C# Mentor

Parsing tweet with Regex in C#

noreply@blogger.com (C# Mentor) — Sat, 24 Dec 2011 08:28:00 +0000

This is a simple snippet which takes raw tweet text and converts it into a formatted tweet. Formatted tweet contains links to user handles, Links and Hashtags

Get RGB Color at a Point in an Image with C#.Net

noreply@blogger.com (C# Mentor) — Sun, 24 May 2009 09:35:00 +0000

It is very simple to get RGB Color at specific point in an image. For this purpose we need to include System.Drawing Namespace in our code.

using System.Drawing;

Steps as below:

Define a point at which, you want to find the color.
Get the image loaded.
Use method GetPixel from Image class instance to get color at a point.

 Bitmap img = Image.FromFile(@"<Image_file_path>") as Bitmap;
 Color colorAtPoint = img.GetPixel(10, 10);

This is simple method getting color at a point.

How to create PowerPoint add in with C#.Net

noreply@blogger.com (C# Mentor) — Sat, 23 May 2009 07:46:00 +0000

Add-in helps us by automating our daily routine work. So let us make simple one.
Create a project of type Shared add-in Visual Studio as shown in a below snapshot.

Click Ok. After clicking a wizard will appear as shown below.

Click next to a language of you choice for development of Add-in. You can select any of the available languages but here, I have selected C# as my preferred language for development of Add-in.

As we are creating add-in for PowerPoint our scope will be only PowerPoint. So Check the Microsoft PowerPoint option only leaving all other unchecked as shown below.

Give a name and description for add-in. We will call our add-in as "Solo Addin" and add a sample description as "Sample Solo Addin"

Choose options for your add-in loading. We will check first option to suggest that PowerPoint should load our add-in when it loads. Second option suggests that the add-in will be available to all users on a machine. You can change this option in deployment deploying.

Next screen shows summary of all the steps we have gone through.

Click on Finish button and that's all. This will create all the necessary framework and code to get started with.

We have main Connect class which will be a mediator between the code we are going to write and PowerPoint. Connect Class will have a unique GUID for an add-in to differentiate between add-ins or to uniquely identify an add-in. You Connect class GUID line will look like the below one.

[GuidAttribute("85D322E5-B30F-48EB-83A4-CB3CD133010F"), ProgId("Solo.Connect")]

Connect class has main Five event

OnConnection - fires immediately after Connect Constructor
OnDisconnection - fires after add-in shutdown
OnAddInsUpdate - fires when add-in updates
OnStartupComplete - fires when loading is complete. We will initialize the add-in here.
OnBeginShutdown - fires when host application begins to shutdown. We will do cleanup things here.

So for now we will just show a MessageBox to know that we are on track. Add reference of System.Windows.Forms dll to the project to get MessageBox work. Add using statement to your Connect class

using System.Windows.Forms;

Show MessageBox on OnStartupComplete event.

/// <summary>
///      Implements the OnStartupComplete method of the IDTExtensibility2 interface.
///      Receives notification that the host application has completed loading.
/// </summary>
/// <param term='custom'>
///      Array of parameters that are host application specific.
/// </param>
/// <seealso class='IDTExtensibility2' />
public void OnStartupComplete(ref System.Array custom)
{
     MessageBox.Show("Hello World!");
}

Build add-in project, Open PowerPoint, and you should get an MessageBox saying "Hello World!"

Conclusion:
This post show how to go get started with PowerPoint add-in development.

Threading: Modal Progress Dialog and BackgroundWorker Thread in C#.Net

noreply@blogger.com (C# Mentor) — Tue, 19 May 2009 16:16:00 +0000

While working with threads, one should be careful about UI Elements. Specially when we are working with BackgroundWorker thread. Here is an example which shows how to show a modal dialog from thread for displaying progress.

 public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        BackgroundWorker worker;
        Form2 frm;
        private void button1_Click(object sender, EventArgs e)
        {
            frm = new Form2();
            worker = new BackgroundWorker();
            worker.WorkerReportsProgress = true;
            worker.DoWork += new DoWorkEventHandler(worker_DoWork);
            worker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(worker_RunWorkerCompleted);
            worker.ProgressChanged += new ProgressChangedEventHandler(worker_ProgressChanged);
            worker.RunWorkerAsync();     
            frm.ShowDialog();
      
        }
        void worker_ProgressChanged(object sender, ProgressChangedEventArgs e)
        {
            frm.ProgressValue = e.ProgressPercentage;
        }
        void worker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            frm.Close();
            MessageBox.Show("Done");
        }
        void worker_DoWork(object sender, DoWorkEventArgs e)
        {
            CountTheTime();      
        }
   
        private void CountTheTime()
        {
            int initialValue = 100;
            for (int count = 0; count < initialValue; count = count + 2)
            {
                Thread.Sleep(1000);
                worker.ReportProgress(count);
            }
        }
    }

In this example, I have simply created two windows forms. The first form [Form1] has one button [button1]. button1 will show create a BackgroundWorker thread and launch it asynchronously. It uses method RunWorkerAsync of BackgroundWorker thread instance for this purpose

BackgroundWorker has three main events

DoWork - will be fired when we launch the thread.
RunWorkerCompleted - will fire when thread completes
ProgressChanged - will fire when thread reports progress

and important property

WorkerReportsProgress – should be set to True to enable progress reporting from a thread.

related method

ReportProgress() – Reports progress back to the calling thread.

In aforementioned code, When we fire DoWork event by calling RunWorkerAsync method on worker thread. Eventhandler for this event will call the method CountTheTime() on the form.

CountTheTime() method intentionally put delay of 1 second. Here you can implement your time consuming code. We call ReportProgress() method on the thread to pass progress from this background thread to the main UI thread which holds our progress bar. This method will fire ProgressChanged Event

  public partial class Form2 : Form
    {
        public Form2()
        {
            InitializeComponent();
        }
        public int ProgressValue
        {
            get { return progressBar1.Value ; }
            set { progressBar1.Value  = value; }
        }
    }

Then ProgressChanged eventhandler, worker_ProgressChanged updates the progressbar on Form2 with the help of ProgressValue property.

Conclusion:
Simple example of modal Progressbar with BackgroundWorker thread.

Debugging: The breakpoint will not currently be hit. No symbols have been loaded for this document.

noreply@blogger.com (C# Mentor) — Mon, 18 May 2009 16:57:00 +0000

This error suggest that you don’t have the latest version of the code matching with the executable(.Dll/.exe) for the debug session.

Case 1: If you are attaching process to its excutable on different path

1. First build you application in debug mode.
(Say E:\app\debug)

2. Take backup of deployed application’s executable.
(Say C:\Program files\app\app.exe to C:\Program files\app\app123.exe).

3. Copy that executable from debug path in step 1 to
the attachable application’s path in step 2
(Say E:\app\debug\app.exe to C:\Program files\app\app.exe)

4. Copy the dependent Dlls, if needed.

And start your debugging by

Running that external application.
Then attaching your project to this application from Debug menu.

Case 2: In case your executable is in GAC

1. First build you application in debug mode.
(Say E:\app\debug)

2. Put it on some path
(Say E:\GacDlls)

3. Add this excutable to GAC.

and happy debugging.

Case very common:

If you are not holding any of the case or above solutions are of no use then try following

1. Look all modules are loaded for the current debugging session.
For this go to

   debug -> Modules

See all your modules are loaded. If any of the entries shows ‘cannot find or open PDB file’ right-click that module and say Load Symbols to browse for modules .PDB File.

if you can’t find Modules under Debug menu. Go to

Tools -> Customize

Find Debug item in Commands Tab on left list choose corresponding Modules item from right list and drag it to Debug menu.

2. Try to shutdown both IDE and external application(if any).
Reopen them, and try debugging.

Scrolling in Multiline TextBox

noreply@blogger.com (C# Mentor) — Tue, 12 May 2009 05:28:00 +0000

In windows forms, We can have feature of scrolling for Multiline TextBox.

We can find text position to scroll up to. One can also scroll to the end of text box by setting the SelectionStart property appropriately.

Following example shows, how to scroll to a specific word in the document. Actually you can use this function for providing search functionality for TextBox.

 public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        int ind = 0;
        int be = 0;
        private void button1_Click(object sender, EventArgs e)
        {
            be = textBox1.Text.ToLower().IndexOf("as", ind + 1);
            if (be >= 0)
            {
                textBox1.SelectionStart = be;
                textBox1.ScrollToCaret();
                textBox1.Select(be, 2);
                textBox1.Focus();
                ind = textBox1.Text.ToLower().IndexOf("as", be);
            }
        }
        private void Form1_Load(object sender, EventArgs e)
        {
            textBox1.Text = "In 1924, Einstein received a description of a statistical model from Indian physicist Satyendra Nath Bose, based on a counting method that assumed that light could be understood as a gas of indistinguishable particles. Bose's statistics applied to some atoms as well as to the proposed light particles, and Einstein submitted his translation of Bose's paper to the Zeitschrift für Physik. Einstein also published his own articles describing the model and its implications, among them the Bose-Einstein condensate phenomenon that should appear at very low temperatures . It was not until 1995 that the first such condensate was produced experimentally by Eric Allin Cornell and Carl Wieman using ultra-cooling equipment built at the NIST-JILA laboratory at the University of Colorado at Boulder. Bose-Einstein statistics are now used to describe the behaviors of any assembly of \"bosons\". Einstein's sketches for this project may be seen in the Einstein Archive in the library of the Leiden University.";
        }
    }

To scroll to the end of the text box use

textBox1.SelectionStart = textBox1.Text.Length

Conclusion:
This is very simple code for searching text in TextBox and Scrolling.

Blogger Labels: Multiline,TextBox,text,scroll,SelectionStart,example,word,Form,InitializeComponent,sender,EventArgs,ToLower,IndexOf,ScrollToCaret,Select,Focus

Parse integers safely

noreply@blogger.com (C# Mentor) — Sat, 02 May 2009 12:21:00 +0000

Most of the times when we write code there is a need of data-type conversion. We may need to convert string into boolean, string into integers etc. Using Convert class to do these type of conversion is commonplace. But this is an error-prone practice as it may generate exception if the input is not convertible to the target type.

So one can use the strategy explained below for converting string to integer-

private void testConversion()
{
        string tempString = "10";
        int safeInt = 0;
        int defaultValue = 1000;
        safeInt = int.TryParse(inputValue, out safeInt ) ? safeInt : defaultValue ;

}

Here almost all built-in types have TryParse static function which can be used for safe type parsing. In this example, int.TryParse parses string into integer and save that converted value in out variable and will return a true value. If the string is not convertible it will return a false value. In case of false value, we can assign a default value to our final variable.

Similar strategy can be employed for other data-type conversions, try it or find me here to help. Cheers!

Hope this will make your code more safer.

Safely retrive attribute from XML Node in a Document

noreply@blogger.com (C# Mentor) — Sat, 02 May 2009 07:26:00 +0000

In XML processing, we commonly encounter a situation where we require to get the attribute value from a given XML Node. But most of the time it happens that the node may not contain the attribute itself. So if we try to get value of the attribute, runtime will definitely throw the exception. And exceptions are evils for the perfomance of any application.

In such scenario, first we need to check for the existence of the attribute in the XML Node. Here XMLElement class comes for the rescue. XMLElement has a static method HasAttribute which will serve the purpose of checking existence of the attribute in the given XML Node.

Here is the sample which show how to get the attribute value safely

private string GetAttributeValue(XmlNode xNode, string attributeToFind)
{
string returnValue = string.Empty;
XmlElement ele = xNode as XmlElement;

if (ele.HasAttribute(attributeToFind))
returnValue= ele.GetAttribute(attributeToFind);

return returnValue;
}

Hope this will help.

I welcome all programmer friends !

noreply@blogger.com (C# Mentor) — Wed, 21 Feb 2007 09:07:00 +0000

I welcome everybody from developer community. I will be writing my experiences,experiments with c#. This may also have feeds form several expert sites, which will helpful to all my friends who are in programming and especially in c#.Net. If you any kind of question regarding programming (not just C#), please feel free to post comment in corresponding section. I value suggestions, and expecting from you.
Have great time!