wpf - 不合理的 WPF DataGrid 加载时间

Question

我一直有很长的 WPF DataGrids 加载时间，我在网上找不到任何类似的报告，所以我怀疑我做错了什么。现在我确定了，因为增加布局复杂性会大大减慢执行速度。在一个非常简单的布局中，DataGrid 会立即填充，而下面的代码大约需要 3 秒才能执行。

在以下代码中，加载 150 行和 11 列需要大约 3 秒，即使每个单元格未绑定(bind)到任何属性且 AutoGenerateColumns=False。 (我有一个带有大量 RAM 的两核 2.6GHz 处理器)。

当 ItemsSource 属性在如下布局中设置时，就会出现瓶颈:

<Window x:Class="datagridtest.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="MainWindow" Height="350" Width="525">
<Border  Background="LightSteelBlue" CornerRadius="10" Margin="10">
    <ScrollViewer Margin="10" HorizontalScrollBarVisibility="Auto">
        <Grid Margin="10,50,0,0">
            <Grid.RowDefinitions>
                <RowDefinition Height="Auto"  />
                <RowDefinition Height="auto" />
                <RowDefinition Height="auto" />

            </Grid.RowDefinitions>
            <Expander IsExpanded="True" Name="expander1"  Grid.Row="0">
                <Grid>
                    <DataGrid VirtualizingStackPanel.IsVirtualizing="True" AutoGenerateColumns="false" Name="dg" Height="auto" CanUserReorderColumns="False" CanUserResizeColumns="False" CanUserResizeRows="False" CanUserSortColumns="False">
                        <DataGrid.Columns>
                            <DataGridTextColumn >
                                <DataGridTextColumn.Header >
                                    <TextBlock Width="140" HorizontalAlignment="Center" TextAlignment="Center">untitled<LineBreak/>column</TextBlock>
                                </DataGridTextColumn.Header>
                            </DataGridTextColumn>



                            <DataGridTextColumn >
                                <DataGridTextColumn.Header >
                                    <TextBlock Width="140" HorizontalAlignment="Center" TextAlignment="Center">untitled<LineBreak/>column</TextBlock>
                                </DataGridTextColumn.Header>
                            </DataGridTextColumn>

                            <DataGridTextColumn >
                                <DataGridTextColumn.Header >
                                    <TextBlock Width="140" HorizontalAlignment="Center" TextAlignment="Center">untitled<LineBreak/>column</TextBlock>
                                </DataGridTextColumn.Header>
                            </DataGridTextColumn>

                            <DataGridTextColumn >
                                <DataGridTextColumn.Header >
                                    <TextBlock Width="140" HorizontalAlignment="Center" TextAlignment="Center">untitled<LineBreak/>column</TextBlock>
                                </DataGridTextColumn.Header>
                            </DataGridTextColumn>

                            <DataGridTextColumn >
                                <DataGridTextColumn.Header >
                                    <TextBlock Width="140" HorizontalAlignment="Center" TextAlignment="Center">untitled<LineBreak/>column</TextBlock>
                                </DataGridTextColumn.Header>
                            </DataGridTextColumn>


                            <DataGridTextColumn >
                                <DataGridTextColumn.Header >
                                    <TextBlock Width="140" HorizontalAlignment="Center" TextAlignment="Center">untitled<LineBreak/>column</TextBlock>
                                </DataGridTextColumn.Header>
                            </DataGridTextColumn>

                            <DataGridTextColumn >
                                <DataGridTextColumn.Header >
                                    <TextBlock Width="140" HorizontalAlignment="Center" TextAlignment="Center">untitled<LineBreak/>column</TextBlock>
                                </DataGridTextColumn.Header>
                            </DataGridTextColumn>

                            <DataGridTextColumn >
                                <DataGridTextColumn.Header >
                                    <TextBlock Width="140" HorizontalAlignment="Center" TextAlignment="Center">untitled<LineBreak/>column</TextBlock>
                                </DataGridTextColumn.Header>
                            </DataGridTextColumn>

                            <DataGridTextColumn >
                                <DataGridTextColumn.Header >
                                    <TextBlock Width="140" HorizontalAlignment="Center" TextAlignment="Center">untitled<LineBreak/>column</TextBlock>
                                </DataGridTextColumn.Header>
                            </DataGridTextColumn>

                            <DataGridTextColumn >
                                <DataGridTextColumn.Header >
                                    <TextBlock Width="140" HorizontalAlignment="Center" TextAlignment="Center">untitled<LineBreak/>column</TextBlock>
                                </DataGridTextColumn.Header>
                            </DataGridTextColumn>

                            <DataGridTextColumn >
                                <DataGridTextColumn.Header >
                                    <TextBlock Width="140" HorizontalAlignment="Center" TextAlignment="Center">untitled<LineBreak/>column</TextBlock>
                                </DataGridTextColumn.Header>
                            </DataGridTextColumn>



                        </DataGrid.Columns>
                        </DataGrid>
                </Grid>
            </Expander>

            <Expander IsExpanded="true"  Grid.Row="1">
                <Grid>
                    <DataGrid AutoGenerateColumns="True"  Height="auto" />
                </Grid>
            </Expander>

            <Expander IsExpanded="true"    Grid.Row="2">
                <Grid>
                    <DataGrid AutoGenerateColumns="True" Height="auto" />
                </Grid>
            </Expander>
            <Button Content="Button" Height="23" HorizontalAlignment="Left" Margin="121,-42,0,0" Name="button1" VerticalAlignment="Top" Width="75" Click="button1_Click_2" />
        </Grid>
    </ScrollViewer>
</Border>

using System.Collections.ObjectModel;

namespace datagridtest
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();


    }

    class row
    {
        public string Name { get; set; }
        public double Age { get; set; }
    }



    private void button1_Click_2(object sender, RoutedEventArgs e)
    {
        ObservableCollection<row> src = new ObservableCollection<row>();

        for (int i = 0; i < 150; i++)
            src.Add(new row { Name = i.ToString(), Age = i / 2 });

        dg.ItemsSource = src;
    }
}
}

Answer 1

仅当 DataGrid 嵌入到 ScrollViewer 中时才会出现此问题，例如:

<ScrollViewer>
    <Datagrid/>
</ScrollViewer>

这是有道理的，因为此配置会导致同时绘制整个 DataGrid(以便能够正确调整 ScrollViewer 的客户区的大小)。本质上，它覆盖了 DataGrid 的内置虚拟化行为，后者实现了自己的 ScrollBars，因此不必同时将其所有内容放在布局中。

换句话说，很少需要在 ScrollViewer 中嵌入 DataGrid，因为 DataGrid 有自己的自动滚动功能。