C / C++ / MFC

Re: reading a string from an unknown position in a file

5-Mar-06 21:32

Ok. Now open the .png file with Notepad and see it actually contains the string.

Steve

SWDevil5-Mar-06 21:37

SWDevil

5-Mar-06 21:37

what .png file? I didn't understand what u meant..

I already opened the .png files with notepad, and they all contain the string. That includes the .png file that is the actual image, and the .png file I just created...

Re: reading a string from an unknown position in a file

Stephen Hewitt5-Mar-06 21:47

Re: reading a string from an unknown position in a file

5-Mar-06 21:47

I can't think of what could be going wrong then. If it finds it the text file it should work for the image file - assuming the string is present. The only think I can suggest is to check that the cases are consistent. i.e. Search string is in upper cast but string in file is in lower case.

Steve

SWDevil5-Mar-06 21:53

SWDevil

5-Mar-06 21:53

I'll tell u something - I copied all of the data from the .png file that is an image file(the original file), to the .png file I constructed from Notepad, and the search for the string works...
So I think the problem is in the fact that the original .png file was originally constructed as an image file...

Re: reading a string from an unknown position in a file

Gary R. Wheeler6-Mar-06 12:41

Gary R. Wheeler

6-Mar-06 12:41

Oops. That should have been strncmp D'Oh! | :doh:

Software Zen: delete this;

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Re: reading a string from an unknown position in a file

David Crow6-Mar-06 3:18

David Crow

6-Mar-06 3:18

Gary R. Wheeler wrote:
2. If the file is large, read it a chunk at a time.

But what if the 'chunk' split the <> in two?

"Let us be thankful for the fools. But for them the rest of us could not succeed." - Mark Twain

"There is no death, only a change of worlds." - Native American Proverb

Re: reading a string from an unknown position in a file

Gary R. Wheeler6-Mar-06 12:44

Gary R. Wheeler

6-Mar-06 12:44

If you read the rest of #2, you'll see I tell him to read more data out of the file, appending to the original chunk. That covers the case where you haven't read enough of the data to include an entire marker.

Software Zen: delete this;

Fold With Us![^]

Re: reading a string from an unknown position in a file

David Crow6-Mar-06 3:15

David Crow

6-Mar-06 3:15

See here.

In summary:

CFile file;
char *pBuffer = new char[file.GetLength() + 1];
file.Read(sBuffer);
sBuffer[file.GetLength()] = '\0';
file.Close();
CString str(sBuffer);
int nIndex1 = str.Find(">>");
int nIndex2 = str.Find("<<", nIndex1 + 2);
CString strData = str.Mid(nIndex1 + 2, nIndex2 - nIndex1 - 2);
or
int nNumber = atoi(str.Mid(nIndex1 + 2));

This can also be done without using CString.

"Let us be thankful for the fools. But for them the rest of us could not succeed." - Mark Twain

"There is no death, only a change of worlds." - Native American Proverb

A beginners question about UINT

Waldermort5-Mar-06 1:04

Re: A beginners question about UINT

5-Mar-06 1:04

I never did properly read this chapter. With a lot of functions you are able to pass more than one paramater in the form of a xor. For example when setting a window style: WS_CHILD | WS_BORDER

If I was to make a function for which I could pass the same form of argument, how do you break them apart again?

I would like to make a function which can enable/disable more than one toolbar at a time. ie.

enable_button(ID_BUTTON1 | ID_BUTTON2);

within the function I would check the button id and send the approprate button a message.

SendMessage(hToolBar,TB_ENABLEBUTTON,ID_BUTTON?,FALSE);

So how do I find out which button id's were passed?

Justin Tay5-Mar-06 1:20

Justin Tay

5-Mar-06 1:20

They are using bitwise OR to combine flags. A 32-bit integer would have 32 bits to tell them apart. You would assign values to the flags in powers of 2.

#define ID_BUTTON1 0x0001
#define ID_BUTTON2 0x0002 // ( 1 << 1 )
#define ID_BUTTON3 0x0004 // ( 1 << 2 )
#define ID_BUTTON4 0x0008 // ( 1 << 3 )

As you can see, there is a limited number of flags you can have (32 in this case).

To tell them apart you would do something like this
bool bButton1 = ((nFlags & ID_BUTTON1) == ID_BUTTON1);

Re: A beginners question about UINT

Waldermort5-Mar-06 1:51

Real time audio capture and processing

5-Mar-06 1:51

Thankyou for that

toolboxx4-Mar-06 23:06

toolboxx

4-Mar-06 23:06

Hello,

I'm looking for a way to capture the sound from the microphone in real time, modify it by applying an effect and output it back to the microphone stream so that other applications which might be recording from the microphone would receive the modified audio. Does anyone have any ideas on how to approach this task?

Thanks.

Re: Real time audio capture and processing

mikanu5-Mar-06 10:14

mikanu

5-Mar-06 10:14

As far as I know the microphone is not a shared resource in Windows. That means that an application that needs to use the microphone input would have to get exclusive ownership of that resource. That being said, in the user mode, only one application may have access to the microphone at a time. Also I don't think that user mode applications are given permission to modify the input buffer (the memory arrea allocated to store data from the microphone input).

To cut to the chace, my opinion is that for the type of functionality you seek, you need to write a Kernel Mode application (a virtual driver) that hooks into the sound driver and intercepts writes to the input buffer and applies whatever effects you need to apply, then let the user mode applications "get" their chance at the mic input buffer.

www.muzikstor.com

Re: Real time audio capture and processing

toolboxx7-Mar-06 17:45

toolboxx

7-Mar-06 17:45

Thanks for pointing me in the right direction. I'll read some articles on driver development now (I found many great ones on this web-site) because I've never developed drivers before.

c++ string class

Waldermort4-Mar-06 22:51

4-Mar-06 22:51

I have decided to change much of my code from C string (char *) to the C++ style string. So far I have noticed that they are pretty easy to use, and much faster when it comes to searching for sub strings, converting string (BSTR to string).

Now a lot of functions in C++ expect C style strings, this is no problem when using c_str(), but what about those functions that would fill a string? c_str() returns a const pointer, this cannot be changed. For example

SendMessage(hwnd,WM_GETTEXT,0,buffer);

normally the buffer would be filled with the text, how do you make this work with the string class?

Stephen Hewitt4-Mar-06 23:52

4-Mar-06 23:52

I'm not sure if there is any portable way of doing this. The reason is that all of the strings characters need not actually be sequentially stored in all implementations. For example an implementation may use a deque like structure to avoid having to copy the entire contents of the string across to a new buffer when the string length exceeds its capacity. I think you'll have to read into a normal char array then assign to a string.

Steve

Waldermort5-Mar-06 0:40

5-Mar-06 0:40

I figured as much, its a shame, these basic_strings are very adaptable, you can do just about anything with them except send them to a frequently used function.

Thanks for the reply anyway Smile | :)

Rob Caldecott5-Mar-06 2:22

Rob Caldecott

5-Mar-06 2:22

I tend to use a std::vector for things like WM_GETTEXT, and then copy this to a std::string when I am done.

The Rob Blog
Google Talk: robert.caldecott

Stephen Hewitt5-Mar-06 15:57

5-Mar-06 15:57

If you use a std::vector make sure it has enough space allocated either by using the appropriate constructor or the reserve function. i.e.

typedef std::vector<char> CharVec;
 
// Constructing it with enough room.
CharVec chars(MAX_PATH);
PathCanonicalize(&chars[0], pPathToCanonicalize);
 
// Sizing an already constructed vector.
chars.reserve(MAX_PATH);
PathCanonicalize(&chars[0], pPathToCanonicalize);

Steve

Checkbox / How do I get the width/height of it?

Gary R. Wheeler5-Mar-06 2:29

Gary R. Wheeler

5-Mar-06 2:29

Most of the C++ string classes will include a member function that will return a pointer to a simple character buffer of a specified length. You pass that to the function, and then release the buffer afterward.

I use the MFC CString class myself, which has member functions GetBufferSetLength() and ReleaseBuffer() for this purpose.

I would imagine the STL string class has something like this.

Software Zen: delete this;

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Sebastian Pipping4-Mar-06 19:02

Re: Checkbox / How do I get the width/height of it?

4-Mar-06 19:02

I have a button with BS_CHECKBOX style and text.
I want to center the checkbox with my dialog so
I need to get the "real" width of the control
(Checkbox + gap + text = full width).

I know how to get the width of the text part
but how do I get the width and height of the
checkbox itself?

I looked at GetSystemMetrics and SystemParametersInfo
but didn't find any. Any ideas where to look at?

The width of the gap between is also needed.
I need a plain WinAPI solution that works on all versions
of Windows (not XP only).

Thanks in advance, Sebastian

-------------------------------------------
My website: http://www.hartwork.org

-- modified at 1:03 Sunday 5th March, 2006

Sebastian Pipping4-Mar-06 21:05

Re: Checkbox / How do I get the width/height of it?

4-Mar-06 21:05

More searching taught me that SM_CXMENUCHECK and
SM_CXMENUSIZE seem to be what I was looking for.

So my new problem is how do I tellGetTextExtentPoint32
to work with the new font and not the default one.
Here's my code:

const TCHAR * const szNeverAgain = TEXT( "Do not ask again" );

SendMessage( hNeverAgain, WM_SETFONT, ( WPARAM )GetStockObject( DEFAULT_GUI_FONT ), ( LPARAM )TRUE );

const HDC hdc = GetDC( hNeverAgain );
SIZE size;
GetTextExtentPoint32( hdc, szNeverAgain, _tcslen( szNeverAgain ), &size );
ReleaseDC( hNeverAgain, hdc );

size.cx is always the width for the old font.
I need the new one - any ideas?

-------------------------------------------
My website: http://www.hartwork.org

Stephen Hewitt4-Mar-06 21:24

Re: Checkbox / How do I get the width/height of it?

4-Mar-06 21:24

Select a font into the DC before calling GetTextExtentPoint32. e.g.

const TCHAR * const szNeverAgain = TEXT( "Do not ask again" );

SendMessage( hNeverAgain, WM_SETFONT, ( WPARAM )GetStockObject( DEFAULT_GUI_FONT ), ( LPARAM )TRUE );

HDC hdc = GetDC( hNeverAgain );
HFONT hOldFont = (HFONT)SelectObject(hdc, hYourFont);
SIZE size;
GetTextExtentPoint32( hdc, szNeverAgain, _tcslen( szNeverAgain ), &size );
SelectObject(hdc, hOldFont);
ReleaseDC( hNeverAgain, hdc );

Steve

Sebastian Pipping4-Mar-06 21:31

Re: Checkbox / How do I get the width/height of it?

4-Mar-06 21:31

This is it! It works!
I'm so happy - Thank you very much!

Best regards, Sebastian

-------------------------------------------
My website: http://www.hartwork.org

Sebastian Pipping4-Mar-06 21:46