get lparam value form the htreeitem c++

Question

I created a dialog with a tree control which fetches data on to a list control when clicked on any particular node of the treecontrol. This is how i tried inserting nodes.

CString *sCommonAppkey = new CString(_szApp + sIsPath);

HTREEITEM hrCommon = m_cTreeCtrl.InsertItem(TVIF_TEXT | TVIF_IMAGE | TVIF_SELECTEDIMAGE | TVIF_PARAM, _T("Common"), icoPlanit, icoPlanit, 0, 0, (LPARAM)(LPCTSTR)sCommonAppkey, NULL, NULL);

When clicked on a node it is being directed to the event handler "OnTvnSelchangedExample" and the data is fetched from the path specified in "lparam" parameter in the insertitem method of HTREEITEM.

void **CExample**::OnTvnSelchangedExample(NMHDR *pNMHDR, LRESULT *pResult)
{
LPNMTREEVIEW pNMTreeView = reinterpret_cast<LPNMTREEVIEW>(pNMHDR);

LPARAM lp = pNMTreeView->itemNew.lParam;

    CString *sTempKey = (CString *)lp;
    CString path = sTempKey->GetBuffer();
}

I can access the lparam value only in the event handler.

Now i want to implement search functionality for the entire tree's data.

so i need the lparam value of all Tree handles sequentially by iterating through it, so that i can search for the specific text in the tree. So without clicking on any node of the tree, is there any possibility to get the lparam value of Tree handle(HTREEITEM)

Answer 1

You can iterate through the tree from the root with TreeView_GetChild, there the handle is the tree handle. To get the handle, call TreeView_GetItem.

TVITEMEX item;
item.mask = TVIF_PARAM;
item.hItem = hrCommon;

TreeView_GetItem(handle_, &item);
CString* text = (CString*)item.lParam;

Answer 2

The tree traversal is easy to implement using recursion:

void CMyTreeCtrl::Iterate(HTREEITEM hItem)
{
    if (hItem)
    {
        // Use the tree node corresponding to hItem
        // .....
        // End of using hItem
        hItem = GetNextItem(hItem, TVGN_CHILD);
        while (hItem)
        {
            Iterate(hItem);
            hItem = GetNextItem(hItem, TVGN_NEXT);
        }
    }
    else
    {
        HTREEITEM hItem = GetNextItem(NULL, TVGN_ROOT);
        while (hItem)
        {
            Iterate(hItem);
            hItem = GetNextItem(hItem, TVGN_NEXT);
        }
    }
}

If you want to get the item data you need to simply call GetItemData(hItem). It returns DWORD_PTR. So in your case you need to cast it to CString*. That's it.

IMPORTANT: In this example CMyTreeCtrl is derived from CTreeCtrl.