstViewInKeyViewLoop];
}

- (BOOL)isLastControlSelected {
  return self.window.firstResponder == [self lastViewInKeyViewLoop];
}

- (void)keyDown:(NSEvent*)event {
  unichar const firstCharacter = [event.characters characterAtIndex:0];

  NSUInteger modifierFlags = event.modifierFlags & NSEventModifierFlagDeviceIndependentFlagsMask;
  // NOTE: we ignore NSEventModifierFlagFunction since it seems to get set even when fn isn't
  // pressed
  BOOL isArrowKeyModifierFlag =
      (modifierFlags & ~NSEventModifierFlagFunction) == NSEventModifierFlagNumericPad;

  switch (firstCharacter) {
  case NSUpArrowFunctionKey: {
    if (isArrowKeyModifierFlag && ![self isFirstControlSelected]) {
      [self.window selectPreviousKeyView:self.window.firstResponder];
      return;
    }
    break;
  }
  case NSDownArrowFunctionKey: {
    if (isArrowKeyModifierFlag && ![self isLastControlSelected]) {
      [self.window selectNextKeyView:self.window.firstResponder];
      return;
    }
    break;
  }
  case NSTabCharacter: {
    [self.window selectKeyViewFollowingView:[self lastViewInKeyViewLoop]];
    return;
  }
  case NSBackTabCharacter: {
    [self.window selectKeyViewPrecedingView:[self firstViewInKeyViewLoop]];
    return;
  }
  }

  [super keyDown:event];
}

@end

@implementation FocusZoneViewManager

RCT_EXPORT_MODULE()

- (RCTPlatformView*)view {
  return [FocusZoneView new];
}

@end