Items and Subitems in List-View control

Question

I'm want to use a List-View control to display results of an LDAP search in a "grid". I've written some test code to see how it works, but it's not being displayed as I want. As I understand it, each Item is equivalent to a "row" (using LVS_REPORTstyle), and the Subitem is equivalent to a "column" (e.g. for each item I can display a number of subitems, each in a separate column on the same row).

Here's my test code, currently set to create four columns, with a single Item and four Subitems (corresponding to the four columns). Two functions: one to create the columns, the other to insert items.

int CreateColumns(HWND *hwndlistbox)
{
    wchar_t *cnames[100];
    LVCOLUMN lvc;
    int i;

    cnames[0] = L"column1";
    cnames[1] = L"column2";
    cnames[2] = L"column3";
    cnames[3] = L"column4";
    cnames[4] = NULL;

    lvc.mask = LVCF_FMT | LVCF_WIDTH | LVCF_TEXT | LVCF_SUBITEM;

    for (i = 0; cnames[i] != NULL; i++)
    {
        lvc.iSubItem = i;
        lvc.pszText = cnames[i];
        lvc.cx = 100;
        lvc.fmt = LVCFMT_LEFT;

        ListView_InsertColumn(*hwndlistbox, i, &lvc);
    }

    return i;
}

void InsertItems(HWND *hwndlistbox, int *columncount)
{
    LVITEM lvi;
    wchar_t *items[100];
    int i, j;

    items[0] = L"text1";
    items[1] = L"text2";
    items[2] = L"text3";
    items[3] = L"text4";
    items[4] = NULL;

    lvi.mask = LVIF_TEXT;
    lvi.iItem = 0;

    for (i = 0; i < *columncount; i++)
    {
        lvi.pszText = items[i];
        lvi.iSubItem = i;
        ListView_InsertItem(*hwndlistbox, &lvi);
    }
}

I expect this to generate a single row (lvi.iItem = 0;) with a text string under each column (lvi.iSubItem = i;). This is what it displays instead:

Changing lvi.iSubItem = i to lvi.iSubItem = 0 results in each text string being displayed as a new row in the first column:

I've played around with it, hardcoding the numbers on both iItem and iSubItem, changing both to i, but I can't get it to display the text anywhere other than the first column. What am I doing wrong?

Answer 1

First of all, your cnames and items arrays are declared as array of pointers, but you are not allocating memory for them; you would need to declare them as an array of strings, like wchar_t cnames[100][40];.

Secondly, you need to use ListView_InsertItem to insert an item and set the value for the first column, then use ListView_SetItem to add additional columns, like

lvi.pszText = items[0];
lvi.iSubItem = 0;
ListView_InsertItem(*hwndlistbox, &lvi);
for (i = 1; i < *columncount; i++)
{   lvi.pszText = items[i];
    lvi.iSubItem = i;
    ListView_SetItem(*hwndlistbox, &lvi);
}

Answer 2

Each row shows a single item so you cannot populate the columns by adding items.

As the documentation says:

"You cannot use ListView_InsertItem or LVM_INSERTITEM to insert subitems. The iSubItem member of the LVITEM structure must be zero. See LVM_SETITEM for information on setting subitems."

The LVM_SETITEM documentation explains how to set the text of a sub-item.