CODEWITHSUNDEEP
winapimfcatl
MyDeveloperDay
MyDeveloperDay

Reputation: 2670

How do you control the width of the dropdown listbox in a ComboBox

Is there anyway to control the width of the dropdown list of a COMBOBOX in win32?

Upvotes: 3

Views: 2156

Answers (1)

Andrew Truckle
Andrew Truckle

Reputation: 19087

I have a public method in my application class:

void CSoundRotaApp::UpdateComboDroppedWidth(CComboBox& rCombo)
{
    int iWidth = theApp.GetRequiredComboDroppedWidth(rCombo);
    if (iWidth > rCombo.GetDroppedWidth())
        rCombo.SetDroppedWidth(iWidth);
}

Which calls this method:

int CSoundRotaApp::GetRequiredComboDroppedWidth(CComboBox& rCombo)
{
    CString    str;
    CSize      sz;
    int        dx = 0;
    TEXTMETRIC tm;
    CDC*       pDC = rCombo.GetDC();
    CFont*     pFont = rCombo.GetFont();

    // Select the listbox font, save the old font
    CFont* pOldFont = pDC->SelectObject(pFont);
    // Get the text metrics for avg char width
    pDC->GetTextMetrics(&tm);

    for (int i = 0; i < rCombo.GetCount(); i++)
    {
        rCombo.GetLBText(i, str);
        sz = pDC->GetTextExtent(str);

        // Add the avg width to prevent clipping
        sz.cx += tm.tmAveCharWidth;

        if (sz.cx > dx)
            dx = sz.cx;
    }
    // Select the old font back into the DC
    pDC->SelectObject(pOldFont);
    rCombo.ReleaseDC(pDC);

    // Adjust the width for the vertical scroll bar and the left and right border.
    dx += ::GetSystemMetrics(SM_CXVSCROLL) + 2 * ::GetSystemMetrics(SM_CXEDGE);

    return dx;
}

Hope this helps.

Upvotes: 6

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