广西网站开发,重庆绝美的十大冷门景点,做ug图纸的网站,wordpress二维码动态图片大小样式提供了基本的格式化能力#xff0c;但它们不能消除到目前为止看到的列表的最重要的局限性#xff1a;不管如何修改ListBoxItem#xff0c;它都只是ListBoxItem#xff0c;而不是功能更强大的元素组合。并且因为每个ListBoxItem只支持单个绑定字段#xff0c;所以不可能…样式提供了基本的格式化能力但它们不能消除到目前为止看到的列表的最重要的局限性不管如何修改ListBoxItem它都只是ListBoxItem而不是功能更强大的元素组合。并且因为每个ListBoxItem只支持单个绑定字段所以不可能实现包含多个字段或图像的富列表。
然而WPF另有一个工具可突破这个相当大的限制并允许组合使用来自绑定对象的多个属性并以特定的方式排列它们或显示比简单字符串更高级的可视化表示。这个工具就是数据模板。
数据模板是一块定义如何显示绑定的数据对象的XAML标记。有两种类型的控件支持数据模板
内容控件 通过ContentTemplate属性支持数据模板。内容模板用于显示任何放置在Content属性中的内容。
列表控件继承自ItemsControl类的控件 通过ItemsTemplate属性支持数据模板。这个模板用于显示作为ItemsSource提供的集合中的每个项或来自DataTable的每一行。
基于列表的模板特性实际上以内容控件模板为基础这是因为列表中的每个项均由内容控件封装。数据模板是一块普通的XAML标记。与其他XAML标记一样数据模板可以包含任意元素的组合还应当包含一个或多个数据绑定表达式从而提取希望显示的信息。
分离和重用模板
数据模板可以写在应用模板控件标签下也可以放在资源内作为公共资源以便复用。放在资源标签内时可以指定模板的Key并在应用控件里面通过Key关联模板与常规的资源没什么两样也可以指定DataType属性会自动应用于绑定与DataType指定的数据类型相同的控件。
DataTemplate x:KeyhighlightTemplate DataType{x:Type local:Order} Grid Margin0 Background{Binding RelativeSource{RelativeSource ModeFindAncestor, AncestorType{x:Type ListBoxItem} }, PathBackground}Border Margin5 BorderThickness1 BorderBrushSteelBlue BackgroundLightYellow CornerRadius4Grid Margin3Grid.RowDefinitionsRowDefinition/RowDefinitionRowDefinition/RowDefinitionRowDefinition/RowDefinition/Grid.RowDefinitionsTextBlock Grid.Row0 FontWeightBold Text{Binding PathPrice} /TextBlock Grid.Row1 FontWeightBold Text{Binding PathVolume} /TextBlock Grid.Row2 FontStyleItalic HorizontalAlignmentRight*** Great for vacations ***/TextBlock/Grid/Border/Grid
/DataTemplate
改变模板
可以通过几种方式为同一个列表使用不同的模板
数据触发器 可根据绑定的数据对象中的属性值使用触发器修改模板中的属性。
值转换器 实现了IValueConverter接口的类能够将值从绑定的对象转换为可用于设置模板中与格式化相关的属性的值。
模板选择器 模板选择器检查绑定的数据对象并在几个不同模板之间进行选择。
数据触发器提供了最简单的方法。基本技术是根据数据项中的某个属性设置模板中某个元素的某个属性。这种方法非常有用但是不能改变与模板相关的复杂细节只能修改模板或容器元素中的单个属性。此外触发器只能测试是否相等不支持更复杂的比较条件。
DataTemplate DataType{x:Type local:Order} DataTemplate.TriggersDataTrigger Binding{Binding PathPrice} Value1000Setter PropertyListBoxItem.Foreground ValueRed/SetterSetter PropertyListBoxItem.FontStyle ValueItalic/Setter/DataTrigger/DataTemplate.Triggers
/DataTemplate
值转换器在数据转换里面介绍过了通过Converter属性设置可以根据绑定的对象调整自身。
Image Grid.Column1 Grid.RowSpan2 Source{Binding PathImage, Converter{StaticResource ImagePathConverter}}/Image
模板选择器是一种更强大的工具可以根据不同的条件应用完全不同的模板。模板选择器继承自DataTemplateSelector需要实现 SelectTemplate() 函数返回应用的DataTemplate。
public class SingleCriteriaHighlightTemplateSelector : DataTemplateSelector
{public System.Windows.DataTemplate DefaultTemplate { get; set; }public System.Windows.DataTemplate HighlightTemplate { get; set; }public override System.Windows.DataTemplate SelectTemplate(object item, DependencyObject container){Order order (Order)item;if (order.Price 10000){return HighlightTemplate;}else{return DefaultTemplate;}}
}
WindowWindow.ResourcesDataTemplate x:KeydefaultTemplate DataType{x:Type local:Order} DataTemplate.TriggersDataTrigger Binding{Binding PathPrice} Value1000Setter PropertyListBoxItem.Foreground ValueRed/Setter/DataTrigger/DataTemplate.TriggersGrid Margin0 BackgroundWhiteBorder Margin5 BorderThickness1 BorderBrushSteelBlueBackground{Binding RelativeSource{RelativeSource ModeFindAncestor, AncestorType{x:Type ListBoxItem} }, PathBackground} CornerRadius4Grid Margin3Grid.ColumnDefinitionsColumnDefinition/ColumnDefinition//Grid.ColumnDefinitionsGrid.RowDefinitionsRowDefinition/RowDefinitionRowDefinition/RowDefinitionRowDefinition/RowDefinition/Grid.RowDefinitionsTextBlock FontWeightBold Text{Binding PathPrice}/TextBlockTextBlock Grid.Row1 Text{Binding PathVolume}/TextBlockImage Grid.Column1 Grid.RowSpan2 Source{Binding PathImage, Converter{StaticResource ImagePathConverter}}/Image/Grid/Border/Grid/DataTemplateDataTemplate x:KeyhighlightTemplate DataType{x:Type local:Order} Grid Margin0 Background{Binding RelativeSource{RelativeSource ModeFindAncestor, AncestorType{x:Type ListBoxItem} }, PathBackground}Border Margin5 BorderThickness1 BorderBrushSteelBlue BackgroundLightYellow CornerRadius4Grid Margin3Grid.RowDefinitionsRowDefinition/RowDefinitionRowDefinition/RowDefinitionRowDefinition/RowDefinition/Grid.RowDefinitionsTextBlock Grid.Row0 FontWeightBold Text{Binding PathPrice} /TextBlock Grid.Row1 FontWeightBold Text{Binding PathVolume} /TextBlock Grid.Row2 FontStyleItalic HorizontalAlignmentRight*** Great for vacations ***/TextBlock/Grid/Border/Grid/DataTemplate/Window.ResourcesListBox Grid.Row0 Grid.Column1 ItemsSource{Binding PathOrders} ItemContainerStyle{StaticResource listBoxItemStyle} HorizontalContentAlignmentStretchListBox.ItemTemplateSelectorlocal:SingleCriteriaHighlightTemplateSelector DefaultTemplate{StaticResource defaultTemplate} HighlightTemplate{StaticResource highlightTemplate}//ListBox.ItemTemplateSelector/ListBox
/Window
完整代码如下
MainWindow.xaml
Window x:ClassDataTemplate.MainWindowxmlnshttp://schemas.microsoft.com/winfx/2006/xaml/presentationxmlns:xhttp://schemas.microsoft.com/winfx/2006/xamlxmlns:dhttp://schemas.microsoft.com/expression/blend/2008xmlns:mchttp://schemas.openxmlformats.org/markup-compatibility/2006xmlns:localclr-namespace:DataTemplatemc:IgnorabledTitleMainWindow Height450 Width800Window.Resourceslocal:ImagePathConverter x:KeyImagePathConverter/local:ImagePathConverterDataTemplate DataType{x:Type local:Order} DataTemplate.TriggersDataTrigger Binding{Binding PathPrice} Value1000Setter PropertyListBoxItem.Foreground ValueRed/SetterSetter PropertyListBoxItem.FontStyle ValueItalic/Setter/DataTrigger/DataTemplate.TriggersGrid Margin0 Border Margin5 BorderThickness1 BorderBrushSteelBlueBackground{Binding RelativeSource{RelativeSource ModeFindAncestor, AncestorType{x:Type ListBoxItem} }, PathBackground} CornerRadius4Grid Margin3Grid.ColumnDefinitionsColumnDefinition/ColumnDefinition//Grid.ColumnDefinitionsGrid.RowDefinitionsRowDefinition/RowDefinitionRowDefinition/RowDefinitionRowDefinition/RowDefinition/Grid.RowDefinitionsTextBlock FontWeightBold Text{Binding PathPrice}/TextBlockTextBlock Grid.Row1 Text{Binding PathVolume}/TextBlockImage Grid.Column1 Grid.RowSpan2 Source{Binding PathImage, Converter{StaticResource ImagePathConverter}}/Image/Grid/Border/Grid/DataTemplateDataTemplate x:KeydefaultTemplate DataType{x:Type local:Order} DataTemplate.TriggersDataTrigger Binding{Binding PathPrice} Value1000Setter PropertyListBoxItem.Foreground ValueRed/Setter/DataTrigger/DataTemplate.TriggersGrid Margin0 BackgroundWhiteBorder Margin5 BorderThickness1 BorderBrushSteelBlueBackground{Binding RelativeSource{RelativeSource ModeFindAncestor, AncestorType{x:Type ListBoxItem} }, PathBackground} CornerRadius4Grid Margin3Grid.ColumnDefinitionsColumnDefinition/ColumnDefinition//Grid.ColumnDefinitionsGrid.RowDefinitionsRowDefinition/RowDefinitionRowDefinition/RowDefinitionRowDefinition/RowDefinition/Grid.RowDefinitionsTextBlock FontWeightBold Text{Binding PathPrice}/TextBlockTextBlock Grid.Row1 Text{Binding PathVolume}/TextBlockImage Grid.Column1 Grid.RowSpan2 Source{Binding PathImage, Converter{StaticResource ImagePathConverter}}/Image/Grid/Border/Grid/DataTemplateDataTemplate x:KeyhighlightTemplate DataType{x:Type local:Order} Grid Margin0 Background{Binding RelativeSource{RelativeSource ModeFindAncestor, AncestorType{x:Type ListBoxItem} }, PathBackground}Border Margin5 BorderThickness1 BorderBrushSteelBlue BackgroundLightYellow CornerRadius4Grid Margin3Grid.RowDefinitionsRowDefinition/RowDefinitionRowDefinition/RowDefinitionRowDefinition/RowDefinition/Grid.RowDefinitionsTextBlock Grid.Row0 FontWeightBold Text{Binding PathPrice} /TextBlock Grid.Row1 FontWeightBold Text{Binding PathVolume} /TextBlock Grid.Row2 FontStyleItalic HorizontalAlignmentRight*** Great for vacations ***/TextBlock/Grid/Border/Grid/DataTemplateStyle x:KeylistBoxItemStyle TargetType{x:Type ListBoxItem}Setter PropertyControl.Padding Value0/SetterStyle.TriggersTrigger PropertyListBoxItem.IsSelected ValueTrueSetter PropertyListBoxItem.Background ValueDarkRed //Trigger/Style.Triggers/Style/Window.ResourcesGrid NamemyGrid Grid.ColumnDefinitionsColumnDefinition /ColumnDefinition //Grid.ColumnDefinitionsGrid.RowDefinitionsRowDefinition /RowDefinition //Grid.RowDefinitionsListBox Grid.Row0 Grid.Column0 ItemsSource{Binding PathOrders} ItemContainerStyle{StaticResource listBoxItemStyle} HorizontalContentAlignmentStretch/ListBox Grid.Row0 Grid.Column1 ItemsSource{Binding PathOrders} ItemContainerStyle{StaticResource listBoxItemStyle} HorizontalContentAlignmentStretchListBox.ItemTemplateSelectorlocal:SingleCriteriaHighlightTemplateSelector DefaultTemplate{StaticResource defaultTemplate} HighlightTemplate{StaticResource highlightTemplate}//ListBox.ItemTemplateSelector/ListBoxListView Grid.Row1 Grid.Column0 ItemsSource{Binding PathOrders} HorizontalContentAlignmentStretch /ListView/Grid
/WindowMainWindow.xaml.cs
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.IO;
using System.Reflection;
using System.Runtime.CompilerServices;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Media.Imaging;namespace DataTemplate;public class ViewModelBase : INotifyPropertyChanged
{public event PropertyChangedEventHandler? PropertyChanged;protected virtual void OnPropertyChanged([CallerMemberName] string? propertyName null){PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));}protected virtual bool SetPropertyT(ref T member, T value, [CallerMemberName] string? propertyName null){if (EqualityComparerT.Default.Equals(member, value)){return false;}member value;OnPropertyChanged(propertyName);return true;}
}
public class Order : ViewModelBase
{public decimal price 0;public decimal Price { get price; set SetProperty(ref price, value); }public int volume 0;public int Volume { get volume; set SetProperty(ref volume, value); }public DateTime orderDate DateTime.Now;public DateTime OrderDate { get orderDate; set SetProperty(ref orderDate, value); }public string image string.Empty;public string Image { get image; set SetProperty(ref image, value); }
}
public class ImagePathConverter : IValueConverter
{private string imageDirectory Directory.GetCurrentDirectory();public string ImageDirectory{get { return imageDirectory; }set { imageDirectory value; }}public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture){string imagePath Path.Combine(ImageDirectory, (string)value);return new BitmapImage(new Uri(imagePath));}public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture){throw new NotSupportedException(The method or operation is not implemented.);}
}public class SingleCriteriaHighlightTemplateSelector : DataTemplateSelector
{public System.Windows.DataTemplate DefaultTemplate { get; set; }public System.Windows.DataTemplate HighlightTemplate { get; set; }public override System.Windows.DataTemplate SelectTemplate(object item, DependencyObject container){Order order (Order)item;if (order.Price 10000){return HighlightTemplate;}else{return DefaultTemplate;}}
}public partial class MainWindow : Window
{public MainWindow(){InitializeComponent();myGrid.DataContext this;Order order1 new Order();Order order2 new Order();Order order3 new Order();Order order4 new Order();order1.Price 100;order1.Volume 10;order1.Image image1.gif;order2.Price 1000;order2.Volume 100;order2.Image image2.gif;order3.Price 10000;order3.Volume 1000;order3.Image image3.gif;order4.Price 100000;order4.Volume 10000;order4.Image image4.gif;Orders.Add(order1);Orders.Add(order2);Orders.Add(order3);Orders.Add(order4);}public ObservableCollectionOrder Orders { get; set; } new();
}
