我遇到了虚拟化如何与WPF DataGrid一起使用的问题。
我正在使用MVVM并将所有行视图模型绑定到IsSelected属性。我需要偶尔取消选择所有行,所以我通过将我的基础行视图模型更新为IsSelected = false来执行此操作。
这开始似乎工作正常,它取消选择一切。我已经验证使用调试消息并设置条件断点将所有行视图模型设置为false。
但是,当我滚动网格时会出现问题。我看到实际选择了一些行。当IsSelected属性设置为true时,我在IsSelected属性上有一个条件断点,在滚动网格之前,这实际上并没有中断。所以,当我向下滚动时,某些东西偶尔会将某些行视图模型更新回IsSelected = true?
我不太明白发生了什么,或者是它的调用堆栈......有人可以向我解释实际发生了什么吗?我认为这与虚拟化有关。我认为可能虚拟化正在回收DataGridRow,反过来又将我的viewmodels更新回IsSelected = true。但是,这两种虚拟化模式(回收和标准)都会发生这种情况。我原本以为每次都会重新创建DataGridRows吗?
MyApp.exe!MyApp.MyViewModel.IsSelected.set(bool value = true) Line 67 C#
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PresentationFramework.dll!MS.Internal.Data.PropertyPathWorker.SetValue(object item, object value) + 0x106 bytes
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WindowsBase.dll!System.Windows.DependencyObject.SetCurrentValueInternal(System.Windows.DependencyProperty dp, object value) + 0x35 bytes
PresentationFramework.dll!System.Windows.Controls.Primitives.Selector.ItemSetIsSelected(object item, bool value) + 0xb2 bytes
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PresentationFramework.dll!System.Windows.Controls.VirtualizingStackPanel.MeasureOverride(System.Windows.Size constraint) + 0x976 bytes
PresentationFramework.dll!System.Windows.Controls.Primitives.DataGridRowsPresenter.MeasureOverride(System.Windows.Size constraint) + 0x28 bytes
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WindowsBase.dll!System.Windows.Threading.DispatcherOperation.InvokeInSecurityContext(object state) + 0x38 bytes
mscorlib.dll!System.Threading.ExecutionContext.runTryCode(object userData) + 0x51 bytes
更新: 我正在发布我的View和ViewModels的代码。通过调用“Select All rows”调用将所有行视图模型更新为IsSelected = true,我能够一致地重现它。在此之后,我向上和向下滚动一下以查看所有选定的行。然后我调用“取消选择所有行”,并且应取消选择所有行视图模型。当我向下滚动时,我可以看到rowviewmodels然后被更新为IsSelected = true(通过调试消息)。如果我打破并看到这是什么,我得到上面的堆栈跟踪。
的ViewModels:
using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Linq;
using System.Windows.Input;
namespace WpfDataGridVirtualization
{
public interface IOrderViewModel : INotifyPropertyChanged
{
Guid Key { get; }
decimal Level { get; }
bool IsSelected { get; set; }
}
public class OrderViewModel : NotifyPropertyChanged, IOrderViewModel
{
private string _market;
private int _quantity;
private decimal _level;
private bool _isSelected;
public OrderViewModel(OrderData orderData)
{
Key = Guid.NewGuid();
Market = orderData.Market;
IsSelected = false;
Quantity = orderData.Quantity;
Level = orderData.Level;
}
public Guid Key { get; private set; }
public bool IsSelected
{
get { return _isSelected; }
set
{
if (value)
System.Diagnostics.Debug.WriteLine("setting isselected to true");
_isSelected = value;
RaisePropertyChanged("IsSelected");
}
}
public string Market
{
get { return _market; }
private set
{
_market = value;
RaisePropertyChanged("Market");
}
}
public int Quantity
{
get { return _quantity; }
private set
{
_quantity = value;
RaisePropertyChanged("Quantity");
}
}
public decimal Level
{
get { return _level; }
private set
{
_level = value;
RaisePropertyChanged("Level");
}
}
}
public class OrderData
{
public OrderData(string market, int qty, decimal level)
{
Key = Guid.NewGuid();
Market = market;
Quantity = qty;
Level = level;
}
public Guid Key { get; set; }
public string Market { get; set; }
public int Quantity { get; set; }
public decimal Level { get; set; }
}
public class OrderCollectionViewModel : NotifyPropertyChanged, IDisposable
{
private readonly ObservableCollection<IOrderViewModel> _orders = new ObservableCollection<IOrderViewModel>();
public ObservableCollection<IOrderViewModel> Orders { get { return _orders; } }
public void AddOrders(IEnumerable<OrderData> orders)
{
orders.ToList().ForEach(o => AddOrder(o));
}
private void AddOrder(OrderData order)
{
var viewModel = _orders.Where(o => o.Key == order.Key).SingleOrDefault();
if (viewModel == null)
{
viewModel = new OrderViewModel(order);
lock (_orders)
{
_orders.Add(viewModel);
}
}
viewModel.IsSelected = false;
}
public void ApplyFiltering()
{
UnSelectAll();
}
public void SelectAll(bool select)
{
UpdateAllOrders(row =>
{
row.IsSelected = select;
});
}
public void SelectSingleRow(Guid key)
{
UpdateAllOrders(row =>
{
row.IsSelected = true;
});
}
public IEnumerable<IOrderViewModel> GetSelected()
{
lock (_orders)
{
return _orders.Where(s => s.IsSelected).ToList();
}
}
public void UnSelectAll()
{
var count = 0;
UpdateAllOrders(row =>
{
row.IsSelected = false;
count++;
});
System.Diagnostics.Debug.WriteLine("{0} orders were unselected", count);
}
private void UpdateAllOrders(Action<IOrderViewModel> action)
{
lock (_orders)
{
_orders.ToList().ForEach(action);
}
}
public void Dispose()
{
_orders.Clear();
}
public class OrderSorter : IComparer
{
public int Compare(object x, object y)
{
var orderX = x as OrderViewModel;
var orderY = y as OrderViewModel;
var result = orderX.Market.CompareTo(orderY.Market);
if (result != 0)
return result;
return orderX.Level.CompareTo(orderY.Level);
}
}
}
public class OrderGridViewModel : NotifyPropertyChanged, IDisposable
{
private ICommand _selectAllOrdersCommand;
private ICommand _unselectAllOrdersCommand;
public OrderGridViewModel()
{
OrderCollection = new OrderCollectionViewModel();
InitializeOrders();
}
public ObservableCollection<IOrderViewModel> Orders { get { return OrderCollection.Orders; } }
public OrderCollectionViewModel OrderCollection { get; private set; }
public ICommand SelectAllOrdersCommand
{
get { return _selectAllOrdersCommand ?? (_selectAllOrdersCommand = new RelayCommand(p => OrderCollection.SelectAll(true))); }
}
public ICommand UnSelectAllOrdersCommand
{
get { return _unselectAllOrdersCommand ?? (_unselectAllOrdersCommand = new RelayCommand(p => OrderCollection.ApplyFiltering())); }
}
private void InitializeOrders()
{
OrderCollection.AddOrders(OrderDataHelper.GetOrderData());
}
public void Dispose()
{
OrderCollection.Dispose();
}
}
public static class OrderDataHelper
{
public static IEnumerable<OrderData> GetOrderData()
{
Dictionary<int, string> marketMap = new Dictionary<int, string>()
{
{0, "AUD"},
{1, "EUR"},
{2, "USD"},
{3, "CAD"},
{4, "CHF"},
{5, "BOBL"},
{6, "EMiniNasdaq"},
{7, "Corn"},
{8, "Oil"},
{9, "Starch"},
};
var multiplyFactor = 1;
for (int j = 0; j < 10; j++)
{
var market = marketMap[j];
for (int i = 0; i < 50 * multiplyFactor; i++)
yield return new OrderData(market, 1000000, 100);
for (int i = 0; i < 50 * multiplyFactor; i++)
yield return new OrderData(market, 1000000, 100);
for (int i = 0; i < 5 * multiplyFactor; i++)
yield return new OrderData(market, 1000000, 100);
for (int i = 0; i < 2 * multiplyFactor; i++)
yield return new OrderData(market, 1000000, 100);
for (int i = 0; i < 5 * multiplyFactor; i++)
yield return new OrderData(market, 1000000, 100);
for (int i = 0; i < 5 * multiplyFactor; i++)
yield return new OrderData(market, 1000000, 100);
for (int i = 0; i < 5 * multiplyFactor; i++)
yield return new OrderData(market, 1000000, 100);
}
}
}
}
查看
<Window x:Class="WpfDataGridVirtualization.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="600" Width="800" Closing="WindowClosing">
<DockPanel>
<DockPanel x:Name="dockHeader" DockPanel.Dock="Top" Background="Transparent">
<Button Content="Select All Orders" Margin="2" Command="{Binding SelectAllOrdersCommand}" />
<Button Content="UnSelect All Orders" Margin="2" Command="{Binding UnSelectAllOrdersCommand}" />
<DockPanel/>
</DockPanel>
<DockPanel DockPanel.Dock="Top">
<DataGrid x:Name="dgOrders" Margin="5"
ItemsSource="{Binding OrderCollection.Orders}"
IsReadOnly="True"
AutoGenerateColumns="False"
SelectionUnit="FullRow"
VirtualizingStackPanel.IsVirtualizing="True"
VirtualizingStackPanel.VirtualizationMode="Standard"
>
<DataGrid.RowStyle>
<Style TargetType="{x:Type DataGridRow}">
<Setter Property="IsSelected" Value="{Binding IsSelected, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />
</Style>
</DataGrid.RowStyle>
<DataGrid.Columns>
<DataGridTextColumn Header="IsSelected" Binding="{Binding IsSelected}" />
<DataGridTextColumn Header="Market" Binding="{Binding Market}" />
<DataGridTextColumn Header="Quantity" Binding="{Binding Quantity}" />
<DataGridTextColumn Header="Level" Binding="{Binding Level}" />
</DataGrid.Columns>
</DataGrid>
</DockPanel>
</DockPanel>
</Window>
查看代码背后
using System.Windows;
namespace WpfDataGridVirtualization
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
private readonly OrderGridViewModel _viewModel;
public MainWindow()
{
InitializeComponent();
_viewModel = new OrderGridViewModel();
DataContext = _viewModel;
}
private OrderGridViewModel GetViewModel()
{
return DataContext as OrderGridViewModel;
}
private void WindowClosing(object sender, System.ComponentModel.CancelEventArgs e)
{
GetViewModel().Dispose();
}
}
}
答案 0 :(得分:0)
这可能是一个线程问题。我看到你正在获取锁定在锁定块内的同一对象的锁定,即命令对象
您应该始终使用专门声明用于锁定关键字的单独新对象实例锁定,例如
private readonly object _lockObject = new Object();
lock(_lockObject)
{
orders.Add(...);
}
尝试对锁定块进行上述代码更改,并查看问题是否得到解决。