Question

我有一个大约有 500 行的 DataGrid。如果我向下滚动让我们排不。 200 并且一个新行被添加到顶部（集合的开始）它会自动向上滚动到第一行，所以我必须再次手动向下滚动。我怎样才能防止这种情况发生？

这是一个示例应用程序来说明问题：

MainWindow.xaml.cs：

using System.Collections.ObjectModel;
using System.Windows;


namespace Testnamespace
{
    public class TestClass
    {
        private int price;
        private int qty;

        public int Price { get => price; set => price = value; }
        public int Qty { get => qty; set => qty = value; }

        public TestClass(int price,int qty)
        {
            this.Price = price;
            this.Qty = qty;
        }
    }
    public partial class MainWindow : Window
    {
        private ObservableCollection<TestClass> data = new ObservableCollection<TestClass>() { new TestClass(3, 1), new TestClass(2, 1), new TestClass(1, 1) };
        public ObservableCollection<TestClass> Data { get => data; set => data = value; }
        public MainWindow()
        {
            InitializeComponent();
            this.DataContext = this;
        }

        private void InsertButton_Click(object sender, RoutedEventArgs e)
        {
            Data.Insert(0, new TestClass(Data.Count, 1));
        }
    }
}

XAML：

<Window x:Class="Testnamespace.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:Testnamespace"
        mc:Ignorable="d"
        Title="MainWindow" Height="300" Width="200">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="80"/>
            <RowDefinition MinHeight="80"/>
        </Grid.RowDefinitions>
        <Button x:Name="InsertButton" Content="Insert(0)" Click="InsertButton_Click" Grid.Column="0" Height="20" Width="50" Background="Red"/>
        <DataGrid x:Name="dataGrid"
                  Grid.Row="1"
                  AutoGenerateColumns="False"
                  ItemsSource="{Binding Data, IsAsync=True}"
                  MaxWidth="800"
                  MaxHeight="1600"
                  Width="100"
                  Height="100"
                  >

            <DataGrid.Columns>
                <DataGridTextColumn Header="Price" Binding="{Binding Price}">
                </DataGridTextColumn>

                <DataGridTextColumn Header="Qty" Binding="{Binding Qty}">
                </DataGridTextColumn>
            </DataGrid.Columns>
        </DataGrid>
    </Grid>
</Window>

该应用程序如下所示：

假设您想关注 price=1 以查看数量是否已更改，但同时添加了新行（通过单击 Insert(0) 按钮）。在这种情况下，您会失去焦点，因为它一直在向上滚动，因此您必须手动向下滚动。我怎样才能防止这种情况发生？

Answer 1

您可以手动滚动另一个 18.96 DIP，这是 Height 的默认 DataGridRow：

private void InsertButton_Click(object sender, RoutedEventArgs e)
{
    ScrollViewer scrollViewer = FindVisualChild<ScrollViewer>(dataGrid);
    double offset = scrollViewer.VerticalOffset;
    Data.Insert(0, new TestClass(Data.Count, 1));
    if (offset > 0)
        scrollViewer.ScrollToVerticalOffset(offset + 18.96);

}

private static T FindVisualChild<T>(Visual visual) where T : Visual
{
    for (int i = 0; i < VisualTreeHelper.GetChildrenCount(visual); i++)
    {
        Visual child = (Visual)VisualTreeHelper.GetChild(visual, i);
        if (child != null)
        {
            T correctlyTyped = child as T;
            if (correctlyTyped != null)
                return correctlyTyped;

            T descendent = FindVisualChild<T>(child);
            if (descendent != null)
                return descendent;
        }
    }
    return null;
}

如果在开头添加新行，如何防止自动向上滚动

1 个答案: