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> WELL, THIS IS THE FUNCTION DRAWING GRAPHIC [...]
Whenever you call CDC::SelectObject(...), you need to store the object that is returned from that function call, and restore it back into the GDI context. Also, deleting a GDI object while it is still Selected into a Device Context (DC) is a bad thing.
My suggestions would be to:
1: Keep track of the objects returned from the call to SelectObject(...), or take a look at the SaveDC(...) and RestoreDC(...) functions. You will need to make sure to restore previously selected objects back into the DC before you delete the CGdiObjects that are currently selected into it.
2: Do not use dynamic memory allocation for the temporary GDI objects you are using (the CPen and CFont objects). Allocate them locally, on the stack, and just reuse them as needed.
Peace!
-=- James.
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Well, I took the idea from a Microsoft Visual C++ example (In the offical book):
void CMyDrawView::SetPenBrush(CDC *pDC, bool bTransparent, UINT nColor)
{
ASSERT(pDC != NULL);
if(bTransparent)
{
m_pBrushOld = (CBrush*)pDC->SelectStockObject(NULL_BRUSH);
}
else
{
m_pBrushOld = (CBrush*)pDC->SelectStockObject(WHITE_BRUSH);
}
ASSERT(m_pBrushOld != NULL);
ASSERT(nColor - ID_COLOR_BLACK >= 0 &&
nColor - ID_COLOR_BLACK <=
(sizeof(arColors) / sizeof(arColors[0])));
m_pPenNew = new CPen(); //------->> here
m_pPenNew->CreatePen(PS_INSIDEFRAME, 0,
arColors[nColor - ID_COLOR_BLACK]);
m_pPenOld = (CPen*)pDC->SelectObject(m_pPenNew);
}
void CMyDrawView::ResetPenBrush(CDC *pDC)
{
ASSERT(pDC != NULL);
pDC->SelectObject(m_pBrushOld);
pDC->SelectObject(m_pPenOld);
delete m_pPenNew; //--------->>>>> here
m_pPenNew = NULL;
m_pPenOld = NULL;
m_pBrushOld = NULL;
}
Which is the solution then?
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> Well, I took the idea from a Microsoft Visual C++ example [...]
> Which is the solution then?
The solution is to never use Microsoft source code as an example of good coding practices (when was the last time you crashed a Microsoft product?)! 
The example code uses dynamic memory allocation because the object is allocated in the scope of one function, and used in the scope of another. While not the best solution, it gets around the scoping problem.
Note, however, that the example code DOES restore the existing objects back into the DC in the ResetPenBrush(..) function. That is what the m_pPenOld and m_pBrushOld are used for.
The original code you posted does not suffer from a scoping problem, so you should be able to use a locally (stack) allocated object.
Peace!
-=- James.
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I've found an interesting article about this. Take a look at: http://www.pgh.net/~newcomer/savedc.htm
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> I've found an interesting article about this.
I have read stuff like tht before. What I am more concerned with, is if your code is working correctly now after making any changes...
Peace!
-=- James.
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I am having a problem with a mailslot. I declared the mailslot and associated file in the initdialog function with no problems. I am writing to the mailslot in a separate function,declared globally, and reading from it in a worker thread. The problem I an having is that in the function where the write is taking place Getmailslotinfo shows that I'm writing to the file with the appropriate message size and messages, but when I go to read the mail slot in the worker thread the info written to the file/mailslot seems to go away. The message size goes from the proper size to 0xfffffff and the number of messages change to zero from one. All of the Handles, DWORDS, etc are global. Anyone have any ideas?
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Hi, I'm new with MFC,, and I have couple pf basic questions
1- CClientDC is called whenever I want to draw something...
2-when do I have to call GetDocument()
3-can I set a value for a variable in my CDoc class, from a dialog box, in OnOk() function
Thanks
Ehsan Behboudi
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1) Typically, if you want to actually render a GDI object of whatever class, you would uses the DC provided by in the OnPaint/OnDraw handlers in the CWnd/CView classes. I rarely use CClientDC, unless I'm getting information related to the dc of a specific window or the system window (CClientDC( NULL ))in order to set up some aspect of the GDI object in question.
2) GetDocument is a CView method which allows the View to access data/functionality in the associated document class. When the View needs to communicate information to, retrieve information from, or in some way affect the Document, it calls GetDocument().
3) Not directly, but you can if you set the code up correctly. However, it does not sound like good codeing practice to me.
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(Also posted on EE...)
I have an interesting problem that I believe is Win2K (Professional) specific...
I am creating a shared memory area using a named MMF. If I create the MMF with a default security descriptor (by using a NULL "SECURITY_ATTRIBUTES" pointer in the call to ::CreateFileMapping), no other processes can open the file mapping object. This occurs regardless of which user creates the file mapping object and which other user tries to open it.
When I try to specify a SECURITY_ATTRIBUTES object with a NULL DACL (so that everyone can get to the object), I get an error of "ERROR_PRIVILEGE_NOT_HELD" from the ::CreateFileMapping call. The only way I can get it to work is to give the IIS user (IWAM_<machinename>) Administrative privileges. Then, the named MMF is created, and all other processes can open it. This, of course, is an unacceptable solution.
(Does anyone know the *specific* privilege that is required to create an object with a NULL DACL? Having a custom local user with this privilege for IIS to use is acceptable.)
I never had this problem under WinNT, so I believe that it is Win2K specific.
Other information: The MMF backed by the paging-file; it is of a fixed size; syncronization is not a issue; multi-CPU system; plenty of free memory and storage; latest platform SDK and documentation.
Hoping to hear from you all...
Peace!
-=- James.
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Hello,
Does anyone know how to impelemt Drag and Drop?
I have a window and some rectangles are draw in it.
How can i move those rectangles inside the window.
I need step by step tutorial and example pls.
tnx.
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Nice Drag'n'drop example was published in Aug'97 issue of MSJ in the "Wicked code" column by Jeff Prosise. It's available online at:
http://msdn.microsoft.com/library/periodic/period97/wicked0897.htm
Tomasz Sowinski -- http://www.shooltz.com.pl
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I require some samples of a tcp/ip sender & a tcp/ip sink. I want to learn the basics of sending & receiving packets of data through tcp/ip.
Just basic code, no connection points or anything.
Thanks.
Gerry.
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There is an example in MSDN called Chatter or something stupid like that - it's a sample client-server CSocket program to let users exchange messages.
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Thanks I'll take alook.
I didn't want to use mfc, just two console apps, it's for a beginners class.
Thanks,
Gerry.
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Hi, I'm having a problem I don't understand. I can't get printerdefaults, and DeviceCapabilities() and DocumentProperties() don't work either. At home everything works fine for my networkprinter, but at work things go wrong. After starting the app, CWinApp::m_hDevMode and CWinApp::m_hDevNames are NULL and stay NULL, suggesting there's no default printer, but there is! Other apps like Word work fine. It's a HP4050TN networkprinter connected directly to a hub and shared on a server through a HP JetDirect port. When I set another networkprinter (connected to workstation through LPT1) as the default printer CWinApp:m_hDevMode and CWinApp::m_hDevNames are properly initialized.
Does anyone have an idea what goes wrong here?
Thanks, Joep
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I had some problems like this, but it dealt with Security Issues regarding user rights.
Gerry.
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Hi !
It may look like a newbie question but ...
I'm implementing a Class into a MFC-extension DLL that handle re-sizable bitset.
The first idea was to use a dynamic array of bitset ( from std::bitset)
the thing is that i cannot acces bitset member and method even if i had the #include <bitset> in my code !!!
If some could help me understand this ???
Thanx all
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> [...] from std::bitset) the thing is that i cannot acces bitset member and
> method even if i had the #include in my code !!!
Please provide an example on how you are trying to access the bitset. Besides, IIRC, the bitset does not resize itself.
Peace!
-=- James.
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I'm facing smiliar problem which related to WM_COPYDATA. Is it possible help me to solve that, anyway, thanks first.
May I ask if I want to pass a bitmap handle (HBITMAP) from a source window to a destination window such that I can display the bitmap in the destination window. How can I deal with that?
My code to SendMessage as follows:
COPYDATASTRUCT dataStruct;
HWND rhwnd; // receiving window handle
HWND shwnd; // sending window handle
// am I wrong in below? Pls point out
dataStruct.dwData=1;
dataStruct.cbData=sizeof(HBITMAP);
dataStruct.lpData=hBitmap;
if (!(rhwnd=::FindWindow(NULL,"Message2")))
AfxMessageBox("Can't find window",MB_OK,0);
else
{
shwnd = (HWND) (this);
::SendMessage(rhwnd,WM_COPYDATA,(WPARAM) shwnd,(LPARAM) &dataStruct);
}
Thank you very much if you can help me.
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I'm facing smiliar problem which related to WM_COPYDATA. Is it possible help me to solve that, anyway, thanks first.
May I ask if I want to pass a bitmap handle (HBITMAP) from a source window to a destination window such that I can display the bitmap in the destination window. How can I deal with that?
My code to SendMessage as follows:
COPYDATASTRUCT dataStruct;
HWND rhwnd; // receiving window handle
HWND shwnd; // sending window handle
// am I wrong in below? Pls point out
dataStruct.dwData=1;
dataStruct.cbData=sizeof(HBITMAP);
dataStruct.lpData=hBitmap;
if (!(rhwnd=::FindWindow(NULL,"Message2")))
AfxMessageBox("Can't find window",MB_OK,0);
else
{
shwnd = (HWND) (this);
::SendMessage(rhwnd,WM_COPYDATA,(WPARAM) shwnd,(LPARAM) &dataStruct);
}
Thank you very much if you can help me.
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I sent you an email reply, but I'll summarize what I said in the email.
Create a struct containing the data you want to send to the other application, and put a (void) pointer to that struct into the lpData field of the COPYDATASTRUCT variable. You can actually send any pointer you want as long as the app know how to handle the pointer. I use the dwData field to indicate what type of struct/pointer I'm sending, and the receiving app traverses a switch statement to determine what to do with the pointer.
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Hi John, I haven't receive your email. Can you send it again or directly go to sly@hkid.com. Thanks so much.
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I've tried to generate a SplitterBar
under the following preconditions: SDI without Document/View Architecture
It didn't work
I used VC++ 6.0, ServicePack5
MFC Wizard
Splitter: Menu Project; Add To Project ; Components..;Visual C++; SplitterBar
Does it work on your PC?
Have you an idea why it doesen't work?
Is there any other Idea how to do it manually?
Greetings
Andrew
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Hi,
I am having trouble keeping a child window maximized within its parent while the parent is resizing.
The child window is a class derived from cwnd and is a member variable of its parent.
The child is created with the dwStyle WS_MAXIMIZE and so starts off maximized. However when the parent is resized the child remains the same.
Is there a way of locking the child in the maximised position?
Or is there a way to direct the WM_SIZE message from the parent to the child?
I would be grateful for any help.
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