create CImagelist for myCComboBoxEx, Debug Assertion Fails, no idea what is wrong?

Question

create CImagelist for myCComboBoxEx, Debug Assertion Fails, no idea what is wrong?

bingbing457 40

i created a class "myCComboBoxEx" derived from CComboBoxEx, and i was trying to create a CImagelist objective for myCComboBoxEx, when it is running, got a run-time-error:

User's image

my code is as following:

...........

//bing, added, create/load the imagelist for the CcomboBoxEx object
	m_imagelist1.Create(30, 30, ILC_COLOR, 2, 2);
	CBitmap m_bitmap_temp;

	m_bitmap_temp.LoadBitmapW(IDB_BITMAP1);
	m_imagelist1.Add(&m_bitmap_temp, (CBitmap*)NULL);
	m_bitmap_temp.Detach();
	m_bitmap_temp.LoadBitmapW(IDB_BITMAP2);
	m_imagelist1.Add(&m_bitmap_temp, (CBitmap*)NULL); //BING, test
	m_bitmap_temp.Detach();
	m_bitmap_temp.LoadBitmapW(IDB_BITMAP3);
	m_imagelist1.Add(&m_bitmap_temp, (CBitmap*)NULL);
	m_bitmap_temp.Detach();
	m_bitmap_temp.LoadBitmapW(IDB_BITMAP4);
	m_imagelist1.Add(&m_bitmap_temp, (CBitmap*)NULL);
	m_bitmap_temp.Detach();
	m_bitmap_temp.LoadBitmapW(IDB_BITMAP5);
	m_imagelist1.Add(&m_bitmap_temp, (CBitmap*)NULL);
	m_bitmap_temp.Detach();
	m_bitmap_temp.LoadBitmapW(IDB_BITMAP6);
	m_imagelist1.Add(&m_bitmap_temp, (CBitmap*)NULL);
	m_bitmap_temp.Detach();
	m_bitmap_temp.LoadBitmapW(IDB_BITMAP7);
	m_imagelist1.Add(&m_bitmap_temp, (CBitmap*)NULL);
	m_bitmap_temp.Detach();
	m_bitmap_temp.LoadBitmapW(IDB_BITMAP8);
	m_imagelist1.Add(&m_bitmap_temp, (CBitmap*)NULL);
	m_bitmap_temp.Detach();

	m_bitmap_temp.DeleteObject(); //bing, to save memory space

	m_comboBoxEx1.SetImageList(&m_imagelist1); //bing, memory leaks？ comboboxex bugs? or limits on images?？??????


	COMBOBOXEXITEM comboboxItem;
	CString  str;

when it runs to here, "Debug Assertion Fails" pops up....l....

m_comboBoxEx1.SetImageList(&m_imagelist1);

i searched so many articles but none of them could answer my question, what should i do?

thanks.

Minxin Yu 13,506 Reputation points Microsoft External Staff

2023-08-24T09:12:40.32+00:00

Is there any update? Did the comment below DDX_Control() solve your problem?
bingbing457 40 Reputation points

2023-08-24T11:17:27.47+00:00

partially, yes. see the accepted answer. thanks

Accepted answer

1 additional answer

Your answer

Minxin Yu 13,506 Reputation points Microsoft External Staff

2023-08-24T09:12:40.32+00:00

Is there any update? Did the comment below DDX_Control() solve your problem?
bingbing457 40 Reputation points

2023-08-24T11:17:27.47+00:00

partially, yes. see the accepted answer. thanks

Answer 1

David Lowndes 2,640 MVP

If you select the Retry option, you'll probably see that the assertion is this one:

_AFXCMN_INLINE CImageList* CComboBoxEx::SetImageList(_In_ CImageList* pImageList)
	{ ASSERT(::IsWindow(m_hWnd)); return CImageList::FromHandle((HIMAGELIST) ::SendMessage(m_hWnd, CBEM_SETIMAGELIST, 0, (LPARAM)pImageList->GetSafeHandle())); }

Which means that at the time you call SetImageList, the combo box window hasn't been created.

bingbing457 40 Reputation points

2023-08-24T11:26:32.9966667+00:00

thanks, you are right, I forgot to do DDX_Control(), and i did not finish downloading all the related files from microsoft servers for debugging though i set up debug in this way:

after adding DDX_Control(), and downloaded all the related files from microsoft servers (took about 15 minutes), it never happened again.

so solved. thanks to you all

Answer 2

RLWA32 49,551

The line in afxcmn2.inl that has the ASSERT is checking for a valid window handle.

It appears that the code is calling CComboBoxEx::SetImageList before the actual window for the control has been created.

It's not clear where the method is being called. For example, calling it from your class constructor will cause this assertion.

bingbing457 40 Reputation points

2023-08-22T15:09:33.8+00:00

"m_comboBoxEx1.SetImageList(&m_imagelist1);" it is called in Ctestccomboboxex3Dlg::OnInitDialog()
David Lowndes 2,640 Reputation points MVP

2023-08-22T15:14:47.8066667+00:00

Ensure that line of code is after you call the base class' OnInitDialog method.
RLWA32 49,551 Reputation points

2023-08-22T15:21:45.8033333+00:00
You probably did not connect your m_comboBoxEx1 variable to a ComboBoxEx control in a dialog template. This is usually handled by the MFC Class Wizard which places the necessary code in the dialog's DoDataExchange method (Dialog Data Exchange). If you are not using a control that has been inserted into the dialog template by the dialog editor then your control variable needs to call its Create method before doing anything else.

For example,

void CMFCComboExTestDlg::DoDataExchange(CDataExchange* pDX) { CDialogEx::DoDataExchange(pDX); DDX_Control(pDX, IDC_COMBOBOXEX1, m_ComboEx); }
bingbing457 40 Reputation points

2023-08-24T11:08:36.43+00:00

thanks, buddy, yes, I also forgot to connect the CComboBoxEx control to myCComboBoxEx objective in DDX_Control(pDX, IDC_COMBOBOXEX1, m_ComboEx), i finally found that the debug "symbles" settings was set up on **microsoft servers (**checked), but the related files were not downloaded, see the answer accepted for this question.
RLWA32 49,551 Reputation points

2023-08-24T11:53:24.4666667+00:00

@bingbing457 So my suggestion to add DDX_Control solved the problem?
bingbing457 40 Reputation points

2023-08-29T16:34:52.58+00:00

i am not very sure if the DDX_CONTROL solved the problem or not, but for sure, my mistake to forget to do DDX.... actually when I tried to derive another Mybutton class from CButton, wrote some code to modify the button background color and text color, similar error window pops up again, then I turned off "owner draw" of the button control in dialog window, the error window did not pop up again, but the button shew only a "normal button", without anychange on background color or text color. may I guess that "owner draw" setting of the button cause this trouble? or some wrong code which can not work in "owner draw" mode?

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create CImagelist for myCComboBoxEx, Debug Assertion Fails, no idea what is wrong?

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