In-place editing of a subitem in a TListView

Question

I have a ListView with 3 columns and would like to edit the third column, aka Subitem[1]. If I set ListView.ReadOnly to True, it allows me to edit the caption of the selected it

Answer 1

I wrote sample code on CodeCentral that shows how to do this.

How to use the Build-in Editor of TListView to Edit SubItems

Update:

Here is an updated version that should compile now:

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics,
  Controls, Forms, Dialogs, ComCtrls;

type
  TForm1 = class(TForm)
    ListView1: TListView;
    procedure ListView1Editing(Sender: TObject; Item: TListItem; var AllowEdit: Boolean);
    procedure ListView1Edited(Sender: TObject; Item: TListItem; var S: string);
    procedure ListView1MouseDown(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer);
    procedure ListView1DrawItem(Sender: TCustomListView; Item: TListItem; Rect: TRect; State: TOwnerDrawState);
  private
    { Private declarations }
    ColumnToEdit: Integer;
    OldListViewEditProc: Pointer;
    hListViewEditWnd: HWND;
    ListViewEditWndProcPtr: Pointer;
    procedure ListViewEditWndProc(var Message: TMessage);
  public
    { Public declarations }
    constructor Create(Owner: TComponent); override;
    destructor Destroy; override;
  end;

var
  Form1: TForm1;

implementation

uses
  Commctrl;

{$R *.dfm}

type
  TListViewCoord = record
    Item: Integer;
    Column: Integer;
  end;

  TLVGetColumnAt = function(Item: TListItem; const Pt: TPoint): Integer;
  TLVGetColumnRect = function(Item: TListItem; ColumnIndex: Integer; var Rect: TRect): Boolean;
  TLVGetIndexesAt = function(ListView: TCustomListView; const Pt: TPoint; var Coord: TListViewCoord): Boolean;

  // TCustomListViewAccess provides access to the protected members of TCustomListView
  TCustomListViewAccess = class(TCustomListView);

var
  // these will be assigned according to the version of COMCTL32.DLL being used
  GetColumnAt: TLVGetColumnAt = nil;
  GetColumnRect: TLVGetColumnRect = nil;
  GetIndexesAt: TLVGetIndexesAt = nil;

//---------------------------------------------------------------------------
//  GetComCtl32Version
//
//  Purpose: Helper function to determine the version of CommCtrl32.dll that is loaded.
//---------------------------------------------------------------------------

var
  ComCtl32Version: DWORD = 0;

function GetComCtl32Version: DWORD;
type
  DLLVERSIONINFO = packed record
    cbSize: DWORD;
    dwMajorVersion: DWORD;
    dwMinorVersion: DWORD;
    dwBuildNumber: DWORD;
    dwPlatformID: DWORD;
  end;
  DLLGETVERSIONPROC = function(var dvi: DLLVERSIONINFO): Integer; stdcall;
var
  hComCtrl32: HMODULE;
  lpDllGetVersion: DLLGETVERSIONPROC;
  dvi: DLLVERSIONINFO;
  FileName: array[0..MAX_PATH] of Char;
  dwHandle: DWORD;
  dwSize: DWORD;
  pData: Pointer;
  pVersion: Pointer;
  uiLen: UINT;
begin
  if ComCtl32Version = 0 then
  begin
    hComCtrl32 := GetModuleHandle('comctl32.dll');
    if hComCtrl32 <> 0 then
    begin
      @lpDllGetVersion := GetProcAddress(hComCtrl32, 'DllGetVersion');
      if @lpDllGetVersion <> nil then
      begin
        ZeroMemory(@dvi, SizeOf(dvi));
        dvi.cbSize := SizeOf(dvi);
        if lpDllGetVersion(dvi) >= 0 then
          ComCtl32Version := MAKELONG(Word(dvi.dwMinorVersion), Word(dvi.dwMajorVersion));
      end;
      if ComCtl32Version = 0 then
      begin
        ZeroMemory(@FileName[0], SizeOf(FileName));
        if GetModuleFileName(hComCtrl32, FileName, MAX_PATH) <> 0 then
        begin
          dwHandle := 0;
          dwSize := GetFileVersionInfoSize(FileName, dwHandle);
          if dwSize <> 0 then
          begin
            GetMem(pData, dwSize);
            try
              if GetFileVersionInfo(FileName, dwHandle, dwSize, pData) then
              begin
                pVersion := nil;
                uiLen := 0;
                if VerQueryValue(pData, '\', pVersion, uiLen) then
                begin
                  with PVSFixedFileInfo(pVersion)^ do
                    ComCtl32Version := MAKELONG(LOWORD(dwFileVersionMS), HIWORD(dwFileVersionMS));
                end;
              end;
            finally
              FreeMem(pData);
            end;
          end;
        end;
      end;
    end;
  end;
  Result := ComCtl32Version;
end;

//---------------------------------------------------------------------------
//  Manual_GetColumnAt
//
//  Purpose: Returns the column index at the specified coordinates,
//    relative to the specified item
//---------------------------------------------------------------------------

function Manual_GetColumnAt(Item: TListItem; const Pt: TPoint): Integer;
var
  LV: TCustomListViewAccess;
  R: TRect;
  I: Integer;
begin
  LV := TCustomListViewAccess(Item.ListView);

  // determine the dimensions of the current column value, and
  // see if the coordinates are inside of the column value

  // get the dimensions of the entire item
  R := Item.DisplayRect(drBounds);

  // loop through all of the columns looking for the value that was clicked on
  for I := 0 to LV.Columns.Count-1 do
  begin
    R.Right := (R.Left + LV.Column[I].Width);
    if PtInRect(R, Pt) then
    begin
      Result := I;
      Exit;
    end;
    R.Left := R.Right;
  end;

  Result := -1;
end;

//---------------------------------------------------------------------------
//  Manual_GetColumnRect
//
//  Purpose: Calculate the dimensions of the specified column,
//    relative to the specified item
//---------------------------------------------------------------------------

function Manual_GetColumnRect(Item: TListItem; ColumnIndex: Integer; var Rect: TRect): Boolean;
var
  LV: TCustomListViewAccess;
  I: Integer;
begin
  Result := False;

  LV := TCustomListViewAccess(Item.ListView);

  // make sure the index is in the valid range
  if (ColumnIndex >= 0) and (ColumnIndex < LV.Columns.Count) then
  begin
    // get the dimensions of the entire item
    Rect := Item.DisplayRect(drBounds);

    // loop through the columns calculating the desired offsets
    for I := 0 to ColumnIndex-1 do
      Rect.Left := (Rect.Left + LV.Column[i].Width);
    Rect.Right := (Rect.Left + LV.Column[ColumnIndex].Width);

    Result := True;
  end;
end;

//---------------------------------------------------------------------------
//  Manual_GetIndexesAt
//
//  Purpose: Returns the Item and Column indexes at the specified coordinates
//---------------------------------------------------------------------------

function Manual_GetIndexesAt(ListView: TCustomListView; const Pt: TPoint; var Coord: TListViewCoord): Boolean;
var
  Item: TListItem;
begin
  Result := False;

  Item := ListView.GetItemAt(Pt.x, Pt.y);
  if Item <> nil then
  begin
    Coord.Item := Item.Index;
    Coord.Column := Manual_GetColumnAt(Item, Pt);
    Result := True;
  end;
end;

//---------------------------------------------------------------------------
//  ComCtl_GetColumnAt
//
//  Purpose: Returns the column index at the specified coordinates, relative to the specified item
//---------------------------------------------------------------------------

function ComCtl_GetColumnAt(Item: TListItem; const Pt: TPoint): Integer;
var
  HitTest: LV_HITTESTINFO;
begin
  Result := -1;

  ZeroMemory(@HitTest, SizeOf(HitTest));
  HitTest.pt := Pt;

  if ListView_SubItemHitTest(Item.ListView.Handle, @HitTest) > -1 then
  begin
    if HitTest.iItem = Item.Index then
      Result := HitTest.iSubItem;
  end;
end;

//---------------------------------------------------------------------------
//  ComCtl_GetColumnRect
//
//  Purpose: Calculate the dimensions of the specified column, relative to the specified item
//---------------------------------------------------------------------------

function ComCtl_GetColumnRect(Item: TListItem; ColumnIndex: Integer; var Rect: TRect): Boolean;
begin
  Result := ListView_GetSubItemRect(Item.ListView.Handle, Item.Index, ColumnIndex, LVIR_BOUNDS, @Rect);
end;

//---------------------------------------------------------------------------
//  ComCtl_GetIndexesAt
//
//  Purpose: Returns the Item and Column indexes at the specified coordinates
//---------------------------------------------------------------------------

function ComCtl_GetIndexesAt(ListView: TCustomListView; const Pt: TPoint; var Coord: TListViewCoord): Boolean;
var
  HitTest: LV_HITTESTINFO;
begin
  Result := False;

  ZeroMemory(@HitTest, SizeOf(HitTest));
  HitTest.pt := Pt;

  if ListView_SubItemHitTest(ListView.Handle, @HitTest) > -1 then
  begin
    Coord.Item := HitTest.iItem;
    Coord.Column := HitTest.iSubItem;
    Result := True;
  end;
end;

//---------------------------------------------------------------------------
//  TForm1    Constructor
//
//  Purpose:  Form constructor
//---------------------------------------------------------------------------

constructor TForm1.Create(Owner: TComponent);
begin
  inherited Create(Owner);

  // no editing yet
  ColumnToEdit := -1;
  OldListViewEditProc := nil;
  hListViewEditWnd := 0;

  ListViewEditWndProcPtr := MakeObjectInstance(ListViewEditWndProc);
  if ListViewEditWndProcPtr = nil then
    raise Exception.Create('Could not allocate memory for ListViewEditWndProc proxy');

  if GetComCtl32Version >= DWORD(MAKELONG(70, 4)) then
  begin
    @GetColumnAt := @ComCtl_GetColumnAt;
    @GetColumnRect := @ComCtl_GetColumnRect;
    @GetIndexesAt := @ComCtl_GetIndexesAt;
  end else
  begin
    @GetColumnAt := @Manual_GetColumnAt;
    @GetColumnRect := @Manual_GetColumnRect;
    @GetIndexesAt := @Manual_GetIndexesAt;
  end;
end;

//---------------------------------------------------------------------------
//  TForm1    Destructor
//
//  Purpose:  Form destructor
//---------------------------------------------------------------------------

destructor TForm1.Destroy;
begin
  if ListViewEditWndProcPtr <> nil then
    FreeObjectInstance(ListViewEditWndProcPtr);
  inherited Destroy;
end;

//---------------------------------------------------------------------------
//  ListViewEditWndProc
//
//  Purpose:  Custom Window Procedure for TListView's editor window
//---------------------------------------------------------------------------

procedure TForm1.ListViewEditWndProc(var Message: TMessage);
begin
  if Message.Msg = WM_WINDOWPOSCHANGING then
  begin
    // this inline editor has a bad habit of re-positioning itself
    // back on top of the Caption after every key typed in,
    // so let's stop it from moving
    with TWMWindowPosMsg(Message).WindowPos^ do flags := flags or SWP_NOMOVE;
    Message.Result := 0;
  end else
  begin
    // everything else
    Message.Result := CallWindowProc(OldListViewEditProc, hListViewEditWnd,
      Message.Msg, Message.WParam, Message.LParam);
  end;
end;

//---------------------------------------------------------------------------
//  ListView1DrawItem
//
//  Purpose:  Handler for the TListView::OnDrawItem event
//---------------------------------------------------------------------------

procedure TForm1.ListView1DrawItem(Sender: TCustomListView; Item: TListItem; Rect: TRect; State: TOwnerDrawState);
var
  LV: TCustomListViewAccess;
  R: TRect;
  P: TPoint;
  I: Integer;
  S: String;
begin
  LV := TCustomListViewAccess(Sender);

  // erase the entire item to start fresh
  R := Item.DisplayRect(drBounds);
  LV.Canvas.Brush.Color := LV.Color;
  LV.Canvas.FillRect(R);

  // see if the mouse is currently held down, and if so update the marker as needed
  if (GetKeyState(VK_LBUTTON) and $8000) <> 0 then
  begin
    // find the mouse cursor onscreen, convert the coordinates to client
    // coordinates on the list view
    GetCursorPos(P);
    ColumnToEdit := GetColumnAt(Item, LV.ScreenToClient(P));
  end;

  // loop through all of the columns drawing each column
  for I := 0 to LV.Columns.Count-1 do
  begin
    // determine the dimensions of the current column value
    if not GetColumnRect(Item, I, R) then
      Continue;

    // mimic the default behavior by only drawing a value as highlighted if
    // the entire item is selected, the particular column matches the marker,
    // and the ListView is not already editing
    if Item.Selected and (I = ColumnToEdit) and (not LV.IsEditing) then
    begin
      LV.Canvas.Brush.Color := clHighlight;
      LV.Canvas.Font.Color := clHighlightText;
    end else
    begin
      LV.Canvas.Brush.Color := LV.Color;
      LV.Canvas.Font.Color := LV.Font.Color;
    end;

    LV.Canvas.FillRect(R);

    // draw the column's text
    if I = 0 then
      S := Item.Caption
    else
      S := Item.SubItems[I-1];

    LV.Canvas.TextRect(R, R.Left + 2, R.Top, S);
  end;
end;

//---------------------------------------------------------------------------
//  ListView1Edited
//
//  Purpose:  Handler for the TListView::OnEdited event
//---------------------------------------------------------------------------

procedure TForm1.ListView1Edited(Sender: TObject; Item: TListItem; var S: string);
begin
  // ignore the Caption, let it do its default handling
  if ColumnToEdit <= 0 then Exit;

  // restore the previous window procedure for the inline editor
  if hListViewEditWnd <> 0 then
  begin
    SetWindowLongPtr(hListViewEditWnd, GWL_WNDPROC, LONG_PTR(OldListViewEditProc));
    hListViewEditWnd := 0;
  end;

  // assign the new text to the subitem being edited
  Item.SubItems[ColumnToEdit-1] := S;

  // prevent the default behavior from updating the Caption as well
  S := Item.Caption;
end;

//---------------------------------------------------------------------------
//  ListView1Editing
//
//  Purpose:  Handler for the TListView::OnEditing event
//---------------------------------------------------------------------------

procedure TForm1.ListView1Editing(Sender: TObject; Item: TListItem; var AllowEdit: Boolean);
var
  Wnd: HWND;
  R: TRect;
begin
  // ignore the Caption, let it do its default handling
  if ColumnToEdit <= 0 then Exit;

  // get the inline editor's handle
  Wnd := ListView_GetEditControl(ListView1.Handle);
  if Wnd = 0 then Exit;

  // determine the dimensions of the subitem being edited
  if not GetColumnRect(Item, ColumnToEdit, R) then Exit;

  // move the inline editor over the subitem
  MoveWindow(Wnd, R.Left, R.Top - 2, R.Right-R.Left, (R.Bottom-R.Top) + 4, TRUE);

  // update the inline editor's text with the subitem's text rather than the Caption
  SetWindowText(Wnd, PChar(Item.SubItems[ColumnToEdit-1]));

  // subclass the inline editor so we can catch its movements
  hListViewEditWnd := Wnd;
  OldListViewEditProc := Pointer(GetWindowLongPtr(Wnd, GWL_WNDPROC));
  SetWindowLongPtr(Wnd, GWL_WNDPROC, LONG_PTR(ListViewEditWndProcPtr));
end;

//---------------------------------------------------------------------------
//  ListView1MouseDown
//
//  Purpose:  Handler for the TListView::OnMouseDown event
//---------------------------------------------------------------------------

procedure TForm1.ListView1MouseDown(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer);
var
  Coord: TListViewCoord;
begin
  if GetIndexesAt(ListView1, Point(X, Y), Coord) then
  begin
    if Coord.Column <> ColumnToEdit then
    begin
      // update the marker
      ColumnToEdit := Coord.Column;

      // cancel the editing so that the listview won't go into
      // its edit mode immediately upon clicking the new item
      ListView1.Items[Coord.Item].CancelEdit;

      // update the display with a new highlight selection
      ListView1.Invalidate;
    end;
  end else
    ColumnToEdit := -1;
end;

end.