检测 RichTextBox 是否为空 [英] Detect if a RichTextBox is empty

问题描述

检测 WPF RichTextBox/FlowDocument 是否为空的最佳方法是什么?

What is the best way to detect if a WPF RichTextBox/FlowDocument is empty?

如果文档中仅存在文本，则以下内容有效.如果它包含 UIElement 的

The following works if only text is present in the document. Not if it contains UIElement's

new TextRange(Document.ContentStart, Document.ContentEnd).IsEmpty

推荐答案

你可以比较指针，这不太可靠:

You could compare the pointers, which is not all too reliable:

var start = rtb.Document.ContentStart;
var end = rtb.Document.ContentEnd;
int difference = start.GetOffsetToPosition(end);

如果 RTB 已加载，则计算结果为 2，如果内容已被再次输入和删除，则计算结果为 4.
如果 RTB 被完全清除，例如通过 select all ->删除的值将是0.

This evaluates to 2 if the RTB is loaded, and 4 if content has been entered and removed again.
If the RTB is completely cleared out e.g. via select all -> delete the value will be 0.

在 MSDN 上的 Silverlight 参考

In the Silverlight reference on MSDN another method is found which can be adapted and improved to:

public bool IsRichTextBoxEmpty(RichTextBox rtb)
{
    if (rtb.Document.Blocks.Count == 0) return true;
    TextPointer startPointer = rtb.Document.ContentStart.GetNextInsertionPosition(LogicalDirection.Forward);
    TextPointer endPointer = rtb.Document.ContentEnd.GetNextInsertionPosition(LogicalDirection.Backward);
    return startPointer.CompareTo(endPointer) == 0;
}

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