ChromeVFX Prototype

ipc_nodejs_addon.cc

void receive_request(const FunctionCallbackInfo<Value>& args) {
  unsigned int priority;
  double msg;
  boost::interprocess::message_queue::size_type recvd_size;
  message_queue_request_->receive(&msg, sizeof(msg), recvd_size, priority);
  auto* isolate = args.GetIsolate();
  args.GetReturnValue().Set(Number::New(isolate, msg));
}

void send_response(const FunctionCallbackInfo<Value>& args) {
  int msg = args[0].As<Int32>()->Value();
  message_queue_response_->send(&msg, sizeof(msg), 0);
}

void save_screenshot(const FunctionCallbackInfo<Value>& args) {
  Local<Object> buffer_obj = args[0]->ToObject();
  const char* png_data = node::Buffer::Data(buffer_obj);
  const size_t png_data_size = node::Buffer::Length(buffer_obj);
  if (png_data_size > mapped_region_->get_size()) {
    std::cout << "WARNING: png data too large " << png_data_size << std::endl;
  } else {
    std::memcpy(mapped_region_->get_address(), png_data, png_data_size);
  }
}

mlt_plugin_render.cc

bool EffectsImpl::render(double time, Image* renderImage) {
  message_queue_request_->send(&time, sizeof(double), 0);
  int image_size;
  unsigned int priority;
  boost::interprocess::message_queue::size_type recvd_size;
  message_queue_response_->receive(&image_size, sizeof(image_size), recvd_size, priority);
  if (image_size > mapped_region_->get_size()) { return false; }
  png_image image;
  if (!read_png(mapped_region_->get_address(), image_size, &image, &png_buffer_)) { return false; }
  if (image.width != renderImage->width() || image.height != renderImage->height() || png_buffer_.size() != renderImage->byteCount()) { return false; }
  std::memcpy(renderImage->pixels(), png_buffer_.data(), png_buffer_.size());
  png_image_free(&image);
  return true;
}

render_server_event_loop.js

while(true) {
  var render_time = ipc.receive_request();
  await page.evaluate(render_time => {
    webvfx.render(render_time);
  }, render_time);

  const screenshot = await page.screenshot({
    type: 'png',
    omitBackground: 'true',
    encoding: 'binary',
  });

  ipc.save_screenshot(screenshot);
  ipc.send_response(screenshot.length);
}