WPF学习历程2----Binding(一)

Binding基础

Eg1让数据源的类实现System.ComponentModel名称空间中的INotifyPropertyChanged接口，当Binding设置了数据源后，Binding就会自动侦听来自这个接口的PropertyChanged事件

xaml代码：

<StackPanel>

<TextBox x:Name="txt_Name" BorderBrush="Blue" Margin="5"></TextBox>

<Button Content="增加" Margin="5" Click="Button_Click"></Button>

</StackPanel>

C#代码：

public partial class MainWindow : Window

{

Student stu;

public MainWindow()

{

InitializeComponent();

stu = new Student();

Binding binding= new Binding();

binding.Source = stu;

binding.Path = new PropertyPath("Name");

BindingOperations.SetBinding(this.txt_Name, TextBox.TextProperty, binding);

}

public void Button_Click(object sender, RoutedEventArgs e)

{

stu.Name += "Name";

}

}

class Student : INotifyPropertyChanged

{

public event PropertyChangedEventHandler PropertyChanged;

public string name;

public string Name

{

get { return name; }

set

{

name = value;

if (this.PropertyChanged != null)

{

this.PropertyChanged.Invoke(this, new PropertyChangedEventArgs("Name"));

}

}

}

}

其中代码可以简写，TextBox这类UI元素的基类FrameworkElement对BindingOperations.SetBinding(……)方法进行了封装，封装的结果也叫SetBinding

C#代码：

public partial class MainWindow : Window

{

Student stu;

public MainWindow()

{

InitializeComponent();

this.txt_Name.SetBinding(TextBox.TextProperty, new Binding("Name") { Source = stu = new Student() });

}

public void Button_Click(object sender, RoutedEventArgs e)

{

stu.Name += "Name";

}

}

建立模型



Binding的源与路径

方法一：

<StackPanel>

<TextBox x:Name="txt_Name" Text="{ Binding Path=Value, ElementName=slider1}" BorderBrush="Blue" Margin="5"></TextBox>

<Slider x:Name="slider1" Maximum="100" Minimum="0" Margin="5"></Slider>

</StackPanel>

方法二：

C#代码

Binding binding = new Binding() { Path = new PropertyPath("Value"), Source = this.slider1 };

this.txt_Name.SetBinding(TextBox.TextProperty, binding);

或者

Binding binding = new Binding("Value") { Source=this.slider1};

this.txt_Name.SetBinding(TextBox.TextProperty, binding);

Binding多路径

<StackPanel>

<TextBox x:Name="textbox1" BorderBrush="Blue" Margin="5"></TextBox>

<TextBlock Text="文本的长度" Margin="5"></TextBlock><TextBox x:Name="showlength" Text="{Binding Path=Text.Length,ElementName=textbox1,Mode=OneWay}" BorderBrush="Blue" Margin="5"></TextBox>

<TextBlock Text="取得第3个文本"></TextBlock><TextBox x:Name="showIndex" Text="{Binding Path=Text[2],ElementName=textbox1,Mode=OneWay}" BorderBrush="Blue" Margin="5"></TextBox>

</StackPanel>

或者

this.showlength.SetBinding(TextBox.TextProperty, new Binding("Text.Length") { Source = this.textbox1, Mode = BindingMode.OneWay });

this.showIndex.SetBinding(TextBox.TextProperty, new Binding("Text[2]") { Source = this.textbox1, Mode = BindingMode.OneWay });

当使用一个集合或者Dadaview作为Binding源时

List<string> stringList = new List<string>() { "iPhone", "Lumia900", "HTC" };

this.textbox1.SetBinding(TextBox.TextProperty, new Binding("/") { Source = stringList });

this.textbox2.SetBinding(TextBox.TextProperty, new Binding("/Length") { Source = stringList, Mode = BindingMode.OneWay });

this.textbox3.SetBinding(TextBox.TextProperty, new Binding("/[2]") { Source = stringList, Mode = BindingMode.OneWay });

“没有Path”的Binding

<StackPanel>

<StackPanel.Resources>

<sys:String x:Key="myString">

iPhone Lumia

HTC

</sys:String>

</StackPanel.Resources>

<TextBlock x:Name="textblock1" TextWrapping="Wrap" Text="{Binding Path=.,Source={StaticResource ResourceKey=myString}}" FontSize="16" Margin="5"></TextBlock>

</StackPanel>

或者

string myString="iphone,Lumia900,HTC";

this.textblock1.SetBinding(TextBlock.TextProperty, new Binding(".") { Source = myString });