网站建设方案计划书人员规划,网站设计_网站建设_手机网站建设,旅游景区网络推广方案,wordpress在评论框中加文字在基本绑定中#xff0c;信息从源到目标的传递过程中没有任何变化。这看起来是符合逻辑的#xff0c;但我们并不总是希望出现这种行为。通常#xff0c;数据源使用的是低级表达方式#xff0c;我们可能不希望直接在用户界面使用这种低级表达方式。WPF提供了两个工具#x…在基本绑定中信息从源到目标的传递过程中没有任何变化。这看起来是符合逻辑的但我们并不总是希望出现这种行为。通常数据源使用的是低级表达方式我们可能不希望直接在用户界面使用这种低级表达方式。WPF提供了两个工具来进行数据转换
字符串格式化
通过设置 Binding.StringFormat 属性对文本形式的数据进行转换——例如包含日期和数字的字符串。
值转换器
该功能更强大使用该功能可以将任意类型的源数据转换为任意类型的对象表示然后可以传递到关联的控件。
使用StringFormat属性
TextBlock Grid.Row0 Grid.Column0 Text{Binding PathPrice, StringFormatConvertDirectly:{0:C}}/TextBlock
TextBox Grid.Row0 Grid.Column1 Text{Binding PathPrice, StringFormat{}{0:C}}/TextBox
TextBox Grid.Row2 Grid.Column1 Text{Binding PathOrderDate, StringFormat{}{0:s}}/TextBox
可以看到后面两个StringFormat属性以花括号 {} 开头完整值是 {}{0:C}而不是 {0:C}第一个则只有 {0:C}这是因为在StringFormat 值以花括号开头时需要 {} 转义序列。
使用值转换器
为创建子转换器需要执行以下四个步骤
1、创建一个实现IValueConverter接口的类
2、为该类声明添加ValueConversion特性并指定目标数据类型
3、实现Convert()方法该方法将数据从原来的格式转换为显示的格式
4、实现ConvertBack()方法该方法执行反向变换将值从显示格式转换为原格式
[ValueConversion(typeof(decimal), typeof(string))]
public class PriceConverter : IValueConverter
{public object Convert(object value, Type targetType, object parameter, CultureInfo culture){decimal price (decimal)value;return price.ToString(C, culture);}public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture){string price (string)value;if (decimal.TryParse(price, System.Globalization.NumberStyles.Any, culture, out decimal result)){return result;}return value;}
}
要使用这个转换器可以将其添加到页面的资源下然后使用 Binding.Converter 指定。
WindowWindow.Resourceslocal:PriceConverter x:KeypriceConverter/local:PriceToBackgroundConverter x:KeypriceToBackgroundConverter MinimumPriceToHighlight100 DefaultBrush{x:Null} HighlightBrushOrange/local:ImagePathConverter x:KeyimagePathConverter/local:MultiValueConverter x:KeymultiValueConverter//Window.ResourcesTextBox Text{Binding PathPrice, Converter{StaticResource priceConverter}}/TextBox
/Window
多重绑定
可以将多个字段绑定到同一个输出控件可以通过 StringFormat 或 MultiBinding.Converter 来格式化数据。多重绑定的值转换器需要实现的接口是 IMultiValueConverter与 IValueConverter 接口比较类似只是转换函数的第一个参数改成了数组形式。 TextBlock Grid.Row4 Grid.Column0TextBlock.TextMultiBinding StringFormat{}{0}, {1}, {2}Binding PathPrice/Binding PathOrderDate/Binding PathVolume//MultiBinding/TextBlock.Text/TextBlockTextBlock Grid.Row5 Grid.Column0TextBlock.TextMultiBinding Converter{StaticResource multiValueConverter}Binding PathPrice/Binding PathVolume//MultiBinding/TextBlock.Text/TextBlock
public class MultiValueConverter : IMultiValueConverter
{public object Convert(object[] values, Type targetType, object parameter, System.Globalization.CultureInfo culture){decimal price (decimal)values[0];int volume (int)values[1];return (price * volume).ToString(C);}public object[] ConvertBack(object value, Type[] targetTypes, object parameter, System.Globalization.CultureInfo culture){throw new NotSupportedException();}
}
完整代码如下
MainWindow.xaml
Window x:ClassTestDataConverter.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:TestDataConvertermc:IgnorabledTitleMainWindow Height450 Width800Window.Resourceslocal:PriceConverter x:KeypriceConverter/local:PriceToBackgroundConverter x:KeypriceToBackgroundConverter MinimumPriceToHighlight100 DefaultBrush{x:Null} HighlightBrushOrange/local:ImagePathConverter x:KeyimagePathConverter/local:MultiValueConverter x:KeymultiValueConverter//Window.ResourcesGrid NamemyGrid Background{Binding PathPrice, Converter{StaticResource priceToBackgroundConverter}}Grid.ColumnDefinitionsColumnDefinition/ColumnDefinition//Grid.ColumnDefinitionsGrid.RowDefinitionsRowDefinition/RowDefinition/RowDefinition/RowDefinition/RowDefinition/RowDefinition//Grid.RowDefinitionsTextBlock Grid.Row0 Grid.Column0 Text{Binding PathPrice, StringFormatConvertDirectly:{0:C}}/TextBlockTextBox Grid.Row0 Grid.Column1 Text{Binding PathPrice, StringFormat{}{0:C}}/TextBoxTextBlock Grid.Row1 Grid.Column0ConvertWithConverter:/TextBlockTextBox Grid.Row1 Grid.Column1 Text{Binding PathPrice, Converter{StaticResource priceConverter}}/TextBoxTextBlock Grid.Row2 Grid.Column0ConvertDateTime:/TextBlockTextBox Grid.Row2 Grid.Column1 Text{Binding PathOrderDate, StringFormat{}{0:s}}/TextBoxTextBlock Grid.Row3 Grid.Column0ConvertImagePath:/TextBlockImage Grid.Row3 Grid.Column1 StretchNone HorizontalAlignmentLeft Source{Binding PathImage, Converter{StaticResource imagePathConverter}}/ImageTextBlock Grid.Row4 Grid.Column0TextBlock.TextMultiBinding StringFormat{}{0}, {1}, {2}Binding PathPrice/Binding PathOrderDate/Binding PathVolume//MultiBinding/TextBlock.Text/TextBlockTextBlock Grid.Row5 Grid.Column0TextBlock.TextMultiBinding Converter{StaticResource multiValueConverter}Binding PathPrice/Binding PathVolume//MultiBinding/TextBlock.Text/TextBlock/Grid
/WindowMainWindow.xaml.cs
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Globalization;
using System.IO;
using System.Runtime.CompilerServices;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Media;
using System.Windows.Media.Imaging;namespace TestDataConverter;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); }
}
[ValueConversion(typeof(decimal), typeof(string))]
public class PriceConverter : IValueConverter
{public object Convert(object value, Type targetType, object parameter, CultureInfo culture){decimal price (decimal)value;return price.ToString(C, culture);}public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture){string price (string)value;if (decimal.TryParse(price, System.Globalization.NumberStyles.Any, culture, out decimal result)){return result;}return value;}
}
[ValueConversion(typeof(decimal), typeof(Brush))]
public class PriceToBackgroundConverter : IValueConverter
{public decimal MinimumPriceToHighlight { get; set; }public Brush HighlightBrush { get; set; }public Brush DefaultBrush { get; set; }public object Convert(object value, Type targetType, object parameter,System.Globalization.CultureInfo culture){decimal price (decimal)value;if (price MinimumPriceToHighlight)return HighlightBrush;elsereturn DefaultBrush;}public object ConvertBack(object value, Type targetType, object parameter,System.Globalization.CultureInfo culture){throw new NotSupportedException();}
}
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 MultiValueConverter : IMultiValueConverter
{public object Convert(object[] values, Type targetType, object parameter, System.Globalization.CultureInfo culture){decimal price (decimal)values[0];int volume (int)values[1];return (price * volume).ToString(C);}public object[] ConvertBack(object value, Type[] targetTypes, object parameter, System.Globalization.CultureInfo culture){throw new NotSupportedException();}
}public partial class MainWindow : Window
{public MainWindow(){InitializeComponent();myGrid.DataContext Order;Order.Price 100;Order.Volume 10;Order.OrderDate DateTime.Now;Order.Image image1.gif;}public Order Order new Order();private void Button_Click(object sender, RoutedEventArgs e){Console.WriteLine();}
}
