WPF DataGrid加载时间不合理 [英] Unreasonable WPF DataGrid Loading Time
问题描述
我一直使用WPF DataGrid加载时间很长，而且我在网上找不到任何类似的报告，因此我怀疑自己做错了什么。现在我可以肯定了，因为增加布局复杂性会大大降低执行速度。在一个非常简单的布局中，DataGrid会立即填充，而下面的代码将花费大约3秒的时间来执行。
I've always had long loading times with WPF DataGrids, and I cannot find any similar reports online, so I suspected that I was doing something wrong. Now I am sure of it, since adding layout complexity considerably slows down execution. In a very simple layout, the DataGrid populates instantaenously, whereas the code below takes around 3 seconds to execute.
在下面的代码中，150行大约需要3秒和11列以加载，即使每个单元格未绑定到任何属性且AutoGenerateColumns = False。 （我有一个两核的2.6GHz处理器，带有足够的RAM）。
In the following code, it takes ~3 seconds for 150 rows and 11 columns to load, even if each cell is not bound to any property and with AutoGenerateColumns=False. (I have a two core, 2.6GHz processor with plenty of RAM).
当将ItemsSource属性设置为以下布局时，就会发生瓶颈：
The bottle neck takes place when the ItemsSource property is set in a layout as the one below:
<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;
}
}
}
推荐答案
仅当DataGrid嵌入在ScrollViewer中时才会出现此问题，例如：
The problem only occurs when the DataGrid is embedded inside a ScrollViewer like:
<ScrollViewer>
<Datagrid/>
</ScrollViewer>
这很有意义，因为此配置会导致同时绘制整个DataGrid（正确调整ScrollViewer的工作区的大小）。从本质上讲，它覆盖了DataGrid的内置虚拟化行为，该行为实现了自己的ScrollBar，因此不必同时将其所有内容都放置在布局中。
This makes sense because this configuration causes the whole DataGrid to be drawn at the same time (to be able to size the ScrollViewer's client area correctly). In essence, it overrides the built-in virtualization behavior of the DataGrid, which implements its own ScrollBars so that not all of its content has to be placed in the layout simultaneously.
换句话说，因为DataGrid具有自己的自动滚动功能，所以很少需要在ScrollViewer中嵌入DataGrid。
In other words, embedding a DataGrid inside a ScrollViewer is rarely needed because the DataGrid has its own automatic scrolling.
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