C / C++ / MFC

27-Jun-07 23:12

The background can you paint in OnEraseBkgnd() Sleepy | :zzz:

Greetings from Germany

Re: OnCtlColor

alias_rizwan28-Jun-07 0:26

alias_rizwan

28-Jun-07 0:26

I guess you are creating a new brush in every time in OnCtlColor function.
if yes a simple solution would be to
1>make the brush object as a memeber of a classs
2>create thebrush object only once say in the constructor.
3>return the same handle every time in the function.
4>delete the object in the destructor.

Thanks
Rizwan

Thread Question

Programm3r27-Jun-07 20:47

27-Jun-07 20:47

Hi all,

Lets say one has created a thread using _beginthread() and now that thread is active and running. Now one wants to pass arguments to that thread function, but remember that the thread was already created. Now ... how can one (if it is possible) call that thread function, without calling _beginthread() again.
I.E

int callThreadFunc()
{
 // call thread function without calling _beginthrad
 // or can one just dio a nornal function call??? 
}
void myThread(void* a)
{
 while (1)
 {
   // do some stuff - not relevent
   Sleep(1000);
 } 
}
void main()
{
 _beginthread(myThread, NULL, 0); // creating the thread
 ...
}

Many Thanks
Regards,

The only programmers that are better than C programmers are those who code in 1's and 0's..... Smile | :)

Programm3r
My Blog: ^_^

KarstenK27-Jun-07 20:57

27-Jun-07 20:57

with global variables, but you have the problem of syncronizing. If threads work together you need to syncronize them!!! Everything else is crap. Mad | :mad:

For instance with WaitForMultipleEvent()

Greetings from Germany

Programm3r27-Jun-07 21:00

27-Jun-07 21:00

Thanks for the info Karsten ... Smile | :)

Greetings from South Africa
Regards,

The only programmers that are better than C programmers are those who code in 1's and 0's..... Smile | :)

Programm3r
My Blog: ^_^

Cedric Moonen27-Jun-07 21:16

Cedric Moonen

27-Jun-07 21:16

You can't really pass arguments to your thread the way you describe. Instead, what you do, is pass a pointer to a certain object when you start your thread. Then, your thread can check this object to retrieve information (now, how it is done really depends on your app). Basically, it doesn't change anything to the fact that it is a separate thread. EXCEPT, that you need to secure the access to the variables using critical sections (for example), so that only one thread will access a variable at a time.

Cédric Moonen
Software developer

Charting control [v1.2]

Programm3r27-Jun-07 22:02

27-Jun-07 22:02

Thanks Cédric,

Cedric Moonen wrote:
that you need to secure the access to the variables using critical sections (for example), so that only one thread will access a variable at a time.

If I understand you correctly ... would it be a good idea using global variables, but keeping it in sync ?

Many Thanks
Regards,

The only programmers that are better than C programmers are those who code in 1's and 0's..... Smile | :)

Programm3r
My Blog: ^_^

Roger Stoltz27-Jun-07 21:55

Roger Stoltz

27-Jun-07 21:55

There are two common ways:

With a UI-thread you post a message with the information you want to pass to the thread
With a worker thread (like your example) you have a place where the thread knows it can find information, such as a queue, a struct on the heap or class member variables. When the thread is supposed to get the new information you signal an event or semaphore that the thread is waiting on with ::WaitForMultipleObjects(...).

Don't forget to synchronize the threads to avoid data corruption.

For more info on workerthreads, read this article[^].
For more info on semaphores and queues between workerthreads, read this article[^].

You will find a third alternative with I/O completion ports here[^]. The article also discuss when thread synchronization isn't needed, or could be avoided.

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

Programm3r27-Jun-07 22:03

Streach or skew a bitmap to fit to resizing button size

27-Jun-07 22:03

Roger Stoltz wrote:
When the thread is supposed to get the new information you signal an event or semaphore that the thread is waiting on

Never though of that, thank you very much Rodger Smile | :)

Regards,

The only programmers that are better than C programmers are those who code in 1's and 0's..... Smile | :)

Programm3r
My Blog: ^_^

Multi threading in c++

role127-Jun-07 20:27

role1

27-Jun-07 20:27

hi i am using the below code for dummy multithreading application.

first function listens request and the thread started with thread function
but some client start receving data but some one not get the single respomnse back . can any one help me what's gona wong with this code

thanks

///////the server function//////////////////

void thread::startserver()
{

DWORD dwStatus;
WSAEVENT handles[1];
struct sockaddr_in cli_addr;
int clilen = sizeof(cli_addr);
memset(&cli_addr,0,sizeof(struct sockaddr));

printf("***********server started****************\n");
while (TRUE)
{

handles[0] = WSACreateEvent();
WSAEventSelect(m_hSockethndl, handles[0], FD_ACCEPT);
dwStatus = WSAWaitForMultipleEvents(1, handles, TRUE, 50, FALSE);
if (dwStatus == WSA_WAIT_EVENT_0)
{
SOCKET cli_socket;
cli_socket=-1;
cli_socket = accept(m_hSockethndl, (struct sockaddr *) &cli_addr, &clilen);

// set linger option
LINGER linger;
linger.l_onoff = 1;
linger.l_linger = 0;
setsockopt(cli_socket, SOL_SOCKET, SO_LINGER, (char *)&linger, sizeof(LINGER));
//setsockopt(cli_socket, IPPROTO_TCP, TCP_NODELAY, NULL, 0);

int flag = 1;
int result = setsockopt(cli_socket, /* socket affected */
IPPROTO_TCP, /* set option at TCP level */
TCP_NODELAY, /* name of option */
(char *) &flag, /* the cast is historical cruft */
sizeof(int)); /* length of option value */
if (result < 0)
{
printf("Client Socket No Delay Option Failed");
}

//printf("Thread started with the server socket=%d and client port=%d and ip=%s\n",cli_socket,cli_addr.sin_port,inet_ntoa(cli_addr.s in_addr));
/*threadParmas thparam;
memset(&thparam,0,sizeof(threadParmas));
thparam.cli_addrth=cli_addr;
thparam.threadsocket=cli_socket;*/

//CreateThread(NULL, 0, StartThread, &thparam, 0, &dwThreadID);
CreateThread(NULL, 0, StartThread, &cli_socket, 0, &dwThreadID);
FD_SET(cli_socket, &set_sockets);
}
WSACloseEvent(handles[0]);
}
}

//////////////////the thread function////////////////////

DWORD WINAPI thread::StartThread (void * thparam)
{
/* struct threadParmas threadparam;
threadparam.threadsocket=((struct threadParmas *)thparam)->threadsocket;
threadparam.cli_addrth=((struct threadParmas *)thparam)->cli_addrth;*/

SOCKET socket_handle;
u_short Clientport;
//socket_handle=threadparam.threadsocket;
socket_handle=*(SOCKET *)thparam;
//Clientport=ntohs(threadparam.cli_addrth.sin_port);
char data[256];
char Resdata[512];
memset(data,0,256);
memset(Resdata,0,512);
int counter=1;
int bytes =1;

while(bytes)
{

WSAEVENT we = WSACreateEvent();
WSAEVENT handles[1];
handles[0] = we;
WSAEventSelect(socket_handle, we, FD_READ | FD_CLOSE);
//receiving data from client
for (int i = 0; i < WAIT_MULTIPLE; i++)
{
DWORD available = WSAWaitForMultipleEvents(1, handles, TRUE, WAIT_TIME, FALSE);
if (available == WSA_WAIT_EVENT_0)
{
if ((bytes = recv(socket_handle, data, 256, 0)) < 0)
{
int er = WSAGetLastError();
printf("Error=%d while receive data from socket %d\n",er,socket_handle);
bytes = 0;
break;
}
else
break;
}
}

WSACloseEvent(we);

strcpy_s(Resdata,512,"Response send Ack");

if(bytes)
{
//printf("socket %d Message %3d received client port=%d, ip=%s size=%d\n",socket_handle,counter,Clientport,inet_ntoa(thread param.cli_addrth.sin_addr),bytes);
//go to sleep for internal processing
//printf("socket %d Message %3d received size %d %s\n",socket_handle,counter,bytes,data);
Sleep(2000);

//sending the dummy response to the client
if (send(socket_handle, Resdata, strlen(Resdata), 0) != strlen(Resdata))
{
int er = WSAGetLastError();
printf("ERROR %d IN SENDING %d RESPONSE by socket =%d\n",er,counter,socket_handle);
return 0;
}
//printf("***Response %3d send by the server socket=%d, client port=%d, ip=%s\n",counter,socket_handle,Clientport,inet_ntoa(thread param.cli_addrth.sin_addr));
//printf("***Response %3d send by the server socket=%d\n",counter,socket_handle);
}
//keeping track how many packets this specific client sends
counter++;
}
return 1;
}

robshere27-Jun-07 20:06

robshere

27-Jun-07 20:06

Hai All,
I'm working in VC++ 6.0.There I've created a dialog based appl in MFC.
1.I've created a CButton and placed a bitmap over it using LoadBitmap function,say,IDB_BITMAP1.
2.Now I need the button to be resized along with the Dailog.
3.I've written the code for the buttton resizing in OnSize ();
4.Now my trouble starts.I want to use the same already loaded bitmap (IDB_BITMAP1)to be resized according to the button size.But now onlt the button is resizing and not the bitmap.

So please tell me is there any way to resize(ie,streach or skew) the bitmap according to the content size.

Thanks in advance

Re: Streach or skew a bitmap to fit to resizing button size

KarstenK27-Jun-07 20:53

Re: You need a ownerdrawn Button

27-Jun-07 20:53

You need a ownerdrawn Button. So look for samples here at CP or write a own one. Override OnPaint() with a StretchBlt

Greetings from Germany

robshere29-Jun-07 2:00

robshere

29-Jun-07 2:00

Hello thanks for your kind reply,

Can you please explain to me in depth how to streach the Bitmap image.I've used the ownerdrawn button.I'm able to resize the control.But the bitmap remains of the same size.

Can you please tell me how to use StrechBlt() function in a much more detailed way.I tried but not getting it correctly.I'm new to to MFC.So please help me.

Thanking You in Advance and appriciating your kindness,

Robshere

Re: You need a ownerdrawn Button

KarstenK29-Jun-07 2:18