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Editing Sub-Items in List Control

, 18 May 2001
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Explains how to edit Sub Items in Report style List Control

Introduction

Almost every one of us who are programming in VC++ , will come across the List control. There are many cases where there is a need to represent data in List Control in multiple columns. By default it is not possible to modify the data in the List control itself. In this small article I am putting a simple way to edit any value in any column in a Report style List control. The logic here is simple, whenever user clicks on an sub-item which he wants to modify at that place I am displaying a edit box and allowing to modify the value. Once modified and by clicking the ENTER key, the updated value is set in the List control. Here I am assuming the user is familiar with VC++ and using Class Wizard

Implementation steps:

  1. Using MFC AppWizard, create a Dialog Based application. Give the application name as MultipleColumns. By default the wizard adds OK and Cancel buttons to the Dialog, Remove these two buttons.
  2. Now Add a List-Control and in properties change the style to Report, this style is necessary if we want multiple columns
  3. Add two buttons to the Dialog and name them as OK and Exit
  4. Add one Edit box and in the properties remove the Border style
  5. Using the Class Wizard add the message handlers for the OK and Exit Buttons. Add the following code to those functions
  6. void CMultipleColumnsDlg::OK() 
    {
        CDialog::EndDialog (0); // Add this line
    }
    
    
    void CMultipleColumnsDlg::OnExit() 
    {
        CDialog::EndDialog (0); // Add this line
    }
    
    
  7. Add a function called InsertItems() to the CMulipleColumnsDlg class.
  8. void InsertItems();
    

    In the function handler add the following code

    // This function inserts the default values 
    // into the listControl
    void CMultipleColumnsDlg::InsertItems()
    {
        HWND hWnd = ::GetDlgItem(m_hWnd, IDC_LIST1);
    
        // Set the LVCOLUMN structure with the required 
        // column information
        LVCOLUMN list;
        list.mask =  LVCF_TEXT |LVCF_WIDTH| 
            LVCF_FMT |LVCF_SUBITEM;
        list.fmt = LVCFMT_LEFT;
        list.cx = 50;
        list.pszText   = "S.No";
        list.iSubItem = 0;
        //Inserts the column
        ::SendMessage(hWnd,LVM_INSERTCOLUMN, 
            (WPARAM)0,(WPARAM)&list);
    
        list.cx = 100;
        list.pszText   = "Name";
        list.iSubItem = 1;
        ::SendMessage(hWnd  ,LVM_INSERTCOLUMN, 
            (WPARAM)1,(WPARAM)&list);
    
        list.cx = 100;
        list.pszText   = "Address";
        list.iSubItem = 2;
        ::SendMessage(hWnd  ,LVM_INSERTCOLUMN, 
            (WPARAM)1,(WPARAM)&list);
    
        list.cx = 100;
        list.pszText   = "Country";
        list.iSubItem = 2;
        ::SendMessage(hWnd  ,LVM_INSERTCOLUMN, 
            (WPARAM)1,(WPARAM)&list);
    
        // Inserts first Row with four columns .
        SetCell(hWnd,"1",0,0);
        SetCell(hWnd,"Prabhakar",0,1);
        SetCell(hWnd,"Hyderabad",0,2);
        SetCell(hWnd,"India",0,3);
    
        // Inserts second Row with four columns .
        SetCell(hWnd,"2",1,0);
        SetCell(hWnd,"Uday",1,1); 
        SetCell(hWnd,"Chennai",1,2);
        SetCell(hWnd,"India",1,3);
    
        // Inserts third Row with four columns .
        SetCell(hWnd,"3",2,0);
        SetCell(hWnd,"Saradhi",2,1); 
        SetCell(hWnd,"Bangolore",2,2);
        SetCell(hWnd,"India",2,3);
    
        // Inserts fourth Row with four columns .
        SetCell(hWnd,"4",3,0);
        SetCell(hWnd,"Surya",3,1); 
        SetCell(hWnd,"Calcutta",3,2);
        SetCell(hWnd,"India",3,3);
    }
    
  9. Add another function called SetCell( ) to the CMultipleColumnsDlg class
  10. void SetCell(HWND hWnd1, CString value, int nRow, int nCol);
    

    In the function handler add the following code

    // This function set the text in the specified 
    // SubItem depending on the Row and Column values
    void CMultipleColumnsDlg::SetCell(HWND hWnd1, 
            CString value, int nRow, int nCol)
    {
        TCHAR     szString [256];
        wsprintf(szString,value ,0);
    
        //Fill the LVITEM structure with the 
        //values given as parameters.
        LVITEM lvItem;
        lvItem.mask = LVIF_TEXT;
        lvItem.iItem = nRow;
        lvItem.pszText = szString;
        lvItem.iSubItem = nCol;
        if(nCol >0)
            //set the value of listItem
            ::SendMessage(hWnd1,LVM_SETITEM, 
                (WPARAM)0,(WPARAM)&lvItem);
        else
            //Insert the value into List
            ListView_InsertItem(hWnd1,&lvItem);
    
    }
    
  11. Add one more function called GetItemText() to the same Class
  12. CString GetItemText(HWND hWnd, int nItem, int nSubItem) const;
    

    Inside the function add the following code

    //this function will returns the item 
    //text depending on the item and SubItem Index
    CString CMultipleColumnsDlg::GetItemText(
        HWND hWnd, int nItem, int nSubItem) const
    {
        LVITEM lvi;
        memset(&lvi, 0, sizeof(LVITEM));
        lvi.iSubItem = nSubItem;
        CString str;
        int nLen = 128;
        int nRes;
        do
        {
            nLen *= 2;
            lvi.cchTextMax = nLen;
            lvi.pszText = str.GetBufferSetLength(nLen);
            nRes  = (int)::SendMessage(hWnd, 
                LVM_GETITEMTEXT, (WPARAM)nItem,
                (LPARAM)&lvi);
        } while (nRes == nLen-1);
        str.ReleaseBuffer();
        return str;
    }
    
  13. Also add two member variables to the CMultipleColumnsDlg class which are of type int
  14. int nItem, nSubItem;
    
  15. From the Class wizard add NM_CLICK notification to the List control. Inside the function handler write the following code
  16. //This function Displays an EditBox at the position 
    //where user clicks on a particular SubItem with 
    //Rectangle are equal to the SubItem, thus allows to 
    //modify the value
    void CMultipleColumnsDlg::OnClickList(
            NMHDR* pNMHDR, LRESULT* pResult) 
    {
        Invalidate();
        HWND hWnd1 =  ::GetDlgItem (m_hWnd,IDC_LIST1);
        LPNMITEMACTIVATE temp = (LPNMITEMACTIVATE) pNMHDR;
        RECT rect;
        //get the row number
        nItem = temp->iItem;
        //get the column number
        nSubItem = temp->iSubItem;
        if(nSubItem == 0 || nSubItem == -1 || nItem == -1)
            return ;
        //Retrieve the text of the selected subItem 
        //from the list
        CString str = GetItemText(hWnd1,nItem ,
            nSubItem);
    
        RECT rect1,rect2;
        // this macro is used to retrieve the Rectanle 
        // of the selected SubItem
        ListView_GetSubItemRect(hWnd1,temp->iItem,
            temp->iSubItem,LVIR_BOUNDS,&rect);
        //Get the Rectange of the listControl
        ::GetWindowRect(temp->hdr.hwndFrom,&rect1);
        //Get the Rectange of the Dialog
        ::GetWindowRect(m_hWnd,&rect2);
    
        int x=rect1.left-rect2.left;
        int y=rect1.top-rect2.top;
        
        if(nItem != -1) 
        ::SetWindowPos(::GetDlgItem(m_hWnd,IDC_EDIT1),
            HWND_TOP,rect.left+x,rect.top+4, 
            rect.right-rect.left - 3,
            rect.bottom-rect.top -1,NULL);
        ::ShowWindow(::GetDlgItem(m_hWnd,IDC_EDIT1),SW_SHOW);
        ::SetFocus(::GetDlgItem(m_hWnd,IDC_EDIT1));
        //Draw a Rectangle around the SubItem
        ::Rectangle(::GetDC(temp->hdr.hwndFrom),
            rect.left,rect.top-1,rect.right,rect.bottom);
        //Set the listItem text in the EditBox
        ::SetWindowText(::GetDlgItem(m_hWnd,IDC_EDIT1),str);
        *pResult = 0;
    }
    
    
  17. To handle the ENTER key we need to write the virtual function OnOk in the MultipleColumnsDlg.h, so add the following as protected member
  18. afx_msg void OnOK();
    

    In MultipleColumnsDlg.cpp write the following code.

    // This function handles the ENTER key 
    void CMultipleColumnsDlg::OnOK() 
    {   
        CWnd* pwndCtrl = GetFocus();
        // get the control ID which is 
        // presently having the focus
        int ctrl_ID = pwndCtrl->GetDlgCtrlID();
        CString str;
        switch (ctrl_ID)
        {   //if the control is the EditBox 
            case IDC_EDIT1:
            //get the text from the EditBox
            GetDlgItemText(IDC_EDIT1,str);
    
            //set the value in the listContorl with the
            //specified Item & SubItem values
            SetCell(::GetDlgItem (m_hWnd,IDC_LIST1),
                str,nItem,nSubItem);
    
            ::SendDlgItemMessage(m_hWnd,IDC_EDIT1,
                WM_KILLFOCUS,0,0);
            ::ShowWindow(::GetDlgItem(m_hWnd,IDC_EDIT1),
                SW_HIDE);
                break;     
            default:
                break;
        }
    }
    
    
  19. The last step in the implementation is add the following code in side the OnInitDialog function
  20. 	
    //Set the style to listControl
    ListView_SetExtendedListViewStyle(::GetDlgItem 
            (m_hWnd,IDC_LIST1),LVS_EX_FULLROWSELECT | 
            LVS_EX_GRIDLINES); 
    
    InsertItems();
    ::ShowWindow(::GetDlgItem(m_hWnd,IDC_EDIT1),SW_HIDE);
    

Conclusion

With this I will hope , it will give an idea to edit any sub items in a List control.

License

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About the Author

s.prabhakarreddy

United States United States
Presently working in VisualSoft in VC++ and COM

Comments and Discussions

 
GeneralModifying the content automatically Pinmembermervick19-Dec-03 5:09 
GeneralCan't get the row PinsussRooster24211-Sep-03 10:12 
GeneralRe: Can't get the row PinsussRooster24211-Sep-03 10:22 
GeneralCEdit placement error Pinmemberpelloq111-Apr-03 4:01 
GeneralRe: CEdit placement error PinmemberCarwarlock16-Jun-03 9:09 
GeneralRe: CEdit placement error PinmemberDima Polyakov29-Aug-03 16:01 
GeneralHandling Events PinsussAnonymous24-Oct-02 9:35 
GeneralRe: Handling Events Pinsussquox5-Aug-03 19:12 
GeneralQuestion... PinsussPuiu24-Sep-02 12:23 
QuestionHow to make the text selected PinmemberJohn Wong13-Sep-02 9:55 
AnswerRe: How to make the text selected PinmemberDima Polyakov29-Aug-03 15:58 
GeneralMissing ReleaseDC PinmemberAntony Kancidrowski15-Nov-01 23:40 
GeneralRe: Missing ReleaseDC PinmemberJamie.20-Nov-02 6:46 
GeneralIt needs more flexibility Pinmembera_dyhrberg12-Sep-01 6:40 
GeneralRe: It needs more flexibility PinmemberAnders Dyhrberg12-Sep-01 7:12 
GeneralRe: It needs more flexibility PinmemberDima Polyakov29-Aug-03 15:57 
GeneralFor most flexibility PinmemberHoangLan12-Apr-05 0:55 
GeneralRe: For most flexibility Pinmembermones28-Jul-08 0:40 
GeneralDon't use EndDialog(0) PinmemberChristian Skovdal Andersen19-May-01 4:00 
GeneralUse PostQuitMessage(0) PinmemberHoangLan12-Apr-05 0:43 
GeneralWhy do it in hard ay PinmemberHesham Desokey19-May-01 2:43 
GeneralRe: Why do it in hard ay Pinmemberbennylee22-Jan-02 2:14 
GeneralRe: Why do it in hard ay PinmemberKluch20-Oct-03 12:16 
GeneralMore legible! PinmemberHoangLan12-Apr-05 0:58 

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