CODEWITHSUNDEEP
windowsc++11winapitreeview
PinkTurtle
PinkTurtle

Reputation: 7041

How to handle click events on a Windows treeview items

How can I handle individual items being clicked in a MS Windows treeview ?

My windows proc has :

LRESULT CALLBACK WndProcTreeView(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam) {
PAINTSTRUCT paintStruct;
HDC hDC;

switch (message)
{
case WM_PAINT:
{
    hDC = BeginPaint(hwnd, &paintStruct);
    EndPaint(hwnd, &paintStruct);
    break;
}

case WM_NOTIFY:
{
    switch (reinterpret_cast<LPNMHDR>(lParam)->code) {
    case NM_CLICK:
        MessageBox(nullptr, "click", "click", MB_OK);
    }
}
default:
{
    return DefWindowProc(hwnd, message, wParam, lParam);
    break;
}
}

Which outputs a message box when I click on the treeview control. How can I handle individual elements ?

Example of a treeview item being added to the list :

std::string vTxt = std::string("Vertex count : ") + std::to_string(mesh.v.size());
tvinsert.hInsertAfter = mesh_items[mesh_items.size() - 1];
tvinsert.hParent = mesh_items[mesh_items.size() - 1];
tvinsert.item.mask = TVIF_TEXT;
tvinsert.item.pszText = (LPSTR)vTxt.c_str();
mesh_items_sub.push_back((HTREEITEM)SendMessage(hwnd, TVM_INSERTITEM, 0, (LPARAM)&tvinsert));

I have seen using SendDlgItemMessage instead (which gives an ID as LOWORD(wParam) inside the windows proc) but it requires IDs set in a resource file - which I don't know how to create.

Upvotes: 1

Views: 1520

Answers (1)

PinkTurtle
PinkTurtle

Reputation: 7041

Two things I needed for my code to work : first give each item a lparam value and changing TVIF_TEXT as item's mask to TVIF_TEXT | TVIF_IMAGE | TVIF_SELECTEDIMAGE | TVIF_PARAM (TVIF_PARAM allowing for an lparam to be passed to the window proc thus identifying the controller).

Working code excerpt :

TV_INSERTSTRUCT tvinsert;
// ...
tvinsert.hInsertAfter = Root;
tvinsert.hParent = Root;
tvinsert.item.pszText = std::string("some text...").c_str();
tvinsert.item.lParam = ID_SOME_ID; // << #defined constant or plain int
tvinsert.item.mask = TVIF_TEXT | TVIF_IMAGE | TVIF_SELECTEDIMAGE | TVIF_PARAM;
root_sub.push_back((HTREEITEM)SendMessage(hwnd, TVM_INSERTITEM, 0, (LPARAM)&tvinsert));

// window proc code below
LRESULT CALLBACK WndProcTreeView(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam) {
    PAINTSTRUCT paintStruct;
    HDC hDC;

    switch (message)
    {
    case WM_PAINT:
    {
        hDC = BeginPaint(hwnd, &paintStruct);
        EndPaint(hwnd, &paintStruct);
        break;
    }

    case WM_NOTIFY:
    {
        LPNM_TREEVIEW pntv = (LPNM_TREEVIEW)lParam;

        if (pntv->hdr.code == TVN_SELCHANGED) {

            switch (pntv->itemNew.lParam) {

            case ID_SOME_ID:
                std::cout << "ID_SOME_ID selected caught here..." << std::endl;
                break;
            }
        }
    }
    default:
    {
        return DefWindowProc(hwnd, message, wParam, lParam);
        break;
    }
    }

    return 0;
}

Good explanation/example here (in french) http://chgi.developpez.com/windows/treeview/

Upvotes: 1

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