写一个stm32用emwin开发3层页面并且具有返回功能，能在主页面显示时间的完整代码

以下是一个基本的3层页面的代码示例，使用STM32和emWin库开发。该程序包括一个主页面，一个子页面和一个子子页面，并具有返回功能。此外，程序还显示当前时间并将其显示在主页面上。

#include "stm32f4xx.h"
#include "GUI.h"
#include "DIALOG.h"
#include <time.h>

#define ID_WINDOW_MAIN  (GUI_ID_USER + 0x00)
#define ID_BUTTON_MENU  (GUI_ID_USER + 0x01)
#define ID_WINDOW_MENU  (GUI_ID_USER + 0x02)
#define ID_BUTTON_SUB   (GUI_ID_USER + 0x03)
#define ID_WINDOW_SUB   (GUI_ID_USER + 0x04)
#define ID_BUTTON_BACK  (GUI_ID_USER + 0x05)
#define ID_WINDOW_SUBSUB (GUI_ID_USER + 0x06)
#define ID_TEXT_TIME     (GUI_ID_USER + 0x07)

static WM_HWIN hWinMain;
static WM_HWIN hWinMenu;
static WM_HWIN hWinSub;
static WM_HWIN hWinSubSub;

static void _cbWindowMain(WM_MESSAGE * pMsg) {
  switch (pMsg->MsgId) {
    case WM_CREATE:
      hWinMain = pMsg->hWin;
      BUTTON_CreateEx(10, 10, 80, 40, hWinMain, WM_CF_SHOW, 0, ID_BUTTON_MENU);
      TEXT_CreateEx(100, 100, 100, 20, hWinMain, WM_CF_SHOW, 0, ID_TEXT_TIME, "00:00:00");
      break;
    case WM_PAINT:
      GUI_SetBkColor(GUI_YELLOW);
      GUI_Clear();
      break;
    default:
      WM_DefaultProc(pMsg);
      break;
  }
}

static void _cbButtonMenu(WM_MESSAGE * pMsg) {
  switch (pMsg->MsgId) {
    case WM_NOTIFY_PARENT:
      if (pMsg->Data.v == WM_NOTIFICATION_RELEASED) {
        hWinMenu = GUI_CreateDialogBox(_aDialogCreateMenu, GUI_COUNTOF(_aDialogCreateMenu), NULL, hWinMain, 0, 0);
      }
      break;
    default:
      BUTTON_Callback(pMsg);
      break;
  }
}

static void _cbWindowMenu(WM_MESSAGE * pMsg) {
  switch (pMsg->MsgId) {
    case WM_CREATE:
      BUTTON_CreateEx(10, 10, 80, 40, pMsg->hWin, WM_CF_SHOW, 0, ID_BUTTON_SUB);
      BUTTON_CreateEx(10, 60, 80, 40, pMsg->hWin, WM_CF_SHOW, 0, ID_BUTTON_BACK);
      break;
    case WM_PAINT:
      GUI_SetBkColor(GUI_LIGHTBLUE);
      GUI_Clear();
      break;
    case WM_DELETE:
      hWinMenu = 0;
      break;
    default:
      WM_DefaultProc(pMsg);
      break;
  }
}

static void _cbButtonSub(WM_MESSAGE * pMsg) {
  switch (pMsg->MsgId) {
    case WM_NOTIFY_PARENT:
      if (pMsg->Data.v == WM_NOTIFICATION_RELEASED) {
        hWinSub = GUI_CreateDialogBox(_aDialogCreateSub, GUI_COUNTOF(_aDialogCreateSub), NULL, hWinMenu, 0, 0);
      }
      break;
    default:
      BUTTON_Callback(pMsg);
      break;
  }
}

static void _cbButtonBack(WM_MESSAGE * pMsg) {
  switch (pMsg->MsgId) {
    case WM_NOTIFY_PARENT:
      if (pMsg->Data.v == WM_NOTIFICATION_RELEASED) {
        GUI_EndDialog(hWinMenu, 0);
      }
      break;
    default:
      BUTTON_Callback(pMsg);
      break;
  }
}

static void _cbWindowSub(WM_MESSAGE * pMsg) {
  switch (pMsg->MsgId) {
    case WM_CREATE:
      BUTTON_CreateEx(10, 10, 80, 40, pMsg->hWin, WM_CF_SHOW, 0, ID_BUTTON_BACK);
      break;
    case WM_PAINT:
      GUI_SetBkColor(GUI_LIGHTGREEN);
      GUI_Clear();
      break;
    case WM_DELETE:
      hWinSub = 0;
      break;
    default:
      WM_DefaultProc(pMsg);
      break;
  }
}

static void _cbWindowSubSub(WM_MESSAGE * pMsg) {
  switch (pMsg->MsgId) {
    case WM_CREATE:
      break;
    case WM_PAINT:
      GUI_SetBkColor(GUI_LIGHTMAGENTA);
      GUI_Clear();
      break;
    case WM_DELETE:
      hWinSubSub = 0;
      break;
    default:
      WM_DefaultProc(pMsg);
      break;
  }
}

static const GUI_WIDGET_CREATE_INFO _aDialogCreateMain[] = {
  {WINDOW_CreateIndirect, "Main", ID_WINDOW_MAIN, 0, 0, 320, 240, 0, 0, _cbWindowMain},
  {BUTTON_CreateIndirect, "Menu", ID_BUTTON_MENU, 230, 10, 80, 40, 0, 0, _cbButtonMenu},
};

static const GUI_WIDGET_CREATE_INFO _aDialogCreateMenu[] = {
  {WINDOW_CreateIndirect, "Menu", ID_WINDOW_MENU, 0, 0, 320, 240, 0, 0, _cbWindowMenu},
  {BUTTON_CreateIndirect, "Sub", ID_BUTTON_SUB, 10, 10, 80, 40, 0, 0, _cbButtonSub},
  {BUTTON_CreateIndirect, "Back", ID_BUTTON_BACK, 10, 60, 80, 40, 0, 0, _cbButtonBack},
};

static const GUI_WIDGET_CREATE_INFO _aDialogCreateSub[] = {
  {WINDOW_CreateIndirect, "Sub", ID_WINDOW_SUB, 0, 0, 320, 240, 0, 0, _cbWindowSub},
  {WINDOW_CreateIndirect, "SubSub", ID_WINDOW_SUBSUB, 10, 10, 300, 220, 0, 0, _cbWindowSubSub},
  {BUTTON_CreateIndirect, "Back", ID_BUTTON_BACK, 10, 190, 80, 40, 0, 0, _cbButtonBack},
};

void SysTick_Handler(void) {
  static time_t last_time = 0;
  time_t current_time = time(NULL);

  if (current_time != last_time) {
    last_time = current_time;
    struct tm *t = localtime(&current_time);
    char buf[9];
    snprintf(buf, 9, "%02d:%02d:%02d", t->tm_hour, t->tm_min, t->tm_sec);
    TEXT_SetText(WM_GetDialogItem(hWinMain, ID_TEXT_TIME), buf);
  }
}

int main(void) {
  SystemInit();
  BSP_Init();

  GUI_Init();

  WM_CreateWindowFromList(_aDialogCreateMain);

  SysTick_Config(SystemCoreClock / 1000);

  while (1) {
    GUI_Delay(100);
  }
}

在上面的代码中，我们定义了四个窗口：主窗口，菜单窗口，子窗口和子子窗口。我们还定义了一些回调函数来处理窗口消息。主窗口包含一个菜单按钮和一个用于显示当前时间的文本框。菜单按钮被点击时，菜单窗口将被创建。菜单窗口包含一个子页面按钮和一个返回按钮。子页面按钮被点击时，子窗口将被创建。返回按钮被点击时，菜单窗口将被销毁。子窗口包含一个返回按钮。返回按钮被点击时，子窗口将被销毁，并返回到菜单窗口。子子窗口只是一个简单的窗口，没有任何按钮或其他控件。

在主函数中，我们首先初始化系统和BSP库。然后，我们初始化GUI库并创建主窗口。最后，我们启用SysTick中断以便更新时间并保持GUI活动。

注意：该程序使用了标准库的time.h头文件来获取当前时间。在使用此程序之前，请确保已正确配置系统时钟并启用了RTC。