TcxSummaryEventOutArguments.Value Field

Stores the value of the currently processed record.

Declaration

Value: Variant

Field Value

Type	Description
Variant	The value of the currently processed record.

Remarks

Assign an intermediate result of custom summary calculation to the Value field within an OnSummary event handler as demonstrated in the following code examples.

Code Examples

Exclude Null Values from Summary Calculation

The following code example excludes all Null Variant record values from summary calculation:

Delphi

procedure TMyForm.cxGrid1DBTableView1DataControllerSummaryDefaultGroupSummaryItemsSummary(
  ASender: TcxDataSummaryItems; Arguments: TcxSummaryEventArguments;
  var OutArguments: TcxSummaryEventOutArguments);
begin
  if (VarIsNull(OutArguments.Value)) then // If the currently processed value is Null Variant
    OutArguments.Done := True;  // Ignores the Null Variant record value
end;

C++

void __fastcall TMyForm::cxGrid1DBTableView1DataControllerSummaryDefaultGroupSummaryItemsSummary(
  TcxDataSummaryItems *ASender, TcxSummaryEventArguments &Arguments,
  TcxSummaryEventOutArguments &OutArguments) {
  if (VarIsNull(OutArguments.Value)) {  // If the currently processed value is Null Variant
    OutArguments.Done = true;  // Ignores the Null Variant record value
  }
}

Custom Summary Calculation

All predefined summary calculation algorithms use record values of only one data item. The OnSummary event allows you to modify a predefined summary calculation algorithm in any manner. For example, you can use values of multiple data items in every iteration of the summary calculation process.

The code example below demonstrates an OnSummary event handler that modifies the predefined algorithm MAX. The event handler calculates the highest population density based on data-aware grid columns that display country areas (DBTableView1Area) and corresponding population values (DBTableView1Population):

Delphi

procedure TMyForm.cxGrid1DBTableView1DataControllerSummaryDefaultGroupSummaryItemsSummary(
  ASender: TcxDataSummaryItems; Arguments: TcxSummaryEventArguments;
  var OutArguments: TcxSummaryEventOutArguments);
var
  AArea, APopulation: Variant;
begin
  // Obtain the area value for the currently processed record
  AArea := ASender.DataController.Values[Arguments.RecordIndex, DBTableView1Area.Index];
  // Obtain the population value for the currently processed record
  APopulation := ASender.DataController.Values[Arguments.RecordIndex, DBTableView1Population.Index];
  OutArguments.Value := APopulation/AArea; // Calculates the custom summary value (maximum population density)
end;

C++

void __fastcall TMyForm::cxGrid1DBTableView1DataControllerSummaryDefaultGroupSummaryItemsSummary(
  TcxDataSummaryItems *ASender, TcxSummaryEventArguments &Arguments,
  TcxSummaryEventOutArguments &OutArguments) {
  // Obtain the area value for the currently processed record
  Variant AArea = ASender->DataController->Values[Arguments.RecordIndex][DBTableView1Area->Index];
  // Obtain the population value for the currently processed record
  Variant APopulation = ASender->DataController->Values[Arguments.RecordIndex][DBTableView1Area->Index];
  OutArguments.Value = APopulation/AArea;  // Calculates the custom summary value (maximum population density)
}