C / C++ / MFC

29-Sep-10 1:23

I have a CComboBox control :

CComboBox* pCombo = (CComboBox*)GetDlgItem(IDC_COMBO1);

and here I fill it :

pCombo->AddString("One");
pCombo->AddString("Two");
pCombo->AddString("Three");
pCombo->AddString("Four");
pCombo->AddString("Five");

and here , in drop down state I want to delete an item ( or two ) :

pCombo->ShowDropDown(TRUE);
pCombo->DeleteString(2);
pCombo->DeleteString(3);

my question is : how can I redimension the drop down window to fit remain items ?

I solve this in dirty way :

pCombo->ShowDropDown(FALSE);
pCombo->ShowDropDown(TRUE);

but is not elegant and in some systems flikering ... can you help me ?

Eugen Podsypalnikov29-Sep-10 1:38

29-Sep-10 1:38

Try it reverse Smile | :)

pCombo->DeleteString(2);
pCombo->DeleteString(3);
pCombo->ShowDropDown(TRUE);

They sought it with thimbles, they sought it with care;
They pursued it with forks and hope;
They threatened its life with a railway-share;
They charmed it with smiles and soap. Smile | :)

mesajflaviu29-Sep-10 2:01

29-Sep-10 2:01

Yes , it is an solution , but in my case is imposible : in OnEditupdateCombo1 handler , depends of some conditions , while combo box is allready in drop down state , I insert / remove items ...

Eugen Podsypalnikov29-Sep-10 2:18

29-Sep-10 2:18

Please see the function ::GetComboBoxInfo(..),

you can access the list in this way
and then move it at the new calculated position
(bottom -= GetItemHeight(..)*delCount) Smile | :)

They sought it with thimbles, they sought it with care;
They pursued it with forks and hope;
They threatened its life with a railway-share;
They charmed it with smiles and soap. Smile | :)

mesajflaviu29-Sep-10 2:42

29-Sep-10 2:42

I use VC6 , so I have not access to GetComboBoxInfo method ... but I try to retrieve rect drop down window information with GetDroppedControlRect(...) method ... I write you if I succeed it ! Thank you !

Eugen Podsypalnikov29-Sep-10 2:58

29-Sep-10 2:58

// I use VC6...

It should be possible Smile | :)

//#include <windows.h>
//#pragma comment(lib, "user32.lib")

void CYourDialog::Test()
{
  CComboBox* pcBox = (CComboBox*) GetDlgItem(IDC_COMBO1);
  if (pcBox->GetSafeHwnd()) {
    pcBox->ShowDropDown(TRUE);
    
    COMBOBOXINFO sCBINFO = {0};
    sCBINFO.cbSize = sizeof(COMBOBOXINFO);
    
    if (::GetComboBoxInfo(pcBox->GetSafeHwnd(), &sCBINFO)) {
      if (sCBINFO.hwndList) {
        CWnd* pcList = CWnd::GetFromHandle(sCBINFO.hwndList);
        CRect cListRect;
        pcList->GetWindowRect(cListRect);
        cListRect.bottom -= 20;
        pcList->MoveWindow(cListRect);
      }
    }
  }
}

They sought it with thimbles, they sought it with care;
They pursued it with forks and hope;
They threatened its life with a railway-share;
They charmed it with smiles and soap. Smile | :)

mesajflaviu29-Sep-10 8:14

29-Sep-10 8:14

I will try this , but tomorrow morning , and I will write you . Thank you !

Eugen Podsypalnikov29-Sep-10 10:53

29-Sep-10 10:53

I have tried it too,
you can call the function at any time Smile | :)

void CYourDialog::AdjustComboBox(CComboBox* pcBox)
{
  if (pcBox->GetSafeHwnd()) {    
    COMBOBOXINFO sCBINFO = {0};
    sCBINFO.cbSize = sizeof(COMBOBOXINFO);
    if (::GetComboBoxInfo(pcBox->GetSafeHwnd(), &sCBINFO)) {
      if (sCBINFO.hwndList) {
        CWnd* pcList = CWnd::FromHandle(sCBINFO.hwndList);
        CRect cListRect;
        pcList->GetWindowRect(cListRect);
        // do not worry, the bottom will be correctly adjusted:
        cListRect.bottom = cListRect.top; 
        pcList->MoveWindow(cListRect);
      }
    }
  }
}

They sought it with thimbles, they sought it with care;
They pursued it with forks and hope;
They threatened its life with a railway-share;
They charmed it with smiles and soap. Smile | :)

David Crow29-Sep-10 3:08

David Crow

29-Sep-10 3:08

mesajflaviu wrote:
I use VC6 , so I have not access to GetComboBoxInfo method...

What are you saying? GetComboBoxInfo() has existed since Windows 98, about the same time that VS6 came out.

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mesajflaviu29-Sep-10 8:12

29-Sep-10 8:12

At my method list of CComboBox I have not this method : GetComboBoxInfo() ...

David Crow29-Sep-10 8:16

David Crow

29-Sep-10 8:16

You're letting IntelliSense dictate what you (don't) have access to?

Cool_Dev29-Sep-10 4:18

Cool_Dev

29-Sep-10 4:18

As GetComboBoxInfo requires windows 98 or above, make sure corresponding platform sdk is with you. I think February-2003 version is the last one that can be neatly compiled by VC6 compiler.
Also just ensure that the #define WINVER in your program meets the windows version for GetComboBoxInfo in winuser.h.

mesajflaviu29-Sep-10 8:15

29-Sep-10 8:15

I have not installed any SDK ... this meen I can't solve the problem without SDK ? My VS6 is naked ! Laugh | :laugh:

Rolf Kristensen29-Sep-10 9:44

Rolf Kristensen

29-Sep-10 9:44

// Resize combobox according to actual element count
int m_MaxHeightItems = 10;
int visibleItemCount =  m_MaxHeightItems < nNumEntries ? m_MaxHeightItems : nNumEntries;
CRect rectExpanded;
pCombo->GetClientRect(rectExpanded);
rectExpanded.bottom += visibleItemCount * pCombo->GetItemHeight(0);
rectExpanded.bottom += GetSystemMetrics(SM_CYEDGE) * 2; // top & bottom edges
pCombo->SetWindowPos(NULL,              // not relative to any other windows
                        0, 0,           // TopLeft corner doesn't change
                        rectExpanded.Width(), rectExpanded.Height(),   // existing width, new height
                        SWP_NOMOVE | SWP_NOZORDER       // don't move box or change z-ordering.
                        );

mesajflaviu30-Sep-10 20:09