如何保存wpf事件行中的更改

Question

问题是wpf不保存更改只有在事件结束后

//code
private void button1_Click(object sender, RoutedEventArgs e)
{
    for (int ii = 0; ii <= 5; ii++)
    {
        Rectangle rectr = (Rectangle)FindName("rect" + ii);
        rectr.Fill = Brushes.Black;
        // need some thing to save changes here 
        Thread.Sleep(100);
    }
}

问题是如何保存更改

我只需要更改每个矩形的背景颜色并休眠一段时间，然后更改下一个矩形

Answer 1

试试这样的东西：

XAML文件：

<Window x:Class="RectangleNS.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="30" />
            <RowDefinition Height="*" />
        </Grid.RowDefinitions>
        <Button Content="Change Color" Click="Button_Click" />
        <StackPanel Grid.Row="1" >
            <Rectangle Name="rect1" Fill="Red" Height="50" />
            <Rectangle Name="rect2" Fill="Yellow" Height="50" />
            <Rectangle Name="rect3" Fill="Green" Height="50" />
            <Rectangle Name="rect4" Fill="AliceBlue" Height="50" />
            <Rectangle Name="rect5" Fill="DarkTurquoise" Height="50" />
        </StackPanel>        
    </Grid>
</Window>

代码隐藏文件：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
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.ComponentModel;
using System.Threading;
namespace RectangleNS
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }
        private void Button_Click(object sender, RoutedEventArgs e)
        {
            BackgroundWorker bw = new BackgroundWorker();
            Grid grid = (Grid)(sender as Button).Parent;
            bw.DoWork += (o, ee) => 
            {
                for (int i = 1; i <= 5; i++)
                {
                    Rectangle rectr = null;
                    Application.Current.Dispatcher.Invoke((Action)(() => { rectr = VTHelper.FindVisualChildByName<Rectangle>(grid, "rect" + i); }));
                    Application.Current.Dispatcher.Invoke((Action)(() => { rectr.Fill = Brushes.Black; }));                 
                    Thread.Sleep(100);
                } 
            };
            bw.RunWorkerAsync();
        }
    }
    public static class VTHelper
    {
        public static T FindVisualChildByName<T>(DependencyObject parent, string name) where T : DependencyObject
        {
            for (int i = 0; i < VisualTreeHelper.GetChildrenCount(parent); i++)
            {
                var child = VisualTreeHelper.GetChild(parent, i);
                string controlName = child.GetValue(Control.NameProperty) as string;
                if (controlName == name)
                {
                    return child as T;
                }
                else
                {
                    T result = FindVisualChildByName<T>(child, name);
                    if (result != null)
                        return result;
                }
            }
            return null;
        }
    }
}

Answer 2

Button_Click由UI线程调用，您不应该在其中做任何需要超过几毫秒的事情，让它休眠100毫秒。在此期间不会处理消息，您的接口没有响应，并且您的应用程序被系统视为"挂起"。

因此，long processing task should be handled by another thread。用这个替换你的代码，它应该对你有用-

for (int ii = 0; ii <= 5; ii++)
            {
                BackgroundWorker backgroundWorker = new BackgroundWorker();
                backgroundWorker.DoWork += (s, args) =>
                    {
                        args.Result = (int)args.Argument;
                        Thread.Sleep(100);
                    };
                backgroundWorker.RunWorkerCompleted += (s, args) =>
                {
                    int value = (int)args.Result;
                    Rectangle rectr = (Rectangle)FindName("rect" + value);
                    rectr.Fill = Brushes.Black;
                };
                backgroundWorker.RunWorkerAsync(ii);
            }