原文: WPF入門:資料綁定
上一篇我們将 XAML 大概做了個了解 ,這篇将繼續學習WPF資料綁定的相關内容
資料源與控件的Binding
Binding
作為資料傳送UI的通道,通過
INotityPropertyChanged
接口的
PropertyChanged
事件通知
Binding
資料屬性發生改變
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;
}
通過Binding關聯UI控件元素
this.txtOfProduct.SetBinding(TextBox.TextProperty, new Binding() { Path = new PropertyPath("Name"), Source = p });
控件之間的Binding
<TextBox x:Name="TextBox1" Text="{Binding ElementName=slider1,Path=Value,Mode=OneWay}"></TextBox>
<Slider x:Name="slider1" Margin="5"></Slider>
我們也可以通過背景C#代碼實作
TextBox1.SetBinding(TextBox.TextProperty, new Binding("Value") { ElementName = "slider1", Mode=BindingMode.OneWay });
統計文本字元長度
<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>
<!--擷取Text的第三個字元-->
<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>
當使用一個集合或者
DataView
作為
Binding
源時,如果我們想把它的預設元素作為Path來使用
List<string> names = new List<string>() { "張三", "李四", "王五" };
//張三
this.TextBox1.SetBinding(TextBox.TextProperty, new Binding("/") { Source = names });
//“張三”字元串的長度
this.TextBox2.SetBinding(TextBox.TextProperty, new Binding("/Length") { Source = names,Mode=BindingMode.OneWay});
//擷取“張三”字元串中的第1個字元
this.TextBox3.SetBinding(TextBox.TextProperty, new Binding("/[0]") { Source = names, Mode = BindingMode.OneWay });
如果集合中嵌套集合,我們依然可以通過多級"/"文法把子集作為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入門手冊
</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技術入門" });
沒有Path和Source,Binding可以通過DataContext擷取資料
<StackPanel.DataContext>
<sys:String>
WPF入門手冊
</sys:String>
</StackPanel.DataContext>
<TextBox x:Name="TextBox1" Margin="5" Text="{Binding Mode=OneWay}" ></TextBox>
選中ListBox元素顯示對應的屬性的一個例子
<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="廈門" },
new City() { Id=5,Name="廣州" }
};
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
當
Binding
有明确的資料源的時,我們可以通過
Soure
或
ElementName
指派辦法關聯
Binding
,但有事我們不知道
Soure
對象的名字是什麼,卻知道它與作為
Binding
目标對象的UI元素布局上的相對關系,通過
RelativeSourceMode
枚舉設定關聯的對象關系
<Grid x:Name="g1">
<StackPanel x:Name="s1">
<DockPanel x:Name="d1">
<TextBox x:Name="TextBox1" Margin="5" ></TextBox>
</DockPanel>
</StackPanel>
</Grid>
背景代碼處理
RelativeSource rs = new RelativeSource(RelativeSourceMode.FindAncestor)
{
AncestorLevel = 1,
AncestorType = typeof(StackPanel)
};
//将StackPanel的Name s1賦給了TextBox1的Text
TextBox1.SetBinding(TextBox.TextProperty, new Binding("Name") { RelativeSource = rs });
也可以通過XAML的方式指派
<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資料驗證
Binding
的
ValidationRules
屬性的類型為
Collection<ValidationRule>
。通過實作
Validate
方法傳回給
ValidationResult
對象,并設定
IsVaild
屬性,
ErrorContent
屬性可以接受一個字元串。
public class RangValidationRule : ValidationRule
{
//驗證資料
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, "資料錯誤");
}
}
<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);
顯示錯誤提示
public MainWindow()
{
InitializeComponent();
Binding binding = new Binding("Value")
{
Source = slider1,
UpdateSourceTrigger = UpdateSourceTrigger.PropertyChanged,
NotifyOnValidationError = true//開啟錯誤通知
};
binding.ValidationRules.Add(new RangValidationRule());
this.TextBox1.SetBinding(TextBox.TextProperty, binding);
//注冊驗證錯誤事件
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
一般我們在做注冊使用者功能的時候,輸入密碼的時候都需要再确認輸入密碼,比較兩次輸入是否一緻,現在我們可以通過多路Binding來簡單的實作這個功能
首先實作一個
IMultiValueConverter
接口功能,如果兩次密碼一緻,送出按鈕狀态為可用
public class SubmitMultiBindingConverter : IMultiValueConverter
{
public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
{
return (!values.Cast<string>().Any(a => string.IsNullOrEmpty(a))/*驗證所有元素非空*/ &&
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代碼
<TextBox x:Name="Password" Margin="5"></TextBox>
<TextBox x:Name="Passworder" Margin="5"></TextBox>
<Button x:Name="Submit" Content="送出" Margin="10" Height="30" Width="100"></Button>
背景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,下篇我将繼續學習依賴屬性和WPF路由事件的相關内容