HOWTO: Insert a Bitmap Into an RTF Document Using the RichEdit Control

• The Microsoft Foundation Classes (MFC), included with:
  • Microsoft Visual C++, 32-bit Editions, version 6.0

SUMMARY

The RichEdit control does not provide a direct method for loading a bitmap and inserting it into an RTF document. The ActiveX control (RichTextBox) provides the Add method through the COleObjects class, but this action loads the bitmap for editing in the registered bitmap editor (usually Paintbrush) before inserting it into the document. Both the DLL and the OCX expose the IRichEditOle interface which, however, provides the InsertObject method. This requires a fully-populated RichEdit Object (REOBJECT) structure to be passed.

MORE INFORMATION

The following code is based on a project in which the Microsoft RichTextBox control has been inserted. With minor changes, it can apply to the RichEdit DLL as well.

1. First, add four OLE interface pointers as member variables:
   




	LPRICHEDITOLE	m_pRichEditOle;
	LPOLEOBJECT	m_lpObject;
	LPSTORAGE         m_lpStorage;
	LPOLECLIENTSITE	m_lpClientSite; 


NOTE: Set these variables to NULL in your constructor.


2. Get the IRichEditOLE interface early on in your program and keep it available in OnInitDialog or OnInitialUpdate. For the RichTextBox control, use the following method:
   




	::SendMessage((HWND)m_ctlRichText.GetHwnd(), EM_GETOLEINTERFACE, 0, (LPARAM)&m_pRichEditOle);
	ASSERT(m_pRichEditOle != NULL); 


NOTE: M_ctlRichText is an instance of the Visual C++ wrapper class MFC generates when inserting a RichTextBox ActiveX control through the component gallery. The MFC CRichEditCtrl class provides the GetRichEditOle() method that wraps code similar to the above and produces the same result.


3. To insert the bitmap, create an embedded object from a file. OLE provides the OleCreateFromFile function call to make this easier, but you still need to prepare for the call. The following code is an amalgam of techniques used within the MFC classes to provide similar functionality.
   




BOOL CRichTextDlg::CreateFromFile(LPCTSTR lpszFileName)
{
	USES_CONVERSION;

	ASSERT_VALID(this);
	ASSERT(m_lpObject == NULL);     // one time only

	ASSERT(m_lpStorage == NULL);
	ASSERT(m_lpClientSite == NULL);
	LPLOCKBYTES lpLockBytes = NULL;
	CLSID clsid = CLSID_NULL;
	OLERENDER render = OLERENDER_DRAW;
	CLIPFORMAT cfFormat = 0;
	LPFORMATETC lpFormatEtc = NULL;

	SCODE sc;

	sc = ::CreateILockBytesOnHGlobal(NULL, TRUE, &lpLockBytes);
	if (sc != S_OK)
		AfxThrowOleException(sc);
	ASSERT(lpLockBytes != NULL);

	sc = ::StgCreateDocfileOnILockBytes(lpLockBytes,
		STGM_SHARE_EXCLUSIVE|STGM_CREATE|STGM_READWRITE, 0, &m_lpStorage);
	if (sc != S_OK)
	{
		VERIFY(lpLockBytes->Release() == 0);
		lpLockBytes = NULL;
		AfxThrowOleException(sc);
	}
	ASSERT(m_lpStorage != NULL);

	// fill in FORMATETC struct
	FORMATETC formatEtc;
	lpFormatEtc = &formatEtc;
	lpFormatEtc->cfFormat = cfFormat;
	lpFormatEtc->ptd = NULL;
	lpFormatEtc->dwAspect = DVASPECT_CONTENT;
	lpFormatEtc->lindex = -1;
	lpFormatEtc->tymed = (DWORD)-1;

	// attempt to create the object
	m_pRichEditOle->GetClientSite(&m_lpClientSite);

	sc = ::OleCreateFromFile(clsid, T2COLE(lpszFileName),
		IID_IUnknown, OLERENDER_NONE, lpFormatEtc, m_lpClientSite, m_lpStorage,
		(void**)&m_lpObject);
	if (sc != S_OK)
		AfxThrowOleException(sc);

	// m_lpObject is currently an IUnknown, convert to IOleObject
	if (m_lpObject != NULL)
	{
		LPUNKNOWN lpUnk = m_lpObject;
		lpUnk->QueryInterface(IID_IOleObject, (void**)&m_lpObject);
		lpUnk->Release();
		if (m_lpObject == NULL)
			AfxThrowOleException(E_OUTOFMEMORY);
	}

	// all items are "contained" -- this makes our reference to this object
	//  weak -- which is needed for links to embedding silent update.
	OleSetContainedObject(m_lpObject, TRUE);

	ASSERT_VALID(this);
	return TRUE;
}
 



4. To use the function, simply pass the full path to a bitmap as the file name parameter. The function creates a byte array in global memory and a compound file storage object in that memory. It then populates the FORMATETC structure, gets the client site, and creates the object within the provided storage. The result is an IUnknown pointer to the object that is then converted to a true IOleObject pointer by a call to QueryInterface.
   




5. Populate the RichEdit Object (REOBJECT) structure so it can call InsertObject through the IRichEditOle pointer stored earlier. The following code fills this structure:
   




	REOBJECT reobject;
	ZeroMemory(&reobject, sizeof(REOBJECT));
	reobject.cbStruct = sizeof(REOBJECT);

	CLSID clsid;
	SCODE sc = m_lpObject->GetUserClassID(&clsid);
	if (sc != S_OK)
		AfxThrowOleException(sc);

	reobject.clsid = clsid;
	reobject.cp = REO_CP_SELECTION;
	reobject.dvaspect = DVASPECT_CONTENT;
	reobject.dwFlags = REO_RESIZABLE | REO_BELOWBASELINE;
	reobject.dwUser = 0;
	reobject.poleobj = m_lpObject;

	ASSERT(m_lpClientSite != NULL);
	reobject.polesite = m_lpClientSite;

	ASSERT(m_lpStorage != NULL);
	reobject.pstg = m_lpStorage;

	SIZEL sizel;
	sizel.cx = sizel.cy = 0;
	reobject.sizel = sizel; 




6. At this point, make the InsertObject call. Insert the bitmap at the bottom of the file. A combination of EM_GETSEL/EM_SETSEL messages selects the document's text and positions the cursor at the end.
   




	HWND hWndRT = (HWND)m_ctlRichText.GetHwnd();
	::SendMessage(hWndRT, EM_SETSEL, 0, -1);
	DWORD dwStart, dwEnd;
	::SendMessage(hWndRT, EM_GETSEL, (WPARAM)&dwStart, (LPARAM)&dwEnd);
	::SendMessage(hWndRT, EM_SETSEL, dwEnd+1, dwEnd+1); 



7. Call InsertObject but add a carriage return first as in the following sample:
   




	CString strCr = "\r\n";
	m_ctlRichText.SetSelText((LPCTSTR)strCr); 


Finally!


	m_pRichEditOle->InsertObject(&reobject); 



8. The bitmap is dropped neatly at the bottom of the document with a carriage return separating it from the body of the text as in the following code sample:
   




	::SendMessage(hWndRT, EM_SCROLLCARET, (WPARAM)0, (LPARAM)0); 



9. This message scrolls the document to the caret position and the bitmap rolls into view. To repeat this, release the interface pointers:
   




	if (m_lpObject)
	{
		m_lpObject->Release();
		m_lpObject = NULL;
	}
	if (m_lpStorage)
	{
		m_lpStorage->Release();
		m_lpStorage = NULL;
	}
	if (m_lpClientSite)
	{
		m_lpClientSite->Release();
		m_lpClientSite = NULL;
	} 



10. Finally, release m_pRichEditOle.

Additional query words:

Keywords          : kbole kbBitmap kbCtrl kbMFC kbRichEdit kbVC600 kbDSupport 
Version           : winnt:6.0
Platform          : winnt 
Issue type        : kbhowto 

Last Reviewed: July 1, 1999