HBITMAP memory leak

Question

No matter how hard I looked and whatever I tried, I couldn't find why this code is leaking. Actually, I'm not sure about the leak but the number of GDI objects increases everytime I use this piece of code.

HBITMAP hBmp;
hBmp = CreateDIBitmap(dc, &stBmpIH, CBM_INIT, m_pBitmapData, m_pBitmapInfo, DIB_RGB_COLORS) ;

Bitmap  *pBMP = NULL;
HPALETTE hPal = NULL;
Color col = 0;

pBMP = Bitmap::FromHBITMAP(hBmp, hPal);

if (m_bFlip)
{
    pBMP->RotateFlip( Rotate90FlipXY );
    pBMP->GetHBITMAP(col,&hBmp);
    m_bFlip = FALSE;
}
else
{
    pBMP->RotateFlip( RotateNoneFlipX );
    pBMP->GetHBITMAP(col,&hBmp);
}

delete pBMP;

I've checked the GDI objects with a tool, and what I found is the HBITMAP hBmp is the one that is leaking. How should I remove it?

DeleteObject is NOT working.

Thanks

Answer 1

DeleteObject is NOT working.

Let's assume that it is actually in your code even though the snippet doesn't show it. Then the next explanation is this statement:

 pBMP->GetHBITMAP(col,&hBmp);

Which overwrites the value for hBmp, preventing you from releasing it properly. Fix:

 HBITMAP prev = hBmp;
 Status status = pBMP->GetHBITMAP(col,&hBmp);
 if (status == Ok) DeleteObject(prev);

You'll probably need to do some more work on the error handling code.

Answer 2

From the FromHBITMAP documentation:

You are responsible for deleting the GDI bitmap and the GDI palette. However, you should not delete the GDI bitmap or the GDI palette until after the GDI+ Bitmap object is deleted or goes out of scope.

Deleting the Bitmap object is not enough, you need to call DeleteObject on hBmp afterwards.

Answer 3

You need a call to DeleteObjectto match the call to CreateDIBitmap. How exactly is it now working?