求助：构造位图并显示出错.急！

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BITMAPINFO* pBmpInfo;
int nSize = sizeof(BITMAPINFO);//sizeof(BITMAPINFOHEADER) + (256 * sizeof( RGBQUAD) );
m_pBmpInfo = (BITMAPINFO*) new UCHAR[nSize];
m_pBmpInfo->bmiHeader.biSize= (DWORD) sizeof(BITMAPINFOHEADER);
m_pBmpInfo->bmiHeader.biWidth= (LONG)pDoc->pTag.ImageWidth; //m_nScreenWidth;
m_pBmpInfo->bmiHeader.biHeight= (LONG)-pDoc->pTag.ImageHeight; //m_nScreenHeight;
m_pBmpInfo->bmiHeader.biPlanes= (WORD)1; //必须是1
m_pBmpInfo->bmiHeader.biBitCount= (DWORD)pDoc->pTag.BitsPerSample; //每个象素的位数
m_pBmpInfo->bmiHeader.biCompression = BI_RGB; //压缩类型
m_pBmpInfo->bmiHeader.biSizeImage= (DWORD)pDoc->pTag.StripByteCounts;//tif->Width * tif->Height * nBitsPerSample / 8;
m_pBmpInfo->bmiHeader.biXPelsPerMeter= (LONG) pDoc->pTag.XResolution; //水平分辨率
m_pBmpInfo->bmiHeader.biYPelsPerMeter= (LONG) pDoc->pTag.YResolution; //垂直分辨率
m_pBmpInfo->bmiHeader.biClrUsed= 0; //all colors are important
m_pBmpInfo->bmiHeader.biClrImportant = 0;

char* pVal;
pVal = pDoc->pTag.DataBuff;
CDC memdc;
memdc.CreateCompatibleDC (pDC);
HBITMAP hBitmap=CreateDIBitmap(pDC->m_hDC,&(pBmpInfo->bmiHeader),CBM_INIT,pVal,pBmpInfo,DIB_RGB_COLORS);//报错！！！
//HBITMAP CreateDIBSection(...);
memdc.SelectObject(hBitmap);

pDC->BitBlt(12,23,230,230,&memdc,0,0,SRCCOPY);
::DeleteObject(hBitmap);
memdc.DeleteDC();

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提示CreateDIBitmap()处出错，请帮忙看看到底问题出在哪里？谢谢
m_pBmpInfo = (BITMAPINFO*) new UCHAR[nSize];//应该申请多大的内存？
如果nSize = sizeof(BITMAPINFO);的话申请了44字节，如果nSize = sizeof(BITMAPINFOHEADER) + (256 * sizeof( RGBQUAD) );申请了1064个字节，也就是多了255*sizeof(RGBQUAD)个字节。
请各位大虾帮忙

[alene_cn]

根据位深度来判断调色板的大小。

int nSizeTable = 0;
if (pBIH->biBitCount < 24)
{
nSizeTable = (1 << pBIH->biBitCount) * sizeof(RGBQUAD);
}

nSize = sizeof(BITMAPINFOHEADER) + nSizeTable;