当将文本键入到TextBox中时，立即触发TextChanged事件
问题描述：
在具有TextChanged事件的wpf TextBox上，它似乎仅在焦点从文本框移开时才触发；但不是因为输入了单个字符.
On a wpf TextBox that has an TextChanged event, it seems to only fires when focus is taken away from the textbox; but not as individual characters are typed in.
是否存在类似于TextChanged的事件，当在文本框中键入字符时而不是在焦点改变时会立即触发 ?
Is there an event similar to TextChanged that fires immediately when a character is typed into the textbox, rather than when focus changes?