Mac多点触控代码技术问询：语言识别、Xcode适配及Touch Designer集成

Hey there! Let's walk through your questions step by step, using the code and context you shared:

1. Is this code C++? #

Nope, this is C code, specifically C99. Here's why:

• The code uses C-style type definitions (typedef struct) and function syntax with no C++-specific features like classes, templates, or function overloading.
• The compile command explicitly specifies -std=c99, which enforces the C99 standard, not C++.

Here's your properly formatted code and compile instructions:

#include <math.h>
#include <unistd.h>
#include <CoreFoundation/CoreFoundation.h>

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

MTDeviceRef MTDeviceCreateDefault();
void MTRegisterContactFrameCallback(MTDeviceRef, MTContactCallbackFunction);
void MTDeviceStart(MTDeviceRef, int);

// thanks comex
int callback(int device, Finger *data, int nFingers, double timestamp, int frame) {
    for (int i=0; i<nFingers; 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);
    }
    printf("\n");
    return 0;
}

int main() {
    MTDeviceRef dev = MTDeviceCreateDefault();
    MTRegisterContactFrameCallback(dev, callback);
    MTDeviceStart(dev, 0);
    printf("Ctrl-C to abort\n");
    sleep(-1);
    return 0;
}

Compile command:

gcc -F/System/Library/PrivateFrameworks -framework MultitouchSupport test.m -o test -std=c99

2. Is it worth investing time in Xcode for this? #

Absolutely, if you plan to take this beyond a quick test. Here's why:

• Xcode has excellent support for Mac system frameworks (including the private MultitouchSupport framework) — you'll get auto-completion, inline documentation, and easy access to debugging tools.
• If you want to package this code into a dynamic library or a Touch Designer-compatible plugin later, Xcode simplifies building and signing these artifacts.
• Even for debugging the current code, Xcode's debugger is far more powerful than terminal-based tools, making it easier to track down issues with touch data handling.

That said, if you're just validating the touch data output, you can stick with terminal compilation. But for long-term development toward your Touch Designer goal, Xcode will save you time and headaches.

3. Is this the right direction for integrating with Touch Designer? #

Yes, this is a solid starting point, but you'll need to extend it to connect with Touch Designer. Here's how to align it with your goal:

• The current code reads raw touch data from the Mac's multitouch system — that's the core input you need. Now you need to get this data into Touch Designer.
• Common approaches include:
  • OSC communication: Modify the code to send touch data (positions, IDs, etc.) as OSC messages to Touch Designer, which has built-in OSC support.
  • Touch Designer C++ SDK: Wrap the multitouch logic into a custom Touch Designer plugin using its SDK. Since you're familiar with Java, C++ has similar syntax fundamentals, and you can leverage your OOP knowledge here.
  • Dynamic library: Compile the multitouch code into a .dylib and load it into Touch Designer via its Python or C++ scripting capabilities.

A quick caveat: The MultitouchSupport framework is private (not officially documented by Apple), so there's a risk that future macOS updates could break this code. For a more stable long-term solution, you might also explore using Apple's public AppKit touch APIs, but those are limited to app windows — the private framework gives you global touch access, which is likely what you need for Touch Designer.

内容的提问来源于stack exchange，提问作者jtittle