// Complile:
// clang -o gittumouse gittumouse.c -framework ApplicationServices

#include <ApplicationServices/ApplicationServices.h>

static CGRect screenBounds;

// callback for mouse click.
CGEventRef
myCGEventCallback(CGEventTapProxy proxy, CGEventType type,
                  CGEventRef event, void *refcon)
{
	  int btn;
    // Do some sanity check.
    if (type != kCGEventOtherMouseDown)
        return event;

    CGPoint location = CGEventGetLocation(event);

		btn = CGEventGetIntegerValueField(event, kCGMouseEventButtonNumber);

    printf("(%f, %f) %i\n", location.x, location.y, btn);

    return event;
}

int
main(void)
{
    CFMachPortRef      eventTap;
    CGEventMask        eventMask;
    CFRunLoopSourceRef runLoopSource;

    // The screen size of the primary display.
    screenBounds = CGDisplayBounds(CGMainDisplayID());
    printf("The main screen is %dx%d\n", (int)screenBounds.size.width,
           (int)screenBounds.size.height);

    // Create an event tap. We are interested in kCGEventOtherMouseDown.
    eventMask = (1 << kCGEventOtherMouseDown);
    eventTap = CGEventTapCreate(
                   kCGSessionEventTap, kCGHeadInsertEventTap,
                   0, eventMask, myCGEventCallback, NULL);
    if (!eventTap) {
        fprintf(stderr, "failed to create event tap\n");
        exit(1);
    }

    // Create a run loop source.
    runLoopSource = CFMachPortCreateRunLoopSource(
                        kCFAllocatorDefault, eventTap, 0);

    // Add to the current run loop.
    CFRunLoopAddSource(CFRunLoopGetCurrent(), runLoopSource,
                       kCFRunLoopCommonModes);

    // Enable the event tap.
    CGEventTapEnable(eventTap, true);

    // Set it all running.
    CFRunLoopRun();

    // In a real program, one would have arranged for cleaning up.

    exit(0);
}