原文:
WPF入门：数据绑定
上一篇我们将XAML大概做了个了解 ，这篇将继续学习WPF数据绑定的相关内容
数据源与控件的Binding
Binding作为数据传送UI的通道，通过INotityPropertyChanged接口的PropertyChanged事件通知Binding数据属性发生改变
public class Product : INotifyPropertyChanged
{
private string name;
public string Name
{
get { return name; }
set
{
name = value;
if (PropertyChanged != null)
{
this.PropertyChanged.Invoke(this, new PropertyChangedEventArgs("Name"));
}
}
}
public event PropertyChangedEventHandler PropertyChanged;
}通过Binding关联UI控件元素
this.txtOfProduct.SetBinding(TextBox.TextProperty, new Binding() { Path = new PropertyPath("Name"), Source = p });控件之间的Binding
<TextBox x:Name="TextBox1" Text="{Binding ElementName=slider1,Path=Value,Mode=OneWay}"></TextBox>
<Slider x:Name="slider1" Margin="5"></Slider>
我们也可以通过后台C#代码实现
TextBox1.SetBinding(TextBox.TextProperty, new Binding("Value") { ElementName = "slider1", Mode=BindingMode.OneWay });统计文本字符长度
<TextBox x:Name="TextBox1" Margin="5" TextWrapping="Wrap" ></TextBox>
<TextBlock Margin="5" TextAlignment="Right" Text="{Binding ElementName=TextBox1, Path=Text.Length}"></TextBlock>
Binding的Path
Path的索引器方式
<TextBox x:Name="TextBox1" Margin="5" TextWrapping="Wrap" ></TextBox>
<!--获取Text的第三个字符-->
<TextBlock Margin="5" TextAlignment="Right" Text="{Binding ElementName=TextBox1, Path=Text.[2]}"></TextBlock>
<TextBlock Margin="5" TextAlignment="Right" Text="{Binding ElementName=TextBox1, Path=Text[2]}"></TextBlock>当使用一个集合或者DataView作为Binding源时，如果我们想把它的默认元素作为Path来使用
List<string> names = new List<string>() { "张三", "李四", "王五" };
//张三
this.TextBox1.SetBinding(TextBox.TextProperty, new Binding("/") { Source = names });
//“张三”字符串的长度
this.TextBox2.SetBinding(TextBox.TextProperty, new Binding("/Length") { Source = names,Mode=BindingMode.OneWay});
//获取“张三”字符串中的第1个字符
this.TextBox3.SetBinding(TextBox.TextProperty, new Binding("/[0]") { Source = names, Mode = BindingMode.OneWay });如果集合中嵌套集合，我们依然可以通过多级"/"语法把子集作为Path的元素
class City
{
public string Name { get; set; }
}
class Province
{
public List<City> Citys { get; set; }
public string Name { get; set; }
}
class Country
{
public List<Province> Provinces { get; set; }
public string Name { get; set; }
} TextBox1.SetBinding(TextBox.TextProperty, new Binding("/Name") { Source = countries });
TextBox2.SetBinding(TextBox.TextProperty, new Binding("/Provinces/Name") { Source = countries });
TextBox3.SetBinding(TextBox.TextProperty, new Binding("/Provinces/Citys/Name") { Source = countries });
省略Path
sys需要引用xmlns:sys="clr-namespace:System;assembly=mscorlib"
<StackPanel.Resources>
<sys:String x:Key="text">
WPF入门手册
</sys:String>
</StackPanel.Resources>
<TextBox x:Name="TextBox1" Margin="5" Text="{Binding .,Source={StaticResource ResourceKey=text}}" ></TextBox>TextBox2.SetBinding(TextBox.TextProperty, new Binding(".") { Source = "WPF技术入门" });没有Path和Source，Binding可以通过DataContext获取数据
<StackPanel.DataContext>
<sys:String>
WPF入门手册
</sys:String>
</StackPanel.DataContext>
<TextBox x:Name="TextBox1" Margin="5" Text="{Binding Mode=OneWay}" ></TextBox>选中ListBox元素显示对应的属性的一个例子
<TextBox x:Name="TextBox1" Margin="5" ></TextBox>
<ListBox x:Name="ListBox1"></ListBox> List<City> cities = new List<City>() {
new City() { Id=1,Name="北京" },
new City() { Id=2,Name="昆明" },
new City() { Id=3,Name="上海" },
new City() { Id=4,Name="厦门" },
new City() { Id=5,Name="广州" }
};
this.ListBox1.ItemsSource = cities;
this.ListBox1.DisplayMemberPath = "Name";
this.TextBox1.SetBinding(TextBox.TextProperty, new Binding("SelectedItem.Id") { Source = this.ListBox1 });
使用Binding的RelativeSource
当Binding有明确的数据源的时，我们可以通过Soure或ElementName赋值办法关联Binding,但有事我们不知道Soure对象的名字是什么，却知道它与作为Binding目标对象的UI元素布局上的相对关系,通过RelativeSourceMode枚举设置关联的对象关系
<Grid x:Name="g1">
<StackPanel x:Name="s1">
<DockPanel x:Name="d1">
<TextBox x:Name="TextBox1" Margin="5" ></TextBox>
</DockPanel>
</StackPanel>
</Grid>后台代码处理
RelativeSource rs = new RelativeSource(RelativeSourceMode.FindAncestor)
{
AncestorLevel = 1,
AncestorType = typeof(StackPanel)
};
//将StackPanel的Name s1赋给了TextBox1的Text
TextBox1.SetBinding(TextBox.TextProperty, new Binding("Name") { RelativeSource = rs });也可以通过XAML的方式赋值
<Grid x:Name="g1">
<StackPanel x:Name="s1">
<DockPanel x:Name="d1">
<TextBox x:Name="TextBox1" Margin="5" Text="{Binding RelativeSource={RelativeSource AncestorType={x:Type DockPanel},AncestorLevel=1,Mode=FindAncestor}, Path=Name}" ></TextBox>
</DockPanel>
</StackPanel>
</Grid>Binding数据验证
Binding的ValidationRules属性的类型为Collection<ValidationRule>。通过实现Validate方法返回给ValidationResult对象，并设置IsVaild属性，ErrorContent属性可以接受一个字符串。
public class RangValidationRule : ValidationRule
{
//验证数据
public override ValidationResult Validate(object value, CultureInfo cultureInfo)
{
double d = 0;
if (double.TryParse(value.ToString(), out d))
{
if (d >= 1 && d <= 100)
{
return new ValidationResult(true, null);
}
}
return new ValidationResult(false, "数据错误");
}
} <TextBox x:Name="TextBox1" Margin="5"></TextBox>
<Slider x:Name="slider1" Minimum="1" Maximum="100" Margin="5"></Slider> Binding binding = new Binding("Value") {
Source=slider1,
UpdateSourceTrigger=UpdateSourceTrigger.PropertyChanged,
};
binding.ValidationRules.Add(new RangValidationRule());
this.TextBox1.SetBinding(TextBox.TextProperty, binding);
显示错误提示
public MainWindow()
{
InitializeComponent();
Binding binding = new Binding("Value")
{
Source = slider1,
UpdateSourceTrigger = UpdateSourceTrigger.PropertyChanged,
NotifyOnValidationError = true//开启错误通知
};
binding.ValidationRules.Add(new RangValidationRule());
this.TextBox1.SetBinding(TextBox.TextProperty, binding);
//注册验证错误事件
this.TextBox1.AddHandler(Validation.ErrorEvent, new RoutedEventHandler(ValidationErrorNotify));
}
private void ValidationErrorNotify(object sender, RoutedEventArgs e)
{
var errors = Validation.GetErrors(this.TextBox1);
if (errors.Count > 0)
{
TextBlock1.Text = errors[0].ErrorContent.ToString();
}
}
多路Binding
一般我们在做注册用户功能的时候，输入密码的时候都需要再确认输入密码，比较两次输入是否一致，现在我们可以通过多路Binding来简单的实现这个功能
首先实现一个IMultiValueConverter接口功能，如果两次密码一致，提交按钮状态为可用
public class SubmitMultiBindingConverter : IMultiValueConverter
{
public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
{
return (!values.Cast<string>().Any(a => string.IsNullOrEmpty(a))/*验证所有元素非空*/ &&
values[0].ToString() == values[1].ToString())/*值1=值2*/;
}
public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
}XAML代码
<TextBox x:Name="Password" Margin="5"></TextBox>
<TextBox x:Name="Passworder" Margin="5"></TextBox>
<Button x:Name="Submit" Content="提交" Margin="10" Height="30" Width="100"></Button>后台Binding
Binding pwdBinding = new Binding("Text") { Source = Password };
Binding pwderBinding = new Binding("Text") { Source = Passworder };
MultiBinding multi = new MultiBinding() { Mode=BindingMode.OneWay};
multi.Bindings.Add(pwdBinding);
multi.Bindings.Add(pwderBinding);
multi.Converter = new SubmitMultiBindingConverter();
Submit.SetBinding(Button.IsEnabledProperty, multi);
以上就是Binding常用到的功能，下篇我将继续学习依赖属性和WPF路由事件的相关内容
