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 took RRUZ's code and decided to make a self-contained unit of it, with a derived TListView object that supports multiple editable columns. It also allows you to move between editable items using the arrows, enter and tab.

unit EditableListView;

interface

uses
  Messages,
  Classes, StdCtrls, ComCtrls, System.Types,
  Generics.Collections;

Const
  ELV_EDIT = WM_USER + 16;

type
  TEditableListView = class(TListView)
  private
    FEditable: TList;

    FEditor: TEdit;
    FItem: TListItem;
    FEditColumn: integer;

    procedure EditListView(var AMessage: TMessage); message ELV_EDIT;

    procedure EditExit(Sender: TObject);
    procedure EditKeyDown(Sender: TObject; var Key: Word; Shift: TShiftState);

    procedure DoEdit;

    procedure CleanupEditable;
    function GetEditable(const I: integer): boolean;
    procedure SetEditable(const I: integer; const Value: boolean);
  protected
    procedure Click; override;
    function DoMouseWheel(Shift: TShiftState; WheelDelta: Integer; MousePos: TPoint): Boolean; override;
  public
    constructor Create(AOwner: TComponent); override;
    destructor Destroy; override;

    property Editable[const I: integer]: boolean read GetEditable write SetEditable;
  end;

implementation

uses
  Windows, SysUtils, CommCtrl, Controls;

{ TEditableListView }

constructor TEditableListView.Create(AOwner: TComponent);
begin
  inherited Create(AOwner);

  FEditable := TList.Create;

  FEditor := TEdit.Create(self);
  FEditor.Parent := self;
  FEditor.OnExit := EditExit;
  FEditor.OnKeyDown := EditKeyDown;
  FEditor.Visible := false;

  ViewStyle := vsReport;   // Default to vsReport instead of vsIcon
end;

destructor TEditableListView.Destroy;
begin
  FEditable.Free;

  inherited Destroy;
end;

procedure TEditableListView.DoEdit;
begin
  if Assigned(FItem) Then
  begin
    // assign the value of the TEdit to the Subitem
    if FEditColumn = 0 then
      FItem.Caption := FEditor.Text
    else if FEditColumn > 0 then
      FItem.SubItems[FEditColumn - 1] := FEditor.Text;
  end;
end;

function TEditableListView.DoMouseWheel(Shift: TShiftState; WheelDelta: Integer; MousePos: TPoint): Boolean;
begin
  DoEdit;
  FEditor.Visible := false;
  SetFocus;

  Result := inherited DoMouseWheel(Shift, WheelDelta, MousePos);
end;

procedure TEditableListView.CleanupEditable;
var
  I: integer;
begin
  for I := FEditable.Count - 1 downto 0 do
  begin
    if not Assigned(Columns.FindItemID(FEditable[I])) then
      FEditable.Delete(I);
  end;
end;

procedure TEditableListView.Click;
var
  LPoint: TPoint;
  LVHitTestInfo: TLVHitTestInfo;
begin
  LPoint := ScreenToClient(Mouse.CursorPos);
  FillChar(LVHitTestInfo, SizeOf(LVHitTestInfo), 0);
  LVHitTestInfo.pt := LPoint;
  // Check if the click was made in the column to edit
  if (perform(LVM_SUBITEMHITTEST, 0, LPARAM(@LVHitTestInfo)) <> -1) Then
    PostMessage(self.Handle, ELV_EDIT, LVHitTestInfo.iItem, LVHitTestInfo.iSubItem)
  else
    FEditor.Visible := false; //hide the TEdit

  inherited Click;
end;

procedure TEditableListView.EditExit(Sender: TObject);
begin
  DoEdit;
end;

procedure TEditableListView.EditKeyDown(Sender: TObject; var Key: Word; Shift: TShiftState);
var
  lNextRow, lNextCol: integer;
begin
  if Key in [VK_RETURN, VK_TAB, VK_LEFT, VK_RIGHT, VK_UP, VK_DOWN] then
  begin
    DoEdit;

    lNextRow := FItem.Index;
    lNextCol := FEditColumn;
    case Key of
      VK_RETURN,
      VK_DOWN:
        lNextRow := lNextRow + 1;
      VK_UP:
        lNextRow := lNextRow - 1;
      VK_TAB,
      VK_RIGHT:
        lNextCol := lNextCol + 1;
      VK_LEFT:
        lNextCol := lNextCol - 1;
    end;

    if not ( (Key = VK_RIGHT) and (FEditor.SelStart+FEditor.SelLength < Length(FEditor.Text)) )
   and not ( (Key = VK_LEFT) and (FEditor.SelStart+FEditor.SelLength > 0) ) then
    begin
      Key := 0;

      if (lNextRow >= 0) and (lNextRow < Items.Count)
     and (lNextCol >= 0) and (lNextCol < Columns.Count) then
        PostMessage(self.Handle, ELV_EDIT, lNextRow, lNextCol);
    end;
  end;
end;

procedure TEditableListView.EditListView(var AMessage: TMessage);
var
  LRect: TRect;
begin
  if Editable[AMessage.LParam] then
  begin
    LRect.Top := AMessage.LParam;
    LRect.Left:= LVIR_BOUNDS;
    Perform(LVM_GETSUBITEMRECT, AMessage.wparam, LPARAM(@LRect));
    //get the current Item to edit
    FItem := Items[AMessage.wparam];
    FEditColumn := AMessage.LParam;
    //set the text of the Edit
    if FEditColumn = 0 then
      FEditor.Text := FItem.Caption
    else if FEditColumn > 0 then
      FEditor.Text := FItem.Subitems[FEditColumn-1]
    else
      FEditor.Text := '';
    //set the bounds of the TEdit
    FEditor.BoundsRect := LRect;
    //Show the TEdit
    FEditor.Visible := true;
    FEditor.SetFocus;
    FEditor.SelectAll;
  end
  else
    FEditor.Visible := false;
end;

function TEditableListView.GetEditable(const I: integer): boolean;
begin
  if (I > 0) and (I < Columns.Count) then
    Result := FEditable.IndexOf(Columns[I].ID) >= 0
  else
    Result := false;
  CleanupEditable;
end;

procedure TEditableListView.SetEditable(const I: integer; const Value: boolean);
var
  Lix: integer;
begin
  if (I > 0) and (I < Columns.Count) then
  begin
    Lix := FEditable.IndexOf(Columns[I].ID);
    if Value and (Lix < 0)then
      FEditable.Add(Columns[I].ID)
    else if not Value and (Lix >= 0) then
      FEditable.Delete(Lix);
  end;
  CleanupEditable;
end;

end.

EDIT1: Added detection for mousewheel scroll to exit editing.
EDIT2: Allow for moving the cursor within the edit box with the arrow keys