Save CBitmap to File

Dhiraj kumar Saini

I have a CBitmap object and want to save it as a file . Please help me how to achieve it. Thanks & regards. Dhiraj

Emilio Garavaglia

Starting from CBitmap (MFC) or a GDI HBITMAP (what MFC wraps) it's not so easy: A sample is on MSDN http://msdn.microsoft.com/en-us/library/ms532340(VS.85).aspx[^] Otherwise, cosider using GDI+, where all this stuffs are wrappen in the Gdiplus::Bitmap class that can be created from an HBITMAP. (but you have to link for GDI+ libraries and run startup/termination appropriately: just llok GDI+ under MSDN)

2 bugs found. > recompile ... 65534 bugs found. :doh:

CPallini

You may use CImage class [^], check out the CImage::Attach method. I suppose (I didn't test it) the following code will do the trick:

CBitmap myBmp;
// bitmap initialization code
CImage myImg;
myImg.Attach(myBmp);
myImg.Save(_T("my.bmp"));
myImg.Detach();

:)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
[My articles]

Dhiraj kumar Saini

Its giving assertion related to size.

CPallini

Dhiraj kumar Saini wrote:

Its giving assertion related to size.

This is not a good way of getting help. You should be more precise and detailed when reporting errors. :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
[My articles]

Hamid Taebi

Did you trace it ? and can you show your code?

Dhiraj kumar Saini

Ya sure.

void CCaptureDesktopDlg::OnBnClickedButton1()
{
// TODO: Add your control notification handler code here

CString sFName;
CDC ScreenDC;
ScreenDC.Attach(::GetDC(NULL));

CBitmap Capture;
CSize Dimensions(GetSystemMetrics(SM_CXSCREEN), GetSystemMetrics(SM_CYSCREEN));
Capture.CreateCompatibleBitmap(&ScreenDC, Dimensions.cx, Dimensions.cy);

CDC MemDC;
MemDC.CreateCompatibleDC(&ScreenDC);

CBitmap *OldBitmap = MemDC.SelectObject(&Capture);

MemDC.BitBlt(0, 0, Dimensions.cx, Dimensions.cy, &ScreenDC, 0, 0, SRCCOPY);

//added on 28Nov08

CFileDialog fd( FALSE, // true for open, false for save

_T("BMP"), // default extention

NULL, // initial filename in box);

OFN_HIDEREADONLY & // flags for detailed behaviour

OFN_OVERWRITEPROMPT,

NULL, // file-filter pairs

NULL); // pointer to parent window

fd.m_ofn.lpstrTitle = _T("Enter file name...");

fd.m_ofn.lpstrInitialDir = NULL;

fd.m_ofn.lpstrFilter = _T("BMP files (*.bmp)\000*.BMP\000");

if(fd.DoModal() == IDOK)

sFName = fd.GetPathName();

else

return;

HANDLE hDib = DDBToDIB( Capture, BI_RGB, NULL );

BOOL b = WriteDIB( sFName.GetBuffer(sFName.GetLength()) , hDib);

if(!b)

{

CString sMess = _T("Unable to write to file: \n");

sMess += sFName;

AfxMessageBox(sMess);

}

MemDC.SelectObject(Capture);

Capture.Detach(); // make sure bitmap not deleted with CBitmap object

//----------------

MemDC.SelectObject(OldBitmap);
MemDC.DeleteDC();

::ReleaseDC(NULL, ScreenDC.Detach());

}
BOOL CCaptureDesktopDlg::WriteDIB( LPTSTR szFile, HANDLE hDIB)

{

BITMAPFILEHEADER hdr;

LPBITMAPINFOHEADER lpbi;

if (!hDIB)

return FALSE;

CFile file;

if( !file.Open( szFile, CFile::modeWrite|CFile::modeCreate) )

return FALSE;

lpbi = (LPBITMAPINFOHEADER)hDIB;

/* int nColors = 1 << lpbi->biBitCount;

*/

int nColors = 1 << lpbi->biBitCount;

if (nColors > 256)

nColors = 0;

// Fill in the fields of the file header

hdr.bfType = ((WORD) ('M' << 8) | 'B'); // is always "BM"

hdr.bfSize = GlobalSize (hDIB) + sizeof( hdr );

hdr.bfReserved1 = 0;

hdr.bfReserved2 = 0;

//// hdr.bfOffBits = (DWORD) (sizeof( hdr ) + lpbi->biSize +

//// nColors * sizeof(RGBQUAD))

Hamid Taebi

Change to it: ;) if(fd.DoModal() == IDOK) sFName = fd.GetPathName(); else return; CImage m2; m2.Attach(Capture); m2.Save(fd.GetPathName()); m2.Detach(); /*HANDLE hDib = DDBToDIB( Capture, BI_RGB, NULL ); BOOL b = WriteDIB( sFName.GetBuffer(sFName.GetLength()) , hDib); if(!b) { CString sMess = _T("Unable to write to file: \n"); sMess += sFName; AfxMessageBox(sMess); } */ MemDC.SelectObject(Capture); Capture.Detach();

Dhiraj kumar Saini

Thanx its working.

Hamid Taebi

You're welcome. ;)