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Create DataGridCheckAllColumn.cs
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‎WPF/DataGridCheckAllColumn.cs

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// Code Auther: Flithor (Mr.Squirrel.Downy)
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// License: MIT
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// =======WARNING=======
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// Use this code at your own risk
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// The newest code may on the https://stackoverflow.com/a/77603913/6859121
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using System;
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using System.Collections.Generic;
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using System.ComponentModel;
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using System.Globalization;
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using System.Linq;
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using System.Reflection;
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using System.Windows;
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using System.Windows.Controls;
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using System.Windows.Controls.Primitives;
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using System.Windows.Data;
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using System.Windows.Media;
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using Expression = System.Linq.Expressions.Expression;
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namespace Flithor_ReusableCodes
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{
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/// <summary>
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/// A DataGrid Column work for binding to Checked property for item element, and can Check All
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/// </summary>
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public class DataGridCheckAllColumn : DataGridBoundColumn
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{
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#region Private Fields
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//CheckBox in header
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private readonly CheckBox checkAllCheckBox;
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//owner DataGrid control for this column
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private DataGrid ownerDatagrid;
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//owner DataGrid current delegate get current list version
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//if version changed then change bindings
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private Func<int> getInnerEnumeratorVersion;
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//cached list version
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private int cachedInnerVersion;
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//default style for CheckBox
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private static Style _defaultElementStyle;
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#endregion
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#region Initialize Control
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public static Style DefaultElementStyle
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{
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get
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{
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if (_defaultElementStyle == null)
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{
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var style = new Style(typeof(CheckBox))
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{
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Setters =
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{
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new Setter(UIElement.FocusableProperty, false),
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new Setter(CheckBox.HorizontalAlignmentProperty, HorizontalAlignment.Center),
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new Setter(CheckBox.VerticalAlignmentProperty, VerticalAlignment.Center)
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}
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};
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style.Seal();
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_defaultElementStyle = style;
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}
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return _defaultElementStyle;
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}
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}
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static DataGridCheckAllColumn()
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{
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//override default element style
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ElementStyleProperty.OverrideMetadata(typeof(DataGridCheckAllColumn), new FrameworkPropertyMetadata(DefaultElementStyle));
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//make column readonly by default
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IsReadOnlyProperty.OverrideMetadata(typeof(DataGridCheckAllColumn), new FrameworkPropertyMetadata(true));
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//not allows move column
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CanUserReorderProperty.OverrideMetadata(typeof(DataGridCheckAllColumn), new FrameworkPropertyMetadata(false));
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//not allows resize column
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CanUserResizeProperty.OverrideMetadata(typeof(DataGridCheckAllColumn), new FrameworkPropertyMetadata(false));
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//not allows order items by click header
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CanUserSortProperty.OverrideMetadata(typeof(DataGridCheckAllColumn), new FrameworkPropertyMetadata(false));
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}
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public DataGridCheckAllColumn()
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{
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//override header
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Header = checkAllCheckBox = new CheckBox();
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}
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protected override void OnPropertyChanged(DependencyPropertyChangedEventArgs e)
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{
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if (ownerDatagrid != null) return;
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ownerDatagrid = GetParentDataGrid();
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if (ownerDatagrid == null) return;
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InitInnerVersionDetect(ownerDatagrid.Items);
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((INotifyPropertyChanged)ownerDatagrid.Items).PropertyChanged += OnPropertyChanged;
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//if DataGrid has items now, init bindings
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checkAllCheckBox.IsEnabled = ownerDatagrid.Items.Count > 0;
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if (checkAllCheckBox.IsEnabled)
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ResetCheckCurrentAllBinding();
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}
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//find parent DataGrid(if not end initialize, may return null)
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private DataGrid GetParentDataGrid()
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{
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DependencyObject elment = checkAllCheckBox;
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do
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{
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elment = VisualTreeHelper.GetParent(elment);
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}
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while (elment != null && !(elment is DataGrid));
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return elment as DataGrid;
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}
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#endregion
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#region Generate Element
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protected override FrameworkElement GenerateElement(DataGridCell cell, object dataItem)
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{
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return GenerateCheckBox(false, cell, dataItem);
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}
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protected override FrameworkElement GenerateEditingElement(DataGridCell cell, object dataItem)
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{
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return GenerateCheckBox(true, cell, dataItem);
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}
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private CheckBox GenerateCheckBox(bool isEditing, DataGridCell cell, object dataItem)
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{
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var checkBox = new CheckBox();
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ApplyStyle(isEditing, checkBox);
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ApplyBinding(dataItem, checkBox);
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return checkBox;
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}
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private void ApplyBinding(object dataItem, CheckBox checkBox)
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{
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var binding = CloneBinding(Binding, dataItem);
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if (binding is Binding newBinding)
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{
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newBinding.Mode = BindingMode.TwoWay;
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newBinding.UpdateSourceTrigger = UpdateSourceTrigger.PropertyChanged;
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}
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BindingOperations.ClearBinding(checkBox, CheckBox.IsCheckedProperty);
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checkBox.SetBinding(CheckBox.IsCheckedProperty, binding);
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}
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internal void ApplyStyle(bool isEditing, FrameworkElement element)
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{
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Style style = PickStyle(isEditing);
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if (style != null)
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{
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element.Style = style;
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}
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}
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private Style PickStyle(bool isEditing)
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{
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Style style = isEditing ? EditingElementStyle : ElementStyle;
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if (isEditing && (style == null))
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{
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style = ElementStyle;
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}
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return style;
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}
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#endregion
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#region Update Binding
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private void OnPropertyChanged(object sender, PropertyChangedEventArgs e)
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{
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if (ownerDatagrid == null || e.PropertyName != nameof(ownerDatagrid.Items.Count))
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return;
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//if items count changed then means the collection may changed
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if (ownerDatagrid.Items.Count == 0)
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{
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//if Items goes empty then clear the check binding and disable check all
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BindingOperations.ClearBinding(checkAllCheckBox, CheckBox.IsCheckedProperty);
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checkAllCheckBox.IsEnabled = false;
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}
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else
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{
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//else update the binding to current displayed items
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ResetCheckCurrentAllBinding();
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checkAllCheckBox.IsEnabled = true;
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}
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}
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private void ResetCheckCurrentAllBinding()
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{
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//If version changed then update binding by current items
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if (ownerDatagrid == null || !InnerVersionChanged()) return;
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var checkAllBinding = new MultiBinding
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{
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Converter = AllBoolStatusConverter.Default,
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Mode = BindingMode.TwoWay
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};
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//binding items by current displayed items
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var currentItems = ownerDatagrid.Items.OfType<object>().ToList();
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foreach (var item in currentItems)
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{
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checkAllBinding.Bindings.Add(CloneBinding((Binding)Binding, item));
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}
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//clear old binding if exists
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BindingOperations.ClearBinding(checkAllCheckBox, CheckBox.IsCheckedProperty);
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checkAllCheckBox.SetBinding(CheckBox.IsCheckedProperty, checkAllBinding);
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}
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//generate DataGrid.Items version get delegate
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private void InitInnerVersionDetect(ItemCollection itemCollection)
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{
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//Timestamp property is the version mark of ItemCollection to tell us is it changed
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var collectionTimestampProerty = itemCollection.GetType()
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.GetProperty("Timestamp", BindingFlags.Instance | BindingFlags.NonPublic);
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//use Linq Expression build a simple delegate to access Timestamp property
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getInnerEnumeratorVersion = Expression.Lambda<Func<int>>(Expression.Property(
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Expression.Constant(itemCollection),
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collectionTimestampProerty)).Compile();
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}
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//get the inner collection version to detect is it changed
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private bool InnerVersionChanged()
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{
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var currentInnerVersion = getInnerEnumeratorVersion.Invoke();
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if (currentInnerVersion != cachedInnerVersion)
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{
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cachedInnerVersion = currentInnerVersion;
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return true;
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}
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return false;
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}
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//create a new binding instance by existed binding
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private static BindingBase CloneBinding(BindingBase bindingBase, object source)
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{
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switch (bindingBase)
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{
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case Binding binding:
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var resultBinding = new Binding
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{
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Source = source,
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AsyncState = binding.AsyncState,
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BindingGroupName = binding.BindingGroupName,
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BindsDirectlyToSource = binding.BindsDirectlyToSource,
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Converter = binding.Converter,
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ConverterCulture = binding.ConverterCulture,
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ConverterParameter = binding.ConverterParameter,
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//ElementName = binding.ElementName,
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FallbackValue = binding.FallbackValue,
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IsAsync = binding.IsAsync,
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Mode = binding.Mode,
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NotifyOnSourceUpdated = binding.NotifyOnSourceUpdated,
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NotifyOnTargetUpdated = binding.NotifyOnTargetUpdated,
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NotifyOnValidationError = binding.NotifyOnValidationError,
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Path = binding.Path,
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//RelativeSource = binding.RelativeSource,
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StringFormat = binding.StringFormat,
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TargetNullValue = binding.TargetNullValue,
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UpdateSourceExceptionFilter = binding.UpdateSourceExceptionFilter,
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UpdateSourceTrigger = binding.UpdateSourceTrigger,
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ValidatesOnDataErrors = binding.ValidatesOnDataErrors,
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ValidatesOnExceptions = binding.ValidatesOnExceptions,
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XPath = binding.XPath,
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};
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foreach (var validationRule in binding.ValidationRules)
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{
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resultBinding.ValidationRules.Add(validationRule);
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}
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return resultBinding;
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case MultiBinding multiBinding:
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var resultMultiBinding = new MultiBinding
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{
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BindingGroupName = multiBinding.BindingGroupName,
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Converter = multiBinding.Converter,
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ConverterCulture = multiBinding.ConverterCulture,
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ConverterParameter = multiBinding.ConverterParameter,
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FallbackValue = multiBinding.FallbackValue,
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Mode = multiBinding.Mode,
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NotifyOnSourceUpdated = multiBinding.NotifyOnSourceUpdated,
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NotifyOnTargetUpdated = multiBinding.NotifyOnTargetUpdated,
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NotifyOnValidationError = multiBinding.NotifyOnValidationError,
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StringFormat = multiBinding.StringFormat,
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TargetNullValue = multiBinding.TargetNullValue,
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UpdateSourceExceptionFilter = multiBinding.UpdateSourceExceptionFilter,
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UpdateSourceTrigger = multiBinding.UpdateSourceTrigger,
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ValidatesOnDataErrors = multiBinding.ValidatesOnDataErrors,
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ValidatesOnExceptions = multiBinding.ValidatesOnDataErrors,
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};
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foreach (var validationRule in multiBinding.ValidationRules)
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{
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resultMultiBinding.ValidationRules.Add(validationRule);
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}
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foreach (var childBinding in multiBinding.Bindings)
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{
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resultMultiBinding.Bindings.Add(CloneBinding(childBinding, source));
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}
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return resultMultiBinding;
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case PriorityBinding priorityBinding:
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var resultPriorityBinding = new PriorityBinding
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{
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BindingGroupName = priorityBinding.BindingGroupName,
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FallbackValue = priorityBinding.FallbackValue,
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StringFormat = priorityBinding.StringFormat,
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TargetNullValue = priorityBinding.TargetNullValue,
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};
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foreach (var childBinding in priorityBinding.Bindings)
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{
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resultPriorityBinding.Bindings.Add(CloneBinding(childBinding, source));
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}
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return resultPriorityBinding;
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default:
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throw new NotSupportedException("Failed to clone binding");
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}
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}
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/// <summary>
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/// A MultiValueConverter to merge all items bound bool value into one
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/// </summary>
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private class AllBoolStatusConverter : IMultiValueConverter
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{
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public static readonly AllBoolStatusConverter Default = new AllBoolStatusConverter();
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public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
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{
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if (values.Length == 0 || values.OfType<bool>().Count() != values.Length)
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return false;
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// detect all items are equals the first
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var firstStatus = values.First();
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foreach (var value in values)
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{
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//any one not equals to first then return null
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if (!Equals(value, firstStatus))
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return null;
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}
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return firstStatus;
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}
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public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)
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{
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//if the check all CheckBox checked or unchecked then update all items bound value
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var res = new object[targetTypes.Length];
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for (int i = 0; i < res.Length; i++)
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res[i] = value;
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return res;
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}
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}
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#endregion
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}
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}

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