C / C++ / MFC

David Crow5-Oct-06 9:22

5-Oct-06 9:22

Johpoke wrote:
So you mean that mouse clicking can not be globaly emulated? But keyboard buttons can be..

Where in the world did you infer this from. Confused | :confused:

Controls respond to both keyboard or mouse, and either can be emulated. One such way is via SendInput(). There are likely other solutions, but without more details as to what you are wanting to achieve...

"Approved Workmen Are Not Ashamed" - 2 Timothy 2:15

"Judge not by the eye but by the heart." - Native American Proverb

Johpoke5-Oct-06 9:39

Johpoke

5-Oct-06 9:39

i searched for that and sneaked around to microsoft, were i found mouse_event, then i found this:

mouse_event(MOUSEEVENTF_LEFTDOWN,0,0,0,NULL);
and
mouse_event(MOUSEEVENTF_LEFTUP,0,0,0,NULL);

which does exactly what i need!

thanks!!

/Johannes

David Crow5-Oct-06 10:07

5-Oct-06 10:07

SendInput() has superseded mouse_event() on Windows NT/2000/XP systems.

"Approved Workmen Are Not Ashamed" - 2 Timothy 2:15

"Judge not by the eye but by the heart." - Native American Proverb

Mark Salsbery5-Oct-06 10:09

Mark Salsbery

5-Oct-06 10:09

Yep!

For longevity's sake, SendInput() should be used instead. mouse_event() is deprecated.

Mark

How to Hide windows

Max++5-Oct-06 6:41

Max++

5-Oct-06 6:41

I want to hide windows when open the program.
I try to use
CWnd::ShowWindow(SW_HIDE);
in OnInitDialog it still no work
but
CWnd::ShowWindow(SW_MINIMIZE);
It's work.
Please suggest me how to solve the problem.

toxcct5-Oct-06 6:48

toxcct

5-Oct-06 6:48

you use CWnd::ShowWindow(SW_HIDE); or this->ShowWindow(SW_HIDE); ?

TOXCCT >>> GEII power

[VisualCalc 3.0 updated ][Flags Beginner's Guide new! ]

Max++5-Oct-06 6:57

Max++

5-Oct-06 6:57

I also try both
the result still same.

David Crow5-Oct-06 7:02

5-Oct-06 7:02

You can't use ShowWindow() in this fashion because one of the last things that happens with a dialog is a call to ShowWindow(SW_SHOW), effectively overiding your attempt to hide the window. The solution is to handle the WM_WINDOWPOSCHANGING message, and then remove the SWP_SHOWWINDOW flag.

"Approved Workmen Are Not Ashamed" - 2 Timothy 2:15

"Judge not by the eye but by the heart." - Native American Proverb

Eric Dahlvang5-Oct-06 8:06

Eric Dahlvang

5-Oct-06 8:06

The Code Project Visual C++ Forum FAQ
7.6: I have a dialog-based application and want the dialog hidden on startup. How do I do this?
http://www.codeproject.com/cpp/cppforumfaq.asp#mfc_hidedlgstartup[^]

--EricDV Sig---------
Some problems are so complex that you have to be highly intelligent and well informed just to be undecided about them.
- Laurence J. Peters

Hamid_RT5-Oct-06 8:37

Hamid_RT

5-Oct-06 8:37

Your answer on http://www.codeproject.com/cpp/cppforumfaq.asp#mfc_hidedlgstartup[^] By Michael Dunn

WhiteSky

led mike5-Oct-06 10:29

EnterCriticalSection() exception issue

5-Oct-06 10:29

Max++ wrote:
How to Hide windows

Install Lynux

led mike

Tnarol5-Oct-06 3:43

5-Oct-06 3:43

Hi,

I have a multithreaded program in which I use the following class object "ClassLock" the synchronize accesses :

<br />
#ifndef CLASSLOCK_H<br />
#define CLASSLOCK_H<br />
<br />
extern CRITICAL_SECTION g_ClassLock;<br />
<br />
class ClassLock<br />
{<br />
public:<br />
	static void InitCriticalSection();<br />
	static void DelCriticalSection();<br />
	inline ClassLock()  { EnterCriticalSection( &g_ClassLock );  }<br />
	inline ~ClassLock() { LeaveCriticalSection( &g_ClassLock ); }<br />
};<br />
<br />
#endif

I protect a function call by instantiating a ClassLock object at the beginning of the function :

<br />
void MyFunc()<br />
{<br />
ClassLock l;<br />
...<br />
}<br />

But sometimes, don't know why, an exception is thrown. How can I deal with this ?
My idea would be the following modification, but I don't know if it's safe and smart :

<br />
inline ClassLock()  { while(!TryEnterCriticalSection( &g_ClassLock )) { } }<br />

Any other ideas ? Thanks

led mike5-Oct-06 4:32

5-Oct-06 4:32

Tnarol wrote:
How can I deal with this ?

Find out what the exception is.

Is the purpose and use model of that class supposed to be evident? I don't get it.

led mike

Tnarol5-Oct-06 4:54

5-Oct-06 4:54

led mike wrote:
Is the purpose and use model of that class supposed to be evident? I don't get it.

Yes,

First at the beginning of your app you call InitCriticalSection() which is in fact InitializeCriticalSection() on a global g_ClassLock variable

Then inside a function when you instantiate a ClassLock object it calls the constructor which locks the g_ClassLock variable using EnterCriticalSection( &g_ClassLock )

When the function return, the ClassLock object goes out of scope, so the destructor is called automatically and it does LeaveCriticalSection( &g_ClassLock )

Therefore the function has the g_ClassLock synchronization token for the duration of its' execution.

Then at the end of the program DelCriticalSection must be called...and it does DeleteCriticalSection( &g_ClassLock ).

led mike5-Oct-06 5:06

5-Oct-06 5:06

Tnarol wrote:
on a global g_ClassLock variable

I don't understand what problem a "global" critical section solves, you want to synchronize everything in the process? Confused | :confused:

led mike

Tnarol5-Oct-06 5:36

5-Oct-06 5:36

It's just that a global variable is a simple kind of synchronization resource that can be seen and shared by several threads in a program.

I could have this variable static in the class, but there are some strange things happening with static variables members of a class, if you use them very early in the program they are sometimes not yet created and it makes you crash. I don't have a logical explanation for this but that's my experience.

led mike5-Oct-06 6:13

5-Oct-06 6:13

Tnarol wrote:
It's just that a global variable is a simple kind of synchronization resource that can be seen and shared by several threads in a program.

I'm sorry but that does not explain anything. A Critical Section is used to synchronize access to data or a section of code, this implies "context" associated with the CS. Have one as "global" elimintates all context.

Tnarol wrote:
they are sometimes not yet created

"Created"? static variable addresses are known at load time, therefore any code that uses them has a good address.

Anyway, global or static, I still don't see how that solves anything in regards to using a CS.

led mike

Mark Salsbery5-Oct-06 7:35

Mark Salsbery

5-Oct-06 7:35

void MyFunc()<br />
{<br />
ClassLock l;<br />
...<br />
}<br />

You're probably getting an exception because you are entering a critical section
that hasn't been initialized yet.
You also don't want to create a new critical section every time you enter the function
otherwise it will never block.

Try this:

class CMyCriticalSection
{
	private:
		CRITICAL_SECTION CritSec;
	protected:
	public:
		CMyCriticalSection()  {::InitializeCriticalSection(&CritSec);}
		virtual ~CMyCriticalSection()  {::DeleteCriticalSection(&CritSec);}

		void Enter()  {::EnterCriticalSection(&CritSec);}
		void Leave()  {::LeaveCriticalSection(&CritSec);}
};

CMyCriticalSection MyFuncCritSec;

void MyFunc()
{
	MyFuncCritSec.Enter();

	... (do thread protected stuff)

	MyFuncCritSec.Leave();
}

Tnarol5-Oct-06 22:07

5-Oct-06 22:07

Thanks, it works fine so far...but the exception occurs very rarely so time will tell.

The problem with this kind of class is that you have to leave critical section explicitly so if you have functions with many return points you must copy the "Leave()" everywhere. Anyway I'm quite confident in this implementation.

Mark Salsbery6-Oct-06 5:08

Mark Salsbery

6-Oct-06 5:08

>>The problem with this kind of class is that you have to leave critical section explicitly so if
>>you have functions with many return points you must copy the "Leave()" everywhere.

Cool. I guess I prefer it that way personally Smile | :)

I can't recall ever needing to block an entire function.

Anyway I suspect the exception is unrelated to the critical section. But if it only rarely
happens I guess it's ok?

Best of luck,
Mark

Blake Miller6-Oct-06 8:50

Blake Miller

6-Oct-06 8:50

You need two SEPARATE objects.

The first object constructor initializes the critical section, and its destructor deletes the critical section.
It has a member function Lock() and Unlock()

The second class, its constructor Enters the critical section of first object, by calling its Lock function. The destructor of this class calls the Unlock() of the first class.

That way, you don't have to worry about calling Unlock() explicitly from your code.
You also don't have to use a 'global' class from your common code, you use instances of the second class.

If you don't want to block out the entire scope of a function, then use the local scoping operators around the second class and the code like so

{
SecondClass MyLocker;
... code
}

and it will release when closing brace is met.

This is also handy when there is an exception, your critical section is not permanently locked and lost by the unwinding of the exception.

Any sufficiently gross incompetence is nearly indistinguishable from malice.

Absolute Addresses

Big CDF5-Oct-06 3:39

Big CDF

5-Oct-06 3:39

Hi all, i'm researching accessing data on a hard drive through using absolute addresses in C/C++. Somthing similar to "peek", and "poke", in
DOS-C. I Dont think its possible using visual studio.net, but someone may know somthing useful. Thanks. Smile | :)

p.s. This is my first question in my first forum, so go easy on me.

Craig

Re: Absolute Addresses

David Crow5-Oct-06 3:47