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maxkatz6maxkatz6
authoredMay 14, 2023
Merge pull request #178 from AvaloniaUI/feature/cell-selection
MVP of cell selection
·
11.1.011.0.0-preview8
2 parents 51336cf + 9f9ed62 commit 78ebc02

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‎docs/column-types.md

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@@ -20,6 +20,24 @@ This is the signature of the `TextColumn` constructor. There are two most import
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**Note**:
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The sample above is taken from [this article](https://github.com/AvaloniaUI/Avalonia.Controls.TreeDataGrid/blob/master/docs/get-started-flat.md). If you feel like you need more examples feel free to check it, there is a sample that shows how to use TextColumns and how to run a whole `TreeDataGrid` using them.
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## CheckBoxColumn
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As its name suggests, `CheckBoxColumn` displays a `CheckBox` in its cells. For a readonly checkbox:
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```csharp
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new CheckColumn<Person>("Firstborn", x => x.IsFirstborn)
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```
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The first parameter defines the column header. The second parameter is an expression which gets the value of the property from the model.
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For a read/write checkbox:
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```csharp
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new CheckColumn<Person>("Firstborn", x => x.IsFirstborn, (o, v) => o.IsFirstborn = v)
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```
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This overload adds a second paramter which is the expression used to set the property in the model.
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## HierarchicalExpanderColumn
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`HierarchicalExpanderColumn` can be used only with `HierarchicalTreeDataGrid` (a.k.a TreeView) thats what Hierarchical stands for in its name, also it can be used only with `HierarchicalTreeDataGridSource`. This type of columns can be useful when you want cells to show an expander to reveal nested data.
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‎docs/selection.md

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# Selection
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Two selection modes are supported:
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- Row selection allows the user to select whole rows
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- Cell selection allows the user to select individial cells
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Both selection types support either single or multiple selection. The default selection type is single row selection.
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## Index Paths
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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.
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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.
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Consider the following data source:
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```
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|- A
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| |- B
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| |- C
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| |- D
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|- E
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```
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- `A` has an index path of `0` as it's the first item at the root of the hierarchy
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- `B` has an index path of `0,0` as it's the first child of the first item
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- `C` has an index path of `0,1` as it's the second child of the first item
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- `D` has an index path of `0,1,0` as it's the first child of `C`
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- `E` has an index path of `1` as it's the second item in the root
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`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.
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## Row Selection
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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.
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By default is single selection. To enable multiple selection set the the `SingleSelect` property to `false`, e.g.:
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```csharp
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Source = new FlatTreeDataGridSource<Person>(_people)
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{
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Columns =
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{
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new TextColumn<Person, string>("First Name", x => x.FirstName),
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new TextColumn<Person, string>("Last Name", x => x.LastName),
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new TextColumn<Person, int>("Age", x => x.Age),
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},
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};
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Source.RowSelection!.SingleSelect = false;
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```
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The properties on `ITreeDataGridRowSelectionModel<TModel>` can be used to manipulate the selection, e.g.:
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```csharp
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Source.RowSelection!.SelectedIndex = 1;
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```
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Or
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```csharp
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Source.RowSelection!.SelectedIndex = new IndexPath(0, 1);
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```
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## Cell Selection
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To enable cell selection for a `TreeDataGridSource`, assign an instance of `TreeDataGridCellSelectionModel<TModel>` to the source's `Selection` property:
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```csharp
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Source = new FlatTreeDataGridSource<Person>(_people)
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{
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Columns =
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{
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new TextColumn<Person, string>("First Name", x => x.FirstName),
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new TextColumn<Person, string>("Last Name", x => x.LastName),
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new TextColumn<Person, int>("Age", x => x.Age),
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},
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};
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Source.Selection = new TreeDataGridCellSelectionModel<Person>(Source);
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```
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Or for multiple cell selection:
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```csharp
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Source.Selection = new TreeDataGridCellSelectionModel<Person>(Source) { SingleSelect = false };
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```
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Cell selection is is exposed via the `CellSelection` property on the `FlatTreeDataGridSource<TModel>` and `HierarchicalTreeDataGridSource<TModel>` classes when enabled.
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The `CellIndex` struct indentifies an individual cell with by combination of an integer column index and an `IndexPath` row index.

‎readme.md

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@@ -32,3 +32,4 @@ We accept issues and pull requests but we answer and review only pull requests a
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- [Creating a flat `TreeDataGrid`](docs/get-started-flat.md)
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- [Creating a hierarchical `TreeDataGrid`](docs/get-started-hierarchical.md)
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- [Supported column types](docs/column-types.md)
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- [Selection](docs/selection.md)

‎samples/TreeDataGridDemo/MainWindow.axaml

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<TabItem Header="Countries">
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<DockPanel>
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<TextBlock Classes="realized-count" DockPanel.Dock="Bottom"/>
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<StackPanel DockPanel.Dock="Right" Spacing="4">
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<StackPanel DockPanel.Dock="Right" Spacing="4" Margin="4 0 0 0">
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<CheckBox IsChecked="{Binding Countries.CellSelection}">Cell Selection</CheckBox>
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<Label Target="countryTextBox">_Country</Label>
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<TextBox Name="countryTextBox">Sealand</TextBox>
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<Label Target="regionTextBox">_Region</Label>
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<ComboBox ItemsSource="{Binding Files.Drives}"
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SelectedItem="{Binding Files.SelectedDrive}"
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DockPanel.Dock="Left"/>
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<CheckBox IsChecked="{Binding Files.CellSelection}"
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Margin="4 0 0 0"
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DockPanel.Dock="Right">
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Cell Selection
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</CheckBox>
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<TextBox Text="{Binding Files.SelectedPath, Mode=OneWay}"
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Margin="4 0 0 0"
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VerticalContentAlignment="Center"

‎samples/TreeDataGridDemo/ViewModels/CountriesPageViewModel.cs

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using Avalonia.Controls;
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using Avalonia.Controls.Models.TreeDataGrid;
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using Avalonia.Controls.Selection;
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using ReactiveUI;
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using TreeDataGridDemo.Models;
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namespace TreeDataGridDemo.ViewModels
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{
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internal class CountriesPageViewModel
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internal class CountriesPageViewModel : ReactiveObject
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{
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private readonly ObservableCollection<Country> _data;
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private bool _cellSelection;
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public CountriesPageViewModel()
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{
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Columns =
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{
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new TextColumn<Country, string>("Country", x => x.Name, (r, v) => r.Name = v, new GridLength(6, GridUnitType.Star), new()
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{
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IsTextSearchEnabled = true
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{
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IsTextSearchEnabled = true
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}),
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new TextColumn<Country, string>("Region", x => x.Region, new GridLength(4, GridUnitType.Star)),
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new TextColumn<Country, int>("Population", x => x.Population, new GridLength(3, GridUnitType.Star)),
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Source.RowSelection!.SingleSelect = false;
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}
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public bool CellSelection
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{
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get => _cellSelection;
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set
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{
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if (_cellSelection != value)
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{
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_cellSelection = value;
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if (_cellSelection)
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Source.Selection = new TreeDataGridCellSelectionModel<Country>(Source) { SingleSelect = false };
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else
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Source.Selection = new TreeDataGridRowSelectionModel<Country>(Source) { SingleSelect = false };
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this.RaisePropertyChanged();
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}
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}
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}
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public FlatTreeDataGridSource<Country> Source { get; }
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public void AddCountry(Country country) => _data.Add(country);

‎samples/TreeDataGridDemo/ViewModels/FilesPageViewModel.cs

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public class FilesPageViewModel : ReactiveObject
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{
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private static IconConverter? s_iconConverter;
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private bool _cellSelection;
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private FileTreeNodeModel? _root;
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private string _selectedDrive;
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private string? _selectedPath;
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});
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}
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public bool CellSelection
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{
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get => _cellSelection;
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set
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{
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if (_cellSelection != value)
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{
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_cellSelection = value;
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if (_cellSelection)
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Source.Selection = new TreeDataGridCellSelectionModel<FileTreeNodeModel>(Source) { SingleSelect = false };
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else
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Source.Selection = new TreeDataGridRowSelectionModel<FileTreeNodeModel>(Source) { SingleSelect = false };
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this.RaisePropertyChanged();
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}
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}
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}
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public IList<string> Drives { get; }
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public string SelectedDrive

‎src/Avalonia.Controls.TreeDataGrid/Avalonia.Controls.TreeDataGrid.csproj

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<PropertyGroup>
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<TargetFramework>net5.0</TargetFramework>
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<IsPackable>True</IsPackable>
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<LangVersion>10</LangVersion>
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<RootNamespace>Avalonia.Controls</RootNamespace>
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</PropertyGroup>
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<PropertyGroup>

‎src/Avalonia.Controls.TreeDataGrid/CellIndex.cs

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namespace Avalonia.Controls
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{
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/// <summary>
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/// Represents a cell in a <see cref="TreeDataGrid"/>.
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/// </summary>
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/// <param name="ColumnIndex">
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/// The index of the cell in the <see cref="TreeDataGrid.Columns"/> collection.
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/// </param>
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/// <param name="RowIndex">
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/// The hierarchical index of the row model in the data source.
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/// </param>
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public readonly record struct CellIndex(int ColumnIndex, IndexPath RowIndex);
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}

‎src/Avalonia.Controls.TreeDataGrid/FlatTreeDataGridSource.cs

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using System.Collections.Generic;
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using System.ComponentModel;
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using System.Linq;
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using Avalonia.Controls.Models;
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using Avalonia.Controls.Models.TreeDataGrid;
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using Avalonia.Controls.Selection;
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using Avalonia.Input;
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/// A data source for a <see cref="TreeDataGrid"/> which displays a flat grid.
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/// </summary>
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/// <typeparam name="TModel">The model type.</typeparam>
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public class FlatTreeDataGridSource<TModel> : ITreeDataGridSource<TModel>, IDisposable
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where TModel: class
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public class FlatTreeDataGridSource<TModel> : NotifyingBase,
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ITreeDataGridSource<TModel>,
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IDisposable
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where TModel: class
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{
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private IEnumerable<TModel> _items;
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private TreeDataGridItemsSourceView<TModel> _itemsView;
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_rows?.SetItems(_itemsView);
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if (_selection is object)
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_selection.Source = value;
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RaisePropertyChanged();
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}
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}
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}
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}
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set
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{
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if (_selection is object)
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throw new InvalidOperationException("Selection is already initialized.");
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_selection = value;
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_isSelectionSet = true;
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if (_selection != value)
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{
68+
if (value?.Source != _items)
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throw new InvalidOperationException("Selection source must be set to Items.");
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_selection = value;
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_isSelectionSet = true;
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RaisePropertyChanged();
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}
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}
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}
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public ITreeDataGridCellSelectionModel<TModel>? CellSelection => Selection as ITreeDataGridCellSelectionModel<TModel>;
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public ITreeDataGridRowSelectionModel<TModel>? RowSelection => Selection as ITreeDataGridRowSelectionModel<TModel>;
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public bool IsHierarchical => false;
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public bool IsSorted => _comparer is not null;

‎src/Avalonia.Controls.TreeDataGrid/HierarchicalTreeDataGridSource.cs

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using System.ComponentModel;
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using System.Diagnostics.CodeAnalysis;
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using System.Linq;
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using Avalonia.Controls.Models;
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using Avalonia.Controls.Models.TreeDataGrid;
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using Avalonia.Controls.Selection;
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using Avalonia.Input;
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/// row may have multiple columns.
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/// </summary>
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/// <typeparam name="TModel">The model type.</typeparam>
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public class HierarchicalTreeDataGridSource<TModel> : ITreeDataGridSource<TModel>,
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public class HierarchicalTreeDataGridSource<TModel> : NotifyingBase,
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ITreeDataGridSource<TModel>,
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IDisposable,
2022
IExpanderRowController<TModel>
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where TModel: class
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}
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set
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{
73-
if (_selection is object)
74-
throw new InvalidOperationException("Selection is already initialized.");
75-
_selection = value;
76-
_isSelectionSet = true;
75+
if (_selection != value)
76+
{
77+
if (value?.Source != _items)
78+
throw new InvalidOperationException("Selection source must be set to Items.");
79+
_selection = value;
80+
_isSelectionSet = true;
81+
RaisePropertyChanged();
82+
}
7783
}
7884
}
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86+
public ITreeDataGridCellSelectionModel<TModel>? CellSelection => Selection as ITreeDataGridCellSelectionModel<TModel>;
8087
public ITreeDataGridRowSelectionModel<TModel>? RowSelection => Selection as ITreeDataGridRowSelectionModel<TModel>;
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public bool IsHierarchical => true;
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public bool IsSorted => _comparison is not null;

‎src/Avalonia.Controls.TreeDataGrid/ITreeDataGridSource.cs

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/// <summary>
1111
/// Represents a data source for a <see cref="TreeDataGrid"/> control.
1212
/// </summary>
13-
public interface ITreeDataGridSource
13+
public interface ITreeDataGridSource : INotifyPropertyChanged
1414
{
1515
/// <summary>
1616
/// Gets the columns to be displayed.

‎src/Avalonia.Controls.TreeDataGrid/Primitives/ITreeDataGridCell.cs

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11
using Avalonia.Controls.Models.TreeDataGrid;
2+
using Avalonia.Controls.Selection;
23

34
namespace Avalonia.Controls.Primitives
45
{
56
internal interface ITreeDataGridCell
67
{
78
int ColumnIndex { get; }
89

9-
void Realize(TreeDataGridElementFactory factory, ICell model, int columnIndex, int rowIndex);
10+
void Realize(
11+
TreeDataGridElementFactory factory,
12+
ITreeDataGridSelectionInteraction? selection,
13+
ICell model,
14+
int columnIndex,
15+
int rowIndex);
16+
1017
void Unrealize();
1118
}
1219
}

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