begin
    if (Key = VK_DELETE) or ((Key = VK_INSERT) and (ssShift in Shift)) then
      FDataLink.Edit;
  end;
end;

procedure TTntDBMemo.KeyPress(var Key: Char{TNT-ALLOW Char});
begin
  inherited KeyPress(Key);
  if FMemoLoaded then
  begin
    if (Key in [#32..#255]) and (FDataLink.Field <> nil) and
      not FDataLink.Field.IsValidChar(Key) then
    begin
      MessageBeep(0);
      Key := #0;
    end;
    case Key of
      ^H, ^I, ^J, ^M, ^V, ^X, #32..#255:
        FDataLink.Edit;
      #27:
        FDataLink.Reset;
    end;
  end else
  begin
    if Key = #13 then LoadMemo;
    Key := #0;
  end;
end;

procedure TTntDBMemo.Change;
begin
  if FMemoLoaded then FDataLink.Modified;
  FMemoLoaded := True;
  inherited Change;
end;

function TTntDBMemo.GetDataSource: TDataSource;
begin
  Result := FDataLink.DataSource;
end;

procedure TTntDBMemo.SetDataSource(Value: TDataSource);
begin
  if not (FDataLink.DataSourceFixed and (csLoading in ComponentState)) then
    FDataLink.DataSource := Value;
  if Value <> nil then Value.FreeNotification(Self);
end;

function TTntDBMemo.GetDataField: WideString;
begin
  Result := FDataLink.FieldName;
end;

procedure TTntDBMemo.SetDataField(const Value: WideString);
begin
  FDataLink.FieldName := Value;
end;

function TTntDBMemo.GetReadOnly: Boolean;
begin
  Result := FDataLink.ReadOnly;
end;

procedure TTntDBMemo.SetReadOnly(Value: Boolean);
begin
  FDataLink.ReadOnly := Value;
end;

function TTntDBMemo.GetField: TField;
begin
  Result := FDataLink.Field;
end;

procedure TTntDBMemo.LoadMemo;
begin
  if not FMemoLoaded and Assigned(FDataLink.Field) and FieldIsBlobLike(FDataLink.Field) then
  begin
    try
      Lines.Text := GetAsWideString(FDataLink.Field);
      FMemoLoaded := True;
    except
      { Memo too large }
      on E:EInvalidOperation do
        Lines.Text := WideFormat('(%s)', [E.Message]);
    end;
    EditingChange(Self);
  end;
end;

procedure TTntDBMemo.DataChange(Sender: TObject);
begin
  if FDataLink.Field <> nil then
    if FieldIsBlobLike(FDataLink.Field) then
    begin
      if FAutoDisplay or (FDataLink.Editing and FMemoLoaded) then
      begin
        FMemoLoaded := False;
        LoadMemo;
      end else
      begin
        Text := WideFormat('(%s)', [FDataLink.Field.DisplayName]);
        FMemoLoaded := False;
        EditingChange(Self);
      end;
    end else
    begin
      if FFocused and FDataLink.CanModify then
        Text := GetWideText(FDataLink.Field)
      else
        Text := GetWideDisplayText(FDataLink.Field);
      FMemoLoaded := True;
    end
  else
  begin
    if csDesigning in ComponentState then Text := Name else Text := '';
    FMemoLoaded := False;
  end;
  if HandleAllocated then
    RedrawWindow(Handle, nil, 0, RDW_INVALIDATE or RDW_ERASE or RDW_FRAME);
end;

procedure TTntDBMemo.EditingChange(Sender: TObject);
begin
  inherited ReadOnly := not (FDataLink.Editing and FMemoLoaded);
end;

procedure TTntDBMemo.UpdateData(Sender: TObject);
begin
  SetAsWideString(FDataLink.Field, Text);
end;

procedure TTntDBMemo.SetFocused(Value: Boolean);
begin
  if FFocused <> Value then
  begin
    FFocused := Value;
    if not Assigned(FDataLink.Field) or not FieldIsBlobLike(FDataLink.Field) then
      FDataLink.Reset;
  end;
end;

procedure TTntDBMemo.WndProc(var Message: TMessage);
begin
  with Message do
    if (Msg = WM_CREATE) or (Msg = WM_WINDOWPOSCHANGED) or
      (Msg = CM_FONTCHANGED) then FPaintControl.DestroyHandle;
  inherited;
end;

procedure TTntDBMemo.CMEnter(var Message: TCMEnter);
begin
  SetFocused(True);
  inherited;
end;

procedure TTntDBMemo.CMExit(var Message: TCMExit);
begin
  try
    FDataLink.UpdateRecord;
  except
    SetFocus;
    raise;
  end;
  SetFocused(False);
  inherited;
end;

procedure TTntDBMemo.SetAutoDisplay(Value: Boolean);
begin
  if FAutoDisplay <> Value then
  begin
    FAutoDisplay := Value;
    if Value then LoadMemo;
  end;
end;

procedure TTntDBMemo.WMLButtonDblClk(var Message: TWMLButtonDblClk);
begin
  if not FMemoLoaded then LoadMemo else inherited;
end;

procedure TTntDBMemo.WMCut(var Message: TMessage);
begin
  FDataLink.Edit;
  inherited;
end;

procedure TTntDBMemo.WMUndo(var Message: TMessage);
begin
  FDataLink.Edit;
  inherited;
end;

procedure TTntDBMemo.WMPaste(var Message: TMessage);
begin
  FDataLink.Edit;
  inherited;
end;

procedure TTntDBMemo.CMGetDataLink(var Message: TMessage);
begin
  Message.Result := Integer(FDataLink);
end;

procedure TTntDBMemo.WMPaint(var Message: TWMPaint);
var
  S: WideString;
begin
  if not (csPaintCopy in ControlState) then
    inherited
  else begin
    if FDataLink.Field <> nil then
      if FieldIsBlobLike(FDataLink.Field) then
      begin
        if FAutoDisplay then
          S := TntAdjustLineBreaks(GetAsWideString(FDataLink.Field)) else
          S := WideFormat('(%s)', [FDataLink.Field.DisplayName]);
      end else
        S := GetWideDisplayText(FDataLink.Field);
    if (not Win32PlatformIsUnicode) then
      SendMessageA(FPaintControl.Handle, WM_SETTEXT, 0, Integer(PAnsiChar(AnsiString(S))))
    else begin
      SendMessageW(FPaintControl.Handle, WM_SETTEXT, 0, Integer(PWideChar(S)));
    end;
    SendMessage(FPaintControl.Handle, WM_ERASEBKGND, Integer(Message.DC), 0);
    SendMessage(FPaintControl.Handle, WM_PAINT, Integer(Message.DC), 0);
  end;
end;

function TTntDBMemo.ExecuteAction(Action: TBasicAction): Boolean;
begin
  Result := inherited ExecuteAction(Action) or (FDataLink <> nil) and
    FDataLink.ExecuteAction(Action);
end;

function TTntDBMemo.UpdateAction(Action: TBasicAction): Boolean;
begin
  Result := inherited UpdateAction(Action) or (FDataLink <> nil) and
    FDataLink.UpdateAction(Action);
end;

{ TTntDBRadioGroup }

constructor TTntDBRadioGroup.Create(AOwner: TComponent);
begin
  inherited Create(AOwner);
  FDataLink := TFieldDataLink.Create;
  FDataLink.Control := Self;
  FDataLink.OnDataChange := DataChange;
  FDataLink.OnUpdateData := UpdateData;
  FValues := TTntStringList.Create;
end;

destructor TTntDBRadioGroup.Destroy;
begin
  FDataLink.Free;
  FDataLink := nil;
  FValues.Free;
  inherited Destroy;
end;

procedure TTntDBRadioGroup.Notification(AComponent: TComponent;
  Operation: TOperation);
begin
  inherited Notification(AComponent, Operation);
  if (Operation = opRemove) and (FDataLink <> nil) and
    (AComponent = DataSource) then DataSource := nil;
end;

function TTntDBRadioGroup.UseRightToLeftAlignment: Boolean;
begin
  Result := inherited UseRightToLeftAlignment;
end;

procedure TTntDBRadioGroup.DataChange(Sender: TObject);
begin
  if FDataLink.Field <> nil then
    Value := GetWideText(FDataLink.Field) else
    Value := '';
end;

procedure TTntDBRadioGroup.UpdateData(Sender: TObject);
begin
  if FDataLink.Field <> nil then
    SetWideText(FDataLink.Field, Value);
end;

function TTntDBRadioGroup.GetDataSource: TDataSource;
begin
  Result := FDataLink.DataSource;
end;

procedure TTntDBRadioGroup.SetDataSource(Value: TDataSource);
begin
  FDataLink.DataSource := Value;
  if Value <> nil then Value.FreeNotification(Self);
end;

function TTntDBRadioGroup.GetDataField: WideString;
begin
  Result := FDataLink.FieldName;
end;

procedure TTntDBRadioGroup.SetDataField(const Value: WideString);
begin
  FDataLink.FieldName := Value;
end;

function TTntDBRadioGroup.GetReadOnly: Boolean;
begin
  Result := FDataLink.ReadOnly;
end;

procedure TTntDBRadioGroup.SetReadOnly(Value: Boolean);
begin
  FDataLink.ReadOnly := Value;
end;

function TTntDBRadioGroup.GetField: TField;
begin
  Result := FDataLink.Field;
end;

function TTntDBRadioGroup.GetButtonValue(Index: Integer): WideString;
begin
  if (Index < FValues.Count) and (FValues[Index] <> '') then
    Result := FValues[Index]
  else if Index < Items.Count then
    Result := Items[Index]
  else
    Result := '';
end;

procedure TTntDBRadioGroup.SetValue(const Value: WideString);
var
  WasFocused: Boolean;
  I, Index: Integer;
begin
  if FValue <> Value then
  begin
    FInSetValue := True;
    try
      WasFocused := (ItemIndex > -1) and (Buttons[ItemIndex].Focused);
      Index := -1;
      for I := 0 to Items.Count - 1 do
        if Value = GetButtonValue(I) then
        begin
          Index := I;
          Break;
        end;
      ItemIndex := Index;
      // Move the focus rect along with the selected index
      if WasFocused then
        Buttons[ItemIndex].SetFocus;
    finally
      FInSetValue := False;
    end;
    FValue := Value;
    Change;
  end;
end;

procedure TTntDBRadioGroup.CMExit(var Message: TCMExit);
begin
  try
    FDataLink.UpdateRecord;
  except
    if ItemIndex >= 0 then
      (Controls[ItemIndex] as TTntRadioButton).SetFocus else
      (Controls[0] as TTntRadioButton).SetFocus;
    raise;
  end;
  inherited;
end;

procedure TTntDBRadioGroup.CMGetDataLink(var Message: TMessage);
begin
  Message.Result := Integer(FDataLink);
end;

procedure TTntDBRadioGroup.Click;
begin
  if not FInSetValue then
  begin
    inherited Click;
    if ItemIndex >= 0 then Value := GetButtonValue(ItemIndex);
    if FDataLink.Editing then FDataLink.Modified;
  end;
end;

procedure TTntDBRadioGroup.SetItems(Value: TTntStrings);
begin
  Items.Assign(Value);
  DataChange(Self);
end;

procedure TTntDBRadioGroup.SetValues(Value: TTntStrings);
begin
  FValues.Assign(Value);
  DataChange(Self);
end;

procedure TTntDBRadioGroup.Change;
begin
  if Assigned(FOnChange) then FOnChange(Self);
end;

procedure TTntDBRadioGroup.KeyPress(var Key: Char{TNT-ALLOW Char});
begin
  inherited KeyPress(Key);
  case Key of
    #8, ' ': FDataLink.Edit;
    #27: FDataLink.Reset;
  end;
end;

function TTntDBRadioGroup.CanModify: Boolean;
begin
  Result := FDataLink.Edit;
end;

function TTntDBRadioGroup.ExecuteAction(Action: TBasicAction): Boolean;
begin
  Result := inherited ExecuteAction(Action) or (DataLink <> nil) and
    DataLink.ExecuteAction(Action);
end;

function TTntDBRadioGroup.UpdateAction(Action: TBasicAction): Boolean;
begin
  Result := inherited UpdateAction(Action) or (DataLink <> nil) and
    DataLink.UpdateAction(Action);
end;

end.