c# - 如何保存 wpf 事件行中的更改

Question

问题是 wpf 不保存更改仅在事件结束后

//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

尝试这样的事情：

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，你不应该做任何需要超过几毫秒的事情，让它休眠 100 毫秒。在那段时间内没有处理消息，您的界面没有响应，并且您的应用程序被系统视为“挂起”。

所以，那个long processing task should be handled by another thread。用这个替换你的代码，它应该适合你 -

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);
            }