TcxDataControllerCompareEvent Type

The procedural type for value comparison events in a data controller.

Declaration

TcxDataControllerCompareEvent = procedure(ADataController: TcxCustomDataController; ARecordIndex1: Integer; ARecordIndex2: Integer; AItemIndex: Integer; const V1: Variant; const V2: Variant; var Compare: Integer) of object;

Parameters

Name	Type	Description
ADataController	TcxCustomDataController	Provides access to the data controller that raised the current value comparison event.
ARecordIndex1	Integer	Returns the index of the record that contains the first compared value (V1). The AItemIndex parameter returns the index of the current dataset field.
ARecordIndex2	Integer	Returns the index of the record that contains the second compared value (V2). The AItemIndex parameter returns the index of the current dataset field.
AItemIndex	Integer	Returns the index of the dataset field where the current comparison operation occurs. ARecordIndex1 and ARecordIndex2 parameters return the indexes of the records where first (V1) and second (V2) compared values are stored.
V1	Variant	Returns the first compared value.
V2	Variant	Returns the second compared value.
Compare	Integer	Specifies the comparison result (-1, 0, or 1). Refer to the following section for details: Comparison Results.

Remarks

Handle a value comparison event to implement a custom sorting algorithm in your application. Refer to the TcxCustomDataController.OnCompare event description for a code example.

Important

Disable multi-threaded calculations for data sort operations in a data controller if your value comparison event handler is not thread-safe.

Set the MultiThreadedOptions.Sorting property to bFalse to disable multi-threading for sort operations in the data controller.

Comparison Results

The following table explains what Compare parameter values correspond to different results of the current value comparison operation:

Compare Value	Description
-1 or other negative value	V1 is treated as a smaller value than V2; therefore, V1 is positioned before V2.
0	V1 and V2 are considered equal. Both values retain their positions.
1 or other positive value	V1 is treated as a larger value than V2; therefore, V1 is positioned after V2

Direct TcxDataControllerCompareEvent Type Reference

The TcxCustomDataController.OnCompare event references the TcxDataControllerCompareEvent procedural type.