Delphi ArcEngine 创建梯度专题 Proportional

function ProportionalSymbolRenderer(pLayer: ILayer; sField: string; pFrontColor, pBackColor: IColor;

iLegendCount:  Integer): Boolean;

//参数依次为 图形，该图层的某一个字段名称，前景色，背景色，图例分级数量

var
  pGeoLayer: IGeoFeatureLayer;
  pTable: ITable;
  iFieldIndex: Integer;
  pRenderer: IProportionalSymbolRenderer;

  pQueryFilter: IQueryFilter;
  pCursor: ICursor;
  pRow: IRow;
  pColor: IColor;

  pDataStatics: IDataStatistics;
  pStaticsResults: IStatisticsResults;

  pFillSymbol: ISimpleFillSymbol;
  pMarkerSymbol: ISimpleMarkerSymbol;
  pSymbol: ISymbol;
  sValue: string;

begin
  pGeoLayer := pLayer as IGeoFeatureLayer;
  pTable := pLayer as ITable;
  pRenderer := CoProportionalSymbolRenderer.Create as IProportionalSymbolRenderer;

  pQueryFilter := CoQueryFilter.Create as IQueryFilter;
  pQueryFilter.AddField(sField);
  pCursor := pTable.Search(pQueryFilter, True);

  pDataStatics := CoDataStatistics.Create as IDataStatistics;
  pDataStatics.Cursor := pCursor;
  pDataStatics.Field := sField;
  pStaticsResults := pDataStatics.Statistics;

  //创建符号
  pFillSymbol := CoSimpleFillSymbol.Create as ISimpleFillSymbol;
  pFillSymbol.Color := pBackColor;

  pMarkerSymbol := CoSimpleMarkerSymbol.Create as ISimpleMarkerSymbol;
  pMarkerSymbol.Color := pFrontColor;
  pMarkerSymbol.Size := 3;
  pMarkerSymbol.Style := esriSMSDiamond;

  pRenderer.ValueUnit := esriUnknownUnits;
  pRenderer.Field := sField;
  pRenderer.MinDataValue := pStaticsResults.Minimum;
  pRenderer.MaxDataValue := pStaticsResults.Maximum;
  pRenderer.BackgroundSymbol := pFillSymbol;
  pRenderer.MinSymbol := pMarkerSymbol as ISymbol;
  pRenderer.LegendSymbolCount:=  iLegendCount;
  pRenderer.CreateLegendSymbols;

  pGeoLayer.Renderer := pRenderer  as IFeatureRenderer;

  Result := True;

end;