将 TCombobox 列添加到 Firemonkey TGrid

Question

这个问题似乎已经回答过了，可能是 MonkeyStyler/Mike Sutton，但是，当我使用 Delphi 10 Seattle 时，提供的代码和指南不再起作用。具体

firemonkey grid basics

不起作用，因为 ApplyStyling 事件处理程序现在只调用一次（在列创建时）

我想向 aTGrid 添加一个 TCombobox 或 TComboboxEdit 列。

type
  TComboColumn = Class(TColumn)
  protected
    function CreateCellControl: TStyledControl; override; // works!
  End;

...

Grid1.AddObject(TComboColumn.Create(Grid1)); 

...

    function TComboColumn.CreateCellControl: TStyledControl;
    begin
      Result := TComboBox.Create(Self);
      TComboBox(Result).Items.Add('A');
      TComboBox(Result).Items.Add('B');
      TComboBox(Result).Items.Add('C');
      TComboBox(Result).OnChange := DoTextChanged; // strange hooks
    end;

这会在网格中创建组合框列，但它是每一行中的相同组合框，我不知道如何添加适用于此处的 GetValue 和 SetValue 方法。

Answer 1

你需要做很多事情。开始吧。 首先，您需要声明一些数据类型来存储ComboBox 列的值。

  TComboRecord = record
    FieldValues: array of string;
    ItemSelected: integer;
    function Selected: string;
  end;


...
{ TComboRecord }

function TComboRecord.Selected: string;
begin
  Result := FieldValues[ItemSelected];
end;

并用一些数据填充TList<TComboRecord>。

var
  ComboData: TList<TComboRecord>;
procedure PopulateComboData(Rows: cardinal);

implementation

procedure PopulateComboData(Rows: cardinal);
var
  RowI: cardinal;
  i: cardinal;
  ComR: TComboRecord;
begin
  for RowI := 1 to Rows do
  begin
    Setlength(ComR.FieldValues, random(5) + 1);
    for i := 0 to length(ComR.FieldValues) - 1 do
      ComR.FieldValues[i] := inttostr(random(64000));
    ComR.ItemSelected := 0;
    ComboData.Add(ComR);
  end;
end;

initialization

ComboData := TList<TComboRecord>.Create;

finalization

ComboData.Free;

您需要创建一个TComboBox 方位，以便它可以存储和操作TComboRecord 类型的数据。

  TComboBoxCell = class(TComboBox)
  private
    FComboData: TComboRecord;
    procedure SetComboData(const Value: TComboRecord);
    function GetComboData: TComboRecord;
  protected
    procedure SetData(const Value: TValue); override;
  public
    property ComboData: TComboRecord read GetComboData write SetComboData;
  end;
...

{ TComboBoxCell }


function TComboBoxCell.GetComboData: TComboRecord;
begin
  FComboData.ItemSelected:=ItemIndex;
  result:=FComboData;
end;

procedure TComboBoxCell.SetComboData(const Value: TComboRecord);
var
  s: string;
begin
  FComboData := Value;
  Items.Clear;
  for s in Value.FieldValues do
    Items.Add(s);
  ItemIndex := Value.ItemSelected;
end;

procedure TComboBoxCell.SetData(const Value: TValue);
begin
  inherited;
  ComboData := Value.AsType<TComboRecord>
end;

比你需要继承一个新的类形式TColumn：

  TComboColumn = class(TColumn)
  protected
    procedure DoComboChanged(Sender: TObject);
    function Grid: TComboExtendedGrid; overload;
    function CreateCellControl: TStyledControl; override; 
  end;
...

{ TComboColumn }

function TComboColumn.CreateCellControl: TStyledControl;
begin
  Result := TComboBoxCell.Create(Self);
  TComboBoxCell(Result).OnChange := DoComboChanged;
end;

procedure TComboColumn.DoComboChanged(Sender: TObject);
var
  P: TPointF;
  LGrid: TComboExtendedGrid;
begin
  LGrid := Grid;
  if not Assigned(LGrid) then
    Exit;
  if FUpdateColumn then
    Exit;
  if FDisableChange then
    Exit;
  P := StringToPoint(TFmxObject(Sender).TagString);
  LGrid.SetValue(Trunc(P.X), Trunc(P.Y),
    TValue.From<TComboRecord>(TComboBoxCell(Sender).ComboData));
  if Assigned(LGrid.FOnEditingDone) then
    LGrid.FOnEditingDone(Grid, Trunc(P.X), Trunc(P.Y));
end;

function TComboColumn.Grid: TComboExtendedGrid;
var
  P: TFmxObject;
begin
  Result := nil;
  P := Parent;
  while Assigned(P) do
  begin
    if P is TCustomGrid then
    begin
      Result := TComboExtendedGrid(P);
      Exit;
    end;
    P := P.Parent;
  end;
end;

你看，现在我们必须对TGrid 类进行子类型化，并且我们必须通过Grid 函数获取它的处理程序，并且需要访问protected FOnEditingDone 变量

  TComboExtendedGrid = class(TGrid)
  private
    FOnEditingDone: TOnEditingDone;
  protected
    procedure SetValue(Col, Row: integer; const Value: TValue); override;
  end;
{ TComboExtendedGrid }

procedure TComboExtendedGrid.SetValue(Col, Row: integer; const Value: TValue);
begin
  inherited;

end;

最后，我们需要在表单单元中设置必要的创建和事件处理机制。在 from 声明中添加一个列变量。

  protected
    CCColumn:TComboColumn;

填充 ComboData 并创建列：

procedure TForm1.Button1Click(Sender: TObject);
begin
  PopulateComboData(Grid2.RowCount);
  CCColumn:=TComboColumn.Create(Grid2);
  CCColumn.Parent := Grid2;
  CCColumn.Header := 'CB';
end;

并处理事件：

procedure TForm1.Grid2GetValue(Sender: TObject; const Col, Row: Integer;
  var Value: TValue);
begin
  case Col of
     6{Combo Column Number}: Value:=TValue.From<TComboRecord>(ComboData[Row])
  end;
end;

procedure TForm1.Grid2SetValue(Sender: TObject; const Col, Row: Integer;
  const Value: TValue);
begin
  case Col of
      6{Combo Column Number}: ShowMessage(Value.AsType<TComboRecord>.Selected);
  end;
end;

不要忘记将更改（如果需要）传递给ComboData 列表。当前的处理程序不会为您执行此操作。我更喜欢在 Grid2SetValue 事件处理程序中进行此操作。

Answer 2

这是将 Combobox 添加到 FMX TGrid 的简单方法。诚然，这个解决方案在每个组合中都有相同的项目，但我现在只能做到这一点。

type
  TComboColumn = class(TPopupColumn)
    function CreateCellControl: TStyledControl; override;
  end;

...

function TComboColumn.CreateCellControl: TStyledControl;
var
  ComR: TComboRecord;
  i: Integer;
begin
   Result := TComboBoxCell.Create(self);
   // now they all have the same drop-down values
   ComR := frmMain.ComboData[0];
   for i := 0 to Length(ComR.FieldValues) do
     TComboBoxCell(Result).Items.Add(ComR.FieldValues[i]);
end

...而且只是为了连续性

procedure TfrmMain.FormCreate(Sender: TObject);
begin
   AGrid := TComboExtendedGrid.Create(Self);
   AGrid.Parent := Self;
   AGrid.Align := TAlignLayout.Client;
   AGrid.Options := AGrid.Options + [TGridOption.AlwaysShowEditor];
   AGrid.OnGetValue := AGridGetValue;
   AGrid.OnSetValue := AGridSetValue;
   AGrid.RowCount := 5;

   ComboData := TList<TComboRecord>.Create;
   PopulateComboData(AGrid.RowCount);

   CCColumn := TComboColumn.Create(AGrid);
   CCColumn.Parent := AGrid;
   CCColumn.Header := 'Combohere';   
end;