c＃wpf窗口不透明度更改错误

Question

I'm working on ac# project with WPF but I've a problem and this makes me crazy :) Here is the problem. I'm trying to change new window's opacity with timer. But when I run the project, "this.Opacity += .1;" code throws an exception like "Invalid operation etc..." I'm opening a window from MainWindow.cs file with this code:

private void MenuItemArchiveClick(object sender, RoutedEventArgs e)
    {
        var archiveWindow = new ArchiveWindow();
        var screenSize = System.Windows.Forms.Screen.PrimaryScreen.Bounds;
        archiveWindow.Width = (screenSize.Width * 95) / 100;
        archiveWindow.Height = (screenSize.Height * 90) / 100;
        archiveWindow.WindowStartupLocation = WindowStartupLocation.CenterScreen;
        archiveWindow.Margin = new Thickness(0, 10, 0, 0);
        archiveWindow.AllowsTransparency = true;
        archiveWindow.Opacity = 0.1;
        archiveWindow.Topmost = true;
        archiveWindow.Show();
    }

My ArchiveWindow code is,

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Timers;
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.Shapes;

namespace POCentury
{
    /// <summary>
    /// Interaction logic for ArchiveWindow.xaml
    /// </summary>
    public partial class ArchiveWindow : Window
    {
        Timer timer1 = new Timer();

        public ArchiveWindow()
        {
            InitializeComponent();
            timer1.Interval = 1 * 1000;
            timer1.Elapsed += new ElapsedEventHandler(opacityChange);
            timer1.Enabled = true;
            timer1.AutoReset = false;
            timer1.Start();

        }
        private void opacityChange(object sender, EventArgs a)
        {
            if (this.Opacity == 1)
            {
                timer1.Stop();
            }
            else
            {
                this.Opacity += .1;
            }

        }
        private void ArchiveWindowClose()
        {
            timer1.Stop();
            this.Close();
        }
        private void btnArchiveWindowClose(object sender, RoutedEventArgs e)
        {
            ArchiveWindowClose();
        }

        private void imgPatternClick(object sender, MouseButtonEventArgs e)
        {
            MessageBox.Show("sd");  
        }
    }
}

Can you help me with doing that? Thank you so much!

Answer 1

Basically, you can't access the timer inside the opacityChange event because it's happening in a different thread. You need the Dispatcher to do that.

Dispatcher.BeginInvoke(new Action(() =>
{
        if (this.Opacity == 1)
        {
            timer1.Stop();
        }
        else
        {
            this.Opacity += .1;
        }
}));