慢速WPF控件（自制带子串高亮的HighlightTextBlock）

告诉我为什么我的控件变慢了，尽管它是从并行线程调用的。

我正在尝试为.NET 4.0 ( HighlightTextBlock )创建一个控件，它将以黄色突出显示子文本。这个想法是，如果找到子文本，则ContentControl的Content变成3 Runs的TextBlock ，其中一个以黄色突出显示。

• result.Add(new Run(stringBefore));

• result.Add(new Run(stringMatch) { Background = this.HighlightBrush });

• result.Add(new Run(stringAfter));

如果未找到子文本，则仅插入文本。

一切都已经证明并有效，但问题在于性能。

我将更详细地描述：

此控件用于可能有数百条记录的工作表中。子文本在TextBox中编辑。绑定到这个文本框如下：HighlightText = "{Binding ElementName=myTextBox, Path=Text}"。如果您编辑此子文本，它会冻结，光标会“跳动”，如图所示。对于每次击键，都会执行代码以突出显示文本，并且很明显它在我的控制下已经减慢了 30 行。

擦除时，文本应该平滑地淡化，但不是很平滑：

在我的控制范围内，我试图这样做：

Dispatcher.BeginInvoke(
(ThreadStart)delegate
{
    //update control
}
);

因此，通过异步：

Task.Factory.StartNew(/*поиск в строке и разбиение строки на 3 части*/)
    .ContinueWith(
        x =>
        {
            //update control
        }
        ,TaskScheduler.FromCurrentSynchronizationContext()
        );

但是不可能摆脱刹车。

您可以检查一个简单示例的控件（我立即手写）。制动已经发生在 30 行。

<TextBox Name="myTextBox"/>
<ItemsControl>
    <ItemsControl.Items>
        <!-- ... -->
        <controls:HighlightTextBlock Text = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ" HighlightText = "{Binding ElementName=myTextBox, Path=Text}"/>
        <controls:HighlightTextBlock Text = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ" HighlightText = "{Binding ElementName=myTextBox, Path=Text}"/>
        <controls:HighlightTextBlock Text = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ" HighlightText = "{Binding ElementName=myTextBox, Path=Text}"/>
        <controls:HighlightTextBlock Text = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ" HighlightText = "{Binding ElementName=myTextBox, Path=Text}"/>
        <controls:HighlightTextBlock Text = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ" HighlightText = "{Binding ElementName=myTextBox, Path=Text}"/>
        <controls:HighlightTextBlock Text = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ" HighlightText = "{Binding ElementName=myTextBox, Path=Text}"/>
        <controls:HighlightTextBlock Text = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ" HighlightText = "{Binding ElementName=myTextBox, Path=Text}"/>
        <!-- ... -->
    </ItemsControl.Items>
</ItemsControl>

这是承诺的完全控制代码。无论有没有调试器，它都会变慢。

public class HighlightTextBlock : ContentControl
{

    public string Text
    {
        get { return (string)GetValue(TextProperty); }
        set
        {
            SetValue(TextProperty, value);
        }
    }

    public static readonly DependencyProperty TextProperty =
        DependencyProperty.Register("Text", typeof(string), typeof(HighlightTextBlock), new UIPropertyMetadata("", new PropertyChangedCallback(TextProperty_PropertyChanged)));

    private static void TextProperty_PropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        var control = d as HighlightTextBlock;
        control.SetContent();
    }



    public string HighlightText
    {
        get { return (string)GetValue(HighlightTextProperty); }
        set
        {
            SetValue(HighlightTextProperty, value);
        }
    }

    public static readonly DependencyProperty HighlightTextProperty =
        DependencyProperty.Register("HighlightText", typeof(string), typeof(HighlightTextBlock), new UIPropertyMetadata("", new PropertyChangedCallback(HighlightTextProperty_PropertyChanged)));

    private static void HighlightTextProperty_PropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        var control = d as HighlightTextBlock;
        control.SetContent();
    }

    public Brush HighlightBrush
    {
        get { return (Brush)GetValue(ColorProperty); }
        set { SetValue(ColorProperty, value); }
    }

    public static readonly DependencyProperty ColorProperty =
        DependencyProperty.Register("HighlightBrush",
        typeof(Brush),
        typeof(HighlightTextBlock),
        new UIPropertyMetadata(Brushes.Orange));


    static HighlightTextBlock()
    {
        //DefaultStyleKeyProperty.OverrideMetadata(typeof(ContentControl), new FrameworkPropertyMetadata(typeof(ContentControl)));
    }


    private TextBlock TextContent
    {
        get { return Content as TextBlock; }
        set { Content = value as TextBlock; }
    }


    public HighlightTextBlock()
    {
        TextContent = new TextBlock();
        SetContent();
    }

    private void SetContent()
    {

        //TextContent.Text = Text;

        var tmpText = Text;
        var tmpHighlightText = HighlightText;
        /*Task.Factory.StartNew<CombinedText>(() => GetCombined(txt, hghlghtTxt))
            .ContinueWith(
                x =>
                {
                    Debug.WriteLine("------- XXXXXXXX -------");
                    var text = (CombinedText)x.Result;

                    TextContent = new TextBlock();
                    TextContent.Inlines.Add(new Run(text.Before ?? ""));
                    TextContent.Inlines.Add(new Run(text.Match ?? "") { Background = HighlightBrush });
                    TextContent.Inlines.Add(new Run(text.After ?? ""));

                    Debug.WriteLine("---------ZZZZZZZZ------------");
                }
                ,TaskScheduler.FromCurrentSynchronizationContext()
            );*/

        Dispatcher.BeginInvoke(
            (ThreadStart)delegate
            {
                var text = GetCombined(tmpText, tmpHighlightText);
                TextContent = new TextBlock();
                TextContent.Inlines.Add(new Run(text.Before ?? ""));
                TextContent.Inlines.Add(new Run(text.Match ?? "") { Background = HighlightBrush });
                TextContent.Inlines.Add(new Run(text.After ?? ""));
            }
            );
    }

    private CombinedText GetCombined(string text, string highlightText)
    {
        Debug.WriteLine("------------1111---------------");
        var result = new CombinedText();
        SharpDebug.WriteLine(text);
        SharpDebug.WriteLine(highlightText);

        if (text != null && highlightText != null)
        {
            Debug.WriteLine("-----------2222----------------");
            var queryLength = highlightText.Length;
            var sourceLength = text.Length;

            var index = text.IndexOf(highlightText, StringComparison.InvariantCultureIgnoreCase);

            if (index >= 0)
            {
                Debug.WriteLine("-------------3333--------------");
                var stringBefore = text.Substring(0, index);
                var stringMatch = text.Substring(index, queryLength);
                var stringAfter = text.Substring(index + queryLength, sourceLength - (index + queryLength));

                if (stringBefore.Length > 0)
                {
                    Debug.WriteLine("-------------4444--------------");
                    result.Before = stringBefore;
                }

                if (stringMatch.Length > 0)
                {
                    Debug.WriteLine("------------5555---------------");
                    result.Match = stringMatch;
                }

                if (stringAfter.Length > 0)
                {
                    Debug.WriteLine("-------------6666--------------");
                    result.After = stringAfter;
                }

                Debug.WriteLine("------------7777---------------");
                return result;
            }
        }
        Debug.WriteLine("-------------9999--------------");

        result.Before = text;
        return result;
    }
}

internal struct CombinedText
{
    public string Before { get; set; }
    public string Match { get; set; }
    public string After { get; set; }
} 

internal static class ControlExtensions
{
    public static void Clear(this TextBlock text)
    {
        text.Text = "";
    }
}