emwin控件使用外部flash存储图片出错的解决办法？

各位大神好，现在我使用emwin中的控件image显示图片，由于图片太多，所以放在外部的flash芯片中。程序代码如下：
[C] 纯文本查看 复制代码
unsigned char _acBuffer[320*4*8];int _GetData(void * p, const U8 ** ppData, unsigned NumBytesReq, U32 Off)  {static int FileAddress = 0;UINT NumBytesRead;FIL *PicFile;PicFile = (FIL *)p;/** Check buffer size*/if (NumBytesReq > sizeof(_acBuffer)) {NumBytesReq = sizeof(_acBuffer);}/** Set file pointer to the required position*/if(Off == 1) FileAddress = 0;else FileAddress = Off;result =f_lseek(PicFile, FileAddress);/** Read data into buffer*/result = f_read(PicFile, _acBuffer, NumBytesReq, &NumBytesRead);/** Set data pointer to the beginning of the buffer*/*ppData = (const U8 *)_acBuffer;/** Return number of available bytes*/return NumBytesRead;}
[C] 纯文本查看 复制代码
void DisplayImageFromExFlash(IMAGE_Handle hObj,const TCHAR* path){    FRESULT res_flash;   res_flash = f_open(&fnew1, path, FA_OPEN_EXISTING | FA_READ);   IMAGE_SetBMPEx ( hObj, _GetData, &fnew1);      f_close(&fnew1);}
发现程序执行到IMAGE_SetBMPEx ( hObj, _GetData, &fnew1);并不会调到int _GetData(void * p, const U8 ** ppData, unsigned NumBytesReq, U32 Off) 中，而是直接执行f_close(&fnew1);过后再执行_GetData(),
导致显示不了图片，请问这是什么原因呢？谢谢