ListCtrl in MFC

Hello All,

As per your suggestion, i have been trying to learn MFC and try to replicate the problem i am solving in the legacy code.

I have comeup with the following code:, But the issue here is the list is growing in the opposite direction from what i was expecting !!!

Code:

---

map<int, vector<int>> m = { { 1, {1,3,4 }} ,{ 2, {4,5,6 } } };
map<int, string> n = { { 1, "Site1", } , { 2, "Site2"} ,{ 3, "Site3" },{ 4, "Site4" },{ 5, "Site5" },{ 6, "Site6" } };


BOOL CMFCApplication2Dlg::OnInitDialog()
{


        // TODO: Add extra initialization here

        priya_list.SetExtendedStyle(LVS_EX_FULLROWSELECT | LVS_EX_GRIDLINES | LVS_EX_ONECLICKACTIVATE);

        int nItem = priya_list.InsertColumn(0, _T("Cell"), LVCFMT_LEFT, -1, 0);
        priya_list.InsertColumn(1, _T("Site"), LVCFMT_LEFT, -1, 0);

        int centralsite;
        vector<int> sites;
        bool bIsfirstCentralsite(false);
        for (const auto pair : m)
        {
                bIsfirstCentralsite = true;
                string centreId;
                int index = pair.first;
                if (index == 1)
                {
                        centreId = "first";
                }
                else
                {
                        centreId = "second";
                }

                CString ccetre(centreId.c_str());
                for (const auto site : pair.second)
                {
                        int nItem(0);
                        if(bIsfirstCentralsite)
                                nItem = priya_list.InsertItem(0, ccetre);
                        else
                                nItem = priya_list.InsertItem(0, _T(""));

                        auto itr = n.find(site);
                        string sSiteId = itr->second;
                        CString cSiteId(sSiteId.c_str());
                        priya_list.SetItemText(nItem, 1, cSiteId);

                        bIsfirstCentralsite = false;

                }
        }

}

---

Sorry my code maynot be well written, but i am able to replicate the issue i have.


Attachment 35929

What i wanted is:

Cell Site

first site1
site3
site4

second site4
site5
site6

Basically, first has sites 1,3,4 and second has sites 4,5 ,6

Hope i am able to convey the problem i am facing


thanks a lot

Again, thanks a lot for having patience with my naive questions..

Merry Christmas and Happy new year

Best wishes
Pdk

I don't know MFC, and I last used win32 API when XP was the current OS!

However, for testing I used a vector of pair to simulate the list and displayed to the console. Given:

Code:

---

#include <map>
#include <vector>
#include <string>
#include <iostream>
#include <utility>
#include <iomanip>

using namespace std;

int main()
{
        const map<int, vector<int>> m = {{ 1, {1,3,4 }} ,{ 2, {4,5,6 } }};
        const map<int, string> n = {{ 1, "Site1", } , { 2, "Site2"} ,{ 3, "Site3" },{ 4, "Site4" },{ 5, "Site5" },{ 6, "Site6" }};

        vector<pair<string, string>> output;
        bool bIsfirstCentralsite {false};

        for (const auto pair : m) {
                string centreId;

                bIsfirstCentralsite = true;

                if (pair.first == 1)
                        centreId = "first";
                else
                        centreId = "second";

                for (const auto site : pair.second) {
                        if (bIsfirstCentralsite)
                                output.emplace_back(centreId, "");
                        else
                                output.emplace_back("", "");

                        const auto itr {n.find(site)};

                        if (itr != n.end())
                                output.back().second = itr->second;

                        bIsfirstCentralsite = false;
                }
        }

        for (const auto& out : output)
                cout << left << setw(8) << out.first << setw(8) << out.second << '\n';
}

---

This displays:

Code:

---

first  Site1
        Site3
        Site4
second  Site4
        Site5
        Site6

---

so this algorithm seems OK. The issue would appear to be in use of the list control.

PS It looks like the list is being sorted by site. Are there any sorting criteria set anywhere?

Thankyou so much kaud. Very helpful for me.

Im so grateful for this forum, esp to you being so responsive, being patient and help with every doubt.

I was working in startup where it was 3gpp (i was good in 3gpp) and c++ linux (not good in c++,linux) work, then company was not doing good. So had to find my current job, where it is windows based, not much 3gpp. So there was no strong point for me , in this project. Almost most collegues here are over 20 years exprience, was very difficult for me to ramp up. Without this forum, i wouldnot have survived in this job. Massive thankyou for , allowing me to ask naive questions, and suggestions and help.

Thankyou

nItem = priya_list.InsertItem(0, ccetre);
You're inserting at the beginning of the control. That's that the 0 is doing. You need to insert at the end.
nItem = priya_list.InsertItem(priya_list.GetItemCount(), ccetre);

@GCDEF : Thanks a lot,

Just before you posted, i also found this answer, googling

Code:

---


        SetIcon(m_hIcon, TRUE);                        // Set big icon
        SetIcon(m_hIcon, FALSE);                // Set small icon

        // TODO: Add extra initialization here

        pdk_list.SetExtendedStyle(LVS_EX_FULLROWSELECT | LVS_EX_GRIDLINES | LVS_EX_ONECLICKACTIVATE);

        int nItem = pdk_list.InsertColumn(0, _T("Cell"), LVCFMT_LEFT, -1, 0);
        pdk_list.InsertColumn(1, _T("Site"), LVCFMT_LEFT, -1, 0);

        int centralsite;
        vector<int> sites;
        bool bIsfirstCentralsite(false);
        for (const auto pair : m)
        {
                bIsfirstCentralsite = true;
                string centreId;
                int index = pair.first;
                if (index == 1)
                {
                        centreId = "first";
                }
                else
                {
                        centreId = "second";
                }

                CString ccetre(centreId.c_str());
                for (const auto site : pair.second)
                {
                        int nItem(0);
                        if(bIsfirstCentralsite)
                                nItem = pdk_list.InsertItem(pdk_list.GetItemCount(), ccetre);
                        else
                                nItem = pdk_list.InsertItem(pdk_list.GetItemCount(), _T(""));

                        auto itr = n.find(site);
                        string sSiteId = itr->second;
                        CString cSiteId(sSiteId.c_str());
                        pdk_list.SetItemText(nItem, 1, cSiteId);

                        bIsfirstCentralsite = false;

                }
        }

---

Now the basic GUI looks ok. Trying to add some more functionality:

Actually, on clicking the row, i want to grab the column text. Note, that some rows maynot have the column info.

I have added the code to get the info of the present row. Not sure how to get the corresponding column text.

Code:

---

void CMFCApplication2Dlg::OnBnClickedAddToSiteDB()
{

        CListCtrl * pdk_ctrl = (CListCtrl *) GetDlgItem(IDC_LIST1);

        int nColumns = pdk_ctrl ->GetHeaderCtrl()->GetItemCount();
        POSITION pos = pdk_ctrl ->GetFirstSelectedItemPosition();
        while (pos)
        {
                int nItem = pdk_ctrl ->GetNextSelectedItem(pos);

                for (int i = 0; i<nColumns; i++)
                {
                        CString sItem = pdk_ctrl ->GetItemText(nItem, i);
                        // TO DO: do stuff with item text here
                }
        }
}

---

in the above figue, if click on row which has "site6", i need to get the corresponding column, ie "second", eventhough the column info on that row is not having any info.

Quote:

---

Originally Posted by pdk5

in the above figue, if click on row which has "site6", i need to get the corresponding column, ie "second", eventhough the column info on that row is not having any info.

---

I'm not sure what that means

Quote:

---

Originally Posted by GCDEF

I'm not sure what that means

---

first Site1
Site3
Site4
second Site4
Site5
Site6

Here, Site1, 3, 4, are supposed to have column 1 as "first". So if i select, site1, we know the corresponding column is "site1". Lets say user selects "site3". Then user has to deduce that column 1 is "first", eventhough in the list it appears as no text.

Basically, if user selects, 1st, 2nd or 3rd row, the function needs to derive "first"...And do some processing based on this.

Otherway, is to explicitly store the column info for each rows... But it maynot look nice

The function is something like this:

OnSiteDB{

if(selection is 1st, 2nd or 3rd row)
coulmn_text = "first";

if(selection is 4th, 5th or 6th row)
column_text = "second"
}

Sorry if im trying to complicate things, or asking vague thing.

Possibly not of interest now as you're fixed the MFC issue, but this is WIN32 code to display the data.

Code:

---

#define WIN32_LEAN_AND_MEAN
#define NOMINMAX

#include <windows.h>
#include <CommCtrl.h>

#include <map>
#include <vector>
#include <string>
#include <utility>

using namespace std;

#define WA_STARTUP        (WM_USER + 1)

const int g_col1sz {200};
const int g_col2sz {200};
const char* const cnam {"myclass"};
const char* const cwin {"mywin"};

HINSTANCE        g_inst {};                        // Current instance
HWND                g_hwndMain {};                // Main window handle
HWND                g_hwndLV {};                // List view window

ATOM                                MyRegisterClass(HINSTANCE hInstance);
HWND                                InitInstance(HINSTANCE, int);
LRESULT CALLBACK        WndProc(HWND, UINT, WPARAM, LPARAM);
bool                                InitCommon();
void                                DoStartup(LPARAM lParam);
void                                DoSize(LPARAM lParam);

const map<int, vector<int>> m {{ 1, {1,3,4 }} ,{ 2, {4,5,6 } }};
const map<int, string> n {{ 1, "Site1", } , { 2, "Site2"} ,{ 3, "Site3" },{ 4, "Site4" },{ 5, "Site5" },{ 6, "Site6" }};

int APIENTRY WinMain(HINSTANCE hInstance, HINSTANCE, LPSTR, int nCmdShow)
{
        if (!InitCommon() || !MyRegisterClass(hInstance) || !(g_hwndMain = InitInstance(hInstance, nCmdShow)))
                return FALSE;

        SendMessage(g_hwndMain, WA_STARTUP, 0, 0);

        MSG msg {};

        while (GetMessage(&msg, nullptr, 0, 0)) {
                TranslateMessage(&msg);
                DispatchMessage(&msg);
        }

        return (int)msg.wParam;
}

bool InitCommon()
{
        INITCOMMONCONTROLSEX icex {};

        InitCommonControls();
        icex.dwSize = sizeof(INITCOMMONCONTROLSEX);
        icex.dwICC = ICC_LISTVIEW_CLASSES;
        return InitCommonControlsEx(&icex);
}

ATOM MyRegisterClass(HINSTANCE hInstance)
{
        WNDCLASSEX cex {0};

        cex.cbSize = sizeof(WNDCLASSEX);
        cex.style = CS_HREDRAW | CS_VREDRAW;
        cex.lpfnWndProc = WndProc;
        cex.hInstance = hInstance;
        cex.hCursor = LoadCursor(NULL, IDC_ARROW);
        cex.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1);
        cex.lpszClassName = cnam;

        return RegisterClassEx(&cex);
}

HWND InitInstance(HINSTANCE hInstance, int nCmdShow)
{
        g_inst = hInstance;

        if (const auto hWnd = CreateWindowEx(0, cnam, cwin, WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, nullptr, nullptr, hInstance, nullptr); hWnd) {
                ShowWindow(hWnd, nCmdShow);
                UpdateWindow(hWnd);
                return hWnd;
        }

        return FALSE;
}

LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
        static LPARAM oldlParam {};

        switch (message) {
                case WA_STARTUP:
                        DoStartup(oldlParam);
                        return TRUE;

                case WM_SIZE:
                        DoSize(oldlParam = lParam);
                        break;

                case WM_DESTROY:
                        PostQuitMessage(0);
                        break;

                case WM_PAINT:
                {
                        PAINTSTRUCT ps;

                        BeginPaint(hWnd, &ps);
                        EndPaint(hWnd, &ps);
                }
                break;

                default:
                        return DefWindowProc(hWnd, message, wParam, lParam);
        }
        return 0;
}

void DoStartup(LPARAM lParam)
{
        if ((g_hwndLV = CreateWindowEx(0, WC_LISTVIEW, "", LVS_REPORT  | WS_CHILD | WS_VISIBLE | WS_TABSTOP | WS_HSCROLL | WS_VSCROLL, 0, 0, 0, 0, g_hwndMain, NULL, g_inst, NULL)) == NULL) {
                MessageBox(0, "Issue creating ListView control", "Error", MB_OK | MB_ICONERROR);
                return;
        }

        DoSize(lParam);
        ShowWindow(g_hwndLV, SW_SHOW);

        LVCOLUMN lvc {};

        lvc.mask = LVCF_FMT | LVCF_WIDTH | LVCF_TEXT;
        lvc.pszText = "cell";
        lvc.cx = g_col1sz;
        lvc.fmt = LVCFMT_LEFT;

        if (ListView_InsertColumn(g_hwndLV, 0, &lvc) < 0) {
                MessageBox(0, "ListView InsertColumn failed!", "Error", MB_OK | MB_ICONERROR);
                return;
        }

        lvc.pszText = "site";
        lvc.cx = g_col2sz;

        if (ListView_InsertColumn(g_hwndLV, 1, &lvc) < 0) {
                MessageBox(0, "ListView InsertColumn failed!", "Error", MB_OK | MB_ICONERROR);
                return;
        }

        bool bIsfirstCentralsite {};
        LVITEM lvi {};

        lvi.mask = LVIF_TEXT;

        for (const auto& pair : m) {
                const string centreId {pair.first == 1 ? "first" : "second"};

                bIsfirstCentralsite = true;

                for (const auto& site : pair.second) {
                        lvi.pszText = bIsfirstCentralsite ? centreId.c_str() : "";

                        const auto ins {ListView_InsertItem(g_hwndLV, &lvi)};

                        if (const auto itr {n.find(site)}; itr != n.end())
                                ListView_SetItemText(g_hwndLV, ins, 1, (char*)itr->second.c_str());

                        bIsfirstCentralsite = false;
                        ++lvi.iItem;
                }
        }
}


void DoSize(LPARAM lParam)
{
        MoveWindow(g_hwndLV, 0, 0, LOWORD(lParam), HIWORD(lParam), TRUE);
}

---

I understand your selection issue. I'll look into it. I think the answer is to use the LPARAM attribute of LVITEM. I'll try a knock-up later and post here.

Quote:

---

Originally Posted by pdk5

first Site1
Site3
Site4
second Site4
Site5
Site6

Here, Site1, 3, 4, are supposed to have column 1 as "first". So if i select, site1, we know the corresponding column is "site1". Lets say user selects "site3". Then user has to deduce that column 1 is "first", eventhough in the list it appears as no text.

Basically, if user selects, 1st, 2nd or 3rd row, the function needs to derive "first"...And do some processing based on this.

Otherway, is to explicitly store the column info for each rows... But it maynot look nice

The function is something like this:

OnSiteDB{

if(selection is 1st, 2nd or 3rd row)
coulmn_text = "first";

if(selection is 4th, 5th or 6th row)
column_text = "second"
}

Sorry if im trying to complicate things, or asking vague thing.

---

You find an empty second column, then read the previous second column until you find one that's not empty any more.

This is one way to do it using WIN32. This will set the window title to the appropriate Cell name when an item/subitem is left-clicked. The LPARAM member of the listview item is set to the numeric value used for the first column - then its just a simple look up. This avoids searching the list backwards until you find what you want.

Sorry, I can't do it in MFC.

Code:

---

#define WIN32_LEAN_AND_MEAN
#define NOMINMAX

#include <windows.h>
#include <CommCtrl.h>

#include <map>
#include <vector>
#include <string>
#include <utility>

using namespace std;

#define WA_STARTUP        (WM_USER + 1)
#define WA_CLICK        (WM_USER + 2)

const char* const cnam {"myclass"};
const char* const cwin {"mywin"};

HINSTANCE        g_inst {};                        // Current instance
HWND                g_hwndMain {};                // Main window handle
HWND                g_hwndLV {};                // List view window

ATOM                                MyRegisterClass(HINSTANCE hInstance);
HWND                                InitInstance(HINSTANCE, int);
LRESULT CALLBACK        WndProc(HWND, UINT, WPARAM, LPARAM);
bool                                InitCommon();
void                                DoStartup(LPARAM lParam);
void                                DoSize(LPARAM lParam);
void                                LVclick(WPARAM wParam);

const map<int, vector<int>> m {{ 1, {1,3,4 }} ,{ 2, {4,5,6 } }};
const map<int, string> n {{ 1, "Site1", } , { 2, "Site2"} ,{ 3, "Site3" },{ 4, "Site4" },{ 5, "Site5" },{ 6, "Site6" }};
const map<int, string> o {{1, "first"}, {2, "second"}};

int APIENTRY WinMain(HINSTANCE hInstance, HINSTANCE, LPSTR, int nCmdShow)
{
        if (!InitCommon() || !MyRegisterClass(hInstance) || !(g_hwndMain = InitInstance(hInstance, nCmdShow)))
                return FALSE;

        SendMessage(g_hwndMain, WA_STARTUP, 0, 0);

        MSG msg {};

        while (GetMessage(&msg, nullptr, 0, 0)) {
                TranslateMessage(&msg);
                DispatchMessage(&msg);
        }

        return (int)msg.wParam;
}

bool InitCommon()
{
        INITCOMMONCONTROLSEX icex {};

        InitCommonControls();
        icex.dwSize = sizeof(INITCOMMONCONTROLSEX);
        icex.dwICC = ICC_LISTVIEW_CLASSES;
        return InitCommonControlsEx(&icex);
}

ATOM MyRegisterClass(HINSTANCE hInstance)
{
        WNDCLASSEX cex {0};

        cex.cbSize = sizeof(WNDCLASSEX);
        cex.style = CS_HREDRAW | CS_VREDRAW;
        cex.lpfnWndProc = WndProc;
        cex.hInstance = hInstance;
        cex.hCursor = LoadCursor(NULL, IDC_ARROW);
        cex.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1);
        cex.lpszClassName = cnam;

        return RegisterClassEx(&cex);
}

HWND InitInstance(HINSTANCE hInstance, int nCmdShow)
{
        g_inst = hInstance;

        if (const auto hWnd = CreateWindowEx(0, cnam, cwin, WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, nullptr, nullptr, hInstance, nullptr); hWnd) {
                ShowWindow(hWnd, nCmdShow);
                UpdateWindow(hWnd);
                return hWnd;
        }

        return FALSE;
}

LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
        static LPARAM oldlParam {};

        switch (message) {
                case WA_STARTUP:
                        DoStartup(oldlParam);
                        return TRUE;

                case WM_SIZE:
                        DoSize(oldlParam = lParam);
                        break;

                case WM_DESTROY:
                        PostQuitMessage(0);
                        break;

                case WM_PAINT:
                {
                        PAINTSTRUCT ps {};

                        BeginPaint(hWnd, &ps);
                        EndPaint(hWnd, &ps);
                }
                break;

                case WA_CLICK:
                        LVclick(wParam);
                        return TRUE;

                case WM_NOTIFY:
                        if (const auto tc = (LPNMHDR)lParam; (tc->hwndFrom == g_hwndLV) && (tc->code == NM_CLICK)) {
                                LVHITTESTINFO lvhit {};

                                GetCursorPos(&lvhit.pt);
                                ScreenToClient(g_hwndLV, &lvhit.pt);
                                if (ListView_SubItemHitTest(g_hwndLV, &lvhit) >= 0 && (lvhit.flags & LVHT_ONITEM))
                                        PostMessage(g_hwndMain, WA_CLICK, lvhit.iItem, 0);
                                else
                                        SetWindowText(g_hwndMain, "Unknown");
                        }
                        break;


                default:
                        return DefWindowProc(hWnd, message, wParam, lParam);
        }
        return 0;
}

void DoStartup(LPARAM lParam)
{
        if ((g_hwndLV = CreateWindowEx(0, WC_LISTVIEW, "", LVS_REPORT  | WS_CHILD | WS_VISIBLE | WS_TABSTOP | WS_HSCROLL | WS_VSCROLL, 0, 0, 0, 0, g_hwndMain, NULL, g_inst, NULL)) == NULL) {
                MessageBox(0, "Issue creating ListView control", "Error", MB_OK | MB_ICONERROR);
                return;
        }

        LVCOLUMN lvc {};

        lvc.mask = LVCF_FMT | LVCF_WIDTH | LVCF_TEXT;
        lvc.fmt = LVCFMT_LEFT;
        lvc.pszText = "cell";

        if (ListView_InsertColumn(g_hwndLV, 0, &lvc) < 0) {
                MessageBox(0, "ListView InsertColumn failed!", "Error", MB_OK | MB_ICONERROR);
                return;
        }

        lvc.pszText = "site";

        if (ListView_InsertColumn(g_hwndLV, 1, &lvc) < 0) {
                MessageBox(0, "ListView InsertColumn failed!", "Error", MB_OK | MB_ICONERROR);
                return;
        }

        DoSize(lParam);
        ShowWindow(g_hwndLV, SW_SHOW);

        bool bIsfirstCentralsite {};
        LVITEM lvi {};

        lvi.mask = LVIF_TEXT | LVIF_PARAM;

        for (const auto& pair : m) {
                const auto oit {o.find(pair.first)};
                const string centreId {oit != o.end() ? oit->second : "Unknown"};

                bIsfirstCentralsite = true;
                lvi.lParam = pair.first;

                for (const auto& site : pair.second) {
                        lvi.pszText = bIsfirstCentralsite ? centreId.c_str() : "";

                        const auto ins {ListView_InsertItem(g_hwndLV, &lvi)};

                        if (const auto itr {n.find(site)}; itr != n.end())
                                ListView_SetItemText(g_hwndLV, ins, 1, (char*)itr->second.c_str());

                        bIsfirstCentralsite = false;
                        ++lvi.iItem;
                }
        }
}

void DoSize(LPARAM lParam)
{
        ListView_SetColumnWidth(g_hwndLV, 0, LOWORD(lParam) / 2);
        ListView_SetColumnWidth(g_hwndLV, 1, LOWORD(lParam) / 2);
        MoveWindow(g_hwndLV, 0, 0, LOWORD(lParam), HIWORD(lParam), TRUE);
}

void LVclick(WPARAM wParam)
{
        LVITEM        lv {};

        lv.mask = LVIF_PARAM;
        lv.iItem = wParam;

        if (ListView_GetItem(g_hwndLV, &lv))
                if (const auto oit = o.find(lv.lParam); oit != o.end()) {
                        SetWindowText(g_hwndMain, o.find(lv.lParam)->second.c_str());
                        return;
                }

        SetWindowText(g_hwndMain, "bad!");
}

---

Attachment 35930

Thankyou very much kaud, very helpful

That would be way less code in MFC. I didn't read what you're doing, but if you're using SetItemData to set the item number of the appropriate second column value, that would be a more elegant solution than the one I suggested.

Quote:

---

That would be way less code in MFC.

---

Almost certainly! :) But I don't know/have never used MFC :cry:

GCDEF, Could you bit elaborate, on how to use SetItemData in this case ?

Quote:

---

Originally Posted by pdk5

GCDEF, Could you bit elaborate, on how to use SetItemData in this case ?

---

Have you read what SetItemData does? It stores an associated DWORD value with a list control item. If you see an item that has text in the second column store that row number somewhere and use it for the value for SetItemData for subsequent items you insert. When you need to get the second column text, use GetItemData to get the item number that has the second column text to retrieve the text.

Here's the order of evolution:
1) win 32
2) MFC
3) something else

Here's the order of evolution for an MFC list control:
1) items copied into the list control
2) setitemdata/getitemdata (better than 1 previous).
3) virtual list control, essentially binds a list control to a list. Better than all the rest.

Search for Arjay and virtual listcontrol in the forum. I bet I have code examples from 10 years ago.

@Arjay: Thanks a lot

I'll check for the tutorials..

As GCDEF mentioned, i need to use setitemdata/getitemdata. Still working on that, not solved yet. Its taking time for me as this is new area, but slowly getting there ! , with all help and inputs here

Arjay,

I went through one of your examples, but couldnot get anything from that.

I am looking for some simple code, so i can relate and learn. May be expand to practical applications later.

It will also be helpful if i get suggestions for MFC c++ books, for beginners. I want to initially learn simple stuff.

Also the microsoft documentation is not helpful at all, at least for beginners without any MFC knowledge

thanks

For MFC, the 'bible' was 'Programming Windows with MFC' 2nd Edition by Jeff Prosise (1337 pages!). It's quite an old book (1999) but covers the basics. There are other's available (and newer) but I can't comment.

Thankyou very much kaud

Looks like I understood the idea behind the SetItemData and GetItem:

Changed my code to following , but i guess, now i can build my code upon this:

Code:

---


BOOL CMFCApplication2Dlg::OnInitDialog()
{


        // TODO: Add extra initialization here

        priya_list.SetExtendedStyle(LVS_EX_FULLROWSELECT | LVS_EX_GRIDLINES | LVS_EX_ONECLICKACTIVATE);

        int nItem = priya_list.InsertColumn(0, _T("Cell"), LVCFMT_LEFT, -1, 0);
        priya_list.InsertColumn(1, _T("Site"), LVCFMT_LEFT, -1, 0);

        int centralsite;
        vector<int> sites;
        bool bIsfirstCentralsite(false);
        for (const auto pair : m)
        {
                bIsfirstCentralsite = true;
                string centreId;
                int index = pair.first;
                if (index == 1)
                {
                        centreId = "first";
                }
                else
                {
                        centreId = "second";
                }

                CString ccetre(centreId.c_str());
                for (const auto site : pair.second)
                {
                        int nItem(0);
                        if (bIsfirstCentralsite)
                                nItem = priya_list.InsertItem(priya_list.GetItemCount(), ccetre);
                        else
                                nItem = priya_list.InsertItem(priya_list.GetItemCount(), _T(""));

                        auto itr = n.find(site);
                        string sSiteId = itr->second;
                        CString cSiteId(sSiteId.c_str());
                        priya_list.SetItemText(nItem, 1, cSiteId);

                        if (centreId == "first")
                        {
                                priya_list.SetItemData(nItem, (DWORD)(1));
                        }
                        else
                                priya_list.SetItemData(nItem, (DWORD)(2));

                        bIsfirstCentralsite = false;

                }
        }
       
        return TRUE;  // return TRUE  unless you set the focus to a control
}


void CMFCApplication2Dlg::OnBnClickedAddToSiteDB()
{

        CListCtrl * priya_ctrl = (CListCtrl *) GetDlgItem(IDC_LIST1);

        POSITION pos = priya_ctrl->GetFirstSelectedItemPosition();

                int nItem = priya_ctrl->GetNextSelectedItem(pos);

                int centreid = (int)priya_ctrl->GetItemData(nItem);

              // derive the centre id string from this number

}

---

But still not able to understand the virtual list ctrl :cry:

Quote:

---

Originally Posted by pdk5

But still not able to understand the virtual list ctrl :cry:

---

It is much more complicated (especially for beginners) than the trivial list control. Try to find some sample code that will help you to understand it.

Note also that virtual list control make sense if your list contains more than a couple hundred of items.

Thankyou Victor. Google doesnot have some good examples (at least for beginners), so i can get the basic concept.

If the MFC experts in the forum, find some spare time and help me comeup with solution with virtual list, will be great help for me .
Or even if come with other simple example will help me a lot ! :D

Quote:

---

Originally Posted by pdk5

But still not able to understand the virtual list ctrl :cry:

---

See my response in this thread. The lvselstate.,zip attachment is a sample project of a virtual list control.
https://forums.codeguru.com/showthre...01#post1919601

Thanks a lot Arjay.

I tried to load the project with my free version of visual studio 2015. (where i have created some simple sample MFC projects yesterday). But i am getting lot of errors , when trying to build and run this project :ehh:

Attachment 35932

Quote:

---

Originally Posted by pdk5

Thanks a lot Arjay.

I tried to load the project with my free version of visual studio 2015. (where i have created some simple sample MFC projects yesterday). But i am getting lot of errors , when trying to build and run this project :ehh:

Attachment 35932

---

I wrote this sample 16 years ago with VC++ 7.1 so I'm not surprised it doesn't compile. I'll look into updating it to Visual Studio 2019 Community Edition.

I've updated the project to VS2019 (sorry I don't have VS2015 installed, and the 2019 community edition is free, so why not use the latest?).

For something that was written 16 years ago, upgrading it to 2019 was painless, I only had to change the WINVER from 0x0500 to 0x0501.

This was originally an x86 ANSI character set VC 7.1 app, but when it converted to VC2019, it build and ran as UNICODE app. Ordinarily, this would have caused a lot of upgrade headaches, but there were no issues because I used the _T("") macros for string literals throughout (had I simply used "my string" literals, I would have had work to do getting it to compile).

To compile this, you'll need the v142 build tools and MFC v142 libraries.
1) Open the Visual Studio 2019 Installer
2) Select 'Modify'
3) Click on the Individual Components tab
4) Under Compilers, build tools and runtimes, select MSVC v142 - VS 2019 C++ x64/x86 build tools
5) Under SDKs, libraries, and frameworks, select C++ v14.2x MFC for v142 build tools (x86 & x64)

Note: there are multiple versions for v14.2x for step 4 and 5 in each category. I don't know which one is being used and am too lazy to track it down, so I just selected them all.

This sample looks dated and it uses images to display a checkbox rather than using the images built into the list control (which may or may not been available 16 years ago). That was around the XP timeframe and they looked okay back then with the standard Windows theme, but they sure are ugly now.

There is a lot going on in this sample:
1) Uses a virtual list control
a) Uses a callback (via an LVN_GETDISPINFO handler) to retrieve the row data from a list
b) Unlike a regular list control, it doesn't initially get populated by copying row data into the control
c) Virtual list controls can handle large data sets (especially when used with a list that is a memory mapped file).
d) Virtual list controls are very responsive. Try scrolling a virtual list control with 10K items, vs. a regular list control with 10K items - the regular list control will be dog slow
2) Uses a background thread to populate the list control
a) The secondary thread doesn't block the UI thread while filling the list
b) The UI remains responsive while the background operations are performed.
3) While this sample does not show this, the background thread can change the list data, and the virtual list control will pick the changes up without needing to do anything (kind of an early form of control binding).
4) Shows list control row 'hit testing'. Because images are used, we are using ON_NOTIFY, NM_CLICK to check if the user has clicked on the icon that represents the check box. If the 'check box' icon has been clicked on we toggle the check state in the underlying list item, and tell the control to update the item (which causes the LVN_GETDISPINFO callback to be called).

Quote:

---

Originally Posted by pdk5

Looks like I understood the idea behind the SetItemData and GetItem:

Changed my code to following , but i guess, now i can build my code upon this:

Code:

---


BOOL CMFCApplication2Dlg::OnInitDialog()
{


        // TODO: Add extra initialization here

        priya_list.SetExtendedStyle(LVS_EX_FULLROWSELECT | LVS_EX_GRIDLINES | LVS_EX_ONECLICKACTIVATE);

        int nItem = priya_list.InsertColumn(0, _T("Cell"), LVCFMT_LEFT, -1, 0);
        priya_list.InsertColumn(1, _T("Site"), LVCFMT_LEFT, -1, 0);

        int centralsite;
        vector<int> sites;
        bool bIsfirstCentralsite(false);
        for (const auto pair : m)
        {
                bIsfirstCentralsite = true;
                string centreId;
                int index = pair.first;
                if (index == 1)
                {
                        centreId = "first";
                }
                else
                {
                        centreId = "second";
                }

                CString ccetre(centreId.c_str());
                for (const auto site : pair.second)
                {
                        int nItem(0);
                        if (bIsfirstCentralsite)
                                nItem = priya_list.InsertItem(priya_list.GetItemCount(), ccetre);
                        else
                                nItem = priya_list.InsertItem(priya_list.GetItemCount(), _T(""));

                        auto itr = n.find(site);
                        string sSiteId = itr->second;
                        CString cSiteId(sSiteId.c_str());
                        priya_list.SetItemText(nItem, 1, cSiteId);

                        if (centreId == "first")
                        {
                                priya_list.SetItemData(nItem, (DWORD)(1));
                        }
                        else
                                priya_list.SetItemData(nItem, (DWORD)(2));

                        bIsfirstCentralsite = false;

                }
        }
       
        return TRUE;  // return TRUE  unless you set the focus to a control
}


void CMFCApplication2Dlg::OnBnClickedAddToSiteDB()
{

        CListCtrl * priya_ctrl = (CListCtrl *) GetDlgItem(IDC_LIST1);

        POSITION pos = priya_ctrl->GetFirstSelectedItemPosition();

                int nItem = priya_ctrl->GetNextSelectedItem(pos);

                int centreid = (int)priya_ctrl->GetItemData(nItem);

              // derive the centre id string from this number

}

---

---

I don't think you did understand. SetItemData should be an item number, not a hard coded value.

As to the virtual list control, it's been a while for me, but I remember that as being a way to speed up performance of a list control with a lot of data. I'm not seeing how it helps with the OP's problem.

Quote:

---

Originally Posted by GCDEF

As to the virtual list control, it's been a while for me, but I remember that as being a way to speed up performance of a list control with a lot of data. I'm not seeing how it helps with the OP's problem.

---

It's the next evolution of using the list control
1) The first is just copying the data into the control
2) The next is getitemdataptr/setitemdataptr (items are still copied into the control, but a pointer is maintained to point back to the list item)
3) The 3rd is a virtual list control where no data is copied into the control - instead there is a callback to retrieve the data directly from a list.

I'm actually not trying to answer the OP's problem directly (I think that's been done). I'm trying to show essentially that there is more out there. Virtual list controls are kind of like the binding in modern (meaning, non-MFC or QT frameworks). I found it helpful to have understood virtual controls - it helped me understand data binding later on.

Thanks a lot Arjay, for all the help. Very much appreciated. I'll try this today

@GCDEF: May be I didnot code properly.
What i understood is:, SetItemData can hold a reference to the index into the list control and a number. The number can be used later to deduce the first column info.

Is this understanding correct ? Could you comment when you have bit spare time please

Code:

---


        int nItem = priya_list.InsertColumn(0, _T("Cell"), LVCFMT_LEFT, -1, 0);
        priya_list.InsertColumn(1, _T("Site"), LVCFMT_LEFT, -1, 0);

        int centralsite;
        vector<int> sites;
        bool bIsfirstCentralsite(false);
        for (const auto pair : m)
        {
                bIsfirstCentralsite = true;
                string centreId;
                int index = pair.first;
                if (index == 1)
                {
                        centreId = "first";
                }
                else
                {
                        centreId = "second";
                }

                CString ccetre(centreId.c_str());
                for (const auto site : pair.second)
                {
                        int nItem(0);
                        if (bIsfirstCentralsite)
                                nItem = priya_list.InsertItem(priya_list.GetItemCount(), ccetre);
                        else
                                nItem = priya_list.InsertItem(priya_list.GetItemCount(), _T(""));

                        auto itr = n.find(site);
                        string sSiteId = itr->second;
                        CString cSiteId(sSiteId.c_str());
                        priya_list.SetItemText(nItem, 1, cSiteId);

                        priya_list.SetItemData(nItem, (DWORD)(index));

                        bIsfirstCentralsite = false;

                }
        }

---

And to retrieve this :

Code:

---

void CMFCApplication2Dlg::OnBnClickedAddToSiteDB()
{

        CListCtrl * priya_ctrl = (CListCtrl *) GetDlgItem(IDC_LIST1);

        POSITION pos = priya_ctrl->GetFirstSelectedItemPosition();

        int nItem = priya_ctrl->GetNextSelectedItem(pos);

        int centreid = (int)priya_ctrl->GetItemData(nItem);

}

---