C / C++ / MFC

Re: How can I ensure that a drive is spinning and ready to write data?

2-Jul-07 15:07

TragicComic wrote:
...if I start to write while the drive is idle, I lose a significant number of initial video frames.

I would be more concerned with data loss than I would with drive speed/idling. Think about it -- even if the data to be written was not very much, if you happened to write to the HD when it was not spinning and it lost that data, you've got much bigger problems.

"A good athlete is the result of a good and worthy opponent." - David Crow

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

Stephen Hewitt2-Jul-07 15:08

Stephen Hewitt

2-Jul-07 15:08

Put your ear on it.....

Steve

Re: How can I ensure that a drive is spinning and ready to write data?

Nuxser2-Jul-07 22:19

Nuxser

2-Jul-07 22:19

This is more about Power Management than Disk Management.

So (assuming that the disk doesn't have inbuilt smartness to act on power management and completely relies on OS for power mgt),

1. You could set the power management policy in windows (Control Panel!!!) so that it doesn't put the HD in sleep. This doesn't require coding but than needs human intervention in every PC where you run your app.

2. Play with power management API ( SetSystemPowerState(..) or alike) so that your app can notify the OS to not step in and do power management. Don't forget to revert system state on application exit (if required).

But must say, above are from my concept rather than any real work relating to such situation. But I know for sure that there exists some API where a app can tell OS to not kick in power mgnt policy.

string help

dellthinker2-Jul-07 10:52

dellthinker

2-Jul-07 10:52

Hi all, im having trouble with the following code:

<br />
void read(void){<br />
	const int buffer4=900;<br />
	char buffer[BUFSIZ]={'\0'};<br />
	char sysfolder4[buffer4];<br />
	ifstream file;<br />
	ExpandEnvironmentStrings("%systemroot%\\file.txt", sysfolder4, buffer4);<br />
	file.open(sysfolder4, ios::in);<br />
	if(file.fail()){<br />
		msg = "PRIVMSG " + chan1 + " file is not detected..\n";<br />
		SendToServer(msg.c_str());<br />
	}<br />
	else{<br />
		msg = "PRIVMSG " + chan1 + " Listing file..\n";<br />
		SendToServer(msg.c_str());<br />
		while(file.getline(buffer, BUFSIZ)){<br />
		Sleep(500);<br />
		msg = "\r\nPRIVMSG " + chan1 + " :" + buffer;  // ***<br />
		SendToServer(msg.c_str());<br />
		}<br />
		file.close();<br />
		msg = "\nPRIVMSG " + chan1 + " :End of file.";<br />
		SendToServer(msg.c_str());<br />
	}<br />
}<br />

Its suppose to read a file, and close when its done reading the file. However it reads the file, and finishes at the very last line, but stops until another command is entered and prints something un-wanted.

Here's what i'd like to happen.
<quote>
[master] list sample
[ client ] sample random text file.
[ client ] test file reading.
[ client ] read.
[ client ] End of file.

And here's what happens instead.

<quote>
[master] list sample
[ client ] sample random text file.
[ client ] test file reading.
[ client ] read.
[ master ] test
[ client ] End of file.PRIVMSG #chan :This is only a test

Can anyone tell me what could be wrong?? I've tried escape characters but they dont seem to do much, what could be wrong with the string buffer? Any help would be appreciated, thanx in advance!

Re: string help

_anil_2-Jul-07 14:30

_anil_

2-Jul-07 14:30

in side the while loop put an if statement to break the loop.
the if statement should come before sending to server. in your case before Sleep
like
if( eof() )
{
break;
}

Regards
Anil

How to declare a variable of type CRITICAL_SECTION

zipliu2-Jul-07 10:18

zipliu

2-Jul-07 10:18

Hi there,

I has a variable that needs to be accessed by multiple threads. To avoid multiple accesses by different threads at the same time, I want to use EnterCriticalSection to enable the exclusive access. However, MSDN instructs that "The process is responsible for allocating the memory used by a critical section object, which it can do by declaring a variable of type CRITICAL_SECTION." I wonder how I should declare a critical section object.

Thanks a lot,

zipliu

Re: How to declare a variable of type CRITICAL_SECTION

zipliu2-Jul-07 10:19

zipliu

2-Jul-07 10:19

I mean, for example, I want to make a integer to be a critial section object. Thanks.

Re: How to declare a variable of type CRITICAL_SECTION

David Crow2-Jul-07 10:49

Re: How to declare a variable of type CRITICAL_SECTION

2-Jul-07 10:49

zipliu wrote:
I wonder how I should declare a critical section object.

CRITICAL_SECTION cs;
EnterCriticalSection(&cs);
...
LeaveCriticalSection(&cs);

"A good athlete is the result of a good and worthy opponent." - David Crow

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

Mark Salsbery2-Jul-07 12:43

2-Jul-07 12:43

To add to DavidCrow's reply...

You can put the CRITICAL_SECTION object anywhere it's accessible by ALL threads that need it.
All threads that need to synchronize need to use the same CRITICAL_SECTION object.

Also, InitializeCriticalSection() (or InitializeCriticalSectionAndSpinCount()) should be called
by one of your threads before using the critical section.

Mark

Mark Salsbery
Microsoft MVP - Visual C++

Variants

tom groezer2-Jul-07 9:24

tom groezer

2-Jul-07 9:24

What is the significance of using Variants data type. Is it sufficient that they only have a union of various data types and that they can be used by dispatch clients.

Re: Variants

David Crow2-Jul-07 9:41

2-Jul-07 9:41

Here is a brief explanation.

"A good athlete is the result of a good and worthy opponent." - David Crow

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

MFC frame

tom groezer2-Jul-07 9:16

tom groezer

2-Jul-07 9:16

How does the frame gets destroyed in MFC? Why is the frame window created on the heap as opposed to other windows which should created on the stack?

Re: MFC frame

Mark Salsbery2-Jul-07 9:39

2-Jul-07 9:39

The Windows object (HWND) gets destroyed like any other window, when DestroyWindow() is called.

The MFC CFrameWnd object is destroyed in response to the WM_NCDESTROY message (see
CFrameWnd::PostNcDestroy()).

tom groezer wrote:
as opposed to other windows which should created on the stack?

Not necessarily true - The same scope rules apply as always. If you want a window to exist after
a function/method returns, the stack might not be a good place for the object.

Mark

Mark Salsbery
Microsoft MVP - Visual C++

Window registeration

tom groezer2-Jul-07 9:00

tom groezer

2-Jul-07 9:00

AfxRegisterWndClass or AfxRegisterClass or RegisterClass. What is the difference between the three and when should be used what?

Re: Window registeration

David Crow2-Jul-07 9:48

2-Jul-07 9:48

tom groezer wrote:
What is the difference between the three...

The first two are MFC. AfxRegisterClass() is a thin wrapper around RegisterClass(), and is a bit more sophisticated than AfxRegisterWndClass().

"A good athlete is the result of a good and worthy opponent." - David Crow

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

Re: Window registeration

Mark Salsbery2-Jul-07 9:49

VMR9 & SampleGrabber at the same time , how ?

2-Jul-07 9:49

RegisterClass[^] is a Windows API, and is used internally by AfxRegisterClass and
AfxRegisterWndClass.

The documentation for AfxRegisterClass and AfxRegisterWndClass (in the remarks section) describes
their usage:

AfxRegisterClass[^]
AfxRegisterWndClass[^]

Mark

Mark Salsbery
Microsoft MVP - Visual C++

Akin Ocal2-Jul-07 8:51

Akin Ocal

2-Jul-07 8:51

http://msdn2.microsoft.com/en-us/library/ms786690.aspx
It says :
Include Qedit.h. This header file is not compatible with Microsoft® Direct3D® headers later than version 7.

My application must do both VMR9 rendering and sample grabbing.

But there are many problems when i include d3d9.h+vmr9.h with qedit.h at the same time , it gives lots of errors when trying to build

how can i use vmr9 filter and samplegrabber filter at the same time ?

Re: VMR9 & SampleGrabber at the same time , how ?

Mark Salsbery2-Jul-07 9:30

Re: VMR9 & SampleGrabber at the same time , how ?

2-Jul-07 9:30

The VMR has a built-in frame grabber that maybe you can use instead.

See IBasicVideo::GetCurrentImage()[^] for VMR in windowed mode

or

IVMRWindowlessControl9::GetCurrentImage()[^] for VMR in windowless mode.

Mark

Mark Salsbery
Microsoft MVP - Visual C++

Akin Ocal2-Jul-07 11:27

Akin Ocal

2-Jul-07 11:27

Thanks but what about audio streams ?
And what about processing imag , will it only give image or can it give chance of processing image buffer just in sample-grabber ?

Re: VMR9 & SampleGrabber at the same time , how ?

Mark Salsbery2-Jul-07 12:28

2-Jul-07 12:28

Well this is unfortunate, but based on messing with this and searching for an answer...

It looks like the only workaround is to separate VMR-related and SampleGrabber-related code into
two different source modules. The two modules will need to include a different set of header
files (which means including them in a pre-compiled header won't work).

Another alternative is to make your own custom grabber filter. The Grabber Filter Sample in the
DirectShow SDK implements one that already works. You'd want to change the names and GUIDs to
your own to differentiate it from the SDK sample filter.

Mark

Mark Salsbery
Microsoft MVP - Visual C++

What is dlg subclass ?

prithaa2-Jul-07 8:21

prithaa

2-Jul-07 8:21

Hello,

What exactly is dlg subclass ?.I went through the docs of CWnd::SubclassDlgItem but did niot understand.

Is it regarding message handling routines when the windows controls are placed on a dialog?
How does subclassing help?

Prithaa

David Crow2-Jul-07 8:32

2-Jul-07 8:32

prithaa wrote:
What exactly is dlg subclass ?.

In general, a subclass is this.

"A good athlete is the result of a good and worthy opponent." - David Crow

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

Mark Salsbery2-Jul-07 9:06

2-Jul-07 9:06

To understand window subclassing and how the MFC framework subclasses windows, you should have a
good understanding of the fundamentals of Windows programming: Windowing[^]

Mark

Mark Salsbery
Microsoft MVP - Visual C++

prithaa3-Jul-07 0:36

prithaa

3-Jul-07 0:36

Hello,

What is the relationship between subclassed dialog item and
DLGTEMPLATE d;
d.cdit
One of the demo code given for "Dynamic creation of Dialogs" saya
if a dialogitem is subclassed only then it can be added to to d.cdit.
This part of subclassed dialog item is what I did not understand.

Thanks for all your replies and cooperation.
Prithaa

Mark Salsbery3-Jul-07 5:50