C / C++ / MFC

Re: How Much of WM_USER+X is used by MFC

10-Mar-16 22:50

I don't know what Bram is smoking these days, but I think he should cut down. Wink | ;)

Bram van Kampen10-Mar-16 15:08

Re: How Much of WM_USER+X is used by MFC

10-Mar-16 15:08

Hi,

Good to talk again.

My header files do not provide a macro for WM_APP. Maybe you could let me know for future reference, if it is a single value. Also AOP has advised me to Register a Windows Message. Probably the way forward for the Future.

Thanks for your contribution.

Bram. Smile | :)

Bram van Kampen

Victor Nijegorodov11-Mar-16 4:17

Victor Nijegorodov

11-Mar-16 4:17

WM_APP (Windows)[^]

Ensuring code runs synchronously

ForNow9-Mar-16 5:01

Re: Ensuring code runs synchronously

9-Mar-16 5:01

Is a crtical section a way of ensuring the your code runs synchrounsly as window message processing seems to take precedence in code execution

Richard MacCutchan9-Mar-16 7:21

Re: Ensuring code runs synchronously

9-Mar-16 7:21

It ensures only one thread can go through that code path: see Critical Section Objects (Windows)[^].

ForNow wrote:
window message processing seems to take precedence

Not sure what you mean by that.

Bram van Kampen9-Mar-16 15:29

Re: Ensuring code runs synchronously

9-Mar-16 15:29

In Short, No!

Critical Sections are Synchronisation Objects, It is of use only if your project is multi threaded,ie Has More than One thread running in the One Program. Each thread of your program, will wait in front of a CriticalSection where you try to Enter It, until all other threads leave it. It is a communal comunication deal between threads in a program. One thread of a program will not allow another thread to run, until the section is released. Other programs can switch thread in the mean time.

The Nature and context of the question worries me! You seem to have to learn an awfull lot more before you are ready to discus critical sections

Smile | :)

Bram van Kampen

Bram van Kampen9-Mar-16 16:04

Non display characters for selection count

9-Mar-16 16:04

No,
It is NOT, and I explained that already!
However, I also answered your other question, in quite a lot of detail. Before you can attempt to learn MFC Multi Threaded Programming, you will need to learn basic MFC Programming, and elements of the Windows SDK. MFC is a thin wrapper around the Windows SDK. Sometimes you need the real thing! Definitely needed in Multithreading.

Cannot Help it, You need to study more before we can help you.

Bram

Bram van Kampen

ForNow8-Mar-16 20:44

8-Mar-16 20:44

Hi

I have 3 rows of text in my rich edit.
At the end of each line I move a carriage return line feed, to force a new line
/r/n. Do these 2 bytes count as 2 characters when determining the count for the selection

Thanks

Richard MacCutchan8-Mar-16 22:45

8-Mar-16 22:45

The documentation at EM_GETSELTEXT message (Windows)[^] does not explicitly say whether it does, or does not. But a simple test should prove it one way or another.

ForNow9-Mar-16 4:55

9-Mar-16 4:55

cr/lf 0X0D0A is treated as 1 character for rich edit purposes

thanks

David Crow9-Mar-16 5:24

9-Mar-16 5:24

Really? I just tested (using VS2008) and it came out as two separate characters. Here's the code I used:

// the control contained the text: David\r\n

void CMyDialog::OnClickedOk()
{
    int len = m_richedit.GetWindowTextLength();
    TRACE(_T("Len = %d\n"), len);

    CString text;
    m_richedit.GetWindowText(text);
    TRACE(_T("Text = %s\n"), text);

    for (int x = 0; x < len; x++)
        TRACE(_T("%#x\n"), text[x]);
}

The resulting output looked like:

Len = 7
Text = David

0x44
0x61
0x76
0x69
0x64
0xd
0xa

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ForNow9-Mar-16 5:32

9-Mar-16 5:32

I was referring to richedit when determining the selection position

David Crow9-Mar-16 5:49

9-Mar-16 5:49

So you are taking whatever text is already present in the edit control and adding CRLF to the end of it? I'm trying to ascertain if this is an appending issue (I've seen some weird ways in which folks try to append to an edit control) or something else.

modified 9-Mar-16 11:41am.

ForNow9-Mar-16 5:58

9-Mar-16 5:58

For Crlf which is 2 bytes in memory aka the buffer
I count 1 for determining the selection count

David Crow9-Mar-16 6:03

9-Mar-16 6:03

But are taking whatever text is already present in the edit control and adding CRLF to the end of it?

ForNow9-Mar-16 6:20

9-Mar-16 6:20

The text is included in the count for the cold I count as 1 character for porpouses of selection not 2 bytes

David Crow9-Mar-16 6:40

9-Mar-16 6:40

I misunderstood what you were attempting.

You are using the GetSel() method to get the starting and ending positions of the control's selected text, correct? I tried that and with all of the text in the control selected, I found that CR and LF are (like I would expect) considered two separate characters. In other words, start = 0 and end = 7.

ForNow9-Mar-16 6:45

9-Mar-16 6:45

I use the Streamout api to get whatever is in the control the edit control has 4 lines at the end of each line is X0D0A CRLF I have to count the 0X0D0A as 1 character for the SetSel api when determining the pos I want to use in the selection

thanks

David Crow9-Mar-16 6:53

9-Mar-16 6:53

So your end game is just to programmatically insert/replace some characters some place in the edit control?

modified 9-Mar-16 12:22pm.

ForNow9-Mar-16 7:21

9-Mar-16 7:21

I have 16 pieces of text in the 4 line edit control any one of whom I could potentially replace

Richard MacCutchan9-Mar-16 7:18

9-Mar-16 7:18

I just tried this with an ordinary Edit control, and it returns both CR LF in the count.

Bram van Kampen9-Mar-16 15:52

9-Mar-16 15:52

You did not try this in a Multi Threaded Environment, as explained in the question previous of this
Smile | :)

Bram van Kampen

Richard MacCutchan9-Mar-16 23:11

9-Mar-16 23:11

Sorry, but I am not sure what relevance that has to the counting of characters.

Bram van Kampen9-Mar-16 15:49

9-Mar-16 15:49

Well,
This is Familiar, in particular with the multi threaded question you asked earlier.

MFC cannot realy handle multiple threads. No one seems to know why, I have asked the question before.

At any rate, the only way MFC objects can communicate between threads is with the Old Fashioned WDK Kernel Function ::SendMessage(hWnd, Param1,Param2);
In MFC you create your Message as WM_USER+(X), Create a Message Handler, and, manually add it to the message map.

Any attempt to call an MFC Object from a different thread than in which it was created always ultimately lead to failure.
The Symptoms are: Works, Add a Virtual Function: It stops Working

Hope this helps

Bram van Kampen

modified 9-Mar-16 21:08pm.

Richard MacCutchan9-Mar-16 23:11