从 TDBGrid 和 cxGrid 迁移到 sgcGrid

object SourceDB: TsgcGridSource_DataSet
  DataSet = cdsProducts
  Grid = GridDB
  KeyField = 'ID'
  Left = 280
  Top = 520
end

procedure TFormMain.chkOptionsClick(Sender: TObject);
begin
  // TDBGrid.ReadOnly / Options dgEditing -> ReadOnly
{$IFDEF SGC_GRID_EDIT}
  GridDB.ReadOnly := not chkEditing.Checked;
{$ENDIF}
  // dgMultiSelect -> gsmMultiRow, dgRowSelect -> gsmRow, neither -> gsmCell
  if chkMultiSelect.Checked then
    GridDB.SelectionMode := gsmMultiRow
  else if chkRowSelect.Checked then
    GridDB.SelectionMode := gsmRow
  else
    GridDB.SelectionMode := gsmCell;
  // dgIndicator -> RowHeader [grhIndicator] (grhNumbers, grhCheckBox too)
  if chkIndicator.Checked then
    GridDB.RowHeader := [grhIndicator]
  else
    GridDB.RowHeader := [];
end;

procedure TFormMain.GridDBCustomDrawCell(Sender: TObject; aCanvas: TsgcUICanvas;
  aRow, aCol, aLeft, aTop, aRight, aBottom: Integer;
  aState: TsgcGridCellDrawStates; var aDefaultDraw: Boolean);
begin
  // TDBGrid.OnDrawColumnCell: Column.FieldName and Field.AsInteger.
  // sgcGrid: aCol is the Columns index, aRow the view row of Data. The
  // background is painted already; aDefaultDraw False would skip the text
  if (aRow < 0) or (aRow >= GridDB.Data.ViewCount) or
    (GridDB.Columns[aCol].FieldName <> 'Qty') then
    Exit;
  if StrToIntDef(VarToStr(GridDB.Data.Cells[aRow, aCol]), 0) < CS_LOW_STOCK
  then
  begin
    // a red marker at the left edge of a low stock cell
    aCanvas.BeginPath;
    aCanvas.Rectangle(aLeft, aTop + 4, aLeft + 4, aBottom - 4);
    aCanvas.ClosePath;
    aCanvas.FillPath($FFDC2626);
  end;
end;

procedure TFormMain.FormCreate(Sender: TObject);
begin
  DoCreateData;
  // TDBGrid: DataSource := dsProducts. sgcGrid: a TsgcGridSource_DataSet
  // with DataSet, Grid and KeyField (set on the form). The grid columns are
  // designed on the form like TDBGrid.Columns, matched by FieldName
{$IFDEF SGC_GRID_EDIT}
  // TDBGrid dgEditing posts edits to the dataset: WriteBack. The current
  // record follows the focused row and back: SyncCursor
  SourceDB.WriteBack := True;
  SourceDB.SyncCursor := True;
{$ELSE}
  chkEditing.Checked := False;
  chkEditing.Enabled := False;
  chkEditing.Caption := 'Editing (Registered edition)';
  GridDB.ReadOnly := True;
{$ENDIF}
  SourceDB.Active := True;
  SourceCx.Active := True;
  chkOptionsClick(nil);
  // cxGrid: drag a column to the GroupByBox. sgcGrid: ShowGroupPanel, and
  // GroupBy from code (cxGridDBColumn.GroupIndex is Columns[i].GroupIndex)
  GridCx.GroupBy(['Category']);

Columns = <
  item
    FieldName = 'ID'
    Caption = 'ID'
    DataType = gdtInteger
    Width = 60
    SummaryType = gsuCount
    Band = 0
  end
  item
    FieldName = 'Product'
    Caption = 'Product'
    Width = 220
    Band = 0
  end
  item
    FieldName = 'Category'
    Caption = 'Category'
    Width = 140
    Band = 0
  end
  item
    FieldName = 'Price'
    Caption = 'Price'
    DataType = gdtFloat
    Width = 110
    DisplayFormat = '#,##0.00'
    SummaryType = gsuAverage
    SummaryFormat = '#,##0.00'
    Band = 1
  end
  item
    FieldName = 'Qty'
    Caption = 'Qty'
    DataType = gdtInteger
    Width = 90
    SummaryType = gsuSum
    Band = 1
  end>
FormatRules = <>
ShowFooter = True
ShowGroupPanel = True
GroupSummaries = True
ShowFilterButtons = True
ShowFilterRow = True
ShowFindPanel = True
Bands = <
  item
    Caption = 'Product'
  end
  item
    Caption = 'Stock and price'
  end>

procedure TFormMain.btnBestFitClick(Sender: TObject);
begin
  // cxGridDBTableView.ApplyBestFit -> BestFitColumns (BestFitColumn(i) for
  // one column, BestFitOnDblClick for the header divider)
  GridCx.BestFitColumns;
end;

function TFormMain.DoLayoutFile: string;
begin
  Result := ExtractFilePath(ParamStr(0)) + 'migratefromdbgrid_layout.json';
end;

procedure TFormMain.btnSaveLayoutClick(Sender: TObject);
begin
  // cxGridDBTableView.StoreToIniFile -> SaveLayoutToFile (JSON: columns,
  // widths, order, sort, grouping, filters, summaries, bands, view)
  GridCx.SaveLayoutToFile(DoLayoutFile);
  DoShowStatus('layout saved to ' + ExtractFileName(DoLayoutFile));
end;

procedure TFormMain.btnLoadLayoutClick(Sender: TObject);
begin
  // cxGridDBTableView.RestoreFromIniFile -> LoadLayoutFromFile
  if GridCx.LoadLayoutFromFile(DoLayoutFile) then
    DoShowStatus('layout loaded')
  else
    DoShowStatus('no saved layout');
end;

procedure TFormMain.chkCardViewClick(Sender: TObject);
begin
{$IFDEF SGC_GRID_ADVANCED}
  // cxGridDBCardView (a second view of the level) -> ViewStyle gvsCard of
  // the same grid, CardOptions for the caption field and the card size
  if chkCardView.Checked then
    GridCx.ViewStyle := gvsCard
  else
    GridCx.ViewStyle := gvsTable;
{$ENDIF}
end;