怎样从文件中读取位图 并初始化CBitmap类

[lovelyhawk]

rt

[bcpl]

CBitmap bmp;
HBITMAP hbmp = (HBITMAP)::LoadImage(AfxGetInstanceHandle(),
"c:\\test.bmp", IMAGE_BITMAP,
0, 0, LR_LOADFROMFILE);
bmp.Attach(hbmp);

[wuchuncai]

void LoadPictureFile(LPCTSTR szFile, CBitmap* pBitmap, CSize& mSize)
{
// open file
HANDLE hFile = CreateFile(szFile, GENERIC_READ, 0, NULL, OPEN_EXISTING, 0, NULL);
_ASSERTE(INVALID_HANDLE_VALUE != hFile);

// get file size
DWORD dwFileSize = GetFileSize(hFile, NULL);
_ASSERTE(-1 != dwFileSize);

LPVOID pvData = NULL;
// alloc memory based on file size
HGLOBAL hGlobal = GlobalAlloc(GMEM_MOVEABLE, dwFileSize);
_ASSERTE(NULL != hGlobal);

pvData = GlobalLock(hGlobal);
_ASSERTE(NULL != pvData);

DWORD dwBytesRead = 0;
// read file and store in global memory
BOOL bRead = ReadFile(hFile, pvData, dwFileSize, &dwBytesRead, NULL);
_ASSERTE(FALSE != bRead);
GlobalUnlock(hGlobal);
CloseHandle(hFile);

LPSTREAM pstm = NULL;
// create IStream* from global memory
HRESULT hr = CreateStreamOnHGlobal(hGlobal, TRUE, &pstm);
_ASSERTE(SUCCEEDED(hr) && pstm);

// Create IPicture from image file
LPPICTURE gpPicture;

hr = ::OleLoadPicture(pstm, dwFileSize, FALSE, IID_IPicture, (LPVOID *)&gpPicture);
_ASSERTE(SUCCEEDED(hr) && gpPicture);
pstm->Release();

OLE_HANDLE m_picHandle;
/*
long hmWidth, hmHeight;
gpPicture->get_Width(&hmWidth);
gpPicture->get_Height(&hmHeight);
int nWidth = MulDiv(hmWidth, GetDeviceCaps(hdc, LOGPIXELSX), HIMETRIC_INCH);
int nHeight = MulDiv(hmHeight, GetDeviceCaps(hdc, LOGPIXELSY), HIMETRIC_INCH);
*/
gpPicture->get_Handle(&m_picHandle);
pBitmap->DeleteObject();
pBitmap->Attach((HGDIOBJ) m_picHandle);

BITMAP bm;
GetObject(pBitmap->m_hObject, sizeof(bm), &bm);
mSize.cx = bm.bmWidth; //nWidth;
mSize.cy = bm.bmHeight; //nHeight;
}

[vcforever]

CBitmap bmp;
HBITMAP hBitmap = (HBITMAP)LoadBitmap(.......);
bmp.Attach(hBitmap);

还有就是bcpl(林平之，感冒中．．．)的那中方法，其实原理都一样就是所用的函数
不一样罢了！

祝你成功！

[Jerrylew]

void LoadFile(CString strDibFileName)
{
if(m_pBitmapInfo) ::GlobalFree(m_hDIB);
Init();
m_strFileName =strDibFileName;
BITMAPFILEHEADER bitmapFileHeader;
CFile dibFile(strDibFileName,CFile::modeRead);
try
{
UINT nBFHsize=dibFile.Read((void*)&bitmapFileHeader,
sizeof(BITMAPFILEHEADER));
if(nBFHsize!=sizeof(BITMAPFILEHEADER))
{
m_bValid=FALSE;
return;
}
}
catch(CFileException* e)
{
e->Delete();
}
if (bitmapFileHeader.bfType == 0x4d42)
{
AfxGetApp()->BeginWaitCursor();
DWORD dwFileLength = dibFile.GetLength();
DWORD dwSize = dwFileLength - sizeof(BITMAPFILEHEADER);
m_hDIB = (HGLOBAL) ::GlobalAlloc(GMEM_MOVEABLE,dwSize);
if (m_hDIB == 0) m_bValid = FALSE;
BYTE* pbyDib= (BYTE*)::GlobalLock(m_hDIB);
if (pbyDib == NULL) m_bValid = FALSE;
try
{
DWORD dwReadSize = dibFile.Read((void*)pbyDib,dwSize);
dibFile.Close();
if(dwReadSize != dwSize)
{
m_bValid = FALSE;
::GlobalUnlock(m_hDIB);
::GlobalFree(m_hDIB);
Init();
return;
}
}
catch(CFileException* e)
{
e->Delete();
}
m_pBitmapInfo = (BITMAPINFO*)pbyDib;
m_pBitmapInfoHeader=(BITMAPINFOHEADER*) pbyDib;
m_nWidth = m_pBitmapInfoHeader->biWidth;
m_nHeight = m_pBitmapInfoHeader->biHeight;
m_nBitCount = (BYTE)m_pBitmapInfoHeader->biBitCount;
m_nTotalColors = GetColorNumber();
if (m_pBitmapInfoHeader->biClrUsed == 0)
m_pBitmapInfoHeader->biClrUsed = m_nTotalColors;
DWORD dwColorTableSize = m_nTotalColors * sizeof(RGBQUAD);
m_pDibData = pbyDib+m_pBitmapInfoHeader->biSize+dwColorTableSize;
m_pRGBQuad=(RGBQUAD*)(pbyDib+m_pBitmapInfoHeader->biSize);
if (m_pRGBQuad == (RGBQUAD*)m_pDibData) m_pRGBQuad = NULL;
m_pBitmapInfoHeader->biSizeImage=GetSize();
::GlobalUnlock(m_hDIB);
AfxGetApp()->EndWaitCursor();
m_bValid = TRUE;
}
else
{
AfxMessageBox("This is not a bitmap file!");
m_bValid = FALSE;
}
}

[Jerrylew]

这是用DIB的方法打开文件的，Load后DIB就被转化成DDB在内存中保存