mfc 数据库图片显示 ，求答案啊。。

[zyx1009]

void CMainFrame::Onread()
{

Cpicrecord pSet;
if (pSet.Open(CRecordset::dynamic,NULL))
{
MessageBox("打开成功");
}
pSet.MoveFirst();//读第一条记录

long lDataSize =pSet.m_pic.m_dwDataLength;//得到数据的长度
if(lDataSize > 0)
{


//2：转换成cbitmap

BYTE* content=new BYTE[pSet.m_pic.m_dwDataLength];
memcpy(content,GlobalLock(pSet.m_pic.m_hData),pSet.m_pic.m_dwDataLength);


void* pBitsDib;
CBitmap* wrk_nBitmap;
CGdiObject* wrk_pGdiObject;
CDC wrk_cdcMem;
HBITMAP hBitmap;
HDC hdc;

LPBITMAPINFO lpbmi = new BITMAPINFO;
ZeroMemory(lpbmi, sizeof(BITMAPINFO));

lpbmi-> bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
lpbmi-> bmiHeader.biPlanes = 1;
lpbmi-> bmiHeader.biCompression = BI_RGB;
lpbmi-> bmiHeader.biClrImportant = 0;
lpbmi-> bmiHeader.biSizeImage = 0;
lpbmi-> bmiHeader.biClrUsed = 0;
lpbmi-> bmiHeader.biBitCount = 24;
lpbmi-> bmiHeader.biWidth = 800;
//lpbmi-> bmiHeader.biHeight = 400;
lpbmi-> bmiHeader.biHeight = 400*(-1);
lpbmi-> bmiHeader.biXPelsPerMeter= 0;
lpbmi-> bmiHeader.biYPelsPerMeter= 0;

hdc = ::GetDC(NULL);
wrk_cdcMem.CreateCompatibleDC(NULL);
hBitmap = ::CreateDIBSection(NULL, lpbmi, DIB_RGB_COLORS, (void**)&pBitsDib, NULL, 0);
wrk_nBitmap = new CBitmap();
wrk_nBitmap->Attach(hBitmap);
wrk_pGdiObject = wrk_cdcMem.SelectObject(wrk_nBitmap);//选择一对象到指定的设备上下文环境中，该新对象替换先前的相同类型的对象

SetDIBits(wrk_cdcMem.GetSafeHdc(),hBitmap,0,400,content,lpbmi,DIB_RGB_COLORS);

wrk_cdcMem.SelectObject(wrk_pGdiObject);
delete lpbmi;
wrk_cdcMem.DeleteDC();
if(hdc != NULL)
{
::ReleaseDC(NULL,hdc);
}
// return wrk_nBitmap;





CString FileName="C://b.bmp";
MessageBox(FileName);


//显示2
//bool SaveBitmapToFile(CBitmap* bitmap, LPSTR lpFileName)

HBITMAP hBitmap1; // 为刚才的屏幕位图句柄
HDC hDC; //设备描述表
int iBits; //当前显示分辨率下每个像素所占字节数
WORD wBitCount; //位图中每个像素所占字节数
DWORD dwPaletteSize = 0, //定义调色板大小
dwBmBitsSize, //位图中像素字节大小
dwDIBSize, //位图文件大小
dwWritten; //写入文件字节数
BITMAP Bitmap; //位图属性结构
BITMAPFILEHEADER bmfHdr; //位图文件头结构
BITMAPINFOHEADER bi; //位图信息头结构
LPBITMAPINFOHEADER lpbi; //指向位图信息头结构
HANDLE fh, //定义文件
hDib, //分配内存句柄
hPal, //调色板句柄
hOldPal = NULL;

//计算位图文件每个像素所占字节数
hBitmap = (HBITMAP)*wrk_nBitmap;
hDC = CreateDC("DISPLAY",NULL,NULL,NULL);
iBits = GetDeviceCaps(hDC, BITSPIXEL) * GetDeviceCaps(hDC, PLANES);
DeleteDC(hDC);

if (iBits <= 1)
wBitCount = 1;
else if (iBits <= 4)
wBitCount = 4;
else if (iBits <= 8)
wBitCount = 8;
else if (iBits <= 24)
wBitCount = 24;
else if (iBits <= 32)
wBitCount = 32;

//计算调色板大小
if (wBitCount <= 8)
dwPaletteSize = (1 << wBitCount) * sizeof (RGBQUAD);

//设置位图信息头结构
GetObject(hBitmap, sizeof (BITMAP), (LPSTR)&Bitmap);
bi.biSize = sizeof (BITMAPINFOHEADER);
bi.biWidth = Bitmap.bmWidth;
bi.biHeight = Bitmap.bmHeight;
bi.biPlanes = 1;
bi.biBitCount = wBitCount;
bi.biCompression = BI_RGB;
bi.biSizeImage = 0;
bi.biXPelsPerMeter = 0;
bi.biYPelsPerMeter = 0;
bi.biClrUsed = 0;
bi.biClrImportant = 0;

dwBmBitsSize = ((Bitmap.bmWidth * wBitCount+31) / 32) * 4 * Bitmap.bmHeight;

//为位图内容分配内存
hDib = GlobalAlloc(GHND, dwBmBitsSize + dwPaletteSize + sizeof (BITMAPINFOHEADER));
lpbi = (LPBITMAPINFOHEADER)GlobalLock(hDib);
*lpbi = bi;

// 处理调色板
hPal = GetStockObject(DEFAULT_PALETTE);
if (hPal)
{
hDC = ::GetDC(NULL);
hOldPal = ::SelectPalette(hDC, (HPALETTE)hPal, FALSE);
RealizePalette(hDC);
}

// 获取该调色板下新的像素值
GetDIBits(hDC, hBitmap, 0, (UINT) Bitmap.bmHeight,
(LPSTR)lpbi + sizeof (BITMAPINFOHEADER) + dwPaletteSize,
(LPBITMAPINFO)lpbi, DIB_RGB_COLORS);

//恢复调色板
if (hOldPal)
{
SelectPalette(hDC, (HPALETTE)hOldPal, TRUE);
RealizePalette(hDC);
::ReleaseDC(NULL, hDC);
}

//创建位图文件
fh = CreateFile(FileName, GENERIC_WRITE,
0, NULL, CREATE_ALWAYS,
FILE_ATTRIBUTE_NORMAL | FILE_FLAG_SEQUENTIAL_SCAN, NULL);

// if (fh == INVALID_HANDLE_VALUE)
// return FALSE;

// 设置位图文件头
bmfHdr.bfType = 0x4D42; // "BM"
dwDIBSize = sizeof (BITMAPFILEHEADER)
+ sizeof (BITMAPINFOHEADER)
+ dwPaletteSize + dwBmBitsSize;
bmfHdr.bfSize = dwDIBSize;
bmfHdr.bfReserved1 = 0;
bmfHdr.bfReserved2 = 0;
bmfHdr.bfOffBits = (DWORD)sizeof (BITMAPFILEHEADER)
+ (DWORD)sizeof (BITMAPINFOHEADER)
+ dwPaletteSize;

// 写入位图文件头
WriteFile(fh, (LPSTR)&bmfHdr, sizeof(BITMAPFILEHEADER), &dwWritten, NULL);

// 写入位图文件其余内容
WriteFile(fh, (LPSTR)lpbi, dwDIBSize,
&dwWritten, NULL);

//清除
GlobalUnlock(hDib);
GlobalFree(hDib);
CloseHandle(fh);


//SaveBitmapToFile(cbm, FileName);

}

}
Cpicrecord的基类是Crecordset，pSet.m_pic是指向数据库的图片
牛人们帮帮忙，现在图片显示出来是一片黑，什么也没有。。。