内存耗尽处理流程

static ret_t wm_on_low_memory(void* ctx, event_t* evt) {
  log_debug("low memory\n");
  return RET_OK;
}

static ret_t wm_on_out_of_memory(void* ctx, event_t* evt) {
  log_debug("out of memory\n");
  return RET_OK;
}

widget_t* wm = window_manager();
widget_on(wm, EVT_LOW_MEMORY, wm_on_low_memory, wm);
widget_on(wm, EVT_OUT_OF_MEMORY, wm_on_out_of_memory, wm);