Mac OS X multitouch

Here's some code I found to directly access the touchpad state of fx. the MacBook from C++ code. It uses the Apple MultitouchSupport framework (which comes with XCode) and can be compiled with G++ like this:

g++ -L/System/Library/PrivateFrameworks/MultitouchSupport.framework \
  -F/System/Library/PrivateFrameworks \
  -framework Cocoa \
  -framework MultitouchSupport \
  *.cpp

The header file is defined like this:

#ifndef TOUCH_H
#define TOUCH_H

#include <mach/mach.h>
#include <IOKit/IOKitLib.h>
#include <CoreFoundation/CoreFoundation.h>

#include <map>
#include <vector>
#include <iostream>

extern TouchPadState touchPadState;

extern "C" {

    typedef struct { float x,y; } mtPoint;
    typedef struct { mtPoint pos,vel; } mtReadout;

    typedef struct {
        int frame;
        double timestamp;
        int identifier, state, foo3, foo4;
        mtReadout normalized;
        float size;
        int zero1;
        float angle, majorAxis, minorAxis; // ellipsoid
        mtReadout mm;
        int zero2[2];
        float unk2;
    } Finger;

    typedef long MTDeviceRef;
    typedef int (*MTContactCallbackFunction)(int,Finger*,int,double,int);

    MTDeviceRef MTDeviceCreateDefault();
    void MTRegisterContactFrameCallback(MTDeviceRef, MTContactCallbackFunction);
    void MTUnregisterContactFrameCallback(MTDeviceRef, MTContactCallbackFunction);
    void MTDeviceStart(MTDeviceRef, int);
    void MTDeviceStop(MTDeviceRef);
    void MTDeviceRelease(MTDeviceRef);
}

extern MTDeviceRef mtDevice;

extern void touchDeviceStart();
extern void touchDeviceStop();

#endif

The implementation is as follows:

#include <stdio.h>
#include "touch.h"

MTDeviceRef mtDevice;

int touchDeviceCallback(int device, Finger *data, int nFingers, double timestamp, int frame) {
    for (int i=0; i        Finger *f = &data[i];
        printf("Frame %7d: Angle %6.2f, ellipse %6.3f x%6.3f; "
            "position (%6.3f,%6.3f) vel (%6.3f,%6.3f) "
            "ID %d, state %d [%d %d?] size %6.3f, %6.3f?\n",
            f->frame,
            f->angle * 90 / atan2(1,0),
            f->majorAxis,
            f->minorAxis,
            f->normalized.pos.x,
            f->normalized.pos.y,
            f->normalized.vel.x,
            f->normalized.vel.y,
            f->identifier, f->state,
            f->foo3,
            f->foo4,
            f->size,
            f->unk2);
        }
        return 0;
}

void touchDeviceStart() {
    printf("Starting touch device...\n");
    mtDevice = MTDeviceCreateDefault();
    MTRegisterContactFrameCallback(mtDevice, touchDeviceCallback);
    MTDeviceStart(mtDevice, 0);
}

void touchDeviceStop() {
    printf("Stopping touch device...\n");
    MTDeviceStop(mtDevice);
    MTUnregisterContactFrameCallback(mtDevice, touchDeviceCallback);
    MTDeviceRelease(mtDevice);
}

Hope it's useful!