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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
using System.Windows.Input;
namespace System.Windows.Controls
{
/// <summary>
/// A column that displays a check box.
/// </summary>
public class DataGridCheckBoxColumn : DataGridBoundColumn
{
static DataGridCheckBoxColumn()
{
ElementStyleProperty.OverrideMetadata(typeof(DataGridCheckBoxColumn), new FrameworkPropertyMetadata(DefaultElementStyle));
EditingElementStyleProperty.OverrideMetadata(typeof(DataGridCheckBoxColumn), new FrameworkPropertyMetadata(DefaultEditingElementStyle));
}
#region Styles
/// <summary>
/// The default value of the ElementStyle property.
/// This value can be used as the BasedOn for new styles.
/// </summary>
public static Style DefaultElementStyle
{
get
{
if (_defaultElementStyle == null)
{
Style baseStyle = null;
if (ThemeManager.IsFluentThemeEnabled)
{
baseStyle = Application.Current.FindResource(typeof(CheckBox)) as Style;
}
Style style = new Style(typeof(CheckBox), baseStyle);
// When not in edit mode, the end-user should not be able to toggle the state
style.Setters.Add(new Setter(UIElement.IsHitTestVisibleProperty, false));
style.Setters.Add(new Setter(UIElement.FocusableProperty, false));
style.Setters.Add(new Setter(CheckBox.HorizontalAlignmentProperty, HorizontalAlignment.Center));
style.Setters.Add(new Setter(CheckBox.VerticalAlignmentProperty, VerticalAlignment.Top));
style.Seal();
_defaultElementStyle = style;
}
return _defaultElementStyle;
}
}
/// <summary>
/// The default value of the EditingElementStyle property.
/// This value can be used as the BasedOn for new styles.
/// </summary>
public static Style DefaultEditingElementStyle
{
get
{
if (_defaultEditingElementStyle == null)
{
Style baseStyle = null;
if (ThemeManager.IsFluentThemeEnabled)
{
baseStyle = Application.Current.FindResource(typeof(CheckBox)) as Style;
}
Style style = new Style(typeof(CheckBox), baseStyle);
style.Setters.Add(new Setter(CheckBox.HorizontalAlignmentProperty, HorizontalAlignment.Center));
style.Setters.Add(new Setter(CheckBox.VerticalAlignmentProperty, VerticalAlignment.Top));
style.Seal();
_defaultEditingElementStyle = style;
}
return _defaultEditingElementStyle;
}
}
#endregion
#region Element Generation
/// <summary>
/// Creates the visual tree for boolean based cells.
/// </summary>
protected override FrameworkElement GenerateElement(DataGridCell cell, object dataItem)
{
return GenerateCheckBox(/* isEditing = */ false, cell);
}
/// <summary>
/// Creates the visual tree for boolean based cells.
/// </summary>
protected override FrameworkElement GenerateEditingElement(DataGridCell cell, object dataItem)
{
return GenerateCheckBox(/* isEditing = */ true, cell);
}
private CheckBox GenerateCheckBox(bool isEditing, DataGridCell cell)
{
CheckBox checkBox = (cell != null) ? (cell.Content as CheckBox) : null;
if (checkBox == null)
{
checkBox = new CheckBox();
}
checkBox.IsThreeState = IsThreeState;
ApplyStyle(isEditing, /* defaultToElementStyle = */ true, checkBox);
ApplyBinding(checkBox, CheckBox.IsCheckedProperty);
return checkBox;
}
protected internal override void RefreshCellContent(FrameworkElement element, string propertyName)
{
if (element is DataGridCell cell && string.Equals(propertyName, "IsThreeState", StringComparison.Ordinal))
{
if (cell.Content is CheckBox checkBox)
{
checkBox.IsThreeState = IsThreeState;
}
}
else
{
base.RefreshCellContent(element, propertyName);
}
}
#endregion
#region Editing
/// <summary>
/// The DependencyProperty for the IsThreeState property.
/// Flags: None
/// Default Value: false
/// </summary>
public static readonly DependencyProperty IsThreeStateProperty =
CheckBox.IsThreeStateProperty.AddOwner(
typeof(DataGridCheckBoxColumn),
new FrameworkPropertyMetadata(false, DataGridColumn.NotifyPropertyChangeForRefreshContent));
/// <summary>
/// The IsThreeState property determines whether the control supports two or three states.
/// IsChecked property can be set to null as a third state when IsThreeState is true
/// </summary>
public bool IsThreeState
{
get { return (bool)GetValue(IsThreeStateProperty); }
set { SetValue(IsThreeStateProperty, value); }
}
/// <summary>
/// Called when a cell has just switched to edit mode.
/// </summary>
/// <param name="editingElement">A reference to element returned by GenerateEditingElement.</param>
/// <param name="editingEventArgs">The event args of the input event that caused the cell to go into edit mode. May be null.</param>
/// <returns>The unedited value of the cell.</returns>
protected override object PrepareCellForEdit(FrameworkElement editingElement, RoutedEventArgs editingEventArgs)
{
CheckBox checkBox = editingElement as CheckBox;
if (checkBox != null)
{
checkBox.Focus();
bool? uneditedValue = checkBox.IsChecked;
// If a click or a space key invoked the begin edit, then do an immediate toggle
if ((IsMouseLeftButtonDown(editingEventArgs) && IsMouseOver(checkBox, editingEventArgs)) ||
IsSpaceKeyDown(editingEventArgs))
{
checkBox.IsChecked = (uneditedValue != true);
}
return uneditedValue;
}
return (bool?) false;
}
internal override void OnInput(InputEventArgs e)
{
// Space key down will begin edit mode
if (IsSpaceKeyDown(e))
{
BeginEdit(e, true);
}
}
private static bool IsMouseLeftButtonDown(RoutedEventArgs e)
{
MouseButtonEventArgs mouseArgs = e as MouseButtonEventArgs;
return (mouseArgs != null) &&
(mouseArgs.ChangedButton == MouseButton.Left) &&
(mouseArgs.ButtonState == MouseButtonState.Pressed);
}
private static bool IsMouseOver(CheckBox checkBox, RoutedEventArgs e)
{
// This element is new, so the IsMouseOver property will not have been updated
// yet, but there is enough information to do a hit-test.
return checkBox.InputHitTest(((MouseButtonEventArgs)e).GetPosition(checkBox)) != null;
}
private static bool IsSpaceKeyDown(RoutedEventArgs e)
{
KeyEventArgs keyArgs = e as KeyEventArgs;
return (keyArgs != null) &&
keyArgs.RoutedEvent == Keyboard.KeyDownEvent &&
((keyArgs.KeyStates & KeyStates.Down) == KeyStates.Down) &&
(keyArgs.Key == Key.Space);
}
#endregion
#region Data
private static Style _defaultElementStyle;
private static Style _defaultEditingElementStyle;
#endregion
}
}
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