TextBox 的键盘焦点事件

显示默认文字，当用户点击，准备输入的时候，TextBox清空，
当用户输入了内容，则不做任何动作
如果没有输入，鼠标离开TextBox焦点，则继续提示
参考源码如下：
//假设 TextBox 的Name为 conditionTextBox

复制代码

1. string defaultSearchConditionText = "默认文字";
2. private void conditionTextBox_KeyUp(object sender, KeyEventArgs e)
3.         {
4.             if (e.Key == Key.Enter)
5.                 this.GetSearchCondition());
6.             if (this.conditionTextBox.Text.Trim() == string.Empty)
7.                 this.conditionTextBox.Text = this.defaultSearchConditionText;
8.         }
10.         private void conditionTextBox_MouseEnter(object sender, MouseEventArgs e)
11.         {
12.             if (this.conditionTextBox.Text.Trim() == this.defaultSearchConditionText)
13.                 this.conditionTextBox.Clear();
14.         }
16.         private void conditionTextBox_MouseLeave(object sender, MouseEventArgs e)
17.         {
18.             if (this.conditionTextBox.Text.Trim() == string.Empty)
19.                 this.conditionTextBox.Text = this.defaultSearchConditionText;
20.         }       
22.         private void conditionTextBox_KeyDown(object sender, KeyEventArgs e)
23.         {
24.             if (e.Key != Key.Enter)
25.             {
26.                 if (this.conditionTextBox.Text.Trim() == this.defaultSearchConditionText)
27.                     this.conditionTextBox.Clear();
28.             }
29.         }

原文地址：http://www.dotnetbbs.com/read.php?tid-229.html