How to insert a bitmap into an RTF document using the RichEdit control in Visual C++ 6.0

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Article ID: 220844 - View products that this article applies to.
This article was previously published under Q220844
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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 RichText control has been inserted. With minor changes, it can apply to the RichEdit DLL as well.
  1. Create a new MFC dialog based application named RichText.
  2. In the dialog editor, add a RichEdit control to the application dialog resource. Use the code wizards to create a member variable, m_ctlRichText, of type CRichEditCtrl, that is associated with the new RichEdit control.
  3. In the beginning of the InitInstance() method of the CWinApp derived class of your project, add a call to AfxInitRichEdit() to initialize the RichEdit common control.
  4. Add four OLE interface pointers as member variables to the CDialog derived class:
    	LPRICHEDITOLE	m_pRichEditOle;
    	LPOLEOBJECT	m_lpObject;
    	LPSTORAGE         m_lpStorage;
    	LPOLECLIENTSITE	m_lpClientSite;
    					
    NOTE: Set these variables to NULL in your constructor. You must include the header file Richole.h for the definition of the type LPRICHEDITOLE.

  5. Get the IRichEditOLE interface early on in your program (in OnInitDialog or OnInitialUpdate) and keep it available. For the RichText control, use the following method:
    	::SendMessage(m_ctlRichText.m_hWnd, EM_GETOLEINTERFACE, 0, (LPARAM)&m_pRichEditOle);
          ASSERT(m_pRichEditOle != NULL); 
    					
  6. 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 = TYMED_NULL;
    
    	// attempt to create the object
    	m_pRichEditOle->GetClientSite(&m_lpClientSite);
    
    	sc = ::OleCreateFromFile(clsid, T2COLE(lpszFileName),
    		IID_IUnknown, OLERENDER_DRAW, 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;
    }
    
    					
  7. 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.
  8. 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;
    					
  9. 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 = m_ctlRichText.m_hWnd;
    	::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);
    					
  10. Call InsertObject but add a carriage return first as in the following sample:
    	CString strCr = "\r\n";
    	m_ctlRichText. ReplaceSel(strCr,TRUE); 
    					
    Finally!
    	m_pRichEditOle->InsertObject(&reobject);
    					
  11. 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);
    					

  12. 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;
    	}
    					
  13. Finally, release m_pRichEditOle.

Properties

Article ID: 220844 - Last Review: November 21, 2006 - Revision: 3.1
APPLIES TO
  • Microsoft Foundation Class Library 4.2, when used with:
    • Microsoft Visual C++ 6.0 Enterprise Edition
    • Microsoft Visual C++ 6.0 Professional Edition
    • Microsoft Visual C++, 32-bit Learning Edition 6.0
Keywords: 
kbhowto kbinfo kbrichedit kbbitmap kbctrl KB220844

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