TTMSFNCGridCell - why FOwner is private?

FNC TMS FNC UI Pack
1

Helo.

I cerate my own TTMSFNCGridCell class and i'd like to access to Owner. But FOwner is only private member.

2

Why do you need access to the Owner? the Owner is the grid. The cell class is not a real child of the grid it acts as a container for drawing.

3

I know that owner is the grid. I handle MouseMove metod and i use FOwner to get TTMSFNCGridCellRec.

procedure TMyGridCell.HandleMouseMove(Shift: TShiftState; X, Y: Single; var AHandled: Boolean; var ACursor: TCursor);
var
  cellXY: TTMSFNCGridCellRec;
begin
  inherited;
  if FOwner is TTMSFNCGrid then
  begin
    cellXY := TTMSFNCGrid(FOwner).XYToCell(X,Y);
    ... some other code ...
  end;
end;
4

Can you please explain a bit more in detail what it is that you want to achieve?

5

I create something as a component in a cell. Yes It's mostly drawing, because according to mine knowledge TTMSFNCGrid does not support TComponents in cells. I use TTMSFNCGridCell to achieve this. This object can process all the events which i need (mouse move, mouse down, mouse up etc). And now i need access to TTMSFNCGridData.Objects property for example. That's why I need access to owner. Now i have solution, but it's embarrassing but it's functional.

type
  TMyGridCell= class(TTMSFNCGridCell)
  private
    FAwkwardOwner: TComponent; // :(
  public
    constructor Create(AOwner: TComponent); override;
  end;

constructor TMyGridCell.Create(AOwner: TComponent);
begin
  inherited Create(AOwner);
  FAwkwardOwner:= AOwner; // :(
end;
6

When creating TMyGridCell, and you pass TMyGridCell as a value to the OnGetCellClass, you can afterwards retrieve the instance via the OnGetCellProperties, and then assign whatever object or value you want to reference inside the cell.

  TMyGridCell = class(TTMSFNCGridCell)
  private
    FObject: TObject;
  public
    property MyObject: TObject read FObject write FObject;
  end;

procedure TForm22.TMSFNCGrid1GetCellClass(Sender: TObject; ACol, ARow: Integer;
  var CellClassType: TTMSFNCGridCellClass);
begin
  CellClassType := TMyGridCell;
end;

procedure TForm22.TMSFNCGrid1GetCellProperties(Sender: TObject; ACol,
  ARow: Integer; Cell: TTMSFNCGridCell);
begin
  (Cell as TMyGridCell).FObject := MyObject;
end;
7

Ok, not bad. I can even add there ACol and ARow values if eventually i need it sometimes. But I still don't understand why it's important for you to keep FOwner private.

I'm not a big fan for massive event processing. In fact, I always prefer direct access for data, properties, settings, actions etc. Because if i create really complicated grid (like screenshot below), i will get events hell in the end. And over time it gets worse and worse. Consequently if i get more code in events than in other metods, it is cumbersome and poorly maintained. I really dont like number of events.

Screenshot 2021-10-26 151454
Screenshot 2021-10-26 1514541321×580 87.4 KB

8

FOwner is not always the grid, therefore it is private. In case of auto-sizing a temporary cell is being created, with nil as a parameter. For exporting to PDF or when printing, the owner can change to something else, therefore it is not exposed. Up until now we didn't have a reason to expose it. We'll write it down and see if we can expose the FOwner, but the above approach is valid and will allow you to be more flexible.

9

Ok. I understand.

10

This topic was automatically closed 60 minutes after the last reply. New replies are no longer allowed.