我正在尝试在WPF RichTextBox中显示基本语法高亮显示。它主要起作用,但渲染性能很糟糕。
首先我天真地尝试过:
/// <summary>
/// Main event handler for syntax highlighting.
/// </summary>
private void XmlChanged(object sender, TextChangedEventArgs e)
{
VM.Dirty = true;
if (VM.Pretty)
{
var range = new TextRange(XmlView.Document.ContentStart, XmlView.Document.ContentEnd);
Render(range.Text);
}
}
/// <summary>
/// Entry point for programmatically resetting the textbox contents
/// </summary>
private void Render(string text)
{
XmlView.TextChanged -= this.XmlChanged;
if (VM.Pretty)
{
var tokens = tokenizer.Tokenize(text);
Format(XmlView.Document, tokens);
}
XmlView.TextChanged += this.XmlChanged;
}
private void Format(FlowDocument doc, List<Token> tokens)
{
var start = doc.ContentStart;
foreach (var token in tokens)
{
TextRange range = new TextRange(start.GetPositionAtOffset(token.StartPosition, LogicalDirection.Forward),
start.GetPositionAtOffset(token.EndPosition, LogicalDirection.Forward));
range.ApplyPropertyValue(TextElement.ForegroundProperty, m_syntaxColors[token.Type]);
}
}
在一个只有100多个令牌的2KB文档上进行测试,每次击键后需要1-2秒才能重绘;显然不能接受。分析表明我的tokenizer比Format()函数快几个数量级。所以我尝试了一些双缓冲:
private void Render(string text)
{
XmlView.TextChanged -= this.XmlChanged;
// create new doc offscreen
var doc = new FlowDocument();
var range = new TextRange(doc.ContentStart, doc.ContentEnd);
range.Text = text;
if (VM.Pretty)
{
var tokens = tokenizer.Tokenize(text);
Format(doc, tokens);
}
// copy to active buffer
var stream = new MemoryStream(65536);
range.Save(stream, DataFormats.XamlPackage);
var activeRange = new TextRange(XmlView.Document.ContentStart, XmlView.Document.ContentEnd);
activeRange.Load(stream, DataFormats.XamlPackage);
XmlView.TextChanged += this.XmlChanged;
}
基准测试表明,Format()在屏幕外渲染的速度稍快,但感知性能现在更差!
正确的方法是什么?
答案 0 :(得分:1)
我尝试尽可能多地从方法/循环中获取对象实例化,然后传入引用。每次按键每次循环都会调用新的几次。