dynamically modifu drop-down combobox

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hi all,

i have a combobox created via the visual designer (not dynamically) and i wanna modify its drop-down liste limit via code. I have to do in that way because in my code i moved the combobox to some place so the dropdown parameter has changed (to zero).

i found some code as below wich make the modification limit possible

C#

void SetDropDownHeight(CComboBox* pMyComboBox, int itemsToShow)
{
    //Get rectangles
    CRect rctComboBox, rctDropDown;
    //Combo rect
    pMyComboBox->GetClientRect(&rctComboBox);
    //DropDownList rect
    pMyComboBox->GetDroppedControlRect(&rctDropDown);

    //Get Item height
    int itemHeight = pMyComboBox->GetItemHeight(-1);
    //Converts coordinates
    pMyComboBox->GetParent()->ScreenToClient(&rctDropDown);
    //Set height
    rctDropDown.bottom = rctDropDown.top + rctComboBox.Height() + itemHeight*itemsToShow;
    //apply changes
    pMyComboBox->MoveWindow(&rctDropDown);
}

the prob : the application crashes when i try to execute this line

C++

SetDropDownHeight(&m_CodeAgence, 5);

thank you

Posted 13-Mar-12 4:22am

Schehaider_Aymen

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Zasky 13-Mar-12 10:29am

How is m_CodeAgence declared?

Nelek 13-Mar-12 14:13pm

And which message do you get when your application steps into the error?

2 solutions

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nv3 · Answer 1 · 2012-03-13T11:55:00

If you have the chance then step with your debugger into the functions and you will see exactly at which point your program crashes.

From just statically looking at your code, my best guess would be that pMyComboBox is an invalid pointer and that you get an access violation.

Second chance is that pMyComboBox points to a CComboBox object, but the m_hWnd in it is not yet initialized, i.e. your dialog initialization has not been completed yet.

Hope that helps you pin-point the problem.

Schehaider_Aymen · Answer 2 · 2012-03-14T03:04:00

Solution 2

After I retrieve a CComboBox from the CWnd related to the ComboBox and worked.

thank you for your answers.

Posted 14-Mar-12 3:04am