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CPBar for latest article briefs (RSS feed)

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6 Jul 2003 1  
This article is about creating a vertical explorer bar which displays CodeProject's latest article briefs from its RSS feed.

Introduction

I have implement this explorer bar with the help of the BandObject base class as well as this article Extending Explorer with Band Objects using .NET and Windows Forms. This vertical explorer bar actually consumes the RSS feed for CodeProject's latest article briefs at http://www.codeproject.com/webservices/articlerss.aspx, extract the details of each article and then display them in a scrolling fashion.

An overview of CPBar design

The CodeProjectBar object is something like a form which you can just drag and drop controls from the toolbox. As for ScrollScreen, it is a custom control that holds many RichLabel objects and coordinate their scrolling through the use of a timer. The RichLabel object does nothing more than just organizing and formatting the data for display. Besides that, it is also supposed to hide the caret. (See Issues yet to address section) 

Consuming CP's RSS Feed

The diagram above shows part of what is contained in the RSS feed file. Each item tag represent an article brief and between them contains information such as article title, description, author, etc. So to extract them, here is what I have done.

private void DownloadCPRSSFeed(string url /* url of the rss feed */)
{
    XmlTextReader xmlTextReader = new XmlTextReader(url);

    // We don't want to handle whitespaces

    xmlTextReader.WhitespaceHandling = WhitespaceHandling.None;

    // Read through the xml document

    while(xmlTextReader.Read())
    {
        // Check if this is an element of name "item", continue reading

        if (xmlTextReader.NodeType == XmlNodeType.Element 
               && xmlTextReader.Name == "item")
        {
            // Continue read

            xmlTextReader.Read();

            // Get the content for each element. Although I am 

            // not interested in the "category"

            // data, i still need to follow the order so that 

            // I can reach the date section.

            string title = xmlTextReader.ReadElementString("title");
            string desc = xmlTextReader.ReadElementString("description");
            string link = xmlTextReader.ReadElementString("link");
            string author = xmlTextReader.ReadElementString("author");
            string category = xmlTextReader.ReadElementString("category");
            string date = xmlTextReader.ReadElementString("pubDate");

            // Add an item for these data to our scroll screen

            scrollArticlesScreen.AddItem(date, title, link, author, desc);
        }
    }
}

Setting up the CPBar

This is a simple setup program to install the CPBar onto your machine. Below shows the code for the installation and uninstallation part.

// Install

private void btnInstallCPBar_Click(object sender, System.EventArgs e)
{            
    // Run "gacutil.exe /i CPBar.dll" and "regasm CPBar.dll"

    System.Diagnostics.Process.Start(Application.StartupPath + 
         '\\' + "gacutil.exe", "/i CPBar.dll");
    System.Diagnostics.Process.Start(Application.StartupPath + 
         '\\' + "regasm.exe", "CPBar.dll");
}

// Uninstall

private void btnUninstallCPBar_Click(object sender, System.EventArgs e)
{
    // Run "regasm /u CPBar.dll" and "gacutil.exe /u CPBar.dll"

    System.Diagnostics.Process.Start(Application.StartupPath + '\\' 
         + "regasm.exe", "/u CPBar.dll");
    System.Diagnostics.Process.Start(Application.StartupPath + '\\' 
         + "gacutil.exe", "/u CPBar.dll");
}

Issues yet to address

Here are some issues that i have encountered but until now, I still couldn't find solution for them.

  • Hand cursor not shown when it is over link in RichLabel (but the link still works)
  • This is actually not the case when the ScrollScreen is not hosted in CodeProjectBar. i.e. I created another application and drag my ScrollScreen control onto it.

  • Caret is still visible when RichLabel is being clicked
  • I couldn't find any method like HideCaret() or something like that in C#.

History

None.

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