C / C++ / MFC

31-Mar-10 7:32

I am creating thread using AfxBeginThread in Visual Studio 2005 and the first parameter of this function is function pointer so i am passing member function pointer of that class but it gives error i.e.

my code is:

AfxBeginThread( &CMultithreadingInDialogDlg::MyThreadProc, GetSafeHwnd() );

in which MyThreadProc is member function. and the error is

error C2665: 'AfxBeginThread' : none of the 2 overloads could convert all the argument types.

but it is working if i am passing function pointer of any static function or global function

thanks in advance.

David Crow31-Mar-10 7:53

31-Mar-10 7:53

Is MyThreadProc() a static member of CMultithreadingInDialogDlg?

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kartikthakre1-Apr-10 7:19

1-Apr-10 7:19

MyThreadProc is not a static function, it is simple member function.

David Crow1-Apr-10 7:48

Re: Multithreading using AfxBeginThread [modified]

1-Apr-10 7:48

Which means it cannot be used an argument to AfxBeginThread().

Eugen Podsypalnikov31-Mar-10 19:58

31-Mar-10 19:58

kartikthakre wrote:
but it is working if i am passing function pointer of any static function or global function

That is also the "classical" way
to pass - for example - a private static function of a dialog... Smile | :)

// .h
...
class CYourDialog : public CDialog
{
  bool          m_bWorking;
  CWinThread*   m_pcThread;
  static DWORD WINAPI  ThreadProc(CYourDialog*);
...
public:
  CYourDialog(CWnd* pcParent = NULL);
  ~CYourDialog();
...
  void On();
  void Off();
...
};
// .cpp
...
CYourDialog::CYourDialog(CWnd* pcParent /*= NULL*/)
  : CDialog(CYourDialog::IDD, pcParent),
    m_bWorking(false),
    m_pcThread(NULL)
{
...
}
CYourDialog::~CYourDialog()
{
  Off();
}
CYourDialog::On()
{
  if (!m_bWorking && !m_pcThread) {
    m_bWorking = true;
    m_pcThread = AfxBeginThread(ThreadProc, this);
  }
}
CYourDialog::Off()
{
  if (m_bWorking && m_pcThread) {
    m_bWorking = false;
    WaitForSingleObject(m_pcThread->m_hThread, INFINITE);
    m_pcThread = NULL;
  }
}
DWORD WINAPI CYourDialog::ThreadProc(CYourDialog* pcDlg)
{
  while (pcDlg && pcDlg->m_bWorking) {
    // Do something
    Sleep(1);
  }
  return 0;
}

virtual void BeHappy() = 0;

modified on Thursday, April 1, 2010 2:42 AM

Roger Stoltz31-Mar-10 21:54

Roger Stoltz

31-Mar-10 21:54

Perhaps it's just a typo, but if not you should be aware of the following:

There's a big risk the thread will never exit as you've failed to declare the m_bWorking variable as volatile.
It depends on your optimization settings.

The compiler may choose to hold the variable in a register in the while-loop, not reading it from its actual memory location since it's not being modified in the while-loop.
Declaring it as volatile will tell the compiler that the variable must be read from its memory location and cannot be optimized into a register.

"It's supposed to be hard, otherwise anybody could do it!" - selfquote
"High speed never compensates for wrong direction!" - unknown

Eugen Podsypalnikov31-Mar-10 22:03

31-Mar-10 22:03

Wow, I did not know it !
Thank you very much, Roger ! Smile | :)

As possible "workaround"
could be also the usage of a limitation function:

bool CYourDialog::IsWorking() {
  return m_bWorking;
}

virtual void BeHappy() = 0;

Roger Stoltz31-Mar-10 22:23

Roger Stoltz

31-Mar-10 22:23

Eugen Podsypalnikov wrote:
Wow, I did not know it !
Thank you very much, Roger !

You're most welcome.

Eugen Podsypalnikov wrote:
As possible "workaround"
could be also the usage of a limitation function:
bool CYourDialog::IsWorking() {
  return m_bWorking;
}

Naah, I wouldn't count on that. This also depends on your optimization settings... Wink | ;)

There's a compiler switch that tells the compiler to expand "any suitable" function as inline, which would generate the same code as if you would have referenced the variable directly even though you haven't declared the function explicitly as inline. Then you would be back to square one, with the possibility that the variable could be optimized into a register.

"It's supposed to be hard, otherwise anybody could do it!" - selfquote
"High speed never compensates for wrong direction!" - unknown

Eugen Podsypalnikov31-Mar-10 22:39

31-Mar-10 22:39

Yes, saved... Smile | :)

Thank you - for the both explanations, Roger !

virtual void BeHappy() = 0;

David Crow1-Apr-10 5:30

1-Apr-10 5:30

Eugen Podsypalnikov wrote:
DWORD WINAPI CYourDialog::ThreadProc(CYourDialog* pcDlg)

Shouldn't this be:

UINT CYourDialog::ThreadProc( LPVOID pcDlg )

Eugen Podsypalnikov1-Apr-10 5:39

1-Apr-10 5:39

Yes, of course Smile | :)

You could use my declaration too
and pass it by the casting (AFX_THREADPROC) ,
so you can use its parameter pcDlg without casting... Smile | :)

virtual void BeHappy() = 0;

kartikthakre1-Apr-10 7:17

1-Apr-10 7:17

Thanks for reply,

But i already written that it is working for static and global function.
What i want is that it is work for member function.

I am waiting for reply

thanks

David Crow1-Apr-10 7:53

1-Apr-10 7:53

kartikthakre wrote:
What i want is that it is work for member function.

You can't do it directly. What you'll have to do is:

void CMyDlg::ThreadProc( void )
{
    ...
}
  
UINT ThreadProc( LPVOID lpParam )
{
    CMyDlg *pDlg = (CMyDlg *) lpParam;
     
    pDlg->ThreadProc();
  
    return 0;
}
  
static UINT CMyDlg::ThreadProc( LPVOID lpParam )
{
    CMyDlg *pDlg = (CMyDlg *) lpParam;
     
    pDlg->ThreadProc();
  
    return 0;
}
   
AfxBeginThread(ThreadProc, this);   // static member
AfxBeginThread(::ThreadProc, this); // global

kartikthakre2-Apr-10 3:54

How to extract the bitmap (HBITMAP) from a BITMAPINFOHEADER variable?

2-Apr-10 3:54

but what is the region, so that member function pointer is not pass to AfxBeginThread.

bioan31-Mar-10 7:10

Re: How to extract the bitmap (HBITMAP) from a BITMAPINFOHEADER variable?

31-Mar-10 7:10

Hello all!

I have a BITMAPINFOHEADER variable and I try to get HBitmap from it.

I have study MSDN documentation and found that BITMAPINFOHEADER variable must be converted to BITMAPINFO and after use CreateDIBSection(...) function like the summary below:

BITMAPINFO*pInfo;

void *pBuffer;
HBITMAP hBitmap;

if ((hBitmap = CreateDIBSection(NULL, pInfo, DIB_RGB_COLORS, &pBuffer, 0, 0)) != NULL)
{
...
}

My problem is that I do not understand very clear how to convert BITMAPINFOHEADER to BITMAPINFO.

According to the same MSDN I know that BITMAPINFO is a structure that contain the initial BITMAPINFOHEADER, my problem is that I do not underatand how to indicate extra RGBQUAD bmiColors[1] as the declaration below:
typedef struct tagBITMAPINFO {
BITMAPINFOHEADER bmiHeader;
RGBQUAD bmiColors[1];
} BITMAPINFO;

Any idea?

C^hris L^osinger31-Mar-10 7:31

31-Mar-10 7:31

Ionut Codrut wrote:
My problem is that I do not understand very clear how to convert BITMAPINFOHEADER to BITMAPINFO.

just cast it.

BITMAPINFO *pBMI = (BITMAPINFO *)pBitmapInfoHeader;

Re: How to extract the bitmap (HBITMAP) from a BITMAPINFOHEADER variable?

bioan31-Mar-10 7:58

Re: How to extract the bitmap (HBITMAP) from a BITMAPINFOHEADER variable?

31-Mar-10 7:58

Thank you Chris for your response!
I try to cast directly as you suggest, but all I've got is just a blank image (so I think the approach is an error)

Acordingly to MSDN http://msdn.microsoft.com/en-us/library/dd318229%28VS.85%29.aspx[^] If you cast the BITMAPINFOHEADER to a BITMAPINFO, the bmiHeader member refers to the BITMAPINFOHEADER and the bmiColors member refers to the first entry in the color table, or the first color mask.

Be aware that if the bitmap uses a color table or color masks, then the size of the entire format structure (the BITMAPINFOHEADER plus the color information) is not equal to sizeof(BITMAPINFOHEADER) or sizeof(BITMAPINFO). You must calculate the actual size for each instance....

So I think we are Close, but no cigar..

Best regards!
Ioan

C^hris L^osinger31-Mar-10 8:06

31-Mar-10 8:06

casting is correct.

but yes, it's also true that you need to find the start of the pixel data in the DIB, and that depends on the number of colors in the palette, any padding, any bitfields masks, etc..

LPBITMAPINFOHEADER      lpbi = (LPBITMAPINFOHEADER)pDIB;
HBITMAP                 hbm;
// how many colors in this DIB?
int nColors = lpbi->biClrUsed ? lpbi->biClrUsed : 
1 << lpbi->biBitCount;
	
BITMAPINFO &bmInfo = *(LPBITMAPINFO)pDIB ;
LPVOID lpDIBBits;
if( bmInfo.bmiHeader.biBitCount > 8 )
{
	lpDIBBits = (LPVOID)((UINT32 *)(bmInfo.bmiColors + 
	bmInfo.bmiHeader.biClrUsed) + 
	((bmInfo.bmiHeader.biCompression == BI_BITFIELDS) ? 3 : 0));
}
else
{
	lpDIBBits = (LPVOID)(bmInfo.bmiColors + nColors);
}

void *ppvBits = NULL;
hbm = CreateDIBSection(hDC,
		   (LPBITMAPINFO)lpbi,
		   DIB_RGB_COLORS,
		   &ppvBits,
		   NULL,
	   0);
		
// copy DIB pixels...
if (ppvBits!=NULL)
{
    memcpy((BYTE *)ppvBits, (BYTE *)lpDIBBits, bmInfo.bmiHeader.biSizeImage);
}

Re: How to extract the bitmap (HBITMAP) from a BITMAPINFOHEADER variable?

bioan31-Mar-10 8:23

Re: How to extract the bitmap (HBITMAP) from a BITMAPINFOHEADER variable?

31-Mar-10 8:23

Hello Chris!
Thank you very much for your extremely fast response!!!

//This is my starting point:
HBITMAP hbm;
BITMAPINFOHEADER *pHeader;
pHeader = (BITMAPINFOHEADER *)(myImage.bmp.begin() );
// doesn' matter myImage.bmp.begin() is coming from

I need to extract fron this pHeader a HBITMAP to put intr-o a dialog as below:

//This is my end point
m_TestBitButtonCtrl.SetBitmap(hbm);

I do not understand the followings:
1. where pDIB comes from
2. if ia necessary the last function (with copy DIB pixels) for what I need
Ioan

C^hris L^osinger31-Mar-10 8:30

31-Mar-10 8:30

pDIB is your input image. it's a pointer to a DIB, which is a device-independent bitmap: a BITMAPINFOHEADER followed by a palette, followed by the pixel data.

you need the memcpy because CreateDIBSection only allocates the memory for the DIBSection. you need to put your own pixel data into the allocated memory.

and note that a DIBSection is not a standard HBITMAP. you can use a DIBSection as if it was an HBITMAP, and it will work exactly the same as a standard HBITMAP for most uses, but it's not exactly the same thing. see the MSDN for the differences. if you need a standard HBITMAP, you can use CreateDIBitmap instead of CreateDIBSection:

hbm = CreateDIBitmap(hDC,       // handle to device context
(LPBITMAPINFOHEADER)lpbi,       // pointer to bitmap info header 
(LONG)CBM_INIT,                 // initialization flag
lpDIBBits,                      // pointer to initialization data 
(LPBITMAPINFO)lpbi,             // pointer to bitmap info
DIB_RGB_COLORS );               // color-data usage

Re: How to extract the bitmap (HBITMAP) from a BITMAPINFOHEADER variable?

bioan31-Mar-10 8:39

Re: How to extract the bitmap (HBITMAP) from a BITMAPINFOHEADER variable?

31-Mar-10 8:39

Chris, I'm a newbie to this deep API functions, all the information I've got from an external API is just this BITMAPINFOHEADER* pHeader, nothing more and I need only HBITMAP to extract from them, do not care by which method, my interest is to set a button picture with this bitmap, and that's all!

So let me understand correctly: to obtain the correct HBITMAP do I need extra info, the BITMAPINFOHEADER provideed is not sufficent?

best wishes!
Ioan

C^hris L^osinger31-Mar-10 9:08

31-Mar-10 9:08

Ionut Codrut wrote:
all the information I've got from an external API is just this BITMAPINFOHEADER* pHeader, nothing more

that's all you need.

what happens if you use the code i posted ?

Re: How to extract the bitmap (HBITMAP) from a BITMAPINFOHEADER variable?

bioan31-Mar-10 9:38

Re: How to extract the bitmap (HBITMAP) from a BITMAPINFOHEADER variable?

31-Mar-10 9:38

I have used your code as below:

BITMAPINFOHEADER *pHeader;
pHeader = (BITMAPINFOHEADER *)(odImage.bmp.begin() );
if(!pHeader)
return TRUE;
HBITMAP hbm;
// how many colors in this DIB?
int nColors = pHeader->biClrUsed ? pHeader->biClrUsed : 1 << pHeader->biBitCount;

BITMAPINFO &bmInfo = *(LPBITMAPINFO)pHeader ;// make cast from BITMAPINFOHEADER!
LPVOID lpDIBBits;
if( bmInfo.bmiHeader.biBitCount > 8 )
{
lpDIBBits = (LPVOID)((UINT32 *)(bmInfo.bmiColors +
bmInfo.bmiHeader.biClrUsed) + ((bmInfo.bmiHeader.biCompression == BI_BITFIELDS) ? 3 : 0));
}
else
{
lpDIBBits = (LPVOID)(bmInfo.bmiColors + nColors);
}

void *ppvBits = NULL;
hbm = CreateDIBSection(NULL,
(LPBITMAPINFO)pHeader,
DIB_RGB_COLORS,
&ppvBits,
NULL,
0);

m_TestBitButtonCtrl.SetBitmap(hbm);

I'm still got a black bitmap, HBITMAP is not NULL (checked with debug!).
Strange!
What I'm wrong?

Ioan

C^hris L^osinger31-Mar-10 9:46

31-Mar-10 9:46

what are the values in the BITMAPINFOHEADER struct ?