Get keyboard type macOS and detect built-in, onscreen or USB

Question

I am developing an application to detect keyboard type for macOS. I have seen several functions which reading the documentation are supposed to return keyboard id.

However when I test those on my laptop it always print 59.

Can someone tell me where does this 59 value come from and its meaning ??

So far I have tried with oncreen keyboard and built-in keyboard. I have also tried with different layouts but I keep getting that 59

This is my code:

- (CGEventRef)processEvent:(CGEventRef)cgEvent
{
   uint32_t kbdType = LMGetKbdType();
   NSLog(@"Testing LMGetKbdType  ----------> %d", kbdType);
   NSEvent* event = [NSEvent eventWithCGEvent:cgEvent];

   NSEventType type = [event type];
   if(type==NSKeyDown || type==NSKeyUp) {
      int64_t val = CGEventGetIntegerValueField(cgEvent, kCGKeyboardEventKeyboardType);
      NSLog(@"CGEventGetIntegerValueField: %lld",val);
      EventRef ce = (EventRef)[event eventRef];

      if(ce) {
         unsigned kbt;
         GetEventParameter(
                        ce,
                        kEventParamKeyboardType,
                        typeUInt32, NULL,
                        sizeof kbt, NULL,
                        & kbt
                        );

         NSLog(@"CARBON Keyboard type: %d",kbt);
      }

      CGEventSourceRef evSrc = CGEventCreateSourceFromEvent( cgEvent );

      if(evSrc) {
         unsigned kbt = (NSUInteger) CGEventSourceGetKeyboardType( evSrc );
         CFRelease(evSrc);
         NSLog(@"COCOA: %d",kbt);
      }
   }
}

Answer 1

I think these are undocumented values with no external meaning. They are only useful for passing back into other APIs that need a keyboard type (e.g. UCKeyTranslate()).

I think that they are of the same kind that used to be documented in <CoreServices/CarbonCore/Gestalt.h>, under gestaltKeyboardType. However, that header is no longer being updated and doesn't list a type 59.

What exactly are you trying to figure out about the keyboard? If it's general layout, you can use KBGetLayoutType() to learn if it's ANSI, JIS, or ISO. You pass in the keyboard type, like the one you're getting from LMGetKbdType().

The active keyboard layout (e.g. U.S. vs. French vs. Dvorak) should not affect the keyboard type. The keyboard type is an aspect of the hardware and doesn't change as the layout (the interpretation of keys into characters) changes.