GridControl.CalculateCustomSummary Event
Allows you to calculate summary values manually.
Namespace: DevExpress.Mobile.DataGrid
Assembly: DevExpress.Mobile.Grid.v18.2.dll
Declaration
Event Data
The CalculateCustomSummary event's data class is CustomSummaryEventArgs. The following properties provide information specific to this event:
| Property | Description |
|---|---|
| FieldName | Gets the processed field name. |
| FieldValue | Gets the processed field value. |
| GroupRowHandle | Gets a value identifying the group row whose child data rows are involved in summary calculation. |
| IsGroupSummary | Gets whether a group summary value is being calculated. |
| IsTotalSummary | Gets whether a total summary value is being calculated. |
| Row | Gets an object that contains information on the currently processed row. |
| SummaryProcess | Gets a value indicating the data summary calculation stage. |
| TotalValue | Gets or sets the total summary value. |
| TotalValueReady | Gets or sets whether the Calculation stage of the custom summary calculation process should be skipped. |
The event data class exposes the following methods:
| Method | Description |
|---|---|
| GetValue(String) | Returns the value in the specified field. |
Remarks
Important
This documentation topic describes legacy technology. We no longer develop new functionality for the GridControl and suggest that you use the new DataGridView control instead.
Total and group summaries provide five predefined aggregate functions (Count, Max, Min, Sum and Average). To calculate a summary value using a custom rule, set the summary item’s GridColumnSummary.Type property to SummaryType.Custom, and handle the CalculateCustomSummary event.
The CalculateCustomSummary event fires for each data row involved in summary calculation. When calculating a total summary value, the event is raised for each data row. When calculating a group summary value, this event fires for each data row within a group. To enable you to perform any initialization and finalization, the event is also raised before and after processing rows.
The summary calculation consists of the three stages.
Initialization
The CalculateCustomSummary event is raised once and the CustomSummaryEventArgs.SummaryProcess property is set to CustomSummaryProcess.Start. At this stage, you can initialize summary values (e.g., reset internal counters).
Calculation
The CalculateCustomSummary event occurs multiple times, once for each data row in the grid or group. The SummaryProcess property is set to CustomSummaryProcess.Calculate. At this stage, you should accumulate summaries.
Finalization
The CalculateCustomSummary event is raised once and the SummaryProcess property is set to CustomSummaryProcess.Finalize. At this point, calculate a final summary value and assign it to the event parameter’s CustomSummaryEventArgs.TotalValue property.
To skip the Calculation stage and calculate a custom summary at the Initialization or Finalization stage, set the event parameter’s CustomSummaryEventArgs.TotalValueReady property to true at the Initialization stage. This automatically skips the Calculation stage and the Finalization stage starts immediately.
Example
This example shows how to use the GridControl.CalculateCustomSummary event to create a custom summary that counts the total number of data rows whose cells in the Shipped column (SwitchColumn) contain false.