C / C++ / MFC Discussion Boards

Toni7819-Jul-04 6:24

19-Jul-04 6:24

If a file has been mapped with MapViewOfFile, will the offsets in memory correspond to the ones in the disk. For example if I try to access the contents at file offset 0x100 in the disk, after I map the file would I still be using offset 0x100 or will the memory alignment make the offset change.

// Afterall, I realized that even my comment lines have bugs

If the sun were to blow up, it would take us 7-8 minutes to realize it.

Re: File Mapping

bikram singh19-Jul-04 11:02

bikram singh

19-Jul-04 11:02

Toni78 wrote:
will the offsets in memory correspond to the ones in the disk

Yes, they will. However, ensure that either the whole file has been mapped, or the relevant portion that you want to access, has been mapped.

Note that the "offset" must be added to the address returned by MapViewOfFile(). Optionally, MapViewOfFileEx() allows you to specify your own base address where the file will be "loaded".

Memory alignment has to be taken into consideration when
the file was opened with FILE_FLAG_NO_BUFFERING in the CreateFile() call.

Bikram Singh

Re: File Mapping

Toni7821-Jul-04 8:47

Toni78

21-Jul-04 8:47

Thank you for your help. Smile | :)

After I posted the question and I got no reply, I realized that I could test this by myself by loading the file and doing a byte compare with the file in the disk Cool | :cool:

. At the end the files were identical so apparently there were no memory alignment issues. But I wasn't aware about FILE_FLAG_NO_BUFFERING Confused | :confused:

. Either way, thank you again.

// Afterall, I realized that even my comment lines have bugs

If the sun were to blow up, it would take us 7-8 minutes to realize it.

Using the Clipboard

tunerica19-Jul-04 6:21

tunerica

19-Jul-04 6:21

Hi All, was hoping I mightbe able to get some help. I have been looking at a few of the clipboard examples on this site and made this code based on some of it:

if(capEditCopy(captureWindow)) //Capture frame from video stream to clipboard
{
if ( OpenClipboard(NULL) )
{
if (!IsClipboardFormatAvailable(CF_BITMAP))
return;

//Get the clipboard data
HBITMAP handle = (HBITMAP)GetClipboardData(CF_BITMAP);
CBitmap * bm = CBitmap::FromHandle(handle);

CSize sz = bm->GetBitmapDimension();

long foo = sz.cx;

CloseClipboard();

}

The long foo was merely created to check whether the bitmap was defined properly, the problem is, foo always comes back as zero. Why is this? Was the bitmap ever created? My aim here is to merely get a bitmap so that I can manipulate some of the pixel values.

Any help would be greatly appreciated. Thanks in advance.

Micheal

Re: Using the Clipboard

PJ Arends19-Jul-04 7:49

PJ Arends

19-Jul-04 7:49

RTFM[^]

[quote]

CBitmap::GetBitmapDimension
CSize GetBitmapDimension( ) const;

Return Value

The width and height of the bitmap, measured in 0.1-millimeter units. The height is in the cy member of the CSize object, and the width is in the cx member. If the bitmap width and height have not been set by using SetBitmapDimension, the return value is 0.

Remarks

Returns the width and height of the bitmap. The height and width are assumed to have been set previously by using the SetBitmapDimension member function.

CBitmap Overview | Class Members | Hierarchy Chart

See Also CBitmap::SetBitmapDimension

[/quote]

Use a BITMAP structure filled with CBitmap::GetBitmap(BITMAP *) to get the bitmaps dimensions.

"You're obviously a superstar." - Christian Graus about me - 12 Feb '03

"Obviously ??? You're definitely a superstar!!!" mYkel - 21 Jun '04

Within you lies the power for good - Use it!

Sending mail using CDOSYS

Mike Beckerleg19-Jul-04 5:41

Mike Beckerleg

19-Jul-04 5:41

I am trying to use CDOSYS in a c++ application to send some emails.
I have used #import to get the libraries and everything seems to be working ok except that the mail messages get stuck in inetpub\mailroot\queue.

Any ideas how to find out what the problem is?

Mike

Re: Sending mail using CDOSYS

Antti Keskinen19-Jul-04 14:35

Antti Keskinen

19-Jul-04 14:35

Could this be an issue with the IIS ? A misconfiguration somewhere ? Can you send normal mail messages using an application such as Outlook Express ?

The CDOSYS API is pretty straightforward, so the errors should be limited to missing sender/recipent or other mail header info. One option here is to see the IIS logs for any tips. Usually when mails are stuck in the queue there's a reason for it, and it's logged. If it's not, you should increase the logging sensitivity (what gets logged) so that everything is written there. Then try again and see if any errors occur.

-Antti Keskinen

----------------------------------------------
The definition of impossible is strictly dependant
on what we think is possible.

failing constructors

Michael Farrugia19-Jul-04 5:24

Michael Farrugia

19-Jul-04 5:24

I would like to implement a class that will deallocate itself if something in the constractor fails. Something to work like this

class MyClass
{
public:
MyClass(char * filenm) {/* if filenm does not exist the class constuction fails*/};
~MyClass() {};
}

MyClass *mine = new MyClass("filename");
if(!mine)return 0;

....

This should be something similar to how ifstream functions. I tried to look at its code but did not manage to understand it.
Is there a way that I can make this work?

Thanks a lot

Michael

Re: failing constructors

peterchen19-Jul-04 5:41

peterchen

19-Jul-04 5:41

1. The clean and legal way in C++ to handle a failing constructor is to throw an exception
2. If your construtor throws an exception, C++ will:
- free the memory allocated for the object itself (if the allocation was dynamic)
- call the desctructors of all members and base classes (that were initialized)

It will NOT, however, call the destructor of the object that failed the construction. Since the object was not constructed completely, it would be dangerous to call the destructor.

we are here to help each other get through this thing, whatever it is Vonnegut jr.

sighist || Agile Programming | doxygen

Re: failing constructors

bikram singh19-Jul-04 11:25

bikram singh

19-Jul-04 11:25

Exceptions are your friends!
I suggest, do what peter says.

However, if you do want to try:
Use a function to return the object instead of doing it with "new". Such a concept is usually called a "Class Factory" (concept from COM), whose sole purpose is to create and return an instance of a class.

void *CreateClassAA(string a)
{
if(a == "")
return 0;
else
.............
}

Bikram Singh

Re: failing constructors

Michael Farrugia19-Jul-04 22:53

Michael Farrugia

19-Jul-04 22:53

Yes this is a good idea.
But how is it done in ifstream? Does it really work fine?!

Thanks
Michael

SetBkColor does not seem to work in OnInitDialog

maxsteel19-Jul-04 5:02

maxsteel

19-Jul-04 5:02

hi,
i have a dialog box with a static control. the problem is that when i try to use setbkcolor for the static control in oninitdialog of the dialog box, it does not produce any results. i have tried to use GetDC() for the static control to get the DC. and then tried to set the background color of the static control. can any one give me a solution?

regards,
kevin

Re: SetBkColor does not seem to work in OnInitDialog

vcplusplus19-Jul-04 5:52

vcplusplus

19-Jul-04 5:52

Look into using the WM_CTLCOLOR Message

http://support.microsoft.com/default.aspx?scid=kb;en-us;32685

Re: SetBkColor does not seem to work in OnInitDialog

maxsteel19-Jul-04 18:42

maxsteel

19-Jul-04 18:42

using WM_CTLCOLOR causes problems in other parts of my code. is there any other solution?

Re: SetBkColor does not seem to work in OnInitDialog

vcplusplus20-Jul-04 3:04

vcplusplus

20-Jul-04 3:04

It should not affect other parts of your code.

Here is a sample of my code.

HBRUSH CMyView::OnCtlColor(CDC* pDC, CWnd* pWnd, UINT nCtlColor) 
{
	HBRUSH hbr = CFormView::OnCtlColor(pDC, pWnd, nCtlColor);
	
	INT nIDCtl = pWnd->GetDlgCtrlID();
	switch(nIDCtl)
	{
	case IDC_STATIC_CTRL1:
		{
			// Change background color to white so that the
			// text is easier to read.
			pDC->SetBkColor(RGB(255, 255, 255));
			CBrush br;
			br.CreateSolidBrush(RGB(255, 255, 255));
			hbr = (HBRUSH)br;
			br.Detach();
		}
		break;
	case IDC_STATIC_CTRL2:
               ....
               ....
	case IDC_STATIC_CTRL3:
               ....
               ....
	case IDC_STATIC_CTRL4:
               ....
               ....
        }
	return hbr;
}

Re: SetBkColor does not seem to work in OnInitDialog

Alexander Wiseman19-Jul-04 5:56

Alexander Wiseman

19-Jul-04 5:56

You could also take a look at this excellent article: http://www.codeproject.com/staticctrl/clabel.asp[^]

Hope that helps!

Sincerely,
Alexander Wiseman

Est melior esse quam videri
It is better to be than to seem

Re: SetBkColor does not seem to work in OnInitDialog

Ravi Bhavnani19-Jul-04 6:54

Ravi Bhavnani

19-Jul-04 6:54

SetBkColor() should be used when handling a WM_PAINT message or within a control's DrawItem() override. Use it to set the background color of the DC for the duration of the painting action.

/ravi

My new year's resolution: 2048 x 1536
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Re: SetBkColor does not seem to work in OnInitDialog

maxsteel19-Jul-04 18:43

maxsteel

19-Jul-04 18:43

even if i use setbkcolor in WM_PAINT is does not do anything.

SDI Project - How do display a new Window object that is NOT On Top of the Main Window??

jerry1211a19-Jul-04 4:56

jerry1211a

19-Jul-04 4:56

I have a SDI project where a user using the menu can select and load another window object. I get the new window, but it is on top of my main window. I want to be able to move the window away from the main window.

This is the code I use to create and show the window:

pStatus->dlg.Create(IDD_FORM_STATUS);
pStatus->dlg.ShowWindow(SW_SHOW);

Can someone help me out?
Thanks.
Jerry

Re: SDI Project - How do display a new Window object that is NOT On Top of the Main Window??

valikac19-Jul-04 5:02

valikac

19-Jul-04 5:02

One solution is MoveWindow().

Kuphryn

How to integrate MFC projects?

pork chop19-Jul-04 3:35

pork chop

19-Jul-04 3:35

hi!

im a newbie with MFC & hope someone can help me with this...

i hv created 2 MFC dialog based programs and need to integrate them together... ie. after integrating, when i click on build on execute, the 2 dialogs shld appear together on the screen.

i've tried using a modal dialog box in program A so as to contain program B but created a mess n it's not functioning too.. as the 2 dialog dialog boxes need not communicate w each other, i wonder if there is a better suggestion?

Re: How to integrate MFC projects?

V.19-Jul-04 3:41

19-Jul-04 3:41

Use Modeless Dialogs...

"If I don't see you in this world, I'll see you in the next one... and don't be late." ~ Jimi Hendrix

VC++6 to VC++7: link pb with CString

ienien19-Jul-04 3:13

ienien

19-Jul-04 3:13

Hi!
I have projects and DLLs made with Visual C++6 and I try to pass to Visual C++7.
I have a link error when I use a function (contained in a DLL) that uses a CString as parameter.
ERROR LINK 2019 non resolved symbol CStringT ...
Everything was alright with VC++6.
How to solve my link problem?
Will any other problems happen soon during the passing of VC++6 to VC++7???
Thanks.

Deleteing a file

si_6919-Jul-04 2:56

si_69

19-Jul-04 2:56

Hi all

does ne1 know the easist way of deleting a file

i have a txt file which i need to remove in certain situations

i tried using

remove(str_SettingsPath);

but that doesnt work Sigh | :sigh:

any ideas ??

si

Re: Deleteing a file

Ravi Bhavnani19-Jul-04 3:04

Ravi Bhavnani

19-Jul-04 3:04

Use unlink(), CFile::Remove() or DeleteFile(). Be sure to specify the file's full pathname.

/ravi

My new year's resolution: 2048 x 1536
Home | Articles | Freeware | Music
ravib@ravib.com

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