WPF问题

Question

现在要以一个TextBlock做一个密码框的水印，现如今要判断密码框中是否存在密码，若有密码我让TextBlock显示，若是没有则不显示，但是我要怎么判断密码框是不是获取了焦点，以为TextBlock显示与否的逻辑是要在密码框没有取得失去焦点时写，怎么解决？

Answer 1

给你参考，用WPF就别用那么土的方式去做事
            <TextBox Margin="5,5,5,5" Width="500" Height="25"
                    HorizontalAlignment="Left" HorizontalContentAlignment="Right">
                <TextBox.Resources>
                    <VisualBrush x:Key="helpBrush" TileMode="Tile"
                                 Stretch="Fill"
                                 AlignmentX="Right" AlignmentY="Center">
                        <VisualBrush.Visual>
                            <Grid Background="{DynamicResource BasicTextBox_Background}"
                                  Width="500" Height="25">
                                <TextBlock Foreground="Gray" Opacity="0.5" Margin="0,0,5,0"
                                           HorizontalAlignment="Right" VerticalAlignment="Center" >
                                    <Italic>我是水印哦  </Italic>
                                    <Run>(*^_^*)</Run>
                                </TextBlock>
                            </Grid>
                        </VisualBrush.Visual>
                    </VisualBrush>
                    <Style TargetType="TextBox" >
                        <Style.Triggers>
                            <Trigger Property="Text" Value="{x:Null}">
                                <Setter Property="Background" Value="{StaticResource helpBrush}"/>
                            </Trigger>
                            <Trigger Property="Text" Value="">
                                <Setter Property="Background" Value="{StaticResource helpBrush}"/>
                            </Trigger>
                        </Style.Triggers>
                    </Style>                    
                </TextBox.Resources>
            </TextBox>

Answer 2

你可以试试在密码框的onfocused事件中处理（onfocused是获取焦点事件）

Answer 3

这位大大PasswordBox里面是没有Text属性的。

Answer 4

我说了，给你参考，只是告诉你解决这个问题的思想，在WPF中用事件去控制UI的方式弱爆了。

Answer 5

嗯嗯,我现在是想用触发器去做这个了.不会Blend有点蛋疼.这位大大Blend的使用要怎么学比较好呢?

Answer 6

其实网上还是有很多怎么给Password添加水印的方法的.