如何提高FlowDocumentScrollViewer的性能？

Question

在前面的一个问题中，我询问了如何在WPF类似文本框的元素(WPF附加了大量的文本阻止UI线程，但是WinForms没有吗？)中获得实时日志输出。那里的答案导致我使用了FlowDocumentScrollViewer，它确实比RichTextBox快得多。但是，我发现运行具有大量文本输出(比如'svn‘)的命令会导致我的WPF应用程序明显放缓。签出3或4个非常大的svn分支后，切换选项卡需要3-4秒，我确信时间会随着结帐次数的增加而增加。滚动也有明显的滞后。

正如我在上面链接的问题中所述，我最近将我的应用程序从Windows窗体切换到了WPF。我非常喜欢WPF --它提供了很多我在形式上没有的优势。然而，在WPF中，性能似乎是一个相当大的问题，至少对我来说是这样。在我的应用程序的表单版本中，我可以将大量文本打印到RichTextBox控件中，并且我的应用程序丝毫没有减速。切换标签即时，滚动是无缝的。这是我想在我的WPF应用程序的体验。

因此，我的问题是:如何提高我的FlowDocumentScrollViewer的性能，使其与Windows RichTextBox的性能相匹配，同时又不失去粗体和斜体等格式化功能，同时又不失去复制/粘贴功能？我愿意切换WPF控件，只要它们提供我正在寻找的格式化功能。

这是我的打印代码，供参考：

public void PrintOutput(String s)
{
    if (outputParagraph.FontSize != defaultFontSize)
    {
        outputParagraph = new Paragraph();
        outputParagraph.Margin = new Thickness(0);
        outputParagraph.FontFamily = font;
        outputParagraph.FontSize = defaultFontSize;
        outputParagraph.TextAlignment = TextAlignment.Left;
        OutputBox.Document.Blocks.Add(outputParagraph);
    }
    outputParagraph.Inlines.Add(s);
    if (!clearOutputButton.IsEnabled) clearOutputButton.IsEnabled = true;
}

public void PrintImportantOutput(String s)
{
    if (outputParagraph.FontSize != importantFontSize)
    {
        outputParagraph = new Paragraph();
        outputParagraph.Margin = new Thickness(0);
        outputParagraph.FontFamily = font;
        outputParagraph.FontSize = importantFontSize;
        outputParagraph.TextAlignment = TextAlignment.Left;
        OutputBox.Document.Blocks.Add(outputParagraph);
    }
    String timestamp = DateTime.Now.ToString("[hh:mm.ss] ");
    String toPrint = timestamp + s;
    outputParagraph.Inlines.Add(new Bold(new Run(toPrint)));
    if (!clearOutputButton.IsEnabled) clearOutputButton.IsEnabled = true;
}

在打印“重要”文本时，我会切换字体大小并使文本粗体化。这段代码之所以有这么多行，是因为我试图对所有文本重复使用相同的段落，直到我点击“重要”文本为止；我添加了一个新段落，包含所有“重要”文本，然后在切换回不重要文本后再添加另一个段落，并添加到那个段落，直到我点击更“重要”的文本。我希望重复使用相同的段落将提高性能。

另外，应该注意的是，我正在将标准输出打印到一个FlowDocumentScrollViewer，将stderr打印到另一个FlowDocumentScrollViewer，同时打印到第三个FlowDocumentScrollViewer。因此，技术上每一行stdout和stderr都打印两次，使我的应用程序的负载翻了一番。同样，这在WinForms中并不是一个问题。

下面是一个完整的代码示例，如注释中所要求的那样。这是非常简单的(3 FlowDocumentScrollViewer的和简单的打印)，但仍然减慢了大约20000行文本的大量时间，更糟糕的是超过了这一点。

编辑:代码示例已被删除。取而代之的是解决我的性能问题的工作代码。它的工作方式与FlowDocumentScrollViewer一样，但有一个例外:不能选择子字符串。我正在考虑解决这个问题，虽然似乎很困难。

Bridge.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Documents;
using System.Threading;
using System.Collections.Concurrent;
using System.Threading.Tasks;

namespace PerformanceTest
{
    public class Bridge
    {
        int counterLimit;

        public BlockingCollection<PrintInfo> output;
        public BlockingCollection<PrintInfo> errors;
        public BlockingCollection<PrintInfo> logs;


        protected static Bridge controller = new Bridge();

        public static Bridge Controller
        {
            get
            {
                return controller;
            }
        }

        public MainWindow Window
        {
            set
            {
                if (value != null)
                {
                    output = value.outputProducer;
                    errors = value.errorProducer;
                    logs = value.logsProducer;
                }
            }
        }

        public bool Running
        {
            get;
            set;
        }

        private Bridge()
        {
            //20000 lines seems to slow down tabbing enough to prove my point.
            //increase this number to get even worse results.
            counterLimit = 40000;
        }

        public void PrintLotsOfText()
        {
            new Thread(new ThreadStart(GenerateOutput)).Start();
            new Thread(new ThreadStart(GenerateError)).Start();
        }

        private void GenerateOutput()
        {
            //There is tons of output text, so print super fast if possible.
            int counter = 1;
            while (Running && counter < counterLimit)
            {
                if (counter % 10 == 0)
                    PrintImportantOutput("I will never say this horrible word again as long I live. This is confession #" + counter++ + ".");
                else
                    PrintOutput("I will never say this horrible word again as long I live. This is confession #" + counter++ + ".");
                //Task.Delay(1).Wait();
            }
            Console.WriteLine("GenerateOutput thread should end now...");
        }

        private void GenerateError()
        {
            int counter = 1;
            while (Running && counter < counterLimit)
            {
                PrintError("I will never forgive your errors as long I live. This is confession #" + counter++ + ".");
                //Task.Delay(1).Wait();
            }
            Console.WriteLine("GenerateError thread should end now...");
        }

        #region Printing
        delegate void StringArgDelegate(String s);
        delegate void InlineArgDelegate(Inline inline);
        public void PrintOutput(String s)
        {
            output.TryAdd(new PrintInfo(s, false));
            PrintLog("d " + s);
        }

        public void PrintImportantOutput(String s)
        {
            output.TryAdd(new PrintInfo(s, true));
            PrintLog("D " + s);
        }

        public void PrintError(String s)
        {
            errors.TryAdd(new PrintInfo(s, false));
            PrintLog("e " + s);
        }

        public void PrintImportantError(String s)
        {
            errors.TryAdd(new PrintInfo(s, true));
            PrintLog("E " + s);
        }

        public void PrintLog(String s)
        {
            logs.TryAdd(new PrintInfo(s, false));
        }
        #endregion
    }

    public class PrintInfo
    {
        public String Text { get; set; }
        public bool IsImportant { get; set; }

        public PrintInfo() { }
        public PrintInfo(String text, bool important)
        {
            Text = text;
            IsImportant = important;
        }
    }
}

MainWindow.xaml

<Window x:Class="PerformanceTest.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow"
        xmlns:l="clr-namespace:PerformanceTest"
        WindowStartupLocation="CenterScreen">
  <Grid>
    <TabControl>
      <TabControl.Resources>
        <Style TargetType="ListBox">
          <Setter Property="TextElement.FontFamily" Value="Consolas" />
          <Setter Property="TextElement.FontSize" Value="12" />
          <Setter Property="VirtualizingStackPanel.IsVirtualizing" Value="True" />
          <Setter Property="VirtualizingStackPanel.VirtualizationMode" Value="Recycling" />
          <Setter Property="l:ListBoxSelector.Enabled" Value="True" />
          <Setter Property="ContextMenu">
            <Setter.Value>
              <ContextMenu>
                <MenuItem Command="Copy" />
              </ContextMenu>
            </Setter.Value>
          </Setter>
        </Style>
        <Style TargetType="ListBoxItem">
          <Setter Property="HorizontalAlignment" Value="Left" />
          <Setter Property="Margin" Value="0" />
          <Setter Property="Template">
            <Setter.Value>
              <ControlTemplate TargetType="ListBoxItem">
                <TextBlock Text="{Binding Text}" TextWrapping="Wrap"
                    Background="{TemplateBinding Background}"
                    Foreground="{TemplateBinding Foreground}"
                    FontWeight="{TemplateBinding FontWeight}" />
                <ControlTemplate.Triggers>
                  <DataTrigger Binding="{Binding IsImportant}" Value="true">
                    <Setter Property="TextElement.FontWeight" Value="SemiBold" />
                    <Setter Property="TextElement.FontSize" Value="14" />
                  </DataTrigger>
                  <Trigger Property="IsSelected" Value="true">
                    <Setter Property="Background" Value="{StaticResource {x:Static SystemColors.HighlightBrushKey}}" />
                    <Setter Property="Foreground" Value="{StaticResource {x:Static SystemColors.HighlightTextBrushKey}}" />
                  </Trigger>
                </ControlTemplate.Triggers>
              </ControlTemplate>
            </Setter.Value>
          </Setter>
        </Style>
      </TabControl.Resources>
      <TabItem Header="Bridge">
        <StackPanel Orientation="Vertical" HorizontalAlignment="Left">
          <Button Content="Start Test" Click="StartButton_Click" />
          <Button Content="End Test" Click="EndButton_Click" />
        </StackPanel>
      </TabItem>
      <TabItem Header="Output">
        <Grid>
          <Grid.ColumnDefinitions>
            <ColumnDefinition Width="*" />
            <ColumnDefinition Width="Auto" />
            <ColumnDefinition Width="*" />
          </Grid.ColumnDefinitions>
          <!--<RichTextBox x:Name="OutputBox" ScrollViewer.VerticalScrollBarVisibility="Auto"/>-->
          <ListBox Grid.Column="0" ItemsSource="{Binding Output,RelativeSource={RelativeSource FindAncestor,AncestorType=Window}}"
                   ScrollViewer.HorizontalScrollBarVisibility="Disabled">
            <ListBox.CommandBindings>
              <CommandBinding Command="Copy" Executed="CopyExecuted" />
            </ListBox.CommandBindings>
          </ListBox>

          <GridSplitter Grid.Column="1" Width="5" ResizeBehavior="PreviousAndNext" />
          <ListBox Grid.Column="2" ItemsSource="{Binding Errors,RelativeSource={RelativeSource FindAncestor,AncestorType=Window}}" 
                   ScrollViewer.HorizontalScrollBarVisibility="Disabled">
            <ListBox.CommandBindings>
              <CommandBinding Command="Copy" Executed="CopyExecuted" />
            </ListBox.CommandBindings>
          </ListBox>
        </Grid>

      </TabItem>
      <TabItem Header="Log">
        <Grid>
          <ListBox Grid.Column="0" ItemsSource="{Binding Logs,RelativeSource={RelativeSource FindAncestor,AncestorType=Window}}" 
                   ScrollViewer.HorizontalScrollBarVisibility="Disabled">
            <ListBox.CommandBindings>
              <CommandBinding Command="Copy" Executed="CopyExecuted" />
            </ListBox.CommandBindings>
          </ListBox>
        </Grid>
      </TabItem>
    </TabControl>
  </Grid>
</Window>

MainWindow.xaml.cs

using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.Windows.Threading;
using System.Threading;

namespace PerformanceTest
{
    /// 
    /// Interaction logic for MainWindow.xaml
    /// 
    public partial class MainWindow : Window
    {
        public BlockingCollection<PrintInfo> outputProducer = new BlockingCollection<PrintInfo>();
        public BlockingCollection<PrintInfo> errorProducer = new BlockingCollection<PrintInfo>();
        public BlockingCollection<PrintInfo> logsProducer = new BlockingCollection<PrintInfo>();

        public ObservableCollection<PrintInfo> Output { get; set; }
        public ObservableCollection<PrintInfo> Errors { get; set; }
        public ObservableCollection<PrintInfo> Logs { get; set; }

        protected FontFamily font = new FontFamily("Consolas");
        protected int defaultFontSize = 12;
        protected int importantFontSize = 14;

        Dispatcher dispatcher;

        public MainWindow()
        {
            Bridge.Controller.Window = this;
            try
            {
                InitializeComponent();
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.InnerException.ToString());
                Console.WriteLine(ex.StackTrace);
            }

            dispatcher = Dispatcher;
            Output = new ObservableCollection<PrintInfo>();
            Errors = new ObservableCollection<PrintInfo>();
            Logs = new ObservableCollection<PrintInfo>();


            new Thread(new ThreadStart(() => Print(outputProducer, Output))).Start();
            new Thread(new ThreadStart(() => Print(errorProducer, Errors))).Start();
            new Thread(new ThreadStart(() => Print(logsProducer, Logs))).Start();
        }

        public delegate void EmptyDelegate();

        public void Print(BlockingCollection<PrintInfo> producer, ObservableCollection<PrintInfo> target)
        {
            try
            {
                foreach (var info in producer.GetConsumingEnumerable())
                {
                    dispatcher.Invoke(new EmptyDelegate(() =>
                    {
                        if (info.IsImportant)
                        {
                            String timestamp = DateTime.Now.ToString("[hh:mm.ss] ");
                            String toPrint = timestamp + info.Text;
                            info.Text = toPrint;
                        }
                        target.Add(info);
                    }), DispatcherPriority.Background);
                }
            }
            catch (TaskCanceledException)
            {
                //window closing before print finish
            }
        }

        private void StartButton_Click(object sender, RoutedEventArgs e)
        {
            if (!Bridge.Controller.Running)
            {
                Bridge.Controller.Running = true;
                Bridge.Controller.PrintLotsOfText();
            }
        }

        private void EndButton_Click(object sender, RoutedEventArgs e)
        {
            Bridge.Controller.Running = false;
        }

        private void CopyExecuted(object sender, ExecutedRoutedEventArgs e)
        {
            ListBox box = sender as ListBox;

            HashSet<PrintInfo> allItems = new HashSet<PrintInfo>(box.Items.OfType<PrintInfo>());
            HashSet<PrintInfo> selectedItems = new HashSet<PrintInfo>(box.SelectedItems.OfType<PrintInfo>());

            IEnumerable<PrintInfo> sortedItems = allItems.Where(i => selectedItems.Contains(i));
            IEnumerable<String> copyItems = from i in sortedItems select i.Text;

            string log = string.Join("\r\n", copyItems);
            Clipboard.SetText(log);
        }
    }
}

ListBoxSelector.cs是@pushpraj的答案。

Answer 1

我执行您提供的示例，除了几个线程问题之外，最大的问题是数据量。它会随着文本的增长而减慢呈现速度。

我试着用不同的方式重写你的代码。我使用任务、BlockingCollection和虚拟化来提高性能，假设应用程序的主要兴趣是日志记录速度。

Bridge.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Documents;
using System.Threading;
using System.Collections.Concurrent;
using System.Threading.Tasks;

namespace PerformanceTest
{
    public class Bridge
    {
        int counterLimit;

        public BlockingCollection<string> output;
        public BlockingCollection<string> impOutput;
        public BlockingCollection<string> errors;
        public BlockingCollection<string> impErrors;
        public BlockingCollection<string> logs;


        protected static Bridge controller = new Bridge();

        public static Bridge Controller
        {
            get
            {
                return controller;
            }
        }

        public MainWindow Window
        {
            set
            {
                if (value != null)
                {
                    output = value.outputProducer;
                    impOutput = value.impOutputProducer;
                    errors = value.errorProducer;
                    impErrors = value.impErrorProducer;
                    logs = value.logsProducer;
                }
            }
        }

        public bool Running
        {
            get;
            set;
        }

        private Bridge()
        {
            //20000 lines seems to slow down tabbing enough to prove my point.
            //increase this number to get even worse results.
            counterLimit = 40000;
        }

        public void PrintLotsOfText()
        {
            Task.Run(() => GenerateOutput());
            Task.Run(() => GenerateError());
        }

        private void GenerateOutput()
        {
            //There is tons of output text, so print super fast if possible.
            int counter = 1;
            while (Running && counter < counterLimit)
            {
                PrintOutput("I will never say this horrible word again as long I live. This is confession #" + counter++ + ".");
                //Task.Delay(1).Wait();
            }
        }

        private void GenerateError()
        {
            int counter = 1;
            while (Running && counter < counterLimit)
            {
                PrintError("I will never forgive your errors as long I live. This is confession #" + counter++ + ".");
                //Task.Delay(1).Wait();
            }
        }

        #region Printing
        delegate void StringArgDelegate(String s);
        delegate void InlineArgDelegate(Inline inline);
        public void PrintOutput(String s)
        {
            output.TryAdd(s);
            PrintLog("d " + s);
        }

        public void PrintImportantOutput(String s)
        {
            impOutput.TryAdd(s);
            PrintLog("D " + s);
        }

        public void PrintError(String s)
        {
            errors.TryAdd(s);
            PrintLog("e " + s);
        }

        public void PrintImportantError(String s)
        {
            impErrors.TryAdd(s);
            PrintLog("E " + s);
        }

        public void PrintLog(String s)
        {
            String text = s;
            logs.TryAdd(text);
        }
        #endregion
    }
}

MainWindow.xaml

<Window x:Class="PerformanceTest.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow"
        WindowStartupLocation="CenterScreen">
    <Grid>
        <TabControl>
            <TabControl.Resources>
                <Style TargetType="ListBox">
                    <Setter Property="TextElement.FontFamily"
                            Value="Consolas" />
                    <Setter Property="TextElement.FontSize"
                            Value="12" />
                    <Setter Property="VirtualizingPanel.IsVirtualizing"
                            Value="True" />
                    <Setter Property="VirtualizingPanel.VirtualizationMode"
                            Value="Recycling" />
                </Style>
            </TabControl.Resources>
            <TabItem Header="Bridge">
                <StackPanel Orientation="Vertical"
                            HorizontalAlignment="Left">
                    <Button Content="Start Test"
                            Click="StartButton_Click" />
                    <Button Content="End Test"
                            Click="EndButton_Click" />
                </StackPanel>
            </TabItem>
            <TabItem Header="Output">
                <Grid>
                    <Grid.ColumnDefinitions>
                        <ColumnDefinition Width="*" />
                        <ColumnDefinition Width="Auto" />
                        <ColumnDefinition Width="*" />
                    </Grid.ColumnDefinitions>
                    <ListBox Grid.Column="0"
                             ItemsSource="{Binding Output,RelativeSource={RelativeSource FindAncestor,AncestorType=Window}}" />

                    <GridSplitter Grid.Column="1"
                                  Width="5"
                                  ResizeBehavior="PreviousAndNext" />
                    <ListBox Grid.Column="2"
                             ItemsSource="{Binding Errors,RelativeSource={RelativeSource FindAncestor,AncestorType=Window}}" />
                </Grid>

            </TabItem>
            <TabItem Header="Log">
                <Grid>
                    <ListBox Grid.Column="0"
                             ItemsSource="{Binding Logs,RelativeSource={RelativeSource FindAncestor,AncestorType=Window}}" />
                </Grid>
            </TabItem>
        </TabControl>
    </Grid>
</Window>

MainWindow.xaml.cs

using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.Windows.Threading;

namespace PerformanceTest
{
    /// 
    /// Interaction logic for MainWindow.xaml
    /// 
    public partial class MainWindow : Window
    {
        public BlockingCollection<string> outputProducer = new BlockingCollection<string>();
        public BlockingCollection<string> impOutputProducer = new BlockingCollection<string>();
        public BlockingCollection<string> errorProducer = new BlockingCollection<string>();
        public BlockingCollection<string> impErrorProducer = new BlockingCollection<string>();
        public BlockingCollection<string> logsProducer = new BlockingCollection<string>();

        public ObservableCollection<object> Output { get; set; }
        public ObservableCollection<object> Errors { get; set; }
        public ObservableCollection<object> Logs { get; set; }

        Dispatcher dispatcher;

        public MainWindow()
        {
            Bridge.Controller.Window = this;
            try
            {
                InitializeComponent();
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.InnerException.ToString());
                Console.WriteLine(ex.StackTrace);
            }

            dispatcher = Dispatcher;
            Output = new ObservableCollection<object>();
            Errors = new ObservableCollection<object>();
            Logs = new ObservableCollection<object>();
            Task.Run(() => Print(outputProducer, Output));
            Task.Run(() => Print(errorProducer, Errors));
            Task.Run(() => Print(logsProducer, Logs));
        }

        public void Print(BlockingCollection<string> producer, ObservableCollection<object> target)
        {
            try
            {
                foreach (var str in producer.GetConsumingEnumerable())
                {
                    dispatcher.Invoke(() =>
                    {
                        target.Insert(0, str);
                    }, DispatcherPriority.Background);
                }
            }
            catch (TaskCanceledException)
            {
                //window closing before print finish
            }
        }

        private void StartButton_Click(object sender, RoutedEventArgs e)
        {
            if (!Bridge.Controller.Running)
            {
                Bridge.Controller.Running = true;
                Bridge.Controller.PrintLotsOfText();
            }
        }

        private void EndButton_Click(object sender, RoutedEventArgs e)
        {
            Bridge.Controller.Running = false;
        }
    }
}

要获得完整的工作示例，请下载PerformanceTest.zip并查看它是否接近您的需要。我只重写了一部分。如果此示例正朝着所需的方向前进，我们可以实现其余的功能。如果您想要减慢生产速度以查看混合日志，否则日志生成太快，因此在logs选项卡中依次出现。

Answer 2

使用FlowDocumentPageViewer将有助于提高性能，因为它异步加载文档。