C / C++ / MFC

When timeSetEvent() start?

26-Jun-13 9:12

Yes, that's fine. Probably you want to do that just in the debug build.

Veni, vidi, vici.

econy25-Jun-13 8:00

Re: When timeSetEvent() start?

25-Jun-13 8:00

According to MSDN, timeSetEvent() run in its own thread, then call timeSetEvent(), when the callback of the timeSetEvent be invoked is undetermined, not like system.threading.timer(), it has a due time to start. right?

David Crow25-Jun-13 9:56

David Crow

25-Jun-13 9:56

econy wrote:
...the callback of the timeSetEvent be invoked is undetermined...

The callback function is called once upon expiration of a single event, or periodically upon expiration of periodic events. That sounds deterministic to me.

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Re: When timeSetEvent() start?

econy25-Jun-13 10:29

Re: When timeSetEvent() start?

25-Jun-13 10:29

I mean, when is it start to count in a new thread?
OS decide which thread to start, right?

David Crow25-Jun-13 10:31

David Crow

25-Jun-13 10:31

econy wrote:
I mean, when is it start to count in a new thread?

When timeSetEvent() returns, I presume.

Convertin from c++ 6 to Visual studio C++ 10

mamoony25-Jun-13 7:41

25-Jun-13 7:41

Hi I am new in c++. Recently I am converting a C++ project to Visual Studio 10 c++ . I am getting an error.

error C2664: 'std::_Vector_iterator<_Myvec>::_Vector_iterator(const std::_Vector_iterator<_Myvec> &)' : cannot convert parameter 1 from 'int' to 'const std::_Vector_iterator<_Myvec> &'

The code is:

XNodes::iterator _tagXMLNode::GetChildIterator( LPXNode node )
{
    XNodes::iterator it = childs.begin();
    for( ; it != childs.end() ; ++(it) )
    {
        if( *it == node )
            return it;
    }
    return NULL;     //error is in here
}

How to fix it?

Thanks in advance,
Sai

CPallini25-Jun-13 8:43

25-Jun-13 8:43

Change from

Quote:
return NULL; //error is in here

C++

return it;

Veni, vidi, vici.

mamoony25-Jun-13 9:01

25-Jun-13 9:01

Hi,

Thanks.

But the logic of the code is if the node matches wuth it then return it else return nothing.

Thanks,
Saimanti

CPallini25-Jun-13 9:09

25-Jun-13 9:09

The 'return it' I suggested returns childs.end() that is the past-the-end iterator (a 'typed' NULL, roughly speaking).

Veni, vidi, vici.

mamoony25-Jun-13 9:41

25-Jun-13 9:41

Thank you. It worked. But now it is giving another error..

error C2451: conditional expression of type 'std::_Vector_iterator<_Myvec>' is illegal

The code below:

bool _tagXMLNode::RemoveChild( LPXNode node )
{
    XNodes::iterator it = GetChildIterator( node );
    if( it )  //error is here
    {
        delete *it;
        childs.erase( it );
        return true;
    }
    return false;
}

Thank in advance,
Saimanti

mamoony25-Jun-13 9:42

25-Jun-13 9:42

I did..

bool _tagXMLNode::RemoveChild( LPXNode node )
{
    XNodes::iterator it = GetChildIterator( node );
    if( it != childs.end())
    {
        delete *it;
        childs.erase( it );
        return true;
    }
    return false;
}

Is this right?

Thanks,
Saimanti

CPallini25-Jun-13 9:53

25-Jun-13 9:53

It should be correct.

Veni, vidi, vici.

mamoony25-Jun-13 9:54

25-Jun-13 9:54

Thank you very much...

Saimanti

JackDingler26-Jun-13 11:37

JackDingler

26-Jun-13 11:37

C++

bool _tagXMLNode::RemoveChild( LPXNode node )
{
    XNodes::iterator it = GetChildIterator( node );
    if( it != childs.end() )  // Fixed it
    {
        delete *it;
        childs.erase( it );
        return true;
    }
    return false;
}

timeSetEvent() question

econy25-Jun-13 6:45

Re: timeSetEvent() question

25-Jun-13 6:45

is this funtion create an event in a asynchronized way? i.e use a background thread?

if I use a timeSetEvent() in a call back function:

void CALLBACK TimerProc1( UINT uID, UINT uMsg, DWORD dwUser, DWORD dw1, DWORD dw2 ) {
 read bus data;
 if (data == true) then
  timeSetEvent( 5, 1, TimerProc3, 0, TIME_ONESHOT ) ;
}

No timeKillEvent(), then is that means the code will create many events in many threads, right? that is , no release resource.

econy25-Jun-13 6:58

Variable synchronization question

25-Jun-13 6:58

if I use same parameters in a timeSetEvent(), then call timeSetEvent() twice, is that mean I created 2 different events?

or Sencond call reset the timer?

econy25-Jun-13 5:19

Re: Variable synchronization question

25-Jun-13 5:19

I have an application, there are 2 loops, one is message loop, one is a timeSetEvent() loop.

There is a global variable in both loops.

Now I meet a problem about redraw the screen. The situation like:

wndProc (UINT message, WPARAM wParam, LPARAM lPara)
{
 if (GetTickCount() - GVarTck > 4000) then 
  redraw screen;
  
  switch (message) { handle message;}

}
///////////////////////

OnPaint() {
 if (g_timeEvent == 0)
   timeSetEvent(50, 5, RefreshScreen,0, TIME_ONESHOT)


}

void CALLBACK RefreshScreen()
{
   do Refresh thing;
   GVarTikc = GetTickCount();
   timeSetEvent(50, 5, RefreshScreen,0, TIME_ONESHOT)
   //With GetTickCount() meassured, the time of refreshScreen() is
   // about 20 ms.
}

Richard MacCutchan25-Jun-13 6:06

Richard MacCutchan

25-Jun-13 6:06

Why do you need to use a timer to decide when to redraw the screen? You should do it in response to a WM_PAINT message, and you can force a repaint by calling the InvalidateRect() function.

Use the best guess

Cycle of Message loop

econy25-Jun-13 4:59

Re: Cycle of Message loop

25-Jun-13 4:59

Hi, I wonder how much is the cycle of message loop.

I looked through some articles in MSDN, but no articles gave an explain about how much time one cycle message loop needs.

Is the message loop depends on hardware, or OS decide it? and if I have a timer event in my program, then is the message loop has higher priority?

jeron125-Jun-13 5:24

jeron1

25-Jun-13 5:24

econy wrote:
Is the message loop depends on hardware, or OS decide it?

Both I'd immagine. Seems like the answer would be non-deterministic, I'm no expert but Windows being a non real-time OS could and will preempt your program and your message pump for some undetermined time.
Maybe you could get some info using this[^]

econy wrote:
timer event in my program, then is the message loop has higher priority?

Not normally see here.[^]

Re: Cycle of Message loop

dusty_dex25-Jun-13 5:25

dusty_dex

25-Jun-13 5:25

econy wrote:
Hi, I wonder how much is the cycle of message loop.

Approximately 100 messages per second.

Moire effect

_Flaviu24-Jun-13 21:18

_Flaviu

24-Jun-13 21:18

Does anyone meet the sitation when a image with many horizontal lines, with low levels zoom (when image is fit to window), is seen with moire effect ? And the drawing is made in classic way:

C++

...
pDC->SetStretchBltMode(COLORONCOLOR);
pDC->StretchBlt(xDst, yDst, nDstWidth, nDstHeight, pMemDC, xSrc, ySrc, nSrcWidth, nSrcHeight, SRCCOPY);
...

I had tried with stretch mode HALFTONE, with the same results ...

After all, I dind't know where the problem come ... (P.S. I draw with GDI).

Re: Moire effect

CPallini24-Jun-13 21:36