AARRRGGG! Retreive/Store image in DB - C / C++ / MFC Discussion Boards

Hi,

Take a look at

http://www.codeproject.com/com/xoffice.asp

Well, is not right just what you were looking for ( is on a View), but maybe you can somehow fake it or make something..

Good luck !
Braulio

Hi,
I have 2 threads & 2 events.In one thread i will set one event & 2nd thread will be waiting for that event.
This logic works fine if i put a messagebox in the 2nd thread,otherwise it hangs.
Any idea?

Could you post some code showing the problem? The explanation sheds little light (to my eyes) about what's going on.

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo

Ok, There is a main thread(application thread) & i have created another thread using _beginthread() function.
Also i have 2 events created as below in the main thread.

CallBackEventHandle= CreateEvent( NULL,TRUE,FALSE,NULL);
ImageEventHandle= CreateEvent( NULL,TRUE,TRUE,NULL);

In my thread function i will be waiting for ImageEventHandle event.there it hangs,but it works fine if i put a messagebox in the thread function.

could you pl help me solve this??

Sounds like you are trying to send a message to something in the secondary thread but don't have any type of message loop. Adding the message box creates a temporary message loop.

Tim Smith

I know what you're thinking punk, you're thinking did he spell check this document? Well, to tell you the truth I kinda forgot myself in all this excitement. But being this here's CodeProject, the most powerful forums in the world and would blow your head clean off, you've got to ask yourself one question, Do I feel lucky? Well do ya punk?

I do have a message loop.Adding a message box creates a temporary message loop,right.So i replaced the messagebox with a message loop,but it hangs.
Could you pl help me...

The third parameter to CreateEvent is whether the event is initially signalled. If you are trying to wait for ImageEventHandle, it won't since it's already signalled.

Joel Lucsy (jjlucsy@ameritech.net)

Anyone knows how to retreive/store an image in a MDB file? I'm using CByteArray and it does not work! I know there's an article on CP that is using CLongBinary but it does not suit my needs (it uses a tmp file, I need an HBITMAP).

HBITMAP CdbCieSet::GetLogo()
{
CByteArray Array;

Array.Copy( m_logo );

if( Array.GetSize() <= 0 )
{
return NULL;
}

// the header of BLOB is OLE stuff like "Paint Brush Application" .... ecc..
// the len is 78 byte ( I do not know for other headers )
int HeaderLen = 78 + sizeof(BITMAPFILEHEADER);
Array.RemoveAt( 0, HeaderLen ); // I cut all Headers

// some BMP information
BITMAPINFOHEADER &bmiHeader = *(LPBITMAPINFOHEADER)Array.GetData() ;
BITMAPINFO &bmInfo = *(LPBITMAPINFO)Array.GetData() ;

// If bmiHeader.biClrUsed is zero we have to infer the number
// of colors from the number of bits used to specify it.
int nColors = bmiHeader.biClrUsed ? bmiHeader.biClrUsed : 1 << bmiHeader.biBitCount;

LPVOID lpDIBBits;
if( bmInfo.bmiHeader.biBitCount > 8 )
{
lpDIBBits = (LPVOID)((LPDWORD)(bmInfo.bmiColors + bmInfo.bmiHeader.biClrUsed) +
((bmInfo.bmiHeader.biCompression == BI_BITFIELDS) ? 3 : 0));
}
else
{
lpDIBBits = (LPVOID)(bmInfo.bmiColors + nColors);
}

CClientDC dc(NULL);

HBITMAP hBmp = CreateDIBitmap( dc.m_hDC, // handle to device context
&bmiHeader, // pointer to bitmap size and format data
CBM_INIT, // initialization flag
lpDIBBits, // pointer to initialization data
&bmInfo, // pointer to bitmap color-format data
DIB_RGB_COLORS); // color-data usage

Array.RemoveAll(); //Release Memory

return hBmp;
}

BOOL CdbCieSet::SetLogo(CString szFileName)
{
CByteArray BlobFile;
CFile aFile(szFileName,CFile::modeRead);
BlobFile.SetSize(aFile.GetLength());
aFile.Read(BlobFile.GetData(),aFile.GetLength());
aFile.Close();
m_logo.Copy(BlobFile);
SetFieldDirty(&m_logo);
SetFieldNull(&m_logo,FALSE);

return TRUE;
}

Thanks!

---------------
http://www.edovia.com

nobody knows? Frown | :(

---------------
http://www.edovia.com

I want to create a DLL which will be used in an EXE. In the DLL, I want to export some simple classes, but they use MFC's CString as memebers. What kind of DLL should I create, how to export them, and import them. Should I use AFX_EXT_CLASS instead ? However, I'm planning remove MFC dependency by using some kind of CString clone in the future.

I tried use __declspec(dllexport) and __declspec(dllimport) with created the DLL as regular MFC DLL. However, in using it, in deleting the heap allocated instances, it has memory violation.

Can anyone tell me the hints ?

Use the multithreaded DLL version of the C run-time library in both the DLL and the EXE. This will ensure only one heap is used globally.

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo

I checked both the EXE and the DLL are using Debug Multithreaded DLL.

You must create a MFC Extension Dll and declare your classes with the AFX_EXT_CLASSES like this:

class AFX_EXT_CLASS CMyClass
{
....
};

Best regards,
Alexandru Savescu

hi,
how do i know when users dial-up to the internet (if success), and when they disconnect from internet ????

thanks !

lenhan

Check internet part in CP,you have to use sockrt programming codes:

http://www.codeproject.com/internet/

Mazy

"The path you tread is narrow and the drop is shear and very high,
The ravens all are watching from a vantage point near by,
Apprehension creeping like a choo-train uo your spine,
Will the tightrope reach the end;will the final cuplet rhyme?"Cymbaline-Pink Floyd

Linking...
mfcs70d.lib(stdafx.obj) : fatal error LNK1000: Internal error during Pass2
Version 7.00.9466
ExceptionCode = C0000005
ExceptionFlags = 00000000
ExceptionAddress = 1031C9BE (10300000) "C:\Program Files\Microsoft Visual Studio .NET\Common7\ide\mspdb70.dll"
NumberParameters = 00000002
ExceptionInformation[ 0] = 00000000
ExceptionInformation[ 1] = 42306940
CONTEXT:
Eax = 10002F4A Esp = 0012E940
Ebx = 10003F4A Ebp = 0012EA7C
Ecx = 023EFEF0 Esi = 02257090
Edx = 022FAC18 Edi = 023EFEEC
Eip = 1031C9BE EFlags = 00010202
SegCs = 0000001B SegDs = 00000023
SegSs = 00000023 SegEs = 00000023
SegFs = 00000038 SegGs = 00000000
Dr0 = 0012E940 Dr3 = 10003F4A
Dr1 = 0012EA7C Dr6 = 023EFEF0

I just suddenly started getting this. It is happening in multiple projects.... not *all*. Is that a MFC dll? One common thread seems to be that all the ones that won't compile use MFC.

The debug version is the only one that gives this error. Release works fine...

Any ideas??

Thanks

Adam Clauss
cabadam@tamu.edu

I just suddenly started getting this. It is happening in multiple projects.... not *all*. Is that a MFC dll?

Ehh, "foo"? No, it's an error (a terminal bug) in the linker.

Reading the MS NG microsoft.public.dotnet.languages.vc I can only come to the conclusion that this release should never have happened. It contains so many (terminal) bugs that it's apparent their so-called QA was on vacation this year also.

For a more authorative answer you should try to post this to that NG (and watch the "maybe fixed in the next version" comment you'll get from MS).

++luck;

/Mike

Did post it there last night, about the same time I posted here. Haven't got an answer there yet.

Adam Clauss
cabadam@tamu.edu

Yup, you have hit an internal bug in the linker. Try a rebuild all.

That MSPDB70.DLL is probably a common DLL they use to support the .PDB debug files.

Tim Smith

I know what you're thinking punk, you're thinking did he spell check this document? Well, to tell you the truth I kinda forgot myself in all this excitement. But being this here's CodeProject, the most powerful forums in the world and would blow your head clean off, you've got to ask yourself one question, Do I feel lucky? Well do ya punk?

Did a full rebuild, made no difference. Still fails in the linking Frown | :(

Adam Clauss
cabadam@tamu.edu

I do some draw action:

void CMyView::OnPaint()
{
CPaintDC dc(this); // device context for painting

if( m_bDraw == FALSE )
return;
/**/
CDC* pDC = GetDC();
CDC cacheDC;
VERIFY( cacheDC.CreateCompatibleDC( pDC ));

if( m_pBitmap == NULL )
{
m_pBitmap = new CBitmap;
VERIFY( m_pBitmap->CreateCompatibleBitmap( pDC, m_ClientRect.Width(), m_ClientRect.Height() ) );
}

CBitmap* pOldBmp = cacheDC.SelectObject( m_pBitmap );

//Draw background
CRect rect( m_ClientRect );
cacheDC.FillSolidRect( &rect, RGB(255, 255, 255) );
//cacheDC.Rectangle( rect );
cacheDC.Draw3dRect( &rect, RGB( 0, 0, 0 ), RGB( 255, 255, 255 ) );

//!! Some draw actions here, use cacheDC

pDC->BitBlt( m_ClientRect.left,
m_ClientRect.top,
m_ClientRect.Width(),
m_ClientRect.Height(),
&cacheDC, 0, 0, SRCCOPY );

cacheDC.SelectObject( pOldBmp );
cacheDC.DeleteDC();

}

When I open tha "TaskManager", I notice that the memory usage of My app is increase, what's wrong with my draw method? Confused | :confused:

I'm amumu, and you?

You are not deleting your m_pBitmap after you are done with it. Your code should look like this:

cacheDC.SelectObject( pOldBmp );
cacheDC.DeleteDC();

m_pBitmap->DeleteObject();

1.I have tried your method, Now, if I send the WM_PAINT to view on mouse click, it seems no effect, but if I delete the clause, it can work properly.

2.If you choose a new object for CDC, for example CPen, CBrush, etc, must you do the DeleteObject() on exit?

3.If I use the this->GetDC() to draw directly, does it cause memory leak or allocated but not freed? I notice the memory is increasing when use the view's CDC directly.

I'm amumu, and you?

qf0421 wrote:
1.I have tried your method, Now, if I send the WM_PAINT to view on mouse click, it seems no effect, but if I delete the clause, it can work properly.

Do not send a WM_PAINT message directly, instead do either one of these two things to force a repaint.

//choice 1
InvalidateRect(hWnd, NULL, TRUE);
UpdateWindow(hWnd);


//choice 2
RedrawWindow(hWnd, NULL, NULL, RDW_ERASE | RDW_INVALIDATE | RDW_UPDATENOW);

qf0421 wrote:
2.If you choose a new object for CDC, for example CPen, CBrush, etc, must you do the DeleteObject() on exit?

Yes, if you create a new brush, pen, palette or bitmap, you must select the original GDI Object back into the DC, and then delete your GDI Object that you allocated.

qf0421 wrote:
3.If I use the this->GetDC() to draw directly, does it cause memory leak or allocated but not freed? I notice the memory is increasing when use the view's CDC directly.

You should not call GetDC from inside of your paint handler. You should use BeginPaint, or the CPaintDC (Which internally calls BeginPaint). Then when you are done with a DC you need to release the DC, otherwise it will use up system resources. If you call BeginPaint to get the DC, then you will need to call EndPaint to release the Dc. If you call GetDC, GetWindowDC, or GetDCEx then you will need to call ReleaseDC to free the DC resource.

Thank you for your help and code, I have got it Smile | :)

I'm amumu, and you?