始终在TValueListEditor中显示选项下拉列表

Question

我正在尝试通过减少执行某些操作所需的点击次数来改进GUI。但是，一个困扰我的VCL组件是TValueListEditor，它包含一个键和值列表，所有这些都由下拉列表控制。选择选项始终需要三次点击，只需要两次：

此时，最上面一行有焦点，可以使用下拉列表（两次点击）更改值。但是，当用户想要编辑不同的密钥时，他首先必须将焦点更改为该密钥才能使用下拉列表（三次点击）。

有没有办法在所有行上显示下拉箭头以防止额外点击？

这是我想要实现的模型示例：

Answer 1

uses
  Vcl.Themes;

type
  TValueListEditor = class(Vcl.ValEdit.TValueListEditor)
  private
    procedure DrawDropDownButton(ACol, ARow: Integer; ARect: TRect;
      AState: TGridDrawState);
    function MouseOverButton(X: Integer): Boolean;
  protected
    procedure DrawCell(ACol, ARow: Integer; ARect: TRect;
      AState: TGridDrawState); override;
    procedure DrawCellHighlight(const ARect: TRect; AState: TGridDrawState;
      ACol, ARow: Integer); override;
    procedure MouseDown(Button: TMouseButton; Shift: TShiftState; X,
      Y: Integer); override;
  end;

{ TValueListEditor }

type
  TInplaceEditListAccess = class(Vcl.Grids.TInplaceEditList);

procedure TValueListEditor.DrawCell(ACol, ARow: Integer; ARect: TRect;
  AState: TGridDrawState);
begin
  inherited DrawCell(ACol, ARow, ARect, AState);
  DrawDropDownButton(ACol, ARow, ARect, AState);
end;

procedure TValueListEditor.DrawCellHighlight(const ARect: TRect;
  AState: TGridDrawState; ACol, ARow: Integer);
var
  R: TRect;
begin
  R := ARect;
  if ItemProps[ARow - FixedRows].HasPickList then
    Dec(R.Right, EditList.ButtonWidth);
  inherited DrawCellHighLight(R, AState, ACol, ARow);
  DrawDropDownButton(ACol, ARow, ARect, AState);
end;

procedure TValueListEditor.DrawDropDownButton(ACol, ARow: Integer;
  ARect: TRect; AState: TGridDrawState);
var
  Details: TThemedElementDetails;
begin
  if (ACol = 1) and (ARow >= FixedRows) and not (gdFocused in AState) and
    ItemProps[ARow - FixedRows].HasPickList then
  begin
    ARect.Left := ARect.Right - EditList.ButtonWidth;
    Details := StyleServices.GetElementDetails(tgDropDownButtonNormal);
    StyleServices.DrawElement(Canvas.Handle, Details, ARect);
  end;
end;

procedure TValueListEditor.MouseDown(Button: TMouseButton; Shift: TShiftState;
  X, Y: Integer);
var
  ACol: Integer;
  ARow: Integer;
begin
  inherited MouseDown(Button, Shift, X, Y);
  MouseToCell(X, Y, ACol, ARow);
  if (Button = mbLeft) and (ARow > FixedRows) and
    ItemProps[ARow - FixedRows].HasPickList and
    not EditList.ListVisible and MouseOverButton(X) then
  begin
    EditorMode := True;
    TInplaceEditListAccess(EditList).DropDown;
  end;
end;

function TValueListEditor.MouseOverButton(X: Integer): Boolean;
begin
  Result := (UseRightToLeftAlignment and (X < EditList.ButtonWidth)) or
    (not UseRightToLeftAlignment and (X > ClientWidth - EditList.ButtonWidth));
end;