Extend List Control with Progress Control

• Download source files - 2.06 KB
• Download demo project - 62.36 KB

Introduction

We want to add a progress control or other controls in the list control sometimes. Traditionally, we could draw these controls using CDC and deal with all messages related to the controls, but it's fairly complex.

This article discusses a method which embeds controls to the list control directly, so we need not draw it, and can manipulate it using predefined MFC classes.

Create Progress Controls Using Custom Draw

If you are not familiar with custom draw, you could read this article. It's a great article about custom draw.

1. We create a class named CProListCtrl derived from CListCtrl.
2. Respond to the NM_CUSTOMDRAW in CProListCtrl using notify reflect.
3. We create and display the controls in the post paint stage of the sub item.

void CProListCtrl::OnCustomDraw( NMHDR* pNMHDR, LRESULT* pResult )
{
    NMLVCUSTOMDRAW* pLVCD = (NMLVCUSTOMDRAW*)pNMHDR;

    *pResult = CDRF_DODEFAULT;

    if (CDDS_PREPAINT == pLVCD->nmcd.dwDrawStage)
    {
        *pResult = CDRF_NOTIFYITEMDRAW;
        return;
    }else if (CDDS_ITEMPREPAINT == pLVCD->nmcd.dwDrawStage)
    {
        *pResult = CDRF_NOTIFYSUBITEMDRAW;
        return;
    }else if ( (CDDS_SUBITEM | CDDS_ITEMPREPAINT) == pLVCD->nmcd.dwDrawStage )
    {
        *pResult = CDRF_NOTIFYPOSTPAINT;
        return;
    }else if ( (CDDS_SUBITEM | CDDS_ITEMPOSTPAINT) == pLVCD->nmcd.dwDrawStage )
    {
        int nItem = pLVCD->nmcd.dwItemSpec;
        int nSubItem = pLVCD->iSubItem;
        if (1 != nSubItem)
            return;
        
        CRect rcSubItem;
        this->GetSubItemRect(nItem, nSubItem, LVIR_BOUNDS, rcSubItem);
        
        CProgressCtrl* pCtrl = (CProgressCtrl*)this->GetItemData(nItem);
        if (NULL == pCtrl)
        {
            pCtrl = new CProgressCtrl;
            if (rcSubItem.Width() > 100)
                rcSubItem.right = rcSubItem.left + 100;

            pCtrl->Create(WS_CHILD|WS_VISIBLE|PBS_SMOOTH, rcSubItem, 
                               this, 0x1000 + nItem);
            ASSERT(pCtrl->GetSafeHwnd());
            pCtrl->SetPos( nItem*10 % 100 );
            this->SetItemData(nItem, (DWORD)pCtrl);
        }
            
        if (rcSubItem.Width() > 100)
            rcSubItem.right = rcSubItem.left + 100;
        pCtrl->MoveWindow(rcSubItem);
        pCtrl->ShowWindow(SW_SHOW);
        *pResult = CDRF_SKIPDEFAULT;
        return;
    }
}

Destroy Progress Controls

We should destroy the controls we had created to avoid the memory leak and resource leak. We could do it when list control is destroying.

void CProListCtrl::OnDestroy()
{
    int nCount = this->GetItemCount();
    CProgressCtrl* pCtrl;
    for(int i = 0; i < nCount; i++)
    {
        pCtrl = (CProgressCtrl*)this->GetItemData(i);
        if (NULL != pCtrl)
            delete pCtrl;
        this->SetItemData(i, 0);
    }
}

Redraw and Move the Progress Controls

When the list control is scrolled, or the head item is changed, we must redraw and move the progress controls.

void CProListCtrl::InvalidateProgressCtrls()
{
    int nFirst = GetTopIndex();
    int nLast = nFirst + GetCountPerPage();

    //Hide the other items.
    int nCount = this->GetItemCount();
    CProgressCtrl* pCtrl;
    for(int i = 0; i < nFirst; i++)
    {
        pCtrl = (CProgressCtrl*)this->GetItemData(i);
        if (NULL != pCtrl)
            pCtrl->ShowWindow(SW_HIDE);        
    }
    for(i = nLast; i < nCount; i++)
    {
        pCtrl = (CProgressCtrl*)this->GetItemData(i);
        if (NULL != pCtrl)
            pCtrl->ShowWindow(SW_HIDE);        
    }

    //Invalidate
    CRect rc(0,0,0,0);
    CRect rcSubItem;
    for(; nFirst < nLast; nFirst++)
    {
        GetSubItemRect(nFirst, 1, LVIR_BOUNDS, rcSubItem);
        VERIFY( rc.UnionRect(rc, rcSubItem) );
    }

    InvalidateRect(rc);
}

Demo Project

It's a dialog based application that covered all I mentioned in this article. You could inspect it in your environment. Any suggestions are welcome.

History

• 27^th March, 2006: Initial post