185 lines
6.0 KiB
Markdown
185 lines
6.0 KiB
Markdown
# 绑定方向及数据更新
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Path 绑定属性名称，Source 绑定数据源，绑定属性必须是依赖属性
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UpdateSourceTrigger 更新源触发器
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PropertyChanged LostFocus Explicit Default
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可以用控件.SetBinding(控件静态属性,new Binding("Path")){Source=xxx}
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如果绑定的集合类的属性仍然是集合，可以用'/'，将子集集合中的元素当作Path
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绑定属性可以为控件静态属性 Path=Text.Length;
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Source本身就代表数据，如字符串的时候，Path可以省略只留下Binding或Binding Path=.或Binding .；
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Binding的源类型（Source）
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- clr类型对象
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- clr集合对象：ItemsSource
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- ADO.Net数据对象 DataTable DataView，DataTable.DefaultView;
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ListView派生与ListBox，GridView继承ViewBase，ListView.View是ViewBase类型。目前ListView.View只能用GridView。
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- XmlDataProvider XML数据，TreeView Menu，XmlDataProvider.Source=new Urine(@"路径")，XPath=(要提取的节点，如/StudentList/Student);可以作为资源把xml内容放在<x:XData>标签内;
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- 依赖对象 Dependency Object 可以作为源和目标，依赖对象的依赖属性作为Path
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- 容器DataContext（上下文数据源,依赖属性），无法明确是从哪个源的属性获取数据时，它上层的DataContext会沿着UI树往下传递，直到找到源中有对应Path的属性后，将该DataContext作为自己的源
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DataContext使用场景：
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a. 当UI上的多个控件使用Binding关注同一个对象时
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b. 当Source对象不能被直接访问时，如Private，B窗口访问A窗口的控件时，将A窗口的控件作为数据源时，可以使用把控件作为窗口A的DataContext（public），暴露数据。
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- ELementName=控件名
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- RelativeSource属性相对地指定Source
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RelativeSource={RelativeSource FindAncestor,AncestorType={x:Type Grid},AncestorLevel=1},Path=Name}
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RelativeSourceMode枚举:
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FindAncestor查找父级，TemplatedParent,PreviousData;
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AncestorType父级类型，AncestorLevel层级便宜量，上一级为1，三个美剧
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- ObjectDataProvider
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```csharp
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ObjectDataProvider odp=new ObjectDataProvider()
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odp.ObjectInstance=new Class();
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odp.MethodName="方法名"
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odp.MethodParameters.Add("参数值")
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Binding bindingToArg1=new Binding("MethodParameters[0]")
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{
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Source=odp,
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BindsDirectlyToSource=true,
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UpdateSourceTrigger=UpdateSourceTrigger.PropertyChanged
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}
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Binding bindingToResult=new Binding("."){Source=odp}
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//关联
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控件.SetBinding(控件静态属性,bindingToArg1)
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控件.SetBinding(控件静态属性,bindingToResult)
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```
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- Linq检索得到的数据对象
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```csharp
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XDocument xdoc=XDocument.Load();
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from element in xdoc.Descendants("节点名称")
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where element.Attribute("特性").Value....
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select new Class()//转实例
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{
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}
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```
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# 数据校验
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```csharp
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public class RangeValidationRule:ValidationRule
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{
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public override ValidationResult Validate(object value, System.Globalization.CultureInfo cultureInfo)
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{
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double d=0;
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if (double.TryParse(value.ToString(),out d))
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{
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if(d>=0&&d<=100>)
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{
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return new ValidationResult(true,null);
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}
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}
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return new ValidationResult(false,"Validation Failed");
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}
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}
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public Window(){
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InitializeComponent();
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Binding binding=new Binding("Value"){Source=this.slider}
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binding.UpdateSourceTrigger=UpdateSourceTrigger.PropertyChanged
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RangeValidationRUle rvr=new RangeValidationRUle()
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rvr.ValidatesOnTargetUpdated=true//校验源数据
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binding.ValudationRules.Add(rvr)
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binding.NotifyOnValidationError=true;//校验错误，发出通知
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this.textBox.SetBinding(TextBox.TextProperty,binding)
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}
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void ValidationError(object sender,RoutedEventArgs e){
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if(Validation.GetErrors(this.textBox).Count>0)
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{
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this.textBox.ToolTip=Validation.GetErrors(this.textBox)[0].ErrorContent.ToString()
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}
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}
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```
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数据转换
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```csharp
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public class CategoryToSourceConverter:IValueConverter
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{
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//源=>目标（控件）
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public object Converter(object value,Type targetType,object parameter,CultureInfo culture)
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{
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Category c=(Category)value;
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switch(c)
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{
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case Category.Bomber:
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return @"Icon/Bomber.png";
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case Category.Fighter:
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return @"Icon/Fighter.png";
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Default:
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return null;
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}
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}
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public object ConvertBack(object value,Type targetType,object parameter,CultureInfo culture)
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{
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throw new NotImplementedException();
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}
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}
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public class StateToNullableBoolConverter:IValueConverter
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{
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//源=>目标（控件）
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public object Converter(object value,Type targetType,object parameter,CultureInfo culture)
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{
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State s=(State)value;
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switch(s)
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{
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case State.Locked:
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return false;
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case State.Available:
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return true;
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default:
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return null;
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}
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}
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public object ConvertBack(object value,Type targetType,object parameter,CultureInfo culture)
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{
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bool? nb=(bool?)value
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switch(nb)
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{
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case false:
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return State.Locked;
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case true:
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return State.Available;
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default:
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return State.Unknown;
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}
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}
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}
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```
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```xaml
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<Window.Resources>
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<local：CategoryToSourceConverter x:Key="cts"/>
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<local：StateToNullableConverter x:Key="stnb"/>
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</Window.Resources>
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<ListBox.ItemTemplate>
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<DataTemplate>
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<StackPanel Orientation="Horizontal">
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<Image Source="{Binding Path=Category,Converter={StaticResource cts}}">//绑定
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<CheckBox IsThreeState="True" IsCheck="{Binding Path=State,Converter={StaticResource stnb}}">
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</StackPanel>
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</DataTemplate>
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</ListBox.ItemTemplate>
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```
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MultBinding使用场景一：需要通过多个对象属性综合进行判断时;
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Binding b1=new Binding("Text){Source=this.textBox1}
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Binding b1=new Binding("Text){Source=this.textBox2}
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MulitBinding mb=new MulitBinding(){Mode=Binding.OneWay}
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mb.Bindings.Add(b1)//注意绑定顺序
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mb.Bindings.Add(b2)
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mb.Converter=LoginMultiBindingConverter()
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this.btn.SetBinding(Button.IsEnabledProperty,mb)
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public class LogoMultiBindingConverter: IMultiValueConverter
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{
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}
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