Re: Passing data to a DLL - C / C++ / MFC Discussion Boards

JWood25-Mar-04 16:56

25-Mar-04 16:56

You can read the data in, then create a small program to export the data to the
{"word1", "word2" ... } text file format, then turn this into an include file. With this this as an array, you can further optimize by putting it into a hash table, or a binary string array. (do a search in CP for more information)

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Passing data to a DLL

Steve Messer25-Mar-04 12:18

Steve Messer

25-Mar-04 12:18

I have a program that basically acts like a menu and all functionality is added using DLL's. I am wondering how to pass data to a DLL when initilizing it. For example I would like to pass:

1) Version number
2) Handle to calling window
3) Handle to misc helper DLL's
4) Pictures Directory
5) Music Directory
6) etc

How do you do this?

Thanks,

Steve

Re: Passing data to a DLL

Prakash Nadar25-Mar-04 14:51

Prakash Nadar

25-Mar-04 14:51

You can either call a Init method and pass all these parameters to the dll...
or passthem as the parameters to the corresponding api that needs it.

*Warning* If you pass handle of the calling window to the dll and you make it global in the dll.. You will have lot of problems. Avoid global variables except for constants.

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Re: Passing data to a DLL

Steve Messer25-Mar-04 15:15

Steve Messer

25-Mar-04 15:15

So, could I just pass a struct to the init method?

struct info
{
CString Version;
CString MusicDir;
CString PictureDir;
};

The reason I am wanting to pass in the handle of the calling window is that I want to be able to pass messages to it. Is there another way? I built in my plugin interface a way to pass messages to the plugins but I don't know how to send messages to the main application ( Dialog app in my case ).

What kind of problems are you refering to in your warning?

Re: Passing data to a DLL

Prakash Nadar25-Mar-04 17:04

Prakash Nadar

25-Mar-04 17:04

smesser wrote:
What kind of problems are you refering to in your warning
Its the problem related to multithreading... What if two applications load your dll and pass handle to window...
if you make it global then which window will it refer to.
Check Thread Local Storage for that matter.

You can use callback functions to notify back the messages.

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Re: Passing data to a DLL

Ryan Binns25-Mar-04 17:21

Ryan Binns

25-Mar-04 17:21

Mr.Prakash wrote:
What if two applications load your dll and pass handle to window...
if you make it global then which window will it refer to.

Each application will get a separate copy of the application data, unless the data section in the DLL is marked as "shared". I think what you mean is two threads from the same application call the Init function with different windows, then there will be a problem as you have indicated. But if the Init function is only called from one thread, then there is no problem using a global variable.

Ryan

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Re: Passing data to a DLL

Steve Messer25-Mar-04 18:33

Steve Messer

25-Mar-04 18:33

Thanks for the explanations all.

Mr.Prakash wrote:
You can use callback functions to notify back the messages.

Could you elaborate on this point? How would a callback function notify back to the calling application.

So that you understand my set up. My main application is a dialog based application and so are the plug-ins. So lets say a plug-in wants to tell the main application that a song has just ended (end of song event).

Thanks

Re: Passing data to a DLL

Roger Allen26-Mar-04 2:10

Roger Allen

26-Mar-04 2:10

Declare a pure virtual class that your dialog etc will inherit from. Then you pass a pointer to your dialog across to the dll and it calls the functions it required on this calss object:

// this is in a header file shared by the EXE and the DLL projects
class MyCallBacks
{
 virtual void Callback1(parameters) = 0;
 virtual bool Callback2(parameters) = 0;
}

// this is in your EXE
CMyDialog : public CDialog, public MyCallbacks
{
 // implementations of the callback functions
 void Callback1(parameters);
 bool Callback2(parameters);
}

So when you init your DLL, pass a MyCallBacks* pointer in the structure across. Then in the DLL, if you need to do a certain actio, you would do:

// this is in your DLL
if (m_pCallback != NULL)
{
m_pCallback->Callback1(parameters);
}

Hopefully this makes some sense!

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Re: Passing data to a DLL

Steve Messer26-Mar-04 5:02

Steve Messer

26-Mar-04 5:02

Yes, that makes sense.

Thanks

How to make a default button at Run Time

Touseef Afzal25-Mar-04 10:42

Touseef Afzal

25-Mar-04 10:42

Hi Gurus:
i m new to VC++. i want to make a make a button , a default button at run time , i know a button could me make a default button at design time be setting its property as default button , but how could this get at run time .......

thanks in advance.....

Touseef Afzal

"Winner's don't do different things , they do things differently "

Re: How to make a default button at Run Time

Robert A. T. Káldy25-Mar-04 11:00

Robert A. T. Káldy

25-Mar-04 11:00

btn->SetButtonStyle(btn->GetButtonStyle() | BS_DEFPUSHBUTTON)

Robert-Antonio

"Love without sex is like a fish without antlers"

Re: How to make a default button at Run Time

Touseef Afzal27-Mar-04 4:25

Touseef Afzal

27-Mar-04 4:25

Hi:
i have an SDI Application in which i have used CFormView as my view Class ,

i have tried this code

btn->SetButtonStyle(btn->GetButtonStyle() | BS_DEFPUSHBUTTON

but it just change the look of button from simple look to a dark black rectange showing that button has now default button property , but the button is not working as default button .....

help please..........

thanks.....

"Winner's don't do different things , they do things differently "

Re: How to make a default button at Run Time

Steve S29-Mar-04 0:56

Steve S

29-Mar-04 0:56

Check out DM_SETDEFID.
You post this to the dialog (in this case, the form view), and pass WPARAM which is the ID of the button you want to be default, leave LPARAM as NULL.

Steve S

DirectSound question

pankajdaga25-Mar-04 10:41

pankajdaga

25-Mar-04 10:41

Hi everyone,

I did not know which forum would get closest in relevance to my question, so I posted it here. I am really sorry if it is the wrong place.

I am trying to learn DirectX and was looking at DirectSound in particular. I was looking at the documentation for mixing various DirectSound buffers and playing them simultaneously. However, this concept of simultaneous playing bothers me. The documentation says that simultaneously played sounds are automatically mixed in the DirectSound primary buffer and played. I could not find an example of mixing multiple wave sources.

Now, here is my question:

Suppose I have 50 DirectSound secondary buffers. I want to ensure that they are mixed first and then played. What I could gather from the documentation is that I loop through the buffers and call Play() on them. However, that will certainly affect the synchronization of the buffers and they will not be played simultaneously. The documentation only states that you play the buffers simultaneously. I could not come across a way on how to do it.

I am pretty sure I am missing something here. So, if any DirectSound expert could shed some light on it, I would be grateful.

Thanks,

Pankaj

Without struggle, there is no progress

Re: DirectSound question

Ryan Binns25-Mar-04 17:28

Ryan Binns

25-Mar-04 17:28

Looping through the buffers and calling Play() won't be a problem. AFAICR, The Play() method is asynchronous, so it flags the buffer to start playing and then returns. The actual delay involved in very minimal, so starting 50 buffers playing will only take a microsecond or so. Compare that with the time between two samples (20.8 microseconds at 48kHz), and the delay involved is much less than a single sample, so by the time the next sample comes along, all of the buffers will be ready. They may be out of sync by a single sample, but this will not be noticeable to us humans.

Hope this helps,

Ryan

"Punctuality is only a virtue for those who aren't smart enough to think of good excuses for being late" John Nichol "Point Of Impact"

Re: DirectSound question

pankajdaga25-Mar-04 20:07

pankajdaga

25-Mar-04 20:07

Hey Ryan,

Thanks a lot for the explanation Smile | :)

This really helps.

Pankaj

Without struggle, there is no progress

SetFocus in EditControl

xzigax25-Mar-04 9:27

xzigax

25-Mar-04 9:27

Hello.

Please, help me, how to set focus into EditControl when I run the application?
I know how to do it in Delphi, does anyone know how to make this in Visual Studio C++ ?

Thanks.

Re: SetFocus in EditControl

Hesham Amin25-Mar-04 9:51

Hesham Amin

25-Mar-04 9:51

use SetFocus (a member of CWnd)

MyEdit->SetFocus();

How to get the handle of a control in properties sheet.

bin892225-Mar-04 9:18

bin8922

25-Mar-04 9:18

Hello, everyone,
In my current project, I want to display xp style button(OK, Cancel and apply) in the properties sheet.
If I do it using MFC, it would be very easy. I just need to
m_btnXPButton.SubclassWindow(GetDlgItem(ID_APPLY_NOW)->m_hWand);
But when I tried to do the same thing in ATL, the returned handle for ID_APPLY_NOW (IDOK and IDCANCEL) is NULL.
How can I get the handle of a control in the properties sheet written in ATL.

Thanks a lot in advance.

bin

Re: How to get the handle of a control in properties sheet.

David Crow25-Mar-04 10:15

David Crow

25-Mar-04 10:15

bin8922 wrote:
How can I get the handle of a control in the properties sheet written in ATL.

Don't forget about this forum.

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Re: How to get the handle of a control in properties sheet.

Prakash Nadar25-Mar-04 19:31

Prakash Nadar

25-Mar-04 19:31

Does GetdlgItem(...) does not work?

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The value returned is NULL

bin892226-Mar-04 5:05

bin8922

26-Mar-04 5:05

I tried to use GetDlgItem(IDOK), but the returned value is NULL

Status bar gripper

sschilachi25-Mar-04 8:50

sschilachi

25-Mar-04 8:50

How do you remove a gripper from a status bar. I created it using:
m_wndStatusBar.Create(this, CBRS_BOTTOM|WS_CHILD|WS_VISIBLE|CBRS_SIZE_FIXED);
I have tried the following to remove the gripper:
m_wndStatusBar.ModifyStyle(SBARS_SIZEGRIP,0);
but it didn't work.

Does anyone know how to remove the gripper.

Thanks

Dialog Help Needed?

modeonetwo25-Mar-04 6:51

modeonetwo

25-Mar-04 6:51

Hello all...I have a dialog based application. What i want to do is, set up a timer in my dialog, say for every 4 minutes, i want my dialog to call a function from another dialog to write some data into a file. How can i accomplish this. I have looked at and tried timers in a regular mfc program, but have not had success with a dialog based program. If anyone has a sample code or an article pertaining to timers and dialogs, i would appricate the help.

none

Re: Dialog Help Needed?

David Crow25-Mar-04 8:27

David Crow

25-Mar-04 8:27

modeonetwo wrote:
...say for every 4 minutes

Which is equal to 240,000 milliseconds.

modeonetwo wrote:
...but have not had success with a dialog based program

Meaning what? To simply state that something did not work is not very informative. I assume that you did not have compiler/linker errors, but had run-time errors instead.

A timer does not care that it was created in the context of a window or a dialog (which is just a specialized window). Once you create it and the specified time has elapsed, the specific callback function is called or a WM_TIMER message is posted to the owning application.

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Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.