如何找到使用 TextChanged 添加的文本 [英] How do I find what text had been added with TextChanged

问题描述

我希望在文本框中的文本和变量中的字符串之间进行同步.我找到了如何获取更改字符串的索引(在文本框中)、添加的长度和删除的长度，但我如何才能真正找到添加的字符串?

I'm looking to synchronize between a text in the textbox and string in a variable. I found how to get the index in which the string was changed (in the textbox), the length added and length removed, but how can I actually find the string added?

到目前为止，我已经使用了 TextChangedEventArgs.Changes，并获得了其中项目的属性 (ICollection).

So far I've used TextChangedEventArgs.Changes, and got the properties of the items in it (ICollection).

我正在尝试创建一个密码框，我可以在其中通过函数显示实际密码.因此我不希望文本框直接同步(例如，在文本框中会出现*****"和字符串hello").

I'm trying to create a password box in which I could show the actual password by a function. hence I do not want the textbox to synchronize directly (for example, in the textbox would appear "*****" and in the string "hello").

推荐答案

如果你只想添加文本，你可以这样做

If you want only text added you can do this

 string AddedText;
 private void textbox_TextChanged(object sender, TextChangedEventArgs e)
 {
     var changes = e.Changes.Last();
     if (changes.AddedLength > 0)
     {
         AddedText = textbox.Text.Substring(changes.Offset,changes.AddedLength);
     }
 }

编辑

如果您想添加和删除所有文本，您可以这样做

If you want all added and remove text you can do this

    string oldText;
    private void textbox_GotFocus(object sender, RoutedEventArgs e)
    {
        oldText = textbox.Text;
    }

    string AddedText;
    string RemovedText;
    private void textbox_TextChanged(object sender, TextChangedEventArgs e)
    {
        var changes = e.Changes.Last();
        if (changes.AddedLength > 0)
        {
            AddedText = textbox.Text.Substring(changes.Offset, changes.AddedLength);
            if (changes.RemovedLength == 0)
            {
                oldText = textbox.Text;
                RemovedText = "";
            }
        }
        if (changes.RemovedLength > 0)
        {
            RemovedText = oldText.Substring(changes.Offset, changes.RemovedLength);
            oldText = textbox.Text;
            if (changes.AddedLength == 0)
            {
                AddedText = "";
            }
        }
    }

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