CODEWITHSUNDEEP
macoskeyboard-hook
moscoquera
moscoquera

Reputation: 288

how to disable keys in OS X?

I've an application that needs disable some keys while the application in running (i.e: A, option, command, shift).

how can I do that?

the language or method used does not matter.

Upvotes: 0

Views: 227

Answers (1)

pkamb
pkamb

Reputation: 35022

You can inspect, modify, and block keyboard events with a CGEventTap.

The user will need to grant your app assistive privileges via the Security pane of System Preferences for events to be disabled before posting.

Something like this: 

- (void)setKeyBlocker {
    // You should filter this better than kCGEventMaskForAllEvents, depending on your needs.
    CFMachPortRef eventTap = CGEventTapCreate(kCGHIDEventTap, kCGHeadInsertEventTap, kCGEventTapOptionDefault, kCGEventMaskForAllEvents, cgEventCallback, NULL);

    CFRunLoopSourceRef runLoopSource = CFMachPortCreateRunLoopSource(kCFAllocatorDefault, eventTap, 0);
    CFRunLoopAddSource(CFRunLoopGetCurrent(), runLoopSource, kCFRunLoopCommonModes);
    CGEventTapEnable(eventTap, true);

    CFRelease(eventTap);
    CFRelease(runLoopSource);
}

CGEventRef callback(CGEventTapProxy proxy, CGEventType type, CGEventRef cgEvent, void *refcon) {
    NSEvent *event = [NSEvent eventWithCGEvent:cgEvent];

    if (event.type == kCGEventKeyDown) {
        if ([event.characters isEqualToString:@"a"]) {
            // Kill event
            return NULL;
        }
    }

    return cgEvent;
}

Upvotes: 1

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