selection.md

Selection

Two selection modes are supported:

• Row selection allows the user to select whole rows
• Cell selection allows the user to select individial cells

Both selection types support either single or multiple selection. The default selection type is single row selection.

Index Paths

Because TreeDataGrid supports hierarchical data, using a simple index to identify a row in the data source isn't enough. Instead indexes are represented using the IndexPath struct.

An IndexPath is essentially an array of indexes, each element of which specifies the index at a succesively deeper level in the hierarchy of the data.

Consider the following data source:

|- A
|  |- B
|  |- C
|     |- D
|- E

• A has an index path of 0 as it's the first item at the root of the hierarchy
• B has an index path of 0,0 as it's the first child of the first item
• C has an index path of 0,1 as it's the second child of the first item
• D has an index path of 0,1,0 as it's the first child of C
• E has an index path of 1 as it's the second item in the root

IndexPath is an immutable struct which is constructed with an array of integers, e.g.: new ItemPath(0, 1, 0). There is also an implicit conversion from int for when working with a flat data source.

Row Selection

Row selection is the default and is exposed via the RowSelection property on the FlatTreeDataGridSource<TModel> and HierarchicalTreeDataGridSource<TModel> classes when enabled. Row selection is stored in an instance of the TreeDataGridRowSelectionModel<TModel> class.

By default is single selection. To enable multiple selection set the the SingleSelect property to false, e.g.:

Source = new FlatTreeDataGridSource<Person>(_people)
{
    Columns =
    {
        new TextColumn<Person, string>("First Name", x => x.FirstName),
        new TextColumn<Person, string>("Last Name", x => x.LastName),
        new TextColumn<Person, int>("Age", x => x.Age),
    },
};

Source.RowSelection!.SingleSelect = false;

The properties on ITreeDataGridRowSelectionModel<TModel> can be used to manipulate the selection, e.g.:

Source.RowSelection!.SelectedIndex = 1;

Or

Source.RowSelection!.SelectedIndex = new IndexPath(0, 1);

Cell Selection

To enable cell selection for a TreeDataGridSource, assign an instance of TreeDataGridCellSelectionModel<TModel> to the source's Selection property:

Source = new FlatTreeDataGridSource<Person>(_people)
{
    Columns =
    {
        new TextColumn<Person, string>("First Name", x => x.FirstName),
        new TextColumn<Person, string>("Last Name", x => x.LastName),
        new TextColumn<Person, int>("Age", x => x.Age),
    },
};

Source.Selection = new TreeDataGridCellSelectionModel<Person>(Source);

Or for multiple cell selection:

Source.Selection = new TreeDataGridCellSelectionModel<Person>(Source) { SingleSelect = false };

Cell selection is is exposed via the CellSelection property on the FlatTreeDataGridSource<TModel> and HierarchicalTreeDataGridSource<TModel> classes when enabled.

The CellIndex struct indentifies an individual cell with by combination of an integer column index and an IndexPath row index.