c# - 当鼠标悬停在列标题上时滚动 ListView

Question

我有以下 WPF 窗口:

<Window x:Class="WPFTest.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="135" Width="150">
    <Grid>
        <ListView>
            <ListView.View>
                <GridView>
                    <GridViewColumn Header="Name" Width="120" />
                </GridView>
            </ListView.View>
            <ListViewItem>
                <TextBlock Text="Bobby" />
            </ListViewItem>
            <ListViewItem>
                <TextBlock Text="Chuck" />
            </ListViewItem>
            <ListViewItem>
                <TextBlock Text="Frank" />
            </ListViewItem>
            <ListViewItem>
                <TextBlock Text="Sarah" />
            </ListViewItem>
            <ListViewItem>
                <TextBlock Text="Sandra" />
            </ListViewItem>
        </ListView>
    </Grid>
</Window>

我可以使用 ScrollViewer.VerticalScrollBarVisibility="Auto" 为整个 ListView 启用滚动，这是默认行为。但是，当鼠标悬停在列标题(显示文本 Name 的地方)时，这不会启用滚动。即使鼠标悬停在列标题上，我如何允许滚动我的姓名列表？

Answer 1

鼠标悬停在列标题区域没有滚动的原因是 ListView 的控件模板。

标题区域包含另一个 ScrollViewer，它处理 PreviewMouseWheel 隧道事件，防止“主”ScrollViewer 执行此操作。

你有两种方法来解决这个问题。

第一种方式:使用代码直接滚动“主”ScrollViewer。

如果您采用这种方式，我建议您创建一个附加属性以使该行为可重用。

public static class AdvancedScrolling
{
    // Attached property boilerplate code begin...
    public static readonly DependencyProperty EnabledProperty =
        DependencyProperty.RegisterAttached("Enabled", typeof(bool), typeof(AdvancedScrolling), new PropertyMetadata(false, EnabledChanged));

    public static void SetEnabled(UIElement element, bool value) => element.SetValue(EnabledProperty, value);

    public static bool GetEnabled(UIElement element) => (bool)element.GetValue(EnabledProperty);

    // ...Attached property boilerplate code end

    private static void EnabledChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        // Affects only list views
        if (e.NewValue is true && d is ListView listview)
        {
            // We need the visual tree of the list view, so wait for loading first
            listview.Loaded += ListViewLoaded;
        }

        void ListViewLoaded(object sender, RoutedEventArgs re)
        {
            listview.Loaded -= ListViewLoaded;

            // The default list view (grid view) control template contains
            // a Chrome Decorator with a ScrollViewer as Child.
            // We need that ScrollViewer.
            if ((VisualTreeHelper.GetChild(listview, 0) as Decorator)?.Child is ScrollViewer scrollViewer)
            {
                // Hooking up the tunneling event
                listview.PreviewMouseWheel += (s, me) =>
                {
                    // Always scroll manually
                    scrollViewer.ScrollToVerticalOffset(
                        scrollViewer.VerticalOffset
                        - Math.Sign(me.Delta) * SystemParameters.WheelScrollLines);

                    // Set Handled to true to prevent the ScrollViewer
                    // from processing the same event one more time.
                    me.Handled = true;
                };
            }
        }
    }
}

用法:

<ListView local:AdvancedScrolling.Enabled="True">

local 是您的命名空间，例如 xmlns:local="clr-namespace:YourNamespace"。

第二种方法是更改​​页眉区域模板。

我们只是从那个区域移除滚动查看器，这样它就不会处理鼠标滚轮事件。这将允许我们的“主”ScrollViewer 在鼠标光标位于标题区域上方时对鼠标输入使用react。

我复制了 default control template并从定义标题区域的 DockPanel 中删除了 ScrollViewer。

然后你会得到这样的东西:

<ListView>
    <ListView.Resources>
        <Style x:Key="{x:Static GridView.GridViewScrollViewerStyleKey}" TargetType="ScrollViewer">
            <Setter Property="Template">
                <Setter.Value>
                    <ControlTemplate TargetType="ScrollViewer">
                        <Grid Background="{TemplateBinding Background}">
                            <Grid.ColumnDefinitions>
                                <ColumnDefinition Width="*" />
                                <ColumnDefinition Width="Auto" />
                            </Grid.ColumnDefinitions>
                            <Grid.RowDefinitions>
                                <RowDefinition Height="*" />
                                <RowDefinition Height="Auto" />
                            </Grid.RowDefinitions>

                            <DockPanel Margin="{TemplateBinding Padding}">

                                <!-- I removed the ScrollViewer here -->

                                    <GridViewHeaderRowPresenter DockPanel.Dock="Top" Margin="2,0,2,0" Columns="{Binding Path=TemplatedParent.View.Columns,
        RelativeSource={RelativeSource TemplatedParent}}" ColumnHeaderContainerStyle="{Binding
        Path=TemplatedParent.View.ColumnHeaderContainerStyle,
        RelativeSource={RelativeSource TemplatedParent}}" ColumnHeaderTemplate="{Binding
        Path=TemplatedParent.View.ColumnHeaderTemplate,
        RelativeSource={RelativeSource TemplatedParent}}" ColumnHeaderTemplateSelector="{Binding 
        Path=TemplatedParent.View.ColumnHeaderTemplateSelector,
        RelativeSource={RelativeSource TemplatedParent}}" AllowsColumnReorder="{Binding
        Path=TemplatedParent.View.AllowsColumnReorder,
        RelativeSource={RelativeSource TemplatedParent}}" ColumnHeaderContextMenu="{Binding
        Path=TemplatedParent.View.ColumnHeaderContextMenu,
        RelativeSource={RelativeSource TemplatedParent}}" ColumnHeaderToolTip="{Binding
        Path=TemplatedParent.View.ColumnHeaderToolTip,
        RelativeSource={RelativeSource TemplatedParent}}" SnapsToDevicePixels="{TemplateBinding
        SnapsToDevicePixels}" />

                                <ScrollContentPresenter Name="PART_ScrollContentPresenter"
                                        KeyboardNavigation.DirectionalNavigation="Local" CanContentScroll="True"
                                        CanHorizontallyScroll="False" CanVerticallyScroll="False" />
                            </DockPanel>

                            <ScrollBar Name="PART_HorizontalScrollBar" Orientation="Horizontal" Grid.Row="1"
                                    Maximum="{TemplateBinding ScrollableWidth}"
                                    ViewportSize="{TemplateBinding ViewportWidth}"
                                    Value="{TemplateBinding HorizontalOffset}"
                                    Visibility="{TemplateBinding ComputedHorizontalScrollBarVisibility}" />

                            <ScrollBar Name="PART_VerticalScrollBar" Grid.Column="1"
                                    Maximum="{TemplateBinding ScrollableHeight}"
                                    ViewportSize="{TemplateBinding ViewportHeight}"
                                    Value="{TemplateBinding VerticalOffset}"
                                    Visibility="{TemplateBinding ComputedVerticalScrollBarVisibility}" />

                        </Grid>
                    </ControlTemplate>
                </Setter.Value>
            </Setter>
        </Style>
    </ListView.Resources>
</ListView>