C / C++ / MFC

Re: ADO Recordset not showing changes just made...

19-Feb-01 20:27

my understanding is that changes are not broadcast across multiple connections as the potential traffic on the network (in a multiuser scenario) would be grim

the solution we came up with was either to build in an auto-refresh every minute or two, or to give the users a refresh button on the data entry screens

sql server works this way to in fact

mostly watching the human race is like watching dogs watch tv ... they see the pictures move but the meaning escapes them

Paul Wolfensberger20-Feb-01 2:48

Paul Wolfensberger

20-Feb-01 2:48

The information seems to be available within a few seconds (somewhere between 2 and 4 seconds) so refreshing every minute wouldn't really help any....and I need the data within a second of having saved it to the database.

I don't want to hardcode a wait into the application, and the whole point of the current set of work that I'm doing is to optimize for speed....having just saved the user 10 seconds, I'd hate to have to give half of it away waiting for data.

I've come across a Q article which indicates that Jet has "lazy" writes and caches information within the connection. I've set a connection property that is suposed to make sure that transaction data is to be saved right to the file, but haven't found any way of making sure that the other connection's cache is refreshed. ;(

Paul

Re: ADO Recordset not showing changes just made...

John M. Drescher20-Feb-01 18:19

John M. Drescher

20-Feb-01 18:19

I had the same problem a couple of months ago with an Access 2000 database and ADO. The solution looks like the following:

pConnection->BeginTrans();

//modify data base in some method

pConnection->CommitTrans();

After CommitTrans() other connections will see the change that occurred between BeginTrans and CommitTrans. This will flush the result back to the database.

There is an article in the MSDN library that explains transactions in ADO. Search MSDN for "Using Transactions in Your Solutions" as an exact phrase. There should be one article, its in Visual Basic but the solution is similar in VC++.

John

How to enable the second monitor by using APIs?

Wang Huaizhi19-Feb-01 14:08

Wang Huaizhi

19-Feb-01 14:08

Now I have a dual-monitor system. Is there any API function with which I can enable or disable the second monitor, but not by using control panel?

Thanks in advance!

Wang Huaizhi

How to get process name from Process Id/Handle?

19-Feb-01 11:14

Hi everyone,

My problem seems simple, but I don't know where to start. The problem is :
Having a process Id or Handle, how do you get the name of the process (whether the process is iexplore, netscape, or something else)?

Thanks for all your help Smile | :)

Re: How to get process name from Process Id/Handle?

Todd Wilson19-Feb-01 12:56

Todd Wilson

19-Feb-01 12:56

GetModuleFileName(processHandle,buffer,buffersize) (9x,NT)
or
GetModuleBaseName(processHandle,moduleHandle,buffer,buffersize) (NT4/5)

Getting closer..

19-Feb-01 10:36

void CTestKeyDlg::OnKeyDown(UINT nChar, UINT nRepCnt, UINT nFlags)
{
UpdateData(TRUE);
char lsChar;
lsChar = char(nChar);

if (lsChar == 83)
{
AfxMessageBox("This is SS!w");
}

else
{
MessageBox("This is not SS!");
}
UpdateData(FALSE);
}

Ok, this is the code i use to get a message box to tell me if the keyboard button was "S" or not.

It works fine, but only if the dialog is complety empty, no buttons nothing at all.
I cant get it to work, any one have a hint to what i have to do??

Thank you a million zillion times Smile | :)

l a u r e n19-Feb-01 10:55

19-Feb-01 10:55

in an empty dialog the dialog itself has focus as there are no controls ... appwizaed sets the focus to the first control after InitDialog() so KeyDn() at the dialog level gets the input ... when you have controls on the dialog they get the focus

the HookWindow() stuff should help or i'm sure there's a more 'correct' way out there
Smile | :)

mostly watching the human race is like watching dogs watch tv ... they see the pictures move but the meaning escapes them

19-Feb-01 21:22

Well i couldt find any info on the
HookWindow() in MSDN, any tips on how to use it.

The thing i need to do, is i need to get focus on the dialog, not the button's or text
is there a way i can get the message if the focus is on a Button??? Like it dosnt matter
if there is focus on the buttons or dialog??

Thank you again.

Christian Graus19-Feb-01 21:33

Christian Graus

19-Feb-01 21:33

Try searching for HookWindow - I got eight matches, including two very useful articles, ( one of which is a Paul DeLascia one on palettes I refer to from time to time )

Christian

The content of this post is not necessarily the opinion of my yadda yadda yadda.

To understand recursion, we must first understand recursion.

ov19-Feb-01 21:56

19-Feb-01 21:56

Use PreTranslateMessage(). Like this:

in TestKeyDlg.h

class CTestKeyDlg : public CDialog {
....
    bool PreTranslateMessage(MSG *pMsg);
....
};

in TestKeyDlg.cpp

bool CTestKeyDlg::PreTranslateMessage(MSG *pMsg) {
    if (pMsg->message == WM_KEYDOWN && pMsg->wParam == 83)
        MessageBox("That's S!");
    return CDialog::PreTranslateMessage(pMsg);
}

With the best regards, Vitaly.

21-Feb-01 6:21

I get this error when i do the same as you do.

Error->(Sorry for the mess)

c:\documents and settings\administrator\my documents\c++\testkey\testkeydlg.h(16) : error C2555: 'CTestKeyDlg::PreTranslateMessage' : overriding virtual function differs from 'CDialog::PreTranslateMessage' only by return type or calling convention
d:\program files\microsoft visual studio\vc98\mfc\include\afxwin.h(2568) : see declaration of 'CDialog'
TestKeyDlg.cpp

c:\documents and settings\administrator\my documents\c++\testkey\testkeydlg.h(16) : error C2555: 'CTestKeyDlg::PreTranslateMessage' : overriding virtual function differs from 'CDialog::PreTranslateMessage' only by return type or calling convention
d:\program files\microsoft visual studio\vc98\mfc\include\afxwin.h(2568) : see declaration of 'CDialog'

C:\Documents and Settings\Administrator\My Documents\C++\TestKey\TestKeyDlg.cpp(128) : warning C4800: 'int' : forcing value to bool 'true' or 'false' (performance warning)
Generating Code...

Need a litle hint Smile | :)

21-Feb-01 6:22

l a u r e n21-Feb-01 6:52

21-Feb-01 6:52

did u use class wizard to generate the correct handlers for the PreTranslateMessage() function?

otherwise you will in fact have different call sig / return value from the defined handler in the afxwin.h file

Smile | :)

mostly watching the human race is like watching dogs watch tv ... they see the pictures move but the meaning escapes them

22-Feb-01 3:30

Opss i was sleeping, i didnt get to much coffie in my cup Smile | :)

Thank you, and thank you all for helping me.

Highlight CWnd?

19-Feb-01 10:27

I would like to highlight any CWnd with a border like Spy++ does.

Now i just draw a rectangle but that overwrites any other window
that could be over the CWnd i would like to highlight. At it does
look very ugly afterwards.
But Spy++ manages to highlight windows without overwriting any
other windows that may cover. How does Spy++ do that?

Re: Highlight CWnd?

l a u r e n19-Feb-01 10:57

Non-overlapped serial comms

19-Feb-01 10:57

SetCapture()
GetWindowFromPoint()
draw the line you want using a region to clip the drawing where other windows are on top

etc etc

Smile | :)

mostly watching the human race is like watching dogs watch tv ... they see the pictures move but the meaning escapes them

Re: Highlight CWnd?

ov19-Feb-01 22:04

19-Feb-01 22:04

IMHO Spy++ uses hooks. So it's dll is loaded in the that window's process. So it can implement it's own WM_NCPAINT handler and draw this lines as they drawn by that window itself.
GetWindowFromPoint() is only used to determine the window to do it with.

With the best regards, Vitaly.

Re: Highlight CWnd?

20-Feb-01 2:10

And does anyone now how this can be done?
Any examples?

Joe Moldovan19-Feb-01 5:47

Joe Moldovan

19-Feb-01 5:47

I have opened a comm port for non-overlapped I/O and set up a thread to watch for read events with WaitCommEvent. I have my main thread doing writes with WriteFile. Neither thread uses any windows.

The problem is that the WriteFile seems to be blocked by the WaitCommEvent in the background thread. This makes sense for file I/O but for serial comms the read and write operations should be completely independent and not block each other. I can overcome this by using overlapped I/O but it complicates things horribly.

Question: Does anyone know of a way to stop the comm Wait from blocking a non-overlapped serial write?

Software Mix of Sound

Datacrime19-Feb-01 2:34

Datacrime

19-Feb-01 2:34

I'd like to mix two or more sound streams.
I don't want to use hardware mixer or DirectSound for two reasons.
i) I want to save the output to a file.
ii)I want absolut control of the timing.
(ex. mix 3463ms of source 1 with 3463ms of source 2)
Of course if you know a way to do both of the above by using DirectSound it whould be welcome.

What i tried is for each WORD of sound1 and sound2
to get differce, divide it by 2 add add it to the lowest value.
What i get was terrible. Frown | :(

A second though is to multiply the two WORDs and divide the result
with 65536 (or shift by 16bits). Although it sounds to be faster,
i thing it's gona be the same. am'i right?

And now comes the real hard stuff.
What i wanna do at the end is to mix 2 -or more- sounds, and
each sound having a weight,
like: sound1(60%) + sound2(31%) + sound3(9%)

any ideas?

Memory leaks is the price we pay

.::RockNix::.19-Feb-01 21:07

.::RockNix::.

19-Feb-01 21:07

To mix several sounds with a specizific gain you have to scale every single sound by a factor and then simply add all sounds together.

this could be sa followed :

float gain1 = 0.6; // 60%
float gain2 = 0.31; // 31%
float gain3 = 0.09; // 9%

int mix; // your mixdown

mix = (int)(gain1*(float)sample1+gain2*(float)sample2 ....)

But BEWARE: If you add to much sounds you will surely get an overflow. So it is better to pre-scale all sounds with the same factor.

hope it helps

Greatings Mario ///

----------------------
www.klangwerker.de
mario@klangwerker.de
----------------------

Datacrime19-Feb-01 22:27

Datacrime

19-Feb-01 22:27

Thanx a lot.

After making several changes i relised that values from streams in .wav files
are of type 'short' and not WORD (a.k.a. 'unsigned short').
In other words, values are between -32k to +32k and not 0 to 64k.

After reading them correctly, i turn them into positive by adding 32k,
mix them and turn the result into real by substructing 32k.

For mixing i use the way you just mention.
If i scale all gains,so that the sum of all gains is 1.00 ,
i don't have to worry about overflows.

I also heard about mixing using L2-node which is equal to:
sqrt(S1^2+S2^2+..+Sv^2)
But in this case you get overflow, and have to scale the
result with sqrt(2)=0.707
Also i don't know how to fit different gains in this formula (yet).

I will try the L2-node , and inform you about which one gives the
best result.

Memory leaks is the price we pay

Joe Moldovan19-Feb-01 23:55

Joe Moldovan

19-Feb-01 23:55

I assume you are mixing 16 bit PCM files streams. If that's the case then you have two problems:

1. The sound is stored as 16 bit SIGNED walues not WORD (unsigned int) values. The amplitude is between –32768 and 32767. You reduce the amplitude by going towards 0.

2. The amplitude is not linear. If you halve the amplitude the sound will not be half as loud. It follows a logarithmic law and something to do with 20*Log(A) where A is the amplitude. (I don't know the theory real well...life is too short.) The library should be full of books which will help you.

Hope you get it working. I love playing around with audio but don't have the time.

------------------------------------------------------------------------------------

PS: I made time! The following is a very primitive C mixer I threw together. It works but probably has bugs. I used CoolEdit to capture raw PCM files. If you use WAV files then just strip the headers first to get to the PCM data. But you probably already know that. You can also use the API to get the data a lot neater.

#include "stdafx.h"
#include <stdio.h>

int APIENTRY WinMain(HINSTANCE hInstance,
HINSTANCE hPrevInstance,
LPSTR lpCmdLine,
int nCmdShow)
{
FILE *f1;
FILE *f2;
FILE *f3;

size_t result1;
size_t result2;

short buffer1[ 0xFFFF ];
short buffer2[ 0xFFFF ];
short buffer3[ 0xFFFF ];

int i;

f1 = fopen( "sound1.pcm", "rb" );
f2 = fopen( "sound2.pcm", "rb" );
f3 = fopen( "sound3.pcm", "wb" );

do
{
result1 = fread( buffer1, sizeof( short ), 0xFFFF, f1 );

result2 = fread( buffer2, sizeof( short ), 0xFFFF, f2 );

for ( i = 0; i < 0xFFFF; i++ )
{
buffer3[ i ] = buffer1[ i ] / 2 + buffer2[ i ] / 2;
}

fwrite( buffer3, sizeof( short ), 0xFFFF, f3 );

} while ( !feof( f1 ));

fclose( f1 );
fclose( f2 );
fclose( f3 );

return 0;
}