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01.31.2008 at 01:15PM PST, ID: 23127879
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Memory Leaks found in an MFC / COM / GDI application (HTML thumbnail image capture class)

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7.0
Zones:

Windows ATL / WTL / COM Programming, C++ Programming Language, Windows MFC Programming

Tags:

C++, MFC, COM, Detected memory leaks!, SelectObject DeleteObject MFC COM C++ GDI HDC CDC DeleteDC GetDC ReleaseDC
Hi, I'm new to Experts-Exchange and this would be my first question.  Thanks in advance, please let me know if the format of my question can be improved to make it easier for the experts :)

I am a beginner in using MFC and COM and I am following up on a windows application.  One of the features is to be able to generate an image from a URL.  I have included the code of the function in the thumbnail capture class (CCreateHTMLImage).  (The original source for this code can be found at http://www.codeproject.com/KB/IP/htmlimagecapture.aspx - I have modified the CreateImage function, integrating with IECapt's SaveSnapShot method found here http://iecapt.sourceforge.net/ ).

When the user chooses to generate a thumbnail capture of a webpage, the application will do the following routine inside a CView derived class:
m_pHTMLImage is a pointer set to NULL initially

            if(m_pHTMLImage == NULL) {
                  OutputDebugString("Initializing m_pHTMLImage\n");
                  m_pHTMLImage = new CCreateHTMLImage();
                  m_pHTMLImage->Create(this);
            }

            if(!m_pHTMLImage -> CreateImage(_T("http://")+URL, AppDirectory + _T("\\temp.jpg"), CSize(1024, 768), CSize(360,300)))
                  return;

            It will then call a function LoadPic(AppDirectory + _T("\\temp.jpg"));

LoadPic(CString PicPath)
{
      CFile file;
      if(!file.Open(PicPath, CFile::modeRead|CFile::shareDenyWrite|CFile::typeBinary))
            return FALSE;
      if(m_dwPicLen != 0)
            delete[] m_BPicData; //if pic already exists, clear and load new data
      m_dwPicLen = (DWORD)(file.GetLength());                                                
      if(!m_Pic.Load(file.GetFilePath()))
            return FALSE;
      m_bIsPic = TRUE; //set display mode to pic
      m_BPicData = new BYTE[m_dwPicLen];
      file.Read(m_BPicData, m_dwPicLen);
      file.Close();
      return TRUE;
}

the memory usage jumps from ~10,000K to ~100,000K, should it be using this much memory?
subsequent calls to this routine of generating an image will raise mem usage by ~10,000K
I only create one instance of CCreateHTMLImage and will do the following routine when the application closes in the CView class' destructor

      if(m_pHTMLImage) {  
            m_pHTMLImage->DestroyWindow();  
            delete m_pHTMLImage;  // EL
            m_pHTMLImage = NULL;  
      }

Are there any problems regarding the Allocation and Release of Interfaces or in Getting and Releasing/Deleting DCs in the CreateImage Function? would i have to delete or release hdcMain?

I have used PurifyPlus and I have attached the results as images.
The leaks seem to come from DLLs, does it mean that it is not related to the classes I am working on?

More recent debug results are from boundschecker.

I am also getting many many of the following errors when i generate a thumbnail
First-chance exception at 0x30195840 in czWeb.exe: 0x80000001: Not implemented.
First-chance exception at 0x30195196 in czWeb.exe: 0x80000001: Not implemented.
Any idea what could generate these errors ?

Any help would be greatly appreciated.  Please let me know if anything was unclear or if you need more information

Thanks
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BOOL CCreateHTMLImage::CreateImage(LPCTSTR szSrcFilename, LPCTSTR szDestFilename, CSize srcSize, CSize outputSize)
{
	USES_CONVERSION;
	ASSERT(GetSafeHwnd());
	ASSERT(IsWindow(GetSafeHwnd()));
	ASSERT(szSrcFilename);
	ASSERT(AfxIsValidString(szSrcFilename));
	ASSERT(szDestFilename);
	ASSERT(AfxIsValidString(szDestFilename));
 
	CRect rect(CPoint(0, 0), srcSize);
 
	//	The WebBrowswer window size must be set to our srcSize
	//	else it won't render everything
	MoveWindow(&rect);
	m_pBrowserWnd.MoveWindow(&rect);
 
	COleVariant	  vUrl(szSrcFilename, VT_BSTR),
				  vFlags(long(navNoHistory | navNoReadFromCache | navNoWriteToCache), VT_I4),
				  vNull(LPCTSTR(NULL), VT_BSTR);
	COleSafeArray vPostData;
 
	if (m_pBrowser->Navigate2(&vUrl, &vFlags, &vNull, &vPostData, &vNull) == S_OK)
		//	We have to pump messages to ensure the event handler (DocumentComplete)
		//	is called.
		RunModalLoop();
	else
		return FALSE;
 
//	We only get here when DocumentComplete has been called, which calls EndModalLoop
	//	and causes RunModalLoop to exit.
 
 
	IHTMLDocument3* pDocument3 = NULL;
        IHTMLDocument2* pDocument  = NULL;
        IHTMLElement2* pElement2   = NULL;
        IHTMLElement* pElement     = NULL;
        IViewObject2* pViewObject  = NULL;
        IDispatch* pDispatch       = NULL;
        //IDispatch* pWebBrowserDisp = NULL;
 
        HRESULT hr;
        long bodyHeight;
        long bodyWidth;
        long rootHeight;
        long rootWidth;
        long height;
        long width;
 
        hr = m_pBrowser->get_Document(&pDispatch);
		if (hr == S_OK) {  // Need to release pDispatch
 
			hr = pDispatch->QueryInterface(IID_IHTMLDocument2, (void**) &pDocument);
			if (hr == S_OK) {  // Need to release pDocument
 
				hr = pDocument->get_body(&pElement);
				if (hr == S_OK) {  // Need to release pElement
 
					hr = pElement->QueryInterface(IID_IHTMLElement2, (void**) &pElement2);
					if (hr == S_OK) {  // Need to release pElement2
 
						hr = pElement2->get_scrollHeight(&bodyHeight);
						if (FAILED(hr))
							return true;
 
						hr = pElement2->get_scrollWidth(&bodyWidth);
						if (FAILED(hr))
							return true;
 
						pElement2->Release();
					}
					pElement->Release();
				}
				pDocument->Release();
			}
 
			hr = pDispatch->QueryInterface(IID_IHTMLDocument3, (void**) &pDocument3);
			if (hr == S_OK) {  // Need to release pDocument3
 
				hr = pDocument3->get_documentElement(&pElement);
				if (hr == S_OK) {  // Need to release pElement
 
					hr = pElement->QueryInterface(IID_IHTMLElement2, (void**) &pElement2);
					if (hr == S_OK) {  // Need to release pElement2
 
						hr = pElement2->get_scrollHeight(&rootHeight);
						if (FAILED(hr))
							return true;
 
						hr = pElement2->get_scrollWidth(&rootWidth);
						if (FAILED(hr))
							return true;
						pElement2->Release();
					}
					pElement->Release();
				}
				pDocument3->Release();
			}
 
 
			width = bodyWidth;
			height = rootHeight > bodyHeight ? rootHeight : bodyHeight;
 
			MoveWindow(0, 0, width, height, TRUE);      
			::MoveWindow(m_pBrowserWnd.GetSafeHwnd(), 0, 0, width, height, TRUE);
 
			hr = m_pBrowser->QueryInterface(IID_IViewObject2, (void**) &pViewObject);
			if (hr == S_OK) {  // Need to release pViewObject
				BITMAPINFOHEADER bih;
				BITMAPINFO bi;
				RGBQUAD rgbquad;
 
				ZeroMemory(&bih, sizeof(BITMAPINFOHEADER));
				ZeroMemory(&rgbquad, sizeof(RGBQUAD));
 
				bih.biSize          = sizeof(BITMAPINFOHEADER);
				bih.biWidth         = width;
				bih.biHeight        = height;
				bih.biPlanes        = 1;
				bih.biBitCount      = 24;
				bih.biClrUsed       = 0;
				bih.biSizeImage     = 0;
				bih.biCompression   = BI_RGB;
				bih.biXPelsPerMeter = 0;
				bih.biYPelsPerMeter = 0;
 
				bi.bmiHeader = bih;
				bi.bmiColors[0] = rgbquad;
 
				CDC* dc = GetDC();
				HDC hdcMain = *dc;
 
				if (!hdcMain)
					return true;
 
				HDC hdcMem = CreateCompatibleDC(hdcMain);
 
				if (!hdcMem)
					return true;
 
				char* bitmapData = NULL;
				HBITMAP hBitmap = CreateDIBSection(hdcMain, &bi, DIB_RGB_COLORS, (void**)&bitmapData, NULL, 0);
 
				if (!hBitmap) {
					// TODO: cleanup
					return true;
				}
 
				// Save original bitmap, note this is needed to be reselected to preven GDI resource leak // EL
				HGDIOBJ oldHBitmap = GetCurrentObject(hdcMem, OBJ_BITMAP);
				if(oldHBitmap == NULL) {
					OutputDebugString("GetCurrentObj failed\n");
					return true;
				}
 
				SelectObject(hdcMem, hBitmap);
 
				RECTL rcBounds = { 0, 0, width, height };
				hr = pViewObject->Draw(DVASPECT_CONTENT, -1, NULL, NULL, hdcMain, hdcMem, &rcBounds, NULL, NULL, 0);
				if (SUCCEEDED(hr)) {
					CImage image;
					image.Create(outputSize.cx, outputSize.cy, 24);
					CImageDC imageDC(image);
					::StretchBlt(imageDC, 0, 0, outputSize.cx, outputSize.cy, hdcMem, 0, 0, width, height, SRCCOPY);
					//::BitBlt(imageDC, 0, 0, width, height, hdcMem, 0, 0, SRCCOPY);
					image.Save(szDestFilename);
				}
				
				SelectObject(hdcMem, oldHBitmap);
				DeleteObject(hBitmap);
				DeleteDC(hdcMem);
				//DeleteDC(hdcMain);
				ReleaseDC(dc);
				pViewObject->Release();
			}
			pDispatch->Release();
		}
		return true;
 
}
Attachments:
 
bcsummary.jpg (74 KB) (File Type Details) 
Summary of results from BoundsChecker
Summary of results from BoundsChecker
 
 
bc1.jpg (134 KB) (File Type Details) 
BC - Memory Leaks
BC - Memory Leaks
 
 
bc2.jpg (264 KB) (File Type Details) 
BC - Other Leaks
BC - Other Leaks
 
 
bc3.jpg (60 KB) (File Type Details) 
BC - Errors
BC - Errors
 
 
purify2.jpg (472 KB) (File Type Details) 
PurifyPlus Results, Memory leak information 1
PurifyPlus Results, Memory leak information 1
 
 
purify3.jpg (446 KB) (File Type Details) 
PurifyPlus Results, Memory leak information 2
PurifyPlus Results, Memory leak information 2
 
 
purify4.jpg (463 KB) (File Type Details) 
PurifyPlus Results, Memory leak information 3
PurifyPlus Results, Memory leak information 3
 
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Answered By: jkr
Expert Since: 09/21/1998
Accepted Solutions: 11959
Computer Expertise: Beginner
jkr has been an Expert for 10 years 3 months, during which he has posted 45602 comments and answered 11959 questions. jkr is just one of 148 experts in the Windows ATL / WTL / COM Programming Zone. 2 experts collaborated on this answer, which was graded an "A" by the asker.
 
 
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