C Binding Data Streams Sample Complete Code

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#include <stdio.h>
#include <inttypes.h> // for PRId64 and timestamps
#include <interaction_lib/interaction_lib_c.h>
// this callback is used for the gaze point data subscription below
void gaze_point_data_callback(IL_GazePointData evt, void* context)
printf("x: %f, y: %f, validity: %s, timestamp: %" PRId64 " us\n",
evt.validity == IL_Validity_Valid ? "valid" : "invalid",
int main(int argc, char* argv[])
// create the interaction library
IL_Context* intlib = NULL;
IL_CreateInteractionLib(&intlib, IL_FieldOfUse_Interactive);
// assume single screen with size 2560x1440 and use full screen (not window local) coordinates
const float width = 2560.0f;
const float height = 1440.0f;
const float offset = 0.0f;
IL_CoordinateTransformAddOrUpdateDisplayArea(intlib, width, height, 0, 0, 0, 0, NULL);
IL_CoordinateTransformSetOriginOffset(intlib, offset, offset);
// subscribe to gaze point data; print data to stdout using the callback defined above
IL_SubscribeGazePointData(intlib, gaze_point_data_callback, NULL);
printf("Starting interaction library update loop.\n");
// setup and maintain device connection, wait for device data between events and
// update interaction library to trigger all callbacks, stop after 200 cycles
const size_t max_cycles = 200;
size_t cycle = 0;
while (cycle++ < max_cycles)
IL_WaitAndUpdate(intlib, 1000);
// cleanup
return 0;