test_emscripten_main_loop_and_blocker.c

// Copyright 2015 The Emscripten Authors.  All rights reserved.
// Emscripten is available under two separate licenses, the MIT license and the
// University of Illinois/NCSA Open Source License.  Both these licenses can be
// found in the LICENSE file.

#include <stdlib.h>
#include <stdio.h>
#include <assert.h>
#include <emscripten.h>

double prevTime = -1.0;
int frame = 0;
bool blockerExecuted = false;

void final(void* arg) {
  assert(frame == 20);
  exit(0);
}

void looper() {
  if (blockerExecuted == false) {
    exit(1);
  }

  frame++;
  double curTime = emscripten_get_now();
  double timeSincePrevious = curTime - prevTime;
  prevTime = curTime;
  printf("frame: %d. dt: %g. absolute: %g\n", frame, timeSincePrevious, curTime);

  if (frame == 20) {
    emscripten_cancel_main_loop();
    emscripten_async_call(final, (void*)0, 1000);
  }
}

void main_loop_blocker(void* arg) {
  blockerExecuted = true;
  emscripten_pause_main_loop();
  emscripten_resume_main_loop();
}

int main() {
  prevTime = emscripten_get_now();
  emscripten_push_uncounted_main_loop_blocker(main_loop_blocker, NULL);
  emscripten_set_main_loop(looper, 60, 1);
  // Should never get here
  assert(false);
  return 99;
}