WPF(五)元素绑定

　　数据绑定是一种关系，WPF从一个源对象提取一些信息，并使用这些信息设置目标对象的属性。

1.将元素绑定到一起

  例如:滑块的拖动，改变TextBlock字体的大小，如果不采用元素绑定，需要为Silder控件添加ValueChanged事件。下面的示例是简单的元素绑定。

  

    <Grid>
            <Slider Name="sliderFontSize" Margin="3" Minimum="1" Maximum="40" Value="10"
                TickFrequency="1" TickPlacement="TopLeft">
            </Slider>
            <TextBlock Margin="10,39,10,62" Text="Simple Text" Name="lblSampleText" FontSize="{Binding ElementName=sliderFontSize,Path=Value}">
            </TextBlock>
        <Button Content="Set to Small" HorizontalAlignment="Left" Margin="36,149,0,0" VerticalAlignment="Top" Width="97"/>
        <Button Content="Set to Normal" HorizontalAlignment="Left" Margin="146,149,0,0" VerticalAlignment="Top" Width="105"/>
        <Button Content="Set to Large" HorizontalAlignment="Left" Margin="264,149,0,0" VerticalAlignment="Top" Width="85"/>

    </Grid>

2.多绑定:

    <Grid Margin="5">
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"></RowDefinition>
            <RowDefinition Height="Auto"></RowDefinition>
            <RowDefinition Height="Auto"></RowDefinition>
            <RowDefinition Height="Auto"></RowDefinition>
            <RowDefinition></RowDefinition>
        </Grid.RowDefinitions>
        <Slider Name="sliderFontSize" Margin="3" Minimum="1" Maximum="40" Value="10"></Slider>
        <TextBox Name="txtContent" Margin="3" Grid.Row="2">Sample Content</TextBox>
        <ListBox Margin="3" Grid.Row="3" Name="lstColors">
            <ListBoxItem Tag="Blue">Blue</ListBoxItem>
            <ListBoxItem Tag="DarkBlue">Dark Blue</ListBoxItem>
            <ListBoxItem Tag="LightBlue">Light Blue</ListBoxItem>
        </ListBox>
        <TextBlock Margin="3" Name="lblSampleText"
                   FontSize="{Binding ElementName=sliderFontSize,Path=Value}" Grid.Row="4"
                   Text="{Binding ElementName=txtContent,Path=Text}"
                   Foreground="{Binding ElementName=lstColors,Path=SelectedItem.Tag}"
                   ></TextBlock>
    </Grid>

  双向绑定:

  

    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"></RowDefinition>
            <RowDefinition Height="*"></RowDefinition>
            <RowDefinition Height="Auto"></RowDefinition>
            <RowDefinition />
        </Grid.RowDefinitions>
        <Slider Name="sliderFontSize" Margin="3" Minimum="1" Maximum="40" Value="10" TickFrequency="1" IsSnapToTickEnabled="True" TickPlacement="TopLeft"></Slider>
        <TextBlock Grid.Row="1" Text="Simple Text" Margin="10" Name="lblSampleText"
                   FontSize="{Binding ElementName=sliderFontSize,Path=Value,Mode=TwoWay}"
                   ></TextBlock>
        <StackPanel Orientation="Horizontal" Margin="5" Grid.Row="2">
            <TextBlock VerticalAlignment="Center" xml:space="preserve">Exact Size:</TextBlock>
            <TextBox Text="{Binding ElementName=lblSampleText, Path=FontSize, UpdateSourceTrigger=PropertyChanged, Mode=TwoWay}" Width="100"></TextBox>
        </StackPanel>
    </Grid>