Cannot Access the CDC class members inside the member function of another class?

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The CDC (SetPixel) function cannot be accessible inside the member function of another class.

//OnPerformIBIT is a member function created by me
void CSplitterOne:: OnPerformIBIT()
{

C#

CDC *myDC = GetDlgItem(IDC_PICBOX)->GetDC();

myDC->SetPixel(0, 0, RGB(0,0,0));
myDC->SetPixel(1, 1, RGB(0,0,0));
myDC->SetPixel(2, 2, RGB(0,0,0));
myDC->SetPixel(3, 3, RGB(0,0,0));
myDC->SetPixel(4, 4, RGB(0,0,0));
myDC->SetPixel(5, 5, RGB(0,0,0));
myDC->SetPixel(6, 6, RGB(0,0,0));

}

//In the above function is called from MainFrm.cpp. In the same function I cannot create the object for CDC. It give assertion. I am not get the Handle for Window (hWnd).
If I am do the same in thing in OnPaint() it works. Please Help me.

//CSplitterOne is FormView class.

Posted 8-Mar-13 23:26pm

Rajeshkumar Ramasamy

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Jochen Arndt 9-Mar-13 7:38am

Is IDC_PICBOX a child window of CSplitterOn?

Rajeshkumar Ramasamy 20-Mar-13 8:02am

Yes, IDC_PICBOX is child window of CSplitterOne class.

1 solution

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nv3 · Accepted Answer · 2013-03-09T03:35:00

Solution 1

It looks like you are calling GetDlgItem at a moment when the window has not been created yet. Then it's m_hWnd is still 0 and you run into an ASSERT.

You can easily verify this assumption by testing m_hWnd before calling GetDlgItem.

Posted 9-Mar-13 3:35am

nv3

Comments

Rajeshkumar Ramasamy 12-Mar-13 8:09am

I had Create same form using Splitter Window. I have to call the OnPerformIBIT() function from MainFrm.cpp. I am not got the handle when I am calling from MainFrm.cpp, If I put the same function from OnPaint & OnInitialUpdate, it works. How can i get the window handle if i'm call from Mainfrm.cpp?