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I set 'VirtualizingStackPanel.IsVirtualizing' to true and 'VirtualizingStackPanel.VirtualizationMode' to 'Recycling', because the items in my ListView are too many. The SelectionMode of the ListView is Extended, the 'IsSelected' property of the ListViewItem is bound to 'IsSelected' property of my model, bind mode is two way.

When I want to use Ctrl+A to select all of the items, it only select part of the items, so I use KeyBinding to write the select all method like below:

 <KeyBinding Command="{Binding SelectAllCommand}"
                            Modifiers="Control"
                            Key="A"/>

SelectAll method will loop the ItemsSource collection and set each of the item's IsSelected property to true. But it also leads to something unexpected. When all of the items are selected, I scroll the scrollbar to the bottom and it will load more items to the ListView, I single click one item and the expected is all other items are unselected, only select this item. But, it seems not unselect other items.

Anybody can help?

4

1 回答 1

-1

Selector 的这种行为是意料之中的，因为它只能对加载的 UI 元素进行操作。由于启用了虚拟化，您只加载了可见区域中包含的那些元素。所以，Selector 并不“知道”其他人。

为了解决这个问题，您必须这样做，选择器“知道”以前选择的项目。换句话说，您必须禁止卸载任何被选中的 UI 元素。

首先，使用二十一点和妓女创建自己的虚拟化面板：

public class MyVirtualizingStackPanel : VirtualizingStackPanel
{
    protected override void OnCleanUpVirtualizedItem(CleanUpVirtualizedItemEventArgs e)
    {
        var item = e.UIElement as ListBoxItem;
        if (item != null && item.IsSelected)
        {
            e.Cancel = true;
            e.Handled = true;
            return;
        }

        var item2 = e.UIElement as TreeViewItem;
        if (item2 != null && item2.IsSelected)
        {
            e.Cancel = true;
            e.Handled = true;
            return;
        }

        base.OnCleanUpVirtualizedItem(e);
    }
}

接下来，替换 ListBox、ListView、TreeView 或其他提供选择器的用户控件中的默认面板。例如，通过样式：

<Setter Property="ItemsPanel">
    <Setter.Value>
        <ItemsPanelTemplate>
            <blackjackandhookers:MyVirtualizingStackPanel/>
        </ItemsPanelTemplate>
    </Setter.Value>
</Setter>

...或者，直接在您的选择器中：

<YourSelector.ItemsPanel>
    <ItemsPanelTemplate>
        <blackjackandhookers:MyVirtualizingStackPanel/>
    </ItemsPanelTemplate>
</YourSelector.ItemsPanel>

享受！

希望我的回答对你有所帮助。

于 2015-04-09T18:04:20.773 回答