Progress Bar in WPF With Anonymous Delegates

Here I created a WPF Progress Bar that will demonstrate many terms, like Threading, Synchronization, Invoke() and begineInvoke() and simplicity!

Progress Bar in WPF

Step 1: Create WPF Project.

Step 2: Drag two Buttons and a Progress Bar to the WPF Window.

The following are some point to be noted:

  • To update progress bar you need to start new thread, Other than the main thread of GUI; that can update progress bar!
  • WPF, or Control in the case of Windows Forms have thread affinity, which means that only the thread that instantiates them.
  • But can subsequently access their members. Violating this causes either unpredictable behavior, or an exception to be thrown. (for e.g if you want to call a member on object X created on another thread Y, you must marshal the request to thread Y).
  • Solution : In WPF you can Use "Dispatcher" Object of "Control" (here Progress bar) to start a new thread.
  • Same solution can be done with BackgroundWorker and Task Objects.

XAML CODE

<Window x:Class="ThreadsProgressBar.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"  Closing="Window_Closing">

    <Grid>

        <ProgressBar Height="26" HorizontalAlignment="Left" Margin="40,32,0,0" Name="progressBar1" 
        VerticalAlignment
="Top" Width="417" />

        <Button Content="Start" Height="23" HorizontalAlignment="Left" Margin="162,128,0,0" Name="button1"
         VerticalAlignment="Top" Width="75" Click="button1_Click" />

        <Button Content="Cancel" Height="23" HorizontalAlignment="Left" Margin="243,128,0,0" Name="button2"
          VerticalAlignment="Top" Width="75" Click="button2_Click" />

    </Grid>

</Window>


CODE BEHIND

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Windows;

using System.Windows.Controls;

using System.Threading;

using System.Windows.Threading;

 

namespace ThreadsProgressBar

{

    /// <summary>

    /// Developer Name : void

    /// Email For Comments : niluniverse@gmail.com

    /// Message : Welcome !

    /// Interaction logic for MainWindow.xaml

    /// </summary>

    public partial class MainWindow : Window

    {

        // Start New Thread here -- Globally --

        Thread t = null;

 

        public MainWindow()

        {

            InitializeComponent();

 

            // You can set this Max limit in XAML also !

            progressBar1.Maximum = 100;

                     

        }

 

        private void Work()

        {

            // Do You Expensive Work Here!

 

            for (int i = 0; i <= 100; i++)

            {

                //This Sleep is Just For Some timepass 

 

                Thread.Sleep(100);

                UpdateProgressBar(i);

            }

 

            MessageBox.Show("Finish !");

        }

 

        private void UpdateProgressBar(int i)

        {

            // Action is delegate (means a function pointer) which is Pointing towards "SetProgress" method

 

            Action action = () => { SetProgress(i);};

 

           // Here Dispacthers Invoke (is a Syncronus)/ BegineInvoke (Is Asyncornus) in Called 

 

            progressBar1.Dispatcher.BeginInvoke(action);

        }

 

        private void SetProgress(int i)

        {

            progressBar1.Value = i;

        }

 

        // Start Thread Button Code

        private void button1_Click(object sender, RoutedEventArgs e)

        {

            // Thread is started here (We can say this is 2nd thread after main Thread !)

 

            t = new Thread(Work);  

            t.Start();

        }

 

        private void Window_Closing(object sender, System.ComponentModel.CancelEventArgs e)

        {

            if (t.IsAlive)

                t.Abort();

        }

 

        // Abort Thread Button Code

        private void button2_Click(object sender, RoutedEventArgs e)

        {

            // Aborti   ng Thread here !

            if (t.IsAlive)

            {

                t.Abort();

                progressBar1.Value = 0;

            }

 

        }

 

       

    }

 

 

}


WINODW


/Progress bar in WPF with Anonymous delegates

Thanks! I hope this will help someone!

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