GridControl.CustomGroupDisplayText Event

Allows you to display custom text in group rows.

Namespace: DevExpress.Xpf.Grid

Assembly: DevExpress.Xpf.Grid.v21.1.dll

Declaration

public event CustomGroupDisplayTextEventHandler CustomGroupDisplayText

Event Data

The CustomGroupDisplayText event's data class is CustomGroupDisplayTextEventArgs. The following properties provide information specific to this event:

Property Description
Cell Gets or sets the CellValue object consisting of information about the cell being processed. Inherited from CellValueEventArgs.
Column Gets a column that contains the edited cell. Inherited from CellValueEventArgs.
DisplayText Gets or sets the text displayed within the processed group row.
Handled Gets or sets a value that indicates the present state of the event handling for a routed event as it travels the route. Inherited from RoutedEventArgs.
OriginalSource Gets the original reporting source as determined by pure hit testing, before any possible Source adjustment by a parent class. Inherited from RoutedEventArgs.
RoutedEvent Gets or sets the RoutedEvent associated with this RoutedEventArgs instance. Inherited from RoutedEventArgs.
Row Gets the processed row. Inherited from RowEventArgs.
RowHandle Gets the processed row’s handle. Inherited from RowEventArgs.
Source Gets or sets a reference to the object that raised the event. Inherited from RoutedEventArgs.
Value Gets or sets the processed cell’s value. Inherited from CellValueEventArgs.

The event data class exposes the following methods:

Method Description
InvokeEventHandler(Delegate, Object) When overridden in a derived class, provides a way to invoke event handlers in a type-specific way, which can increase efficiency over the base implementation. Inherited from RoutedEventArgs.
OnSetSource(Object) When overridden in a derived class, provides a notification callback entry point whenever the value of the Source property of an instance changes. Inherited from RoutedEventArgs.

Remarks

You can group rows using custom rules by handling the GridControl.CustomColumnGroup event. In this instance, it may be useful to replace the default text displayed within group rows. To do this, handle the CustomGroupDisplayText event. The event arguments allow you to identify group rows and replace their display text.

In the CustomGroupDisplayText event handler, you can use methods listed in the Obtain and Set Cell Values in Code topic to obtain the required column values and the DisplayText property to set a string value you want to display.

The code sample below shows how to display a particular column’s value in the group row:

private void grid_CustomGroupDisplayText(object sender, CustomGroupDisplayTextEventArgs e) {
    e.DisplayText = grid.GetCellDisplayText(e.RowHandle, "Id");
} 

If you want to maintain a clean MVVM pattern and specify custom group row text in a View Model, create a command and bind it to the CustomGroupDisplayTextCommand property.

Example

The following example shows how to apply custom rules to group rows. When you group data by the Unit Price column, rows in this column that have values between 0 and 10 are combined into a single group. Rows whose values fall between 10 and 20 are combined into another group, and so forth.

DevExpress WPF | Grid Control - Custom Group Rules

View Example: How to Apply Custom Rules to Group Rows

<dxg:GridControl x:Name="grid" 
                 CustomColumnGroup="OnCustomColumnGroup" 
                 CustomGroupDisplayText="OnCustomGroupDisplayText">
    <dxg:GridControl.Columns>
        <dxg:GridColumn FieldName="FirstName" />
        <dxg:GridColumn FieldName="LastName" />
        <dxg:GridColumn FieldName="UnitPrice" SortMode="Custom" GroupIndex="0">
            <dxg:GridColumn.EditSettings>
                <dxe:SpinEditSettings DisplayFormat="c2" />
            </dxg:GridColumn.EditSettings>
        </dxg:GridColumn>
    </dxg:GridControl.Columns>
    <dxg:GridControl.View>
        <dxg:TableView AutoWidth="True" ShowGroupedColumns="True"/>
    </dxg:GridControl.View>
</dxg:GridControl>
void OnCustomColumnGroup(object sender, CustomColumnSortEventArgs e) {
    if(e.Column.FieldName != "UnitPrice")
        return;
    double x = Math.Floor(Convert.ToDouble(e.Value1) / 10);
    double y = Math.Floor(Convert.ToDouble(e.Value2) / 10);
    e.Result = x > 9 && y > 9 ? 0 : x.CompareTo(y);
    e.Handled = true;
}

void OnCustomGroupDisplayText(object sender, CustomGroupDisplayTextEventArgs e) {
    if(e.Column.FieldName != "UnitPrice")
        return;
    string interval = IntervalByValue(e.Value);
    e.DisplayText = interval;
}

// Gets the interval which contains the specified value.
private string IntervalByValue(object val) {
    double d = Math.Floor(Convert.ToDouble(val) / 10);
    string ret = string.Format("{0:c} - {1:c} ", d * 10, (d + 1) * 10);
    if(d > 9)
        ret = string.Format(">= {0:c} ", 100);
    return ret;
}
See Also