Question

write a general example of polling in C language with comments

Answer 1

 #undef __cplusplus
     
     #include <stdio.h>
     #include <stdlib.h>
     
     #ifdef _WIN32
     #include <Windows.h>
     #else
     #include <unistd.h>
    #endif
    
    #include "LeapC.h"
    #include "ExampleConnection.h"
    
    int64_t lastFrameID = 0;                                 //The last frame received
    
    int main(int argc, char** argv) {
      OpenConnection();
      while(!IsConnected)
        millisleep(100);                                         //wait a bit to let the connection complete
    
      printf("Connected.");
      LEAP_DEVICE_INFO* deviceProps = GetDeviceProperties();        // leap device information
      if(deviceProps)
        printf("Using device %s.\n", deviceProps->serial);
    
      for(;;){                                                                                            //using loop
        LEAP_TRACKING_EVENT *frame = GetFrame();
        if(frame && (frame->tracking_frame_id > lastFrameID)){
          lastFrameID = frame->tracking_frame_id;
          printf("Frame %lli with %i hands.\n", (long long int)frame->tracking_frame_id, frame->nHands);
          for(uint32_t h = 0; h < frame->nHands; h++){
            LEAP_HAND* hand = &frame->pHands[h];
            printf("    Hand id %i is a %s hand with position (%f, %f, %f).\n",
                        hand->id,
                        (hand->type == eLeapHandType_Left ? "left" : "right"),
                        hand->palm.position.x,
                        hand->palm.position.y,
                        hand->palm.position.z);
          }
        }
      } 
      return 0;
    }