How to show checkbox in TListView header column?

Question

I need to check the box in the header of the TListView column:

I tried the following code:

with CheckBox1 do begin Parent := ListView1; Top := 0; Left := 4; end; 

but the checkbox does not always work properly. How to create a checkbox in the TListView header column correctly?

Answer 1

The following code will add a check box to the list title and show how to handle the click event for it.

Please note that the following code is supported with Windows Vista.

 unit Unit1; interface uses Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, Dialogs, ComCtrls, CommCtrl; type TForm1 = class(TForm) ListView1: TListView; procedure FormCreate(Sender: TObject); private HeaderID: Integer; procedure WMNotify(var AMessage: TWMNotify); message WM_NOTIFY; public { Public declarations } end; var Form1: TForm1; implementation {$R *.dfm} procedure TForm1.WMNotify(var AMessage: TWMNotify); begin if AMessage.NMHdr^.idFrom = HeaderID then if AMessage.NMHdr^.code = HDN_ITEMSTATEICONCLICK then ShowMessage('You have clicked the header check box'); inherited; end; procedure TForm1.FormCreate(Sender: TObject); var HeaderHandle: HWND; HeaderItem: HD_ITEM; HeaderStyle: Integer; begin ListView_SetExtendedListViewStyle(ListView1.Handle, LVS_EX_CHECKBOXES or LVS_EX_FULLROWSELECT); HeaderHandle := ListView_GetHeader(ListView1.Handle); HeaderStyle := GetWindowLong(HeaderHandle, GWL_STYLE); HeaderStyle := HeaderStyle or HDS_CHECKBOXES; SetWindowLong(HeaderHandle, GWL_STYLE, HeaderStyle); HeaderItem.Mask := HDI_FORMAT; Header_GetItem(HeaderHandle, 0, HeaderItem); HeaderItem.fmt := HeaderItem.fmt or HDF_CHECKBOX or HDF_FIXEDWIDTH; Header_SetItem(HeaderHandle, 0, HeaderItem); HeaderID := GetDlgCtrlID(HeaderHandle); end; end. 

Answer 2

If you are targeting Vista or later, TLama's obvious answer. If not, check the box in the header control and not in the list box (again, when TLama commented on the question). The checkbox will send notifications to its parent, the header control, so you need to subclass it. Working sample:

 type TForm1 = class(TForm) ListView1: TListView; procedure FormCreate(Sender: TObject); procedure FormDestroy(Sender: TObject); private FListHeaderWnd: HWND; FListHeaderChk: TCheckBox; FSaveListHeaderWndProc, FListHeaderWndProc: Pointer; procedure ListHeaderWndProc(var Msg: TMessage); end; var Form1: TForm1; implementation uses commctrl; {$R *.dfm} function GetCheckSize: TPoint; // from checklst.pas begin with TBitmap.Create do try Handle := LoadBitmap(0, PChar(OBM_CHECKBOXES)); Result.X := Width div 4; Result.Y := Height div 3; finally Free; end; end; procedure TForm1.FormCreate(Sender: TObject); var CheckSize: TPoint; HeaderSize: TRect; begin ListView1.HandleNeeded; FListHeaderWnd := ListView_GetHeader(ListView1.Handle); FListHeaderChk := TCheckBox.Create(nil); CheckSize := GetCheckSize; FListHeaderChk.Height := CheckSize.X; FListHeaderChk.Width := CheckSize.Y; // the below won't show anything since the form is not visible yet ShowWindow(ListView1.Handle, SW_SHOWNORMAL); // otherwise header is not sized windows.GetClientRect(FListHeaderWnd, HeaderSize); FListHeaderChk.Top := (HeaderSize.Bottom - FListHeaderChk.Height) div 2; FListHeaderChk.Left := FListHeaderChk.Top; FListHeaderChk.Parent := Self; windows.SetParent(FListHeaderChk.Handle, FListHeaderWnd); FListHeaderWndProc := classes.MakeObjectInstance(ListHeaderWndProc); FSaveListHeaderWndProc := Pointer(GetWindowLong(FListHeaderWnd, GWL_WNDPROC)); SetWindowLong(FListHeaderWnd, GWL_WNDPROC, NativeInt(FListHeaderWndProc)); end; procedure TForm1.FormDestroy(Sender: TObject); begin SetWindowLong(FListHeaderWnd, GWL_WNDPROC, NativeInt(FSaveListHeaderWndProc)); classes.FreeObjectInstance(FListHeaderWndProc); FListHeaderChk.Free; end; procedure TForm1.ListHeaderWndProc(var Msg: TMessage); begin if (Msg.Msg = WM_COMMAND) and (HWND(Msg.LParam) = FListHeaderChk.Handle) and (Msg.WParamHi = BN_CLICKED) then begin FListHeaderChk.Checked := not FListHeaderChk.Checked; // code that checks/clears all items end; Msg.Result := CallWindowProc(FSaveListHeaderWndProc, FListHeaderWnd, Msg.Msg, Msg.WParam, Msg.LParam); end; 

Note that if you have “ColumnClick” installed, it looks awkward that the checkbox does not “click” the title button when you click on it.