Creating a DIB from HANDLE not DDB

Chambers

Hi all, I have a strange (but probably simple) question on DIB's and DDB's. I have a HANDLE (essentially a HBITMAP), and from this I want to create a DIB so that I may access "the bits" etc. Now at the moment, I have the following code, which manages to create a valid HBITMAP (and later on Blits it to the screen - no problem). However, i have had terrible trouble getting access to "the bits" later on in my program, and I think its something to do with the GetDIBitmap function (MSDN says it returns a DDB FROM A DIB). I cannot seem to use the GetObject function either to get a DIBSECTION or BITMAP structure which my program relies on (that is essentially what I need from this, plus the HBITMAP of course). Any help on this would be hugely appreciated (including any better ways of going about converting the HANDLE to a HBITMAP), I have been working on this for days, thats why I haven`t been seen for a while!

void CMainFrame::GetImage(HANDLE handle)
{
CBitmapDoc* pBitmapDoc = NewDocument(); //new doc.
CBitmapFrame* pBitmapWnd = (CBitmapFrame*)NewWindow(pBitmapDoc);

BYTE* lpVoid, *pBits;
LPBITMAPINFO pHead;
lpVoid = (BYTE*)GlobalLock(handle);
pHead = (LPBITMAPINFO)lpVoid;
GlobalUnlock(lpVoid);

pBits = (BYTE*)lpVoid + sizeof(BITMAPINFOHEADER);

HBITMAP newbitmap = CreateDIBitmap(pBitmapWnd->GetDC()->m_hDC, &pHead->bmiHeader, CBM_INIT, pBits, pHead, DIB_RGBCOLORS);
}

Thanks anyway for looking at my problem, Alan.:confused: "When I left you I was but the learner, now I am the Master" - Darth Vader:mad:

Chris Losinger

from DDB to DIB, you want GetDIBits. here's how i do it (edit out what you don't want):

HANDLE CISImgUtil::DDBToDIB( HBITMAP bitmap, UINT32 dwCompression, HPALETTE hPal )
{

CCallbackLock lock;

UINT32                   dwLen;
HANDLE                  hDIB;

ISASSERT( bitmap );

// The function has no arg for bitfields
if( dwCompression == BI\_BITFIELDS )
{
	m\_error=IS\_ERR\_INTERNAL;
	return NULL;
}

// If a palette has not been supplied use default palette
if (hPal==NULL)
	hPal = (HPALETTE) GetStockObject(DEFAULT\_PALETTE);

BITMAP bm;
// Get bitmap information
::GetObject(bitmap, sizeof(bm),(LPSTR)&bm);

// Initialize the bitmapinfoheader
BITMAPINFOHEADER        bi;
bi.biSize               = sizeof(BITMAPINFOHEADER);
bi.biWidth              = bm.bmWidth;
bi.biHeight             = bm.bmHeight;
bi.biPlanes             = 1;
bi.biBitCount           = bm.bmPlanes \* bm.bmBitsPixel;
bi.biCompression        = dwCompression;
bi.biSizeImage          = 0;
bi.biXPelsPerMeter      = 0;
bi.biYPelsPerMeter      = 0;
bi.biClrUsed            = 0;
bi.biClrImportant       = 0;

// Compute the size of the  infoheader and the color table
int nColors = (1 << bi.biBitCount);

if( nColors > 256 ) 
	nColors = 0;

if (bi.biBitCount>31)
	nColors=0;

dwLen  = bi.biSize + nColors \* sizeof(RGBQUAD);

// We need a device context to get the DIB from
HDC hDC = GetDC(NULL);
hPal = SelectPalette(hDC,hPal,FALSE);
RealizePalette(hDC);

// Allocate enough memory to hold bitmapinfoheader and color table
hDIB = (HGLOBAL)ISAlloc(dwLen);

if (hDIB==NULL)
{
	SelectPalette(hDC,hPal,FALSE);
	ReleaseDC(NULL,hDC);
	m\_error=IS\_ERR\_MEM;
	return NULL;
}

LPBITMAPINFOHEADER lpbi = (LPBITMAPINFOHEADER)hDIB;

\*lpbi = bi;

// Call GetDIBits with a NULL lpBits param, so the device driver 
// will calculate the biSizeImage field 
if (!GetDIBits(hDC, bitmap, 0L, (UINT32)bi.biHeight,
	(LPBYTE)NULL, (LPBITMAPINFO)lpbi, (UINT32)DIB\_RGB\_COLORS))
{
	// error
	ISFree(hDIB);
	
	// Reselect the original palette
	SelectPalette(hDC,hPal,FALSE);
	ReleaseDC(NULL,hDC);
	
	m\_error=IS\_ERR\_GETDIB;
	return NULL;
}

bi = \*lpbi;

// If the driver did not fill in the biSizeImage field, then compute it
// Each scan line of the image is aligned on a UINT32 (32bit) boundary
if (bi.biSizeImage == 0){
	bi.biSizeImage = ((((bi.biWidth \* bi.biBitCount) + 31) & ~31) / 8) 
		\* bi.biHeight;
	
	// If a com

Chambers

Geeze, thanks for that Chris, its exactly what i need (minus the palette stuff cos I`m dealing with 24-bit DIBs). I cannot thank you enough for both the detail and accuracy of your response. Many, many thanks, Alan.:-D "When I left you I was but the learner, now I am the Master" - Darth Vader:mad:

Chris Losinger

no problem. actually, that's a chunk of code i got off of codeguru a couple of years ago - it's always worked well for me. just sharing the wealth. -c

POKE 808,234