object Form21: TForm21
  Left = 0
  Top = 0
  Caption = 'Test'
  ClientHeight = 290
  ClientWidth = 557
  FormFactor.Width = 320
  FormFactor.Height = 480
  FormFactor.Devices = [Desktop]
  DesignerMasterStyle = 0
  object Button1: TButton
    Position.X = 464.000000000000000000
    Position.Y = 24.000000000000000000
    Text = 'Button1'
    OnClick = Button1Click
  end
  object Panel: TRectangle
    Anchors = [akLeft, akTop, akBottom]
    Fill.Color = x00FFFFFF
    Position.X = 8.000000000000000000
    Position.Y = 8.000000000000000000
    Size.Width = 440.000000000000000000
    Size.Height = 271.000000000000000000
    Size.PlatformDefault = False
    object ScrollBox1: TScrollBox
      Align = Client
      Margins.Left = 4.000000000000000000
      Margins.Top = 4.000000000000000000
      Margins.Right = 4.000000000000000000
      Margins.Bottom = 4.000000000000000000
      Size.Width = 432.000000000000000000
      Size.Height = 263.000000000000000000
      Size.PlatformDefault = False
      Viewport.Width = 432.000000000000000000
      Viewport.Height = 263.000000000000000000
      object StringGrid1: TStringGrid
        CanFocus = True
        ClipChildren = True
        Size.Width = 205.000000000000000000
        Size.Height = 100.000000000000000000
        Size.PlatformDefault = False
        RowHeight = 20.000000000000000000
        RowCount = 1
        Options = [ColumnResize, ColumnMove, ColLines, RowLines, Tabs, Header, HeaderClick, AutoDisplacement]
        OnSelectCell = StringGridSelectCell
        Viewport.Width = 201.000000000000000000
        Viewport.Height = 75.000000000000000000
        object StringColumn1: TStringColumn
          Header = 'Test 1'
        end
        object StringColumn2: TStringColumn
          Header = 'Test 2'
        end
      end
      object StringGrid2: TStringGrid
        CanFocus = True
        ClipChildren = True
        Position.X = 208.000000000000000000
        Size.Width = 205.000000000000000000
        Size.Height = 100.000000000000000000
        Size.PlatformDefault = False
        RowHeight = 20.000000000000000000
        RowCount = 1
        Options = [ColumnResize, ColumnMove, ColLines, RowLines, Tabs, Header, HeaderClick, AutoDisplacement]
        OnSelectCell = StringGridSelectCell
        Viewport.Width = 201.000000000000000000
        Viewport.Height = 75.000000000000000000
        object StringColumn3: TStringColumn
          Header = 'Test 3'
        end
        object StringColumn4: TStringColumn
          Header = 'Test 4'
        end
      end
    end
  end
end

unit Unit21;

interface

uses
  System.SysUtils, System.Types, System.UITypes, System.Classes, System.Variants,
  FMX.Types, FMX.Controls, FMX.Forms, FMX.Graphics, FMX.Dialogs, System.Rtti, FMX.Grid.Style, FMX.Grid,
  FMX.Controls.Presentation, FMX.ScrollBox, FMX.Layouts, FMX.StdCtrls, FMX.Objects;

type
  TForm21 = class(TForm)
    Button1: TButton;
    Panel: TRectangle;
    ScrollBox1: TScrollBox;
    StringGrid1: TStringGrid;
    StringColumn1: TStringColumn;
    StringColumn2: TStringColumn;
    StringGrid2: TStringGrid;
    StringColumn3: TStringColumn;
    StringColumn4: TStringColumn;
    procedure Button1Click(Sender: TObject);
    procedure StringGridSelectCell(Sender: TObject; const ACol, ARow: Integer; var CanSelect: Boolean);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form21: TForm21;

implementation

{$R *.fmx}

procedure TForm21.Button1Click(Sender: TObject);
begin
  var Rows:=StringGrid1.RowCount+20;

  StringGrid1.Height:=(StringGrid1.RowHeight+1)*(Rows+1)+3;
  StringGrid2.Height:=(StringGrid2.RowHeight+1)*(Rows+1)+3;

  StringGrid1.RowCount:=Rows;
  StringGrid2.RowCount:=Rows;
  for var i:=0 to Rows-1 do begin
    StringGrid1.Cells[0,i]:=i.ToString;
    StringGrid1.Cells[1,i]:=i.ToString;
    StringGrid2.Cells[0,i]:=i.ToString;
    StringGrid2.Cells[1,i]:=i.ToString;
  end;
end;

procedure TForm21.StringGridSelectCell(Sender: TObject; const ACol, ARow: Integer; var CanSelect: Boolean);
begin
  var Y1:=(StringGrid1.RowHeight+1)*(ARow);
  if Y1<ScrollBox1.ViewportPosition.Y then begin
    ScrollBox1.ScrollTo(0,ScrollBox1.ViewportPosition.Y-Y1);
  end;

  var Y2:=(StringGrid1.RowHeight+1)*(ARow+2)+2;
  if Y2>ScrollBox1.ViewportPosition.Y+ScrollBox1.ClientHeight then begin
    ScrollBox1.ScrollTo(0,-(Y2-ScrollBox1.ViewportPosition.Y-ScrollBox1.ClientHeight));
  end;
end;

end.