public class DelCommand : ICommand { public event EventHandler CanExecuteChanged { add { CommandManager.RequerySuggested += value; } remove { CommandManager.RequerySuggested -= value; } } private Action<object> execute; private Predicate<object> canExecute; public DelCommand(Action<object> executeValue, Predicate<object> canExecuteValue = null) { execute = executeValue; canExecute = canExecuteValue; } public bool CanExecute(object parameter) { if (canExecute == null) { return true; } return canExecute(parameter); } public void Execute(object parameter) { execute(parameter); } } public DelCommand ExportCommand { get; set; } ExportCommand = new DelCommand(ExportCommandExecuted); private void ExportCommandExecuted(object obj) { var dg = obj as DataGrid; if (dg != null) { var items = dg.ItemsSource.Cast<Book>()?.ToList(); if (items != null && items.Any()) { string fileName = $"{DateTime.Now.ToString("yyyyMMddHHmmssffff")}_{Guid.NewGuid().ToString("N")}.json"; var msgBoxResult = MessageBox.Show($"Are you sure to export to \n{fileName}?", "Export", MessageBoxButton.YesNo, MessageBoxImage.Question, MessageBoxResult.Yes); if(msgBoxResult == MessageBoxResult.Yes) { var fStream=File.Create(fileName); fStream.SerializeBigCollectionSerializer<Book>(BooksCollection); MessageBox.Show($"Export to \n{fileName}", "Export"); } } } }
//xaml <Window x:Class="WpfApp26.MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:behavior="http://schemas.microsoft.com/xaml/behaviors" xmlns:local="clr-namespace:WpfApp26" mc:Ignorable="d" WindowState="Maximized" Title="MainWindow" Height="450" Width="800"> <Window.DataContext> <local:BookVM/> </Window.DataContext> <Window.Resources> <local:SizeConverter x:Key="sizeConverter"/> <Style TargetType="{x:Type Button}" x:Key="btnStyle"> <Setter Property="Width" Value="200"/> <Setter Property="FontSize" Value="30"/> </Style> </Window.Resources> <Grid> <Grid.RowDefinitions> <RowDefinition Height="50"/> <RowDefinition/> </Grid.RowDefinitions> <ToolBar Grid.Row="0"> <Button Content="Load" Command="{Binding LoadCommand}" CommandParameter="{Binding ElementName=dg}" Style="{StaticResource btnStyle}"/> <Button Content="Clear" Command="{Binding ClearCommand}" CommandParameter="{Binding ElementName=dg}" Style="{StaticResource btnStyle}"/> <Button Content="Export" Command="{Binding ExportCommand}" CommandParameter="{Binding ElementName=dg}" Style="{StaticResource btnStyle}"/> </ToolBar> <DataGrid Grid.Row="1" x:Name="dg" ItemsSource="{Binding BooksCollection,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}" CanUserAddRows="False" AutoGenerateColumns="False" SelectionMode="Extended"> <behavior:Interaction.Triggers> <behavior:EventTrigger EventName="SelectionChanged"> <behavior:CallMethodAction MethodName="DataGrid_SelectionChanged" TargetObject="{Binding}"/> </behavior:EventTrigger> </behavior:Interaction.Triggers> <DataGrid.Columns> <DataGridTextColumn Header="Id" Binding="{Binding Id}"/> <DataGridTextColumn Header="ISBN" Binding="{Binding ISBN}"/> <DataGridTemplateColumn Header="Image"> <DataGridTemplateColumn.CellTemplate> <DataTemplate> <Border Width="{Binding ActualWidth,RelativeSource={RelativeSource Mode=FindAncestor,AncestorType={x:Type Window}}, Converter={StaticResource sizeConverter}}" Height="{Binding ActualHeight,RelativeSource={RelativeSource Mode=FindAncestor,AncestorType={x:Type Window}}, Converter={StaticResource sizeConverter}}"> <Border.Background> <ImageBrush ImageSource="{Binding ImgSource}" Stretch="Uniform" /> </Border.Background> </Border> </DataTemplate> </DataGridTemplateColumn.CellTemplate> </DataGridTemplateColumn> </DataGrid.Columns> </DataGrid> </Grid> </Window> //cs using System; using System.Collections.Generic; using System.Collections.ObjectModel; using System.ComponentModel; using System.Linq; using System.Security.Policy; using System.Text; using System.Threading.Tasks; using System.Windows; using System.Windows.Controls; using System.Windows.Data; using System.Windows.Documents; using System.Windows.Input; using System.Windows.Media; using System.Windows.Media.Imaging; using System.Windows.Navigation; using System.Windows.Shapes; using System.IO; using System.Data.SqlTypes; using System.Globalization; using Newtonsoft.Json; namespace WpfApp26 { /// <summary> /// Interaction logic for MainWindow.xaml /// </summary> public partial class MainWindow : Window { public MainWindow() { InitializeComponent(); } } public class BookVM : INotifyPropertyChanged { private List<string> imgsList { get; set; } private int imgsCount = 0; public BookVM() { InitData(); InitCommands(); } private void InitCommands() { LoadCommand = new DelCommand(LoadCommandExecuted); ClearCommand = new DelCommand(ClearCommandExecuted); ExportCommand = new DelCommand(ExportCommandExecuted); } private void ExportCommandExecuted(object obj) { var dg = obj as DataGrid; if (dg != null) { var items = dg.ItemsSource.Cast<Book>()?.ToList(); if (items != null && items.Any()) { string fileName = $"{DateTime.Now.ToString("yyyyMMddHHmmssffff")}_{Guid.NewGuid().ToString("N")}.json"; var msgBoxResult = MessageBox.Show($"Are you sure to export to \n{fileName}?", "Export", MessageBoxButton.YesNo, MessageBoxImage.Question, MessageBoxResult.Yes); if(msgBoxResult == MessageBoxResult.Yes) { var fStream=File.Create(fileName); fStream.SerializeBigCollectionSerializer<Book>(BooksCollection); MessageBox.Show($"Export to \n{fileName}", "Export"); } } } } private void ClearCommandExecuted(object obj) { var dg = obj as DataGrid; if (dg != null) { BooksCollection?.Clear(); } } private void LoadCommandExecuted(object obj) { BooksCollection?.Clear(); InitData(); } private void InitData() { var imgs = Directory.GetFiles(@"../../Images"); if (imgs != null && imgs.Any()) { imgsCount = imgs.Count(); imgsList = new List<string>(imgs); BooksCollection = new ObservableCollection<Book>(); for (int i = 0; i < 2000000; i++) { Book book = new Book() { Id = i + 1, ISBN = $"ISBN_{Guid.NewGuid().ToString("N")}", Name = $"Name_{i + 1}", Topic = $"Topic_{i + 1}", ImgUrl = $"{imgs[i % imgsCount]}", ImgSource = GetImgSource(imgs[i % imgsCount]) }; BooksCollection.Add(book); } } } private ImageSource GetImgSource(string url) { BitmapImage bmi = new BitmapImage(); bmi.BeginInit(); bmi.UriSource = new Uri(url, UriKind.RelativeOrAbsolute); bmi.EndInit(); if (bmi.CanFreeze) { bmi.Freeze(); } return bmi; } public void DataGrid_SelectionChanged(object sender, SelectionChangedEventArgs e) { var dg = e.OriginalSource as DataGrid; if (dg != null) { var items = dg.SelectedItems?.Cast<Book>().ToList(); if (items != null && items.Any()) { MessageBox.Show($"Selected {items.Count()}!\n"); } } } public event PropertyChangedEventHandler PropertyChanged; private void OnPropertyChanged(string propertyName) { var handler = PropertyChanged; if (handler != null) { handler?.Invoke(this, new PropertyChangedEventArgs(propertyName)); } } private ObservableCollection<Book> booksCollection; public ObservableCollection<Book> BooksCollection { get { if (booksCollection == null) { booksCollection = new ObservableCollection<Book>(); } return booksCollection; } set { if (booksCollection != value) { booksCollection = value; OnPropertyChanged(nameof(BooksCollection)); } } } public DelCommand LoadCommand { get; set; } public DelCommand ClearCommand { get; set; } public DelCommand ExportCommand { get; set; } } public static class BigCollectionStream { public static void SerializeBigCollectionSerializer<T>(this Stream stream,IEnumerable<T> items) { using(StreamWriter streamWriter =new StreamWriter(stream)) { var serializer = new JsonSerializer(); serializer.Formatting = Formatting.Indented; serializer.Serialize(streamWriter, items); } } } public class SizeConverter : IValueConverter { public object Convert(object value, Type targetType, object parameter, CultureInfo culture) { double d = 0; if (double.TryParse(value?.ToString(), out d)) { return d / 2; } return d; } public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture) { throw new NotImplementedException(); } } public class Book { public int Id { get; set; } public string Name { get; set; } public string Topic { get; set; } public string ImgUrl { get; set; } public string ISBN { get; set; } public ImageSource ImgSource { get; set; } } public class DelCommand : ICommand { public event EventHandler CanExecuteChanged { add { CommandManager.RequerySuggested += value; } remove { CommandManager.RequerySuggested -= value; } } private Action<object> execute; private Predicate<object> canExecute; public DelCommand(Action<object> executeValue, Predicate<object> canExecuteValue = null) { execute = executeValue; canExecute = canExecuteValue; } public bool CanExecute(object parameter) { if (canExecute == null) { return true; } return canExecute(parameter); } public void Execute(object parameter) { execute(parameter); } } }
标签:ICommand,delegatecommand,mvvm,object,System,private,new,using,public From: https://www.cnblogs.com/Fred1987/p/18523654