Ownerdraw listctrl with transparent background and customized items image on WinCE

 Introduction 

  Download ownerDrawList.zip - 4.76 MB  

 Owner-draw listctrl with transparent background and customized items(with checkbox) image on wince

 

Background   

I am developing a media player which should be running on windows embedded compact 7 system with customized hardware. Before this project, I have 0 experience of MFC and last time I did a windows based development was 10 years ago using C++builder. I am now actually a linux developer. Luckily with help of google/codeproject, I finished all things in 2 weeks. The purpose of this article is to help those developers which may have similar situation.

At first since I did not get hardware on hand, I have done all the development on windows desktop environment( windows 7). When I am trying to port code to wince platform, I found that  wince did not support owner-draw listbox which I used to display playlist. Then I turn to use listctrl. I spent a day to convert my code from listbox to listctrl. Thanks again for codeproject.

Using the code

I create a new class MyListCtrl inherited from MFC ListCtrl and adding below features

• ability to set bitmap image for item icon
• ability to set bitmap image for item highlight
• ability to set bitmap image for item checkbox
• ability to be transparent to parent window
• ability to set item height

 Below are corresponding interfaces for setting the image from resource ID

    //set highlight image     
    void SetItemHighlightImg(UINT id); 

    // set item icon
    void SetItemIcon(UINT id); 

    // set image of "Checkbox" in unchecked status
    void SetItemCheckedImg(UINT id);

    // set image of "Checkbox" in checked status
    void SetItemUnCheckedImg(UINT id); 

    // set background
    void SetBk(CDC *pDC); 

The core function for a owner-draw list ctrl is DrawItem

void MyListCtrl::DrawItem( LPDRAWITEMSTRUCT lpDrawItemStruct )
{
    ASSERT(::IsWindow(m_hWnd));
    ASSERT(lpDrawItemStruct != 0);
    CDC* pDC = CDC::FromHandle(lpDrawItemStruct->hDC);
    CRect rcItem(lpDrawItemStruct->rcItem);
    int nItem = lpDrawItemStruct->itemID;

    LV_ITEM lvi;
    lvi.mask = LVIF_STATE;
    lvi.iItem = nItem;
    lvi.iSubItem = 0;
    lvi.stateMask = 0xFFFF;     // get all state flags
    GetItem(&lvi);

    BOOL bHighlight = lvi.state & LVIS_FOCUSED;

    CRect rcBounds;
    GetItemRect(nItem, rcBounds, LVIR_BOUNDS);
    CString sLabel = GetItemText(nItem, 0);

    PaintBk(pDC, rcItem);

    HBITMAP		hbmOldBmp	= NULL;

    CDC bitmapDC;
    bitmapDC.CreateCompatibleDC(pDC);

    
    if (bHighlight)
    {
        hbmOldBmp = (HBITMAP)bitmapDC.SelectObject(m_SelImg);
        pDC->BitBlt(rcItem.left, rcItem.top, rcItem.Width(), rcItem.Height(), &bitmapDC,0,0,SRCCOPY);
        bitmapDC.SelectObject(hbmOldBmp);
    }

    ResConfigRec iRec = SkinConfigMgr::GetResConfig(IDB_IMG_ITEM_ICON);
    hbmOldBmp = (HBITMAP)bitmapDC.SelectObject(m_ItemIcon);
    pDC->BitBlt(rcItem.left + iRec.resX, rcItem.top + iRec.resY, iRec.resW, iRec.resH, &bitmapDC,0,0,SRCCOPY);
    bitmapDC.SelectObject(hbmOldBmp);

    // NOTE: Please replace below code block with your own logic
    // In my implementation, I used std::vector<int> to store checkbox status of each items
    // std::vector<int>* m_pStatusMap
#if 0
    iRec = SkinConfigMgr::GetResConfig(IDB_IMG_ITEM_UC);
    int checked = m_pStatusMap->at(nItem);
    if ((rcItem.left + iRec.resX < bMouseDownPos.x && bMouseDownPos.x < rcItem.left + iRec.resX +iRec.resW)
        &&(rcItem.top + iRec.resY < bMouseDownPos.y && bMouseDownPos.y < rcItem.top + iRec.resY +iRec.resH))
    {
        std::vector<int>::iterator iter = m_pStatusMap->begin()+nItem;
        if (checked == 1)
        {
            *iter = 0;
        }
        else
        {
            *iter = 1;
        }
        checked = *iter;
        bMouseDownPos.x = 0;
        bMouseDownPos.y = 0;
    }
#endif

    CFont font;
    font.CreatePointFont(200, _T("Times New Roman")); 
    pDC->SelectObject(&font);
    pDC->SetTextColor(RGB(255,255,255));
    pDC->DrawText(sLabel,rcItem, DT_CENTER);

    if (checked == 1)
    {
        hbmOldBmp = (HBITMAP)bitmapDC.SelectObject(m_CbChecked);
        pDC->BitBlt(rcItem.left + iRec.resX, rcItem.top + iRec.resY, iRec.resW, iRec.resH, &bitmapDC,0,0,SRCCOPY);
        bitmapDC.SelectObject(hbmOldBmp);
    }
    else
    {
        hbmOldBmp = (HBITMAP)bitmapDC.SelectObject(m_CbUnChecked);
        pDC->BitBlt(rcItem.left + iRec.resX, rcItem.top + iRec.resY, iRec.resW, iRec.resH, &bitmapDC,0,0,SRCCOPY);
        bitmapDC.SelectObject(hbmOldBmp);
    }

}

To change the status of checkbox, we need to handle message ON_WM_LBUTTONDOWN  and record mouse down position

CPoint bMouseDownPos;

void MyListCtrl::OnLButtonDown( UINT nFlags, CPoint point )
{
    bMouseDownPos = point;
    Default();
    int iPos = GetNextItem( -1, LVNI_ALL | LVNI_SELECTED);
    CRect rcItem;
    GetItemRect(iPos, &rcItem, LVIR_BOUNDS);
    // NOTE: replace this code with your own logic
    //ResConfigRec iRec = SkinConfigMgr::GetResConfig(IDB_IMG_ITEM_UC);
    //if ((rcItem.left + iRec.resX < bMouseDownPos.x && bMouseDownPos.x < rcItem.left + iRec.resX +iRec.resW)
     //   &&(rcItem.top + iRec.resY < bMouseDownPos.y && bMouseDownPos.y < rcItem.top + iRec.resY +iRec.resH))
    //{
    //    InvalidateRect(&rcItem);
    //}
}

Points of Interest  

   The usage of MeasureItem to set item height did not work for listctrl. A simple way to set item height is to use a imagelist.

    m_imageList.Create(24, 58, ILC_COLOR4,10,10 );   
    myList.SetImageList(   &m_imageList,   LVSIL_SMALL   );

History 

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