Windows Phone MultiBinding ：Cimbalino Toolkit
在WPF和WIN8中是支持MultiBinding
这个有啥用呢，引用下MSDN的例子http://msdn.microsoft.com/en-us/library/system.windows.data.multibinding.aspx：
MultiBinding allows you to bind a binding target property to a list of source properties and then apply logic to produce a value with the given inputs. This example demonstrates how to use MultiBinding.
In the following example, NameListData refers to a collection of PersonName objects, which are objects that contain two properties, firstName and lastName. The following example produces a TextBlock that shows the first and last names of a person with the last name first.
<TextBlock Name="textBox2" DataContext="{StaticResource NameListData}">
<TextBlock.Text>
<MultiBinding Converter="{StaticResource myNameConverter}"
ConverterParameter="FormatLastFirst">
<Binding Path="FirstName"/>
<Binding Path="LastName"/>
</MultiBinding>
</TextBlock.Text>
</TextBlock>
public class NameConverter : IMultiValueConverter
{
public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
{
string name;
switch ((string)parameter)
{
case "FormatLastFirst":
name = values[1] + ", " + values[0];
break;
case "FormatNormal":
default:
name = values[0] + " " + values[1];
break;
}
return name;
}
public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)
{
string[] splitValues = ((string)value).Split(' ');
return splitValues;
}
}
可惜在wp中这个被砍掉了
想要 MultiBinding 需要自己来实现（方法见高手博客：http://www.devdiv.com/wp_amp_win_-blog-55433-51080.html）
当然也有一个稍微简单点的方法，使用Cimbalino Windows Phone Toolkit（http://cimbalino.org/），Cimbalino Toolkit 的作者为我们提供了一个MultiBindingBehavior，可以比较方便的实现 MultiBinding
下面看一个实例把，这里我们模拟一个显示学生各科成绩的应用，在应用中有一个ListPicker，应用会根据ListPicker的值来作为阈值，对成绩的颜色进行修改，下面是实现:
我们先新建一个wp工程（7.1，8.0都行，Cimbalino toolkit is compatible with the Windows Phone SDK 7.1.x and Windows Phone 8.0，这里我用7.1的，主要是机器不行，8.0的模拟器太卡…）
添加成绩类：
namespace PhoneIValueConverterMultibinding1
{
public class Score
{
public string name { get; set; }
public int number { get; set; }
}
}
在工程中添加Cimbalino Windows Phone Toolkit
然后定义我们的颜色转换类（由于我没用双向绑定，所以没写ConvertBack…）：
using System;
using System.Windows.Media;
using System.Globalization;
using Cimbalino.Phone.Toolkit.Converters;
namespace PhoneIValueConverterMultibinding1
{
public class ColorChange : MultiValueConverterBase
{
public override object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
{
if (values.Length < 2)
{
return new SolidColorBrush(Colors.White);
}
if ((values[0] != null) && (values[1] != null))
{
//根据输入，判断返回值
try
{
int limitnumber = System.Convert.ToInt32((string)values[0]);
int studentscore = (int)values[1];
if (limitnumber < studentscore)
{
return new SolidColorBrush(Colors.Red);
}
else
{
return new SolidColorBrush(Colors.Green);
}
}
catch (FormatException)
{
return new SolidColorBrush(Colors.White);
}
catch (Exception)
{
return new SolidColorBrush(Colors.White);
}
}
else
{
return new SolidColorBrush(Colors.White);
}
}
public override object[] ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
}
}
然后在xaml里添加引用：
xmlns:toolkit="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone.Controls.Toolkit"
xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"
xmlns:Local="clr-namespace:PhoneIValueConverterMultibinding1"
xmlns:cimbalinoBehaviors="clr-namespace:Cimbalino.Phone.Toolkit.Behaviors;assembly=Cimbalino.Phone.Toolkit"
添加ListPicker
<toolkit:ListPicker Header="成绩阈值" Name="listpicker1" SelectionChanged="listpicker1_SelectionChanged">
<toolkit:ListPickerItem Content="50" />
<toolkit:ListPickerItem Content="60" />
<toolkit:ListPickerItem Content="70" />
<toolkit:ListPickerItem Content="80" />
<toolkit:ListPickerItem Content="90" />
</toolkit:ListPicker>
添加页面资源
<phone:PhoneApplicationPage.Resources> <Local:ColorChange x:Key="ColorConverter" /> </phone:PhoneApplicationPage.Resources>
然后添加绑定的listbox，并在其中添加MultiBindingBehavior ，因为我们要改变的是文字的颜色，所以设置PropertyName="Foreground"
<ListBox Height="510" Name="lb1" Margin="12,12,0,0" >
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Width="432" Orientation="Horizontal">
<TextBlock TextWrapping="Wrap" Text="{Binding name}" FontSize="32" Width="200" />
<TextBlock TextWrapping="Wrap" Text="{Binding number}" FontSize="32" Margin="0" >
<i:Interaction.Behaviors>
<cimbalinoBehaviors:MultiBindingBehavior Converter="{StaticResource ColorConverter}" PropertyName="Foreground" >
<cimbalinoBehaviors:MultiBindingItem Value="{Binding ElementName=listpicker1, Path=SelectedItem.Content}" />
<cimbalinoBehaviors:MultiBindingItem Value="{Binding number}" />
</cimbalinoBehaviors:MultiBindingBehavior>
</i:Interaction.Behaviors>
</TextBlock>
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
最后数据绑定：
ObservableCollection<Score> StudentScore = new ObservableCollection<Score>();
private void PhoneApplicationPage_Loaded(object sender, RoutedEventArgs e)
{
StudentScore.Add(new Score { name = "语文", number = 55 });
StudentScore.Add(new Score { name = "数学", number = 66 });
StudentScore.Add(new Score { name = "英语", number = 76 });
StudentScore.Add(new Score { name = "物理", number = 72 });
StudentScore.Add(new Score { name = "化学", number = 97 });
StudentScore.Add(new Score { name = "生物", number = 86 });
StudentScore.Add(new Score { name = "地理", number = 68 });
StudentScore.Add(new Score { name = "历史", number = 95 });
StudentScore.Add(new Score { name = "政治", number = 39 });
}
private void listpicker1_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
if (listpicker1 != null)
{
if (listpicker1.SelectedIndex != -1)
{
lb1.ItemsSource = StudentScore;
}
}
}
看看效果：
最后说下Ms强烈建议不要在复杂绑定中是使用Converter
另外Cimbalino Windows Phone Toolkit还有许多其他的功能
大家可以试试
源码：
参考：
http://msdn.microsoft.com/en-us/library/system.windows.data.multibinding.aspx
https://github.com/Cimbalino/Cimbalino-Phone-Toolkit
http://www.pedrolamas.com/2013/05/17/cimbalino-windows-phone-toolkit-multibindingbehavior/
