如何使用回调函数

Question

    var DT = 150; // time between faces detection

    var client, io, lastPng;
    var tracking = false;
    var debug = true;  
    var processingImage = false;
    var face_cascade = new 
  .cv.CascadeClassifier(path.join(__dirname,'node_modules','opencv','data','haarcascade_frontalface_alt2.xml'));


/** 
 *  Controllers initialization.
 */
var ver_ctrl = new Controller(0.3, 0.01, 0.1)
  , hor_ctrl = new Controller(0.4, 0.01, 0.1)
  ;

function log(string) {
    if (debug) {
        console.log(string);
    }
}

var times = [];

function detectFaces() {
  if(tracking && (!processingImage) && lastPng) {
    processingImage = true;

    async.waterfall([
      function(cb) {
        // 1. Stop the Drone before taking picture
        client.stop();
        setTimeout(function() { // wait the drone stabilization for a new image
          EventEmitter.once('newPng', function() {
            cb();
          });
        }, 200);
      },
      function(cb) {
        // 2. Read picture (takes between 60 and 100 ms)
        cv.readImage( lastPng, function(err, im) {
          cb(err,im);
        });
      },
      function(im, cb) {
        // 3. Detect faces (takes between 200 and 250 ms)
        var opts = {};
        face_cascade.detectMultiScale(im, function(err, faces) {
          cb(err, faces, im);
        }, opts.scale, opts.neighbors
         , opts.min && opts.min[0], opts.min && opts.min[1]);
      },
      function(faces, im, cb) {
        // 4. Analyze faces
        var face;
        var biggestFace;
        var dt = DT; // minimum time for the next detection

        for(var k = 0; k < faces.length; k++) {
          face = faces[k];
          if( !biggestFace || biggestFace.width < face.width ) biggestFace = face;
        }

        if( biggestFace ) {
          face = biggestFace;
          io.sockets.emit('face', { x: face.x, y: face.y, w: face.width, h: face.height, iw: im.width(), ih: im.height() });

          face.centerX = face.x + face.width * 0.5;
          face.centerY = face.y + face.height * 0.5;

          var centerX = im.width() * 0.5;
          var centerY = im.height() * 0.5;

          var heightAmount = -( face.centerY - centerY ) / centerY;
          var turnAmount = -( face.centerX - centerX ) / centerX;

          heightAmount = ver_ctrl.update(-heightAmount); // pid
          turnAmount   = hor_ctrl.update(-turnAmount);   // pid

          var lim = 0.1;
          if( Math.abs( turnAmount ) > lim || Math.abs( heightAmount ) > lim ){
            log( "  turning " + turnAmount );
            if (debug) io.sockets.emit('/message', 'turnAmount : ' + turnAmount);
            if( turnAmount < 0 ) client.clockwise( Math.abs( turnAmount ) );
            else client.counterClockwise( turnAmount );

            log( "  going vertical " + heightAmount );
            if (debug) io.sockets.emit('/message', 'heightAmount : ' + heightAmount);
            if(  heightAmount < 0 ) client.down( Math.abs(heightAmount) );
            else client.up( heightAmount );
          }
          else {
            if (debug) io.sockets.emit('/message', 'pause!');
            client.stop();
          }

          // to determine how much time the drone will move, we use the lower of the changes [-1,1], and multiply by a reference time.
          dt = Math.min(Math.abs(turnAmount), Math.abs(heightAmount));
          dt = dt * 2000;
        }

        processingImage = false;
        cb(null, dt);
      }
    ], function(err, dt) {
      dt = Math.max(dt, DT);
      setTimeout(detectFaces, dt);
    });
  } else {
    if (tracking) setTimeout(detectFaces, DT);
  };
};

function copterface(name, deps) {
    debug = deps.debug || false;
    io = deps.io;
    io.sockets.on('connection', function (socket) {
        socket.on('/copterface', function (cmd) {
            console.log("copterface", cmd);
            if (cmd == "toggle") {
              client.stop(); // make sure to stop the helicopter if stop copterface
              tracking = tracking ? false : true;
              if (tracking) detectFaces();
            } 
        });
    });

    client = deps.client;
    client.createPngStream()
      .on('error', console.log)
      .on('data', function(pngBuffer) {
      lastPng = pngBuffer;
      EventEmitter.emit('newPng');
    });

}

module.exports = copterface;

In the opinterface function of index.js, I am not sure how socket.on('/cop Interface', function(cmd) works.

My prediction is that the directory structure is marked with yellow highlighter. It sounds like you're calling copterface.js. (function (window, undefined) is not output.

Is there a way to call up the copterface.js file at index.js??

Answer 1

If you look at the API, the usage method is socket.on(eventName, callback).

The '/corpterface' of '/copterface' and '/copterface' (cmd) is not a request, it's just an event name.

This API means that after receiving connection event, you will receive /copinterface event in the future.

You should study socket.io This is the link. https://socket.io/docs/server-api/#socket-on-eventName-callback