WPF DataGrid开箱即用支持全部勾选的DataGridCheckBoxColumn
本文由 飞羽流星(Flithor/毛茸茸松鼠先生/Mr.Squirrel.Downy)原创,欢迎分享转载,但禁止以原创二次发布
原文地址：https://www.cnblogs.com/Flithor/p/17877473.html以往在WPF的DataGrid上实现实时勾选交互非常麻烦,要用DataGridTemplateColumn写样式还要写一些后端代码，还有绑定和转换器，或者处理事件。
但是现在都不需要了，使用开箱即用的DataGridCheckAllColumn，简化你的勾选代码实现！
它支持列表筛选变化反馈，支持虚拟化，支持单项勾选变化的更新反馈。
效果预览：
而且非常简单好用：
<DataGrid.Columns> <!-- 像使用DataGridCheckBoxColumn那样使用和绑定就行 --> <fc:DataGridCheckAllColumn Binding="{Binding IsChecked}" /> <!-- 其它列 --> <DataGridTextColumn Binding="{Binding EntityName}" /> </DataGrid.Columns>
注意！
如果你在DataGrid上设置了VirtualizingPanel.IsVirtualizing="True"应用虚拟化
需要同时设置VirtualizingPanel.VirtualizationMode="Standard"，避免出现绑定实例错误的Bug
本控件确认不会造成内存泄漏，如果发现内存泄漏问题，请检查用于绑定的对象是否实现了INotifyPropertyChanged，用于绑定的集合是否实现了INotifyCollectionChanged
DataGridCheckAllColumn类的实现：
// 代码作者: 飞羽流星(Flithor/Mr.Squirrel.Downy/毛茸茸松鼠先生)
// 开源许可: MIT
// =======警告=======
// 使用开源代码的风险自负
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Globalization;
using System.Linq;
using System.Reflection;
using System.Runtime.Remoting.Messaging;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Controls.Primitives;
using System.Windows.Data;
using System.Windows.Media;
using Expression = System.Linq.Expressions.Expression;
namespace Flithor_Codes
{
/// <summary>
/// 一个支持勾选所有的DataGrid列
/// </summary>
public class DataGridCheckAllColumn : DataGridBoundColumn
{
#region 私有字段
//列头中的CheckBox
private readonly CheckBox checkAllCheckBox;
//所属DataGrid控件
private DataGrid DataGridOwner;
//所属DataGrid控件的列表版本,如果版本号改变则说明列表改变
private Func<int> getInnerEnumeratorVersion;
//缓存的列表版本号
private int cachedInnerVersion;
//CheckBox的默认样式
private static Style _defaultElementStyle;
#endregion
#region 初始化控件
public static Style DefaultElementStyle
{
get
{
if (_defaultElementStyle == null)
{
var style = new Style(typeof(CheckBox))
{
Setters =
{
new Setter(UIElement.FocusableProperty, false),
new Setter(CheckBox.HorizontalAlignmentProperty, HorizontalAlignment.Center),
new Setter(CheckBox.VerticalAlignmentProperty, VerticalAlignment.Center)
}
};
style.Seal();
_defaultElementStyle = style;
}
return _defaultElementStyle;
}
}
static DataGridCheckAllColumn()
{
//重写单元格元素默认样式
ElementStyleProperty.OverrideMetadata(typeof(DataGridCheckAllColumn), new FrameworkPropertyMetadata(DefaultElementStyle));
//使列默认只读
IsReadOnlyProperty.OverrideMetadata(typeof(DataGridCheckAllColumn), new FrameworkPropertyMetadata(true));
//不允许重排此列
CanUserReorderProperty.OverrideMetadata(typeof(DataGridCheckAllColumn), new FrameworkPropertyMetadata(false));
//不允许修改此列宽度
CanUserResizeProperty.OverrideMetadata(typeof(DataGridCheckAllColumn), new FrameworkPropertyMetadata(false));
//不允许点击列头排序项目
CanUserSortProperty.OverrideMetadata(typeof(DataGridCheckAllColumn), new FrameworkPropertyMetadata(false));
}
public DataGridCheckAllColumn()
{
//设置列头
Header = checkAllCheckBox = new CheckBox();
}
protected override void OnPropertyChanged(DependencyPropertyChangedEventArgs e)
{
InitInnerVersionDetect(DataGridOwner.Items);
((INotifyPropertyChanged)DataGridOwner.Items).PropertyChanged += OnPropertyChanged;
//如果DataGrid当前已有项目,则初始化绑定
checkAllCheckBox.IsEnabled = DataGridOwner.Items.Count > 0;
if (checkAllCheckBox.IsEnabled)
ResetCheckCurrentAllBinding();
base.OnPropertyChanged(e);
}
//寻找所属DataGrid控件(如果还没初始化完毕,可能返回空值)
private DataGrid GetParentDataGrid()
{
DependencyObject elment = checkAllCheckBox;
do
{
elment = VisualTreeHelper.GetParent(elment);
}
while (elment != null && !(elment is DataGrid));
return elment as DataGrid;
}
#endregion
#region 构建单元格元素(方法的功能不言自明)
protected override FrameworkElement GenerateElement(DataGridCell cell, object dataItem)
{
return GenerateCheckBox(false, cell, dataItem);
}
protected override FrameworkElement GenerateEditingElement(DataGridCell cell, object dataItem)
{
return GenerateCheckBox(true, cell, dataItem);
}
private CheckBox GenerateCheckBox(bool isEditing, DataGridCell cell, object dataItem)
{
var checkBox = new CheckBox();
ApplyStyle(isEditing, checkBox);
ApplyBinding(dataItem, checkBox);
return checkBox;
}
private void ApplyBinding(object dataItem, CheckBox checkBox)
{
var binding = CloneBinding(Binding, dataItem);
if (binding is Binding newBinding)
{
newBinding.Mode = BindingMode.TwoWay;
newBinding.UpdateSourceTrigger = UpdateSourceTrigger.PropertyChanged;
}
BindingOperations.ClearBinding(checkBox, CheckBox.IsCheckedProperty);
checkBox.SetBinding(CheckBox.IsCheckedProperty, binding);
}
internal void ApplyStyle(bool isEditing, FrameworkElement element)
{
Style style = PickStyle(isEditing);
if (style != null)
{
element.Style = style;
}
}
private Style PickStyle(bool isEditing)
{
Style style = isEditing ? EditingElementStyle : ElementStyle;
if (isEditing && (style == null))
{
style = ElementStyle;
}
return style;
}
#endregion
#region 更新绑定
private void OnPropertyChanged(object sender, PropertyChangedEventArgs e)
{
if (e.PropertyName != nameof(DataGridOwner.Items.Count))
return;
//如果项目数量发生改变意味着列表更新了
if (DataGridOwner.Items.Count == 0)
{
//如果列表空了,那就移除绑定并禁用列头勾选控件
BindingOperations.ClearBinding(checkAllCheckBox, CheckBox.IsCheckedProperty);
checkAllCheckBox.IsEnabled = false;
}
else
{
//否则基于当前列表显示项更新绑定
ResetCheckCurrentAllBinding();
checkAllCheckBox.IsEnabled = true;
}
}
private void ResetCheckCurrentAllBinding()
{
//如果列表版本号改变则更新,否则无需更新
if (!InnerVersionChanged()) return;
var checkAllBinding = new MultiBinding
{
Converter = AllBoolStatusConverter.Default,
Mode = BindingMode.TwoWay
};
//基于所有列表显示项创建绑定
var currentItems = DataGridOwner.Items.OfType<object>().ToList();
foreach (var item in currentItems)
{
checkAllBinding.Bindings.Add(CloneBinding((Binding)Binding, item));
}
//清除旧绑定
BindingOperations.ClearBinding(checkAllCheckBox, CheckBox.IsCheckedProperty);
checkAllCheckBox.SetBinding(CheckBox.IsCheckedProperty, checkAllBinding);
}
//创建获取内部列表版本号的委托
private void InitInnerVersionDetect(ItemCollection itemCollection)
{
//Timestamp属性是内部列表的版本号标识,用于表示列表变更的次数
var collectionTimestampProerty = itemCollection.GetType()
.GetProperty("Timestamp", BindingFlags.Instance | BindingFlags.NonPublic);
//使用Linq的Expression来构建访问Timestamp属性的委托方法
getInnerEnumeratorVersion = Expression.Lambda<Func<int>>(Expression.Property(
Expression.Constant(itemCollection),
collectionTimestampProerty)).Compile();
}
//检查内部列表是否发生了更新
private bool InnerVersionChanged()
{
var currentInnerVersion = getInnerEnumeratorVersion.Invoke();
if (currentInnerVersion != cachedInnerVersion)
{
cachedInnerVersion = currentInnerVersion;
return true;
}
return false;
}
//基于已有绑定对象创建一个副本,使用指定的数据源
private static BindingBase CloneBinding(BindingBase bindingBase, object source)
{
switch (bindingBase)
{
case Binding binding:
var resultBinding = new Binding
{
Source = source,
AsyncState = binding.AsyncState,
BindingGroupName = binding.BindingGroupName,
BindsDirectlyToSource = binding.BindsDirectlyToSource,
Converter = binding.Converter,
ConverterCulture = binding.ConverterCulture,
ConverterParameter = binding.ConverterParameter,
//ElementName = binding.ElementName,
FallbackValue = binding.FallbackValue,
IsAsync = binding.IsAsync,
Mode = binding.Mode,
NotifyOnSourceUpdated = binding.NotifyOnSourceUpdated,
NotifyOnTargetUpdated = binding.NotifyOnTargetUpdated,
NotifyOnValidationError = binding.NotifyOnValidationError,
Path = binding.Path,
//RelativeSource = binding.RelativeSource,
StringFormat = binding.StringFormat,
TargetNullValue = binding.TargetNullValue,
UpdateSourceExceptionFilter = binding.UpdateSourceExceptionFilter,
UpdateSourceTrigger = binding.UpdateSourceTrigger,
ValidatesOnDataErrors = binding.ValidatesOnDataErrors,
ValidatesOnExceptions = binding.ValidatesOnExceptions,
XPath = binding.XPath,
};
foreach (var validationRule in binding.ValidationRules)
{
resultBinding.ValidationRules.Add(validationRule);
}
return resultBinding;
case MultiBinding multiBinding:
var resultMultiBinding = new MultiBinding
{
BindingGroupName = multiBinding.BindingGroupName,
Converter = multiBinding.Converter,
ConverterCulture = multiBinding.ConverterCulture,
ConverterParameter = multiBinding.ConverterParameter,
FallbackValue = multiBinding.FallbackValue,
Mode = multiBinding.Mode,
NotifyOnSourceUpdated = multiBinding.NotifyOnSourceUpdated,
NotifyOnTargetUpdated = multiBinding.NotifyOnTargetUpdated,
NotifyOnValidationError = multiBinding.NotifyOnValidationError,
StringFormat = multiBinding.StringFormat,
TargetNullValue = multiBinding.TargetNullValue,
UpdateSourceExceptionFilter = multiBinding.UpdateSourceExceptionFilter,
UpdateSourceTrigger = multiBinding.UpdateSourceTrigger,
ValidatesOnDataErrors = multiBinding.ValidatesOnDataErrors,
ValidatesOnExceptions = multiBinding.ValidatesOnDataErrors,
};
foreach (var validationRule in multiBinding.ValidationRules)
{
resultMultiBinding.ValidationRules.Add(validationRule);
}
foreach (var childBinding in multiBinding.Bindings)
{
resultMultiBinding.Bindings.Add(CloneBinding(childBinding, source));
}
return resultMultiBinding;
case PriorityBinding priorityBinding:
var resultPriorityBinding = new PriorityBinding
{
BindingGroupName = priorityBinding.BindingGroupName,
FallbackValue = priorityBinding.FallbackValue,
StringFormat = priorityBinding.StringFormat,
TargetNullValue = priorityBinding.TargetNullValue,
};
foreach (var childBinding in priorityBinding.Bindings)
{
resultPriorityBinding.Bindings.Add(CloneBinding(childBinding, source));
}
return resultPriorityBinding;
default:
throw new NotSupportedException("Failed to clone binding");
}
}
/// <summary>
/// 用于合并所有bool值到一个值的多值转换器
/// </summary>
private class AllBoolStatusConverter : IMultiValueConverter
{
public static readonly AllBoolStatusConverter Default = new AllBoolStatusConverter();
public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
{
if (values.Length == 0 || values.OfType<bool>().Count() != values.Length)
return false;
// 检查所有项是否和第一项相同
var firstStatus = values.First();
foreach (var value in values)
{
//如果有不同就返回null,表示第三态
if (!Equals(value, firstStatus))
return null;
}
return firstStatus;
}
public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)
{
//如果汇总的值发生变化则更新所有项目
var res = new object[targetTypes.Length];
for (int i = 0; i < res.Length; i++)
res[i] = value;
return res;
}
}
#endregion
}
}代码使用了System.Linq.Expressions.Expression，意味着需要使用.NET Framework 3.5以上的运行时。
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