C / C++ / MFC

CPallini14-May-14 21:39

14-May-14 21:39

What? Could you please elaborate a bit your scenario?

Veni, vidi, vici.

Legor14-May-14 21:54

Legor

14-May-14 21:54

You have to be more specific. What does a dialog have to do with how you save an image? And what do you mean by saving the image directly in memory?

Richard MacCutchan14-May-14 21:56

Richard MacCutchan

14-May-14 21:56

What image and where are you trying to save it?

Software_Developer15-May-14 4:35

Software_Developer

15-May-14 4:35

Double buffering articles.

Double Buffering With GDI+[^]

Flicker Free Drawing In MFC[^]

http://www.robertelder.ca/doublebuffering/[^

Can I properly derive from CMFCPropertyGridColorProperty ?

Stefan_Lang15-May-14 22:21

Stefan_Lang

15-May-14 22:21

When your dialog contains an image, and it is flickering, then you're doing the drawing at the wrong place in your code. You should place your drawing code in the OnDraw(...) callback. See http://msdn.microsoft.com/en-us/library/e6htdchf.aspx[^]

GOTOs are a bit like wire coat hangers: they tend to breed in the darkness, such that where there once were few, eventually there are many, and the program's architecture collapses beneath them. (Fran Poretto)

Point in case: http://www.infoq.com/news/2014/02/apple_gotofail_lessons[^]

Maximilien14-May-14 4:10

Maximilien

14-May-14 4:10

I'm trying to derive from CMFCPropertyGridColorProperty and cannot override the virtual function because my derived class is not a friend of CMFCPropertyGridCtrl.

Here is a minimal representation of the problem.

C++

class CMFCPropertyGridCtrl 
{
	friend class CMFCPropertyGridColorProperty;

protected:
	CRect m_rectList; // Properies area
};

class CMFCPropertyGridColorProperty
{
	friend class CMFCPropertyGridCtrl;

public:
	virtual void AdjustInPlaceEditRect(CRect& rectEdit, CRect& rectSpin);

protected:
	// back pointer
	CMFCPropertyGridCtrl* m_pWndList;
};

void CMFCPropertyGridColorProperty::AdjustInPlaceEditRect(CRect& rectEdit, CRect& rectSpin)
{
	// original code removed for clarity.

	// access to CMFCPropertyGridCtrl::m_rectList;
	m_pWndList->m_rectList.left += 20;
}

class MyPropertyGrid : public CMFCPropertyGridColorProperty 
{
	virtual void AdjustInPlaceEditRect(CRect& rectEdit, CRect& rectSpin);
};

void MyPropertyGrid::AdjustInPlaceEditRect(CRect& rectEdit, CRect& rectSpin)
{
	// original code removed for clarity.
	// access to CMFCPropertyGridCtrl::m_rectList;
	m_pWndList->m_rectList.left += 40;  // ERROR.
}

trying to compile this, I get the following understandable error :
error C2248: 'CMFCPropertyGridCtrl::m_rectList' : cannot access protected member declared in class 'CMFCPropertyGridCtrl'
1> d:\projects\testfriend\testfriend\testfriend.cpp(21) : see declaration of 'CMFCPropertyGridCtrl::m_rectList'
1> d:\projects\testfriend\testfriend\testfriend.cpp(17) : see declaration of 'CMFCPropertyGridCtrl'

---

I'd like to be able to override the method

virtual void AdjustInPlaceEditRect(CRect& rectEdit, CRect& rectSpin);

void CMFCPropertyGridColorProperty::AdjustInPlaceEditRect(CRect& rectEdit, CRect& rectSpin)
{
	ASSERT_VALID(this);
	ASSERT_VALID(m_pWndList);

	rectSpin.SetRectEmpty();

	rectEdit = m_Rect;
	rectEdit.DeflateRect(0, 2);

	int nMargin = m_pWndList->m_bMarkModifiedProperties && m_bIsModified ? m_pWndList->m_nBoldEditLeftMargin : m_pWndList->m_nEditLeftMargin;

	rectEdit.left = m_pWndList->m_rectList.left + m_pWndList->m_nLeftColumnWidth + m_Rect.Height() + AFX_TEXT_MARGIN - nMargin + 1;

	AdjustButtonRect();
	rectEdit.right = m_rectButton.left;
}

To change the edit box position in the CMFCPropertyGridColorProperty class; but since I do not have access to the CMFCPropertyGridCtrl class (via m_pWndList), I cannot really override it.

Any hints/tips or something else that I might have missed?

Thanks.

Max.

I'd rather be phishing!

Re: Can I properly derive from CMFCPropertyGridColorProperty ?

CPallini14-May-14 6:42

Re: Can I properly derive from CMFCPropertyGridColorProperty ?

14-May-14 6:42

Why don't you inherit from both classes?

Veni, vidi, vici.

Maximilien14-May-14 7:30

Maximilien

14-May-14 7:30

YUCK!!!

A colleague offered the same suggestion.

I tried and it works... but I do not really like it.

I'd rather be phishing!

Re: Can I properly derive from CMFCPropertyGridColorProperty ?

CPallini14-May-14 7:32

Re: Can I properly derive from CMFCPropertyGridColorProperty ?

14-May-14 7:32

Maximilien wrote:
I tried and it works... but I do not really like it.

You will love multiple inheritance. Big Grin | :-D

Veni, vidi, vici.

Maximilien14-May-14 8:02

Maximilien

14-May-14 8:02

Yeah, but ultimately it does not work.

I cannot inherit from both CMFCPropertyGridColorProperty and CMFCPropertyGridCtrl.

The CMFCPropertyGridCtrl is a UI container class containing instances of CMFCPropertyGridProperty.

the CMFCPropertyGridCtrl is constructed before the CMFCPropertyGridProperty are constructed; and if I multiple inherit from CMFCPropertyGridCtrl , there will be 2 "instances" of the class and there should be only one.

I'm still working on something.

I'd rather be phishing!

Re: Can I properly derive from CMFCPropertyGridColorProperty ?

CPallini14-May-14 9:17

14-May-14 9:17

You could make a class inheriting from CMFCPropertyGridCtrl, say MaximilenMFCPropertyGridCtrl which only purpose is being a good friend of MyPropertyGrid.

Veni, vidi, vici.

CFile Error When Writing

AmbiguousName14-May-14 1:52

AmbiguousName

14-May-14 1:52

Hello. I am trying to write some wave data into pcm file. I pass this data and its length to the write function but it raises this exception An unknown error occurred while accessing file ..... file path + name ....
I am using following line code to open this file and write contents into it

CFile* pFile = new CFile;
pFile->Open("Output.pcm", CFile::modeCreate|modeReadWrite);
pFile->Write((void*)pData, dwLength); // exception raised here
pFile->Close();

What could be wrong here? Thanks for any input.

This world is going to explode due to international politics, SOON.

CPallini14-May-14 2:34

14-May-14 2:34

Why didn't you check Open return value (see, for instance, the documentation[^])?

Veni, vidi, vici.

AmbiguousName14-May-14 6:57

AmbiguousName

14-May-14 6:57

File opens successfully. It is the Write() function that is raising this exception.

This world is going to explode due to international politics, SOON.

Software_Developer14-May-14 6:36

Software_Developer

14-May-14 6:36

Since the exception is "An unknown error occurred while accessing file ",
Do you still get errors with the unicode syntax _T( ) , e.g CFile file (_T ("File.txt"), CFile::modeReadWrite) );

C++

CFile file;
CFileException e;
if (file.Open (_T ("File.txt"), CFile::modeReadWrite, &e)) {
    // It worked!
      
}
else {
    // Open failed. Tell the user why.
    e.ReportError ();
}

AmbiguousName14-May-14 6:56

AmbiguousName

14-May-14 6:56

The file opens successfully. The problem occurs when I try to write something using it. Please see me code again, I have commented it there as well.

This world is going to explode due to international politics, SOON.

Software_Developer14-May-14 7:27

Software_Developer

14-May-14 7:27

The error should be obvious, the inners of write look like this..

C++

virtual void Write( 
   const void* lpBuf, 
   UINT nCount  
);

Parameters
lpBuf - A pointer to the user-supplied buffer that contains the data to be written to the file.

nCount - The number of bytes to be transferred from the buffer. For text-mode files, carriage return–linefeed pairs are counted as single characters.

Official MSDN example:

C++

CFile cfile;
cfile.Open(_T("Write_File.dat"), CFile::modeCreate |   CFile::modeReadWrite);

char pbufWrite[100];

memset(pbufWrite, 'a', sizeof(pbufWrite));

cfile.Write(pbufWrite, 100);         
cfile.Flush();

http://msdn.microsoft.com/en-us/library/esb6sz20.aspx[^]

Richard MacCutchan14-May-14 21:55

Richard MacCutchan

14-May-14 21:55

AmbiguousName wrote:
The file opens successfully.

How can you be sure of that, since you do not check the return status?

leon de boer15-May-14 4:26

leon de boer

15-May-14 4:26

Supercoder has given you the most likely answer although I agree with Richard you haven't conclusively shown the file is open.

If the file doesn't exist you could have a problem because you probably need to open it with
CFile::modeCreate | CFile::modeReadWrite

Stick a debug point on the fail case and check.

For the write you have a single line

=> pFile->Write((void*)pData, dwLength);

Either

1.) pData is not a pointer to an actual array of data
2.) dwLength has not been set or exceeds the data in pData

So all you have to do is work out which of the three things you got wrong and fix it.

If you can't fix it we need to see how you defined pData and where you set dwLength probably.

In vino veritas

modified 15-May-14 10:36am.