How to move an item up and down in a wxListCtrl (wxwidgets)

This should be pretty easy but I'm having a heck of a time doing it. Basically I want to move a row in my wxListCtrl up or down. I posted this to wxwidgets forum and got the following code.

m_list->Freeze(); 
wxListItem item; 
item.SetId(item_id); // the one which is selected 
m_list->GetItem(item); // Retrieve the item 
m_list->DeleteItem(item_id); // Remove it 
item.SetId(item_id - 1); // Move it up 
m_list->SetItem(item); // Apply it's new pos in the list 
m_list->Thaw();

which doesn't work. The element is deleted but not moved up (I guess the setitem line is not working). Then I thought to just switch the text and the i开发者_Python百科mage but I can't even get the text from the row reliably. I have

int index = m_right->GetNextItem(-1, wxLIST_NEXT_ALL, wxLIST_STATE_SELECTED);
wxString label = m_right->GetItemText(index);

if(index == 0)
  return;

wxListItem item; 
item.SetId(index); 
bool success = m_right->GetItem(item); 
wxString text = item.GetText();

but text is blank even though there is text and the index is correct. So, I'm stuck not even being able to do the most basic task. Anybody know how to do this? The code runs in a button callback (the user presses a little up arrow and my code executes to try to move it). I'm using 2.9.1 on windows.

I made it work like this with wxWidgets 2.9.3 :

void FileSelectionPanel::OnMoveUp( wxCommandEvent& WXUNUSED(evt) )
{
    int idx = _listCtrl->GetNextItem( -1, wxLIST_NEXT_ALL, wxLIST_STATE_SELECTED );
    if( idx == 0) idx = _listCtrl->GetNextItem( 0, wxLIST_NEXT_ALL, wxLIST_STATE_SELECTED );

    _listCtrl->Freeze();
    while( idx > -1 ) {    
        wxListItem item;
        item.SetId(idx); _listCtrl->GetItem(item);
        item.SetId(idx-1); _listCtrl->InsertItem(item);

        _listCtrl->SetItemData( idx-1, _listCtrl->GetItemData( idx+1 ));
        for( int i = 0; i < _listCtrl->GetColumnCount(); i++ ) {
            _listCtrl->SetItem( idx-1, i, _listCtrl->GetItemText( idx+1, i ));
        }
        _listCtrl->DeleteItem( idx + 1 );
        idx = _listCtrl->GetNextItem( idx-1, wxLIST_NEXT_ALL, wxLIST_STATE_SELECTED );
    }
    _listCtrl->Thaw();
}

The thing I noticed it that wxListItem is more of a convenience struct, for storing state of the view and help pass values into the wxListCtrl "nicely". It is in no way bound to what is actually inside of the wxListCtrl.

Hope this still helps anyone !

Even there is already an answer that is checked. I have the same problem here, but my list is unordered. By looking into wxWidgets' code I found out there is another important information inside the wxListItem object - the mask. I got my reordering to work correctly by setting the mask value to -1, which means that all data shall be copied. This includes the item text as well as other information, like the item data (which was important in my case).

wxListItem item;
item.SetId(item_id);         // set needed id
item.SetMask(-1);            // set needed data
m_list->GetItem(item);       // actually retrieve the item
m_list->DeleteItem(item_id); // remove old copy
item.SetId(item_id - 1);     // move item up
m_list->InsertItem(item);    // insert copy of item

I also had to use "InsertItem" instead of "SetItem". Otherwise, there was no new item inserted, but an existing one overwritten (see also tomcat31's answer).

Is the list ordered? if it is auto ordering it may be ignoring the order you are trying to apply.

From recollection the internal order was not necessarily sequential, you might have to get the index of the previous item and go one before it.