如何在 MouseUp 上觸發 SelectionChanged 事件

Question

我有一個 ListView，我想改變行為，所以SelectionChanged事件會在 MouseUp 上觸發，而不是在 MouseDown 上觸發。 我想改變行為的原因是，當我想拖動對象（在 MouseMove 上）時，當我在要移動的對象上單擊（MouseDown）時，選擇會改變。

我找到了那段代碼，但這僅適用於簡單的選擇，我想允許選擇多個項目。

public static class SelectorBehavior
{
    #region bool ShouldSelectItemOnMouseUp

    public static readonly DependencyProperty ShouldSelectItemOnMouseUpProperty =
        DependencyProperty.RegisterAttached(
            "ShouldSelectItemOnMouseUp", typeof(bool), typeof(SelectorBehavior),
            new PropertyMetadata(default(bool), HandleShouldSelectItemOnMouseUpChange));

    public static void SetShouldSelectItemOnMouseUp(DependencyObject element, bool value)
    {
        element.SetValue(ShouldSelectItemOnMouseUpProperty, value);
    }

    public static bool GetShouldSelectItemOnMouseUp(DependencyObject element)
    {
        return (bool)element.GetValue(ShouldSelectItemOnMouseUpProperty);
    }

    private static void HandleShouldSelectItemOnMouseUpChange(
        DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        if (d is Selector selector)
        {
            selector.PreviewMouseDown -= HandleSelectPreviewMouseDown;
            selector.MouseUp -= HandleSelectMouseUp;

            if (Equals(e.NewValue, true))
            {
                selector.PreviewMouseDown += HandleSelectPreviewMouseDown;
                selector.MouseUp += HandleSelectMouseUp;
            }
        }
    }

    private static void HandleSelectMouseUp(object sender, MouseButtonEventArgs e)
    {
        var selector = (Selector)sender;

        if (e.ChangedButton == MouseButton.Left && e.OriginalSource is Visual source)
        {
            var container = selector.ContainerFromElement(source);
            if (container != null)
            {
                var index = selector.ItemContainerGenerator.IndexFromContainer(container);
                if (index >= 0)
                {
                    selector.SelectedIndex = index;
                }
            }
        }
    }

    private static void HandleSelectPreviewMouseDown(object sender, MouseButtonEventArgs e)
    {
        e.Handled = e.ChangedButton == MouseButton.Left;
    }

    #endregion

}

這是我的 Xaml：

<ListView x:Name="ListViewContract" SelectedItem="{Binding SelectedContract}"  ItemsSource="{Binding ListContractsView}" Grid.Row="1" Grid.Column="0" Grid.ColumnSpan="4" MouseDoubleClick="ListViewContract_DoubleClick" GridViewColumnHeader.Click ="GridViewHeaderClicked" SelectionChanged="ListViewContract_SelectionChanged" Visibility="{Binding Grid1Visible, Converter={StaticResource BoolToVisConverter}}" 
    MouseMove="ListViewContract_MouseMove" local:SelectorBehavior.ShouldSelectItemOnMouseUp="True">
    <ListView.View>
        <GridView AllowsColumnReorder="true" x:Name="GridViewContract">
            <GridViewColumn DisplayMemberBinding="{Binding ID}" Header="ID" Width="{Binding WidthIDs, Mode=TwoWay}"/>
            <GridViewColumn DisplayMemberBinding="{Binding Name}" Header="{x:Static p:Resources.Name}" Width="{Binding WidthColumnContractName, Mode=TwoWay}"/>
            <GridViewColumn DisplayMemberBinding="{Binding Code}" Header="{x:Static p:Resources.Number}" Width="{Binding WidthColumnContractCode, Mode=TwoWay}"/>
            <GridViewColumn DisplayMemberBinding="{Binding Comm}" Header="{x:Static p:Resources.Commentary}" Width="{Binding WidthColumnContractComm, Mode=TwoWay}"/>
            <GridViewColumn DisplayMemberBinding="{Binding Revision}" Header="{x:Static p:Resources.Revision}" Width="{Binding WidthColumnContractRev, Mode=TwoWay}"/>
            <GridViewColumn Header="{x:Static p:Resources.Advancement}" Width="{Binding WidthColumnContractAdv, Mode=TwoWay}">
                <GridViewColumn.CellTemplate>
                    <DataTemplate>
                        <StackPanel>
                            <Rectangle Name="AFF_Track"  Height="12" Stroke="black" StrokeThickness="1" Fill="{Binding RectangleProgression}" Tag="{Binding ID}" MouseMove="mouseOverProgressionContractAss">
                                <Rectangle.ToolTip>
                                    <ContentControl  Template="{StaticResource ToolTipOperations}"/>
                                </Rectangle.ToolTip>
                            </Rectangle>
                            <Rectangle Name="AFF_Track2"  Height="12" Stroke="black" StrokeThickness="1" Fill="{Binding RectangleProgressionWeight}" Tag="{Binding ID}" MouseMove="mouseOverProgressionContractAss">
                                <Rectangle.ToolTip>
                                    <ContentControl  Template="{StaticResource ToolTipOperations}"/>
                                </Rectangle.ToolTip>
                            </Rectangle>
                        </StackPanel>

                    </DataTemplate>
                </GridViewColumn.CellTemplate>
            </GridViewColumn>

            <GridViewColumn Header="{x:Static p:Resources.Advancement}" Width="{Binding WidthColumnContractAdvRep, Mode=TwoWay}">
                <GridViewColumn.CellTemplate>
                    <DataTemplate>
                        <StackPanel>
                            <Rectangle Name="AFF_TrackRep"  Height="12" Stroke="black" StrokeThickness="1" Fill="{Binding RectangleProgressionRep}" Tag="{Binding ID}" MouseMove="mouseOverProgressionContractRep">
                                <Rectangle.ToolTip>
                                    <ContentControl  Template="{StaticResource ToolTipOperations}"/>
                                </Rectangle.ToolTip>
                            </Rectangle>
                            <Rectangle Name="AFF_Track2Rep"  Height="12" Stroke="black" StrokeThickness="1" Fill="{Binding RectangleProgressionRepWeight}" Tag="{Binding ID}" MouseMove="mouseOverProgressionContractRep">
                                <Rectangle.ToolTip>
                                    <ContentControl  Template="{StaticResource ToolTipOperations}"/>
                                </Rectangle.ToolTip>
                            </Rectangle>
                        </StackPanel>

                    </DataTemplate>
                </GridViewColumn.CellTemplate>
            </GridViewColumn>
            <GridViewColumn DisplayMemberBinding="{Binding Manager.CompleteName}" Header="{x:Static p:Resources.ProjectManager}" Width="{Binding WidthColumnContractManager, Mode=TwoWay}"/>
            <GridViewColumn DisplayMemberBinding="{Binding Client.Name}" Header="{x:Static p:Resources.Customer}" Width="{Binding WidthColumnContractCustomer, Mode=TwoWay}"/>
            <GridViewColumn DisplayMemberBinding="{Binding Source}" Header="{x:Static p:Resources.Source}" Width="{Binding WidthColumnContractSource, Mode=TwoWay}"/>
        </GridView>
    </ListView.View>
</ListView>

Answer 1

您可以修改您的行為以分別處理擴展MultiSelector （如DataGrid ）和ListBox的控件。 ListBox （因此也是ListView ）不是MultiSelector ，但在將ListBox.SelectionMode屬性設置為不同於SelectionMode.Single （這是默認設置）時支持多選。
對於每個其他簡單的選擇器，您都必須手動跟蹤所選項目。 您還必須攔截Selector.Unselected事件，以防止 Selector 在多選模式下取消選擇所選項目 - Selector僅支持單個項目選擇。

以下示例顯示了在附加的Selector不是ListBox或MultiSelector的情況下如何跟蹤所選項目。 出於這個原因，該行為公開了一個公共的只讀SelectedItems依賴屬性。

該示例還顯示了如何觀察按下的鍵盤鍵以過濾多選用戶操作。 此示例將 Shift或Ctrl鍵過濾為觸發多選行為的手勢：按下CTRL時隨機多選和按下Shift鍵時進行范圍選擇。 否則， Selector將像往常一樣運行（釋放鼠標左鍵時單選）。

選擇器服務.cs

public class SelectorService : DependencyObject
{
  #region IsSelectItemOnMouseUpEnabled attached property

  public static readonly DependencyProperty IsSelectItemOnMouseUpEnabledProperty = DependencyProperty.RegisterAttached(
    "IsSelectItemOnMouseUpEnabled",
    typeof(bool),
    typeof(SelectorService),
    new PropertyMetadata(default(bool), OnIsSelectItemOnMouseUpEnabledChanged));

  public static void SetIsSelectItemOnMouseUpEnabled(DependencyObject attachedElement, bool value) => attachedElement.SetValue(IsSelectItemOnMouseUpEnabledProperty, value);
  public static bool GetIsSelectItemOnMouseUpEnabled(DependencyObject attachedElement) => (bool)attachedElement.GetValue(IsSelectItemOnMouseUpEnabledProperty);

  #endregion IsSelectItemOnMouseUpEnabled attached property

  #region SelectedItems attached property

  public static IList GetSelectedItems(DependencyObject attachedElement) => (IList)attachedElement.GetValue(SelectedItemsProperty);
  public static void SetSelectedItems(DependencyObject attachedElement, IList value) => attachedElement.SetValue(SelectedItemsPropertyKey, value);

  private static readonly DependencyPropertyKey SelectedItemsPropertyKey = DependencyProperty.RegisterAttachedReadOnly(
    "SelectedItems",
    typeof(IList),
    typeof(SelectorService),
    new PropertyMetadata(default));

  public static readonly DependencyProperty SelectedItemsProperty = SelectedItemsPropertyKey.DependencyProperty;

  #endregion SelectedItems attached property

  #region SelectionMode attached property (private)

  private static SelectionMode GetOriginalSelectionModeBackup(DependencyObject attachedElement) => (SelectionMode)attachedElement.GetValue(OriginalSelectionModeBackupProperty);
  private static void SetOriginalSelectionModeBackup(DependencyObject attachedElement, SelectionMode value) => attachedElement.SetValue(OriginalSelectionModeBackupProperty, value);

  private static readonly DependencyProperty OriginalSelectionModeBackupProperty = DependencyProperty.RegisterAttached(
    "OriginalSelectionModeBackup",
    typeof(SelectionMode),
    typeof(SelectorService),
    new PropertyMetadata(default));


  #endregion SelectionMode attached property

  private static bool IsRandomMultiSelectEngaged
  => Keyboard.Modifiers is ModifierKeys.Control;

  private static bool IsRangeMultiSelectEngaged
    => Keyboard.Modifiers is ModifierKeys.Shift;

  private static Dictionary<Selector, bool> IsMultiSelectAppliedMap { get; } = new Dictionary<Selector, bool>();

  private static int SelectedRangeStartIndex { get; set; } = -1;

  private static int SelectedRangeEndIndex { get; set; } = -1;

  private static void OnIsSelectItemOnMouseUpEnabledChanged(DependencyObject attachedElement, DependencyPropertyChangedEventArgs e)
  {
    if (attachedElement is not Selector selector)
    {
      return;
    }

    if ((bool)e.NewValue)
    {
      WeakEventManager<FrameworkElement, MouseButtonEventArgs>.AddHandler(selector, nameof(selector.PreviewMouseLeftButtonDown), OnPreviewLeftMouseButtonDown);
      WeakEventManager<FrameworkElement, MouseButtonEventArgs>.AddHandler(selector, nameof(selector.PreviewMouseLeftButtonUp), OnPreviewLeftMouseButtonUp);
      if (selector.IsLoaded)
      {
        InitializeAttachedElement(selector);
      }
      else
      {
        selector.Loaded += OnSelectorLoaded;
      }
    }
    else
    {
      WeakEventManager<FrameworkElement, MouseButtonEventArgs>.RemoveHandler(selector, nameof(selector.PreviewMouseLeftButtonDown), OnPreviewLeftMouseButtonDown);
      WeakEventManager<FrameworkElement, MouseButtonEventArgs>.RemoveHandler(selector, nameof(selector.PreviewMouseLeftButtonUp), OnPreviewLeftMouseButtonUp);

      SetSelectedItems(selector, null);
      IsMultiSelectAppliedMap.Remove(selector);
      selector.Loaded -= OnSelectorLoaded;

      if (selector is ListBox listBox)
      {
        listBox.SelectionMode = GetOriginalSelectionModeBackup(listBox);
      }
    }
  }

  private static void OnSelectorLoaded(object sender, RoutedEventArgs e)
  {
    var selector = sender as Selector;
    selector.Loaded -= OnSelectorLoaded;
    InitializeAttachedElement(selector);
  }

  private static void InitializeAttachedElement(Selector selector)
  {
    IList selectedItems = new List<object>();
    if (selector is ListBox listBox)
    {
      ValidateListBoxSelectionMode(listBox);
      selectedItems = listBox.SelectedItems;
    }
    else if (selector is MultiSelector multiSelector)
    {
      selectedItems = multiSelector.SelectedItems;
    }
    else if (selector.SelectedItem is not null)
    {
      selectedItems.Add(selector.SelectedItem);
    }

    SetSelectedItems(selector, selectedItems);
    IsMultiSelectAppliedMap.Add(selector, false);
  }

  private static void OnUnselected(object? sender, RoutedEventArgs e)
  {
    var itemContainer = sender as DependencyObject;
    Selector.SetIsSelected(itemContainer, true);
    Selector.RemoveUnselectedHandler(itemContainer, OnUnselected);
  }

  private static void OnPreviewLeftMouseButtonUp(object sender, MouseButtonEventArgs e)
  {
    var selector = sender as Selector;
    DependencyObject itemContainerToSelect = ItemsControl.ContainerFromElement(selector, e.OriginalSource as DependencyObject);
    DependencyObject currentSelectedItemContainer = selector.ItemContainerGenerator.ContainerFromItem(selector.SelectedItem);
    if (itemContainerToSelect is null)
    {
      return;
    }

    if (IsRandomMultiSelectEngaged)
    {
      MultiSelectItems(selector, itemContainerToSelect, currentSelectedItemContainer);
    }
    else if (IsRangeMultiSelectEngaged)
    {
      MultiSelectRangeOfItems(selector, itemContainerToSelect, currentSelectedItemContainer);
    }
    else
    {
      SingleSelectItem(selector, itemContainerToSelect, currentSelectedItemContainer);
    }

    IsMultiSelectAppliedMap[selector] = IsRandomMultiSelectEngaged || IsRangeMultiSelectEngaged;
  }

  private static void MultiSelectRangeOfItems(Selector selector, DependencyObject itemContainerToSelect, DependencyObject currentSelectedItemContainer)
  {
    int clickedContainerIndex = selector.ItemContainerGenerator.IndexFromContainer(itemContainerToSelect);

    // In case there is not any preselected item. Otherwis SingleSlectItem() has already set the SelectedRangeStartIndex property.
    if (SelectedRangeStartIndex == -1)
    {
      SelectedRangeStartIndex = clickedContainerIndex;
      DependencyObject itemContainer = selector.ItemContainerGenerator.ContainerFromIndex(SelectedRangeStartIndex);
      MultiSelectItems(selector, itemContainer, currentSelectedItemContainer);
      return;
    }
    // Complete the range selection
    else if (SelectedRangeEndIndex == -1)
    {
      bool isSelectionRangeFromTopToBotton = clickedContainerIndex > SelectedRangeStartIndex;
      if (isSelectionRangeFromTopToBotton)
      {
        SelectedRangeEndIndex = clickedContainerIndex;
      }
      else
      {
        // Selection is from bottom to top, so we need to swap start and end index
        // as they are used to initialize the for-loop.
        SelectedRangeEndIndex = SelectedRangeStartIndex;
        SelectedRangeStartIndex = clickedContainerIndex;
      }

      for (int itemIndex = SelectedRangeStartIndex; itemIndex <= SelectedRangeEndIndex; itemIndex++)
      {
        DependencyObject itemContainer = selector.ItemContainerGenerator.ContainerFromIndex(itemIndex);
        bool isContainerUnselected = !Selector.GetIsSelected(itemContainer);
        if (isContainerUnselected)
        {
          MultiSelectItems(selector, itemContainer, currentSelectedItemContainer);
        }
      }

      // Only remember start index to append sequential ranges (more clicks while Shift key is pressed)
      // and invalidate the end index.
      SelectedRangeEndIndex = -1;
    }
  }

  private static void MultiSelectItems(Selector? selector, DependencyObject itemContainerToSelect, DependencyObject currentSelectedItemContainer)
  {
    bool oldIsSelectedValue = Selector.GetIsSelected(itemContainerToSelect);

    // Toggle the current state
    bool newIsSelectedValue = oldIsSelectedValue ^= true;

    if (selector is ListBox listBox)
    {
      // In case the mode was overriden externally, force it back
      // but store the changed value to allow roll back when the behavior gets disabled.
      ValidateListBoxSelectionMode(listBox);
    }

    // If the current Selector instance does not support native multi select
    // we need to prevent the Selector from unselecting previous selected items.
    // By setting unselected items back to selected we can enforce a visual multi select feedback.
    if (selector is not MultiSelector and not ListBox)
    {
      if (newIsSelectedValue && currentSelectedItemContainer is not null)
      {
        Selector.AddUnselectedHandler(currentSelectedItemContainer, OnUnselected);
      }
    }

    Selector.SetIsSelected(itemContainerToSelect, newIsSelectedValue);
    (itemContainerToSelect as UIElement)?.Focus();

    if (selector is not MultiSelector and not ListBox)
    {
      object item = selector.ItemContainerGenerator.ItemFromContainer(itemContainerToSelect);
      IList selectedItems = GetSelectedItems(selector);
      if (newIsSelectedValue)
      {
        selectedItems.Add(item);
      }
      else
      {
        selectedItems.Remove(item);
      }
    }
  }

  private static void SingleSelectItem(Selector? selector, DependencyObject itemContainerToSelect, DependencyObject currentSelectedItemContainer)
  {
    bool isPreviousSelectMultiSelect = IsMultiSelectAppliedMap[selector];

    if (!isPreviousSelectMultiSelect)
    {
      // Unselect the currently selected
      if (currentSelectedItemContainer is not null)
      {
        Selector.SetIsSelected(currentSelectedItemContainer, false);
      }
    }
    // If the Selector has multiple selected items and an item was clicked without the modifier key pressed,
    // then we need to switch back to single selection mode and only select the currently clicked item.
    else
    {
      // Invalidate tracked multi select range
      SelectedRangeStartIndex = -1;
      SelectedRangeEndIndex = -1;
      if (selector is ListBox listBox)
      {
        ValidateListBoxSelectionMode(listBox);
        listBox.UnselectAll();
      }
      else if (selector is MultiSelector multiSelector)
      {
        multiSelector.UnselectAll();
      }
      else
      {
        IList selectedItems = GetSelectedItems(selector);
        foreach (object item in selectedItems)
        {
          DependencyObject itemContainer = selector.ItemContainerGenerator.ContainerFromItem(item);
          Selector.SetIsSelected(itemContainer, false);
        }

        selectedItems.Clear();
      }
    }

    // Execute single selection
    Selector.SetIsSelected(itemContainerToSelect, true);
    (itemContainerToSelect as UIElement)?.Focus();

    if (selector is not MultiSelector and not ListBox)
    {
      IList selectedItems = GetSelectedItems(selector);
      selectedItems.Clear();
      selectedItems.Add(selector.SelectedItem);
    }

    // Track index in case the next click enabled select range (press Shift while click)
    int clickedContainerIndex = selector.ItemContainerGenerator.IndexFromContainer(itemContainerToSelect);
    SelectedRangeStartIndex = clickedContainerIndex;

    return;
  }

  private static void ValidateListBoxSelectionMode(ListBox listBox)
  {
    if (listBox.SelectionMode is not SelectionMode.Extended)
    {
      // In case the mode was overriden externally, force it back
      // but store the changed value to allow roll back when the behavior gets disabled.
      SetOriginalSelectionModeBackup(listBox, listBox.SelectionMode);
      listBox.SelectionMode = SelectionMode.Extended;
    }
  }

  private static void OnPreviewLeftMouseButtonDown(object sender, MouseButtonEventArgs e)
    => e.Handled = true;
}

Answer 2

除了@BionicCode 的代碼：代碼不負責DoubleClick 。 我可以添加該代碼來解決它：（BionicCode，如果您可以為未來的訪問者編輯答案，謝謝）。

- 在類中添加一個靜態變量：

public static DateTime lastClickDateTime = DateTime.Now;

然后在SingleSelectItem函數的最開始：

TimeSpan interval = DateTime.Now - lastClickDateTime;
if(interval.TotalMilliseconds<500)
{
    if(selector is ListBox listBox)
    {
        MouseButtonEventArgs doubleClickEvent = new MouseButtonEventArgs(Mouse.PrimaryDevice, (int)DateTime.Now.Ticks, MouseButton.Left);
        doubleClickEvent.RoutedEvent = Control.MouseDoubleClickEvent;
        doubleClickEvent.Source = selector;
        selector.RaiseEvent(doubleClickEvent);
        return;
    }
                
}
lastClickDateTime = DateTime.Now;

再次感謝你的幫助 ：）