.NET

Look Mom, no parameters! Relaxed delegates in Visual Basic 2008 (VB9)

Mike McIntyre [MVP Visual Basic] — Thu, 01 May 2008 18:59:00 GMT

Relaxed delegate conversion, introduced in Visual Basic 2008, enables you to assign subs and functions to delegates or handlers even when the signatures are not identical. Therefore, binding to delegates becomes consistent with the binding already allowed in method invocations.

In Visual Basic prior to 2008:

Sub OnClick(ByVal sender As Object, ByVal e As EventArgs) Handles RunButton.Click
MessageBox.Show("Visual Basic prior to VB 2008")
End Sub

In Visual Basic 2008 (VB9)

Sub OnClick() Handles RunButton.Click
MessageBox.Show("Look Mom, no parameters!")
End Sub

Details: Relaxed Delegate Conversion

Mike McIntyre
www.getdotnetcode.com

Visual Web Gui - ASP.NET web applications built with a .NET Windows Forms project!

Mike McIntyre [MVP Visual Basic] — Tue, 29 Apr 2008 19:19:00 GMT

Visual Web Gui is an open source product for porting .NET Windows Forms applications to the web.

It is used to create ASP.NET web applications with a very AJAX like experience - without the AJAX programming hassle.

It may be worth it to you to give it a try. Though it's little rough around the edges at this point, this product can be used today to produce web applications from .NET Windows Forms projects. And - the developer is rapidly improving the product each month.

It's easy to get started and it to produce useful web applications. I've been playing around with it for about a week and have already created two small web applications for IT management.

The process is straight-forward:

1. Download and install the free Visual Web Gui Visual Studio project templates.

2. Create a Visual Web Gui project. This is a Visual Studio Windows Forms project.

3. Build out the Windows Froms application.

4. Compile.

5. Run result in web browser.

6. Deploy to web server.

Visual Web Gui web site: http://www.visualwebgui.com/

Visual Web Gui at CodePlex: http://www.codeplex.com/VWGSilverlight

Mike McIntyre

www.getdotnetcode.com

PInvoke Interop Assistant (FREE) - Making PInvoke Easier to Use

Mike McIntyre [MVP Visual Basic] — Sun, 16 Mar 2008 09:29:00 GMT

Jaren Parsons of the Microsoft Visual Basic Team created PInvoke Interop Assistant. In a blog announcing the tool he says: “The motivation behind this tool is writing PInvoke is a hard and often tedious task. There are many rules you must obey and many exceptions that must be taken into account.”

Read about the tool and get a link to download it at: Making PInvoke Easy

Visual Basic 2008 Books (UPDATED)

Mike McIntyre [MVP Visual Basic] — Sat, 01 Mar 2008 07:30:00 GMT

The list has more than doubled since I first published it here.

Below, in alphabetical order, is a partial listing of Visual Basic 2008 books. Some have already been published, some will be published over the next several months.

Accelerated VB 2008 (Accelerated)

Beginning ASP.NET 3.5 in VB 2008 - Programming Techniques

Beginning VB 2008 Databases: From Novice to Professional

Beginning Microsoft Visual Basic 2008

Clearly Visual Basic: Programming with Microsoft Visual Basic 2008

Introduction to Programming Using Visual Basic 2008

LINQ in Action

Mastering Microsoft Visual Basic 2008

Microsoft Visual Basic 2008 Express Edition: Build a Program Now!

Microsoft Visual Basic 2008: RELOADED

Murach's Visual Basic 2008

Pro VB 2008 and the .NET 3.5 Platform

Programming in Visual Basic 2008

Programming Visual Basic 2008: Build .NET 3.5 Applications with Microsoft's Popular RAD Tool for Business

Programming Windows Services with Microsoft Visual Basic 2008

Sams Teach Yourself Visual Basic 2008 in 24 Hours: Complete Starter Kit

Simply Visual Basic 2008

Starting Out With Visual Basic 2008

Visual Basic 2008 For Dummies

Visual Basic 2008 for Windows and Mobile Applications: Introductory

Visual Basic 2008 for Windows, Mobile, Web, Office, and Database Applications: Comprehensive

Visual Basic 2008 How to Program

Visual Basic 2008 Programmer's Reference

Visual Basic 2008 Recipes: A Problem-Solution Approach

Mike McIntyre

Get Dot Net Code

Free Visual Studio 2008 eBook Offer

Mike McIntyre [MVP Visual Basic] — Fri, 11 Jan 2008 06:49:00 GMT

Get it at: Free eBook Offer

Visual Studio 2008

Preview the first chapter from any of these Microsoft Press Visual Studio 2008 titles. When you're ready, sign up for the free download offer to get additional content.

More VB XNA Stuff at ILoveVB.com

Mike McIntyre [MVP Visual Basic] — Mon, 24 Dec 2007 09:06:00 GMT

For more VB XNA game code visit: http://ilovevb.net/Web/

Checkout the downloads section.

Free Line and Shape Controls for Visual Basic 2005

Mike McIntyre [MVP Visual Basic] — Sat, 06 Oct 2007 08:40:00 GMT

Do you get frustrated trying to add graphics to you .NET Windows Forms applications? Learning to use the .NET graphics classes is not easy. Managing the graphics you create with the classes increases the amount of code you need to write.

There was a line and shape control for creating graphics in Visual Basic before .NET. It was widely used by developers to easily decorate the Windows Forms they created with graphics. It was easy to use.

The line and shape control was missing-in-action in Visual Basic for .NET 2002 and 2003.

For Visual Basic 2005, Microsoft has provided a Power Pack that adds line and shape controls to Visual Studio 2005. The Power Pack includes controls that enable you to draw lines, ovals, and rectangles on forms and containers at design time.

These controls provide an easy way to decorate a Windows Forms with graphics just like the VB6 line and shape control.

And, the Power Pack controls introduce powerful new features to the shapes such as events. With events you can change the appearance of graphics at runtime based on events occurring in the application. This adds a whole new dimension to line and shape controls. For example, add click and double-click events allow developers to respond and interact with end users.

The new Line and Shape controls included in this version of the Visual Basic 2005 Power Packs are a set of three graphical controls that enable you to draw lines, ovals, and rectangles on forms and containers at design time.

Line and Shape controls encapsulate many of the graphics methods that are contained in the System.Drawing namespace. This enables you to draw lines and shapes in a single step without having to create graphics objects, pens, and brushes. Complex graphics techniques such as gradient fills can be accomplished by just setting some properties.

Download and Try the Visual Basic Power Pack Line and Shape Controls

Download an installer at:

Microsoft Visual Basic 2005 Power Packs 2.0

During installation line and shape control Help is installed installed. To learn how to use the line and shape controls search Visual Studio help for this topic:

Introduction to the Line and Shape Controls

Also during installation, a Visual Studio PowerPacks v2.0 Toolbox Tab is added to Visual Studio 2005:

With it you can drag a line, and oval shape, or a rectangle shape onto the design surface of a Windows form.

Select a shape and use the 'Properties' pane to manipulate the shape.

The possibilities are nearly endless.

Mike McIntyre http://www.getdotnetcode.com

Build an ASP.NET 2.0 Web Site Navigation System Pt3

Mike McIntyre [MVP Visual Basic] — Thu, 03 May 2007 15:06:00 GMT

Source Code: Build an ASP.NET 2.0 Web Site Navigation System Pt3

Build an ASP.NET 2.0 Web Site Navigation System Pt3

This is part three of a three part article that demonstrates how to build an ASP.NET navigation system. In part one, web pages were added to a web site and then referenced in a ASP.NET 2.0 SiteMap file. In part two an ASP.NET 2.0 Menu control was tied to the SiteMap file created in part one. In part three an ASP.NET SiteMapPath (bread crumbs menu) is tied to the SiteMap created in part one and the Menu added in part two.

Read previous parts of the article -> Part 1, Part 2

Clean Up the Master Page

The master page used in parts 1 and 2 was getting cluttered so I clean it up. Here are the steps I took:

1. Removed the Read Me and GetDotNetCode links below the banner header.

2. Merged the two cells below the banner header.

3. Removed the row above the banner header that contained the words: 'Bread Crumbs Menu (Will be added in Part Three)'

Add an ASP.NET 2.0 SiteMapPath Control to the Master Page

An ASP.NET 2.0 SiteMapPath control was drug from the Toolbox to the row under the banner header.

Because a site map with the name Web.sitemap was already present in the web sites root directory, the new control was automatically wired to it. (The site map was added in part one of this article.)

Test the Site Map

Run the application. Select any page from the application, from the left menu. As you do, the SiteMapPath control will display a 'bread crumbs' menu that shows the path to the page you select.

About the ASP.NET SiteMapPath Class

The SiteMapPath control is a site navigation control that reflects data provided by the SiteMap object. The SiteMapPath class displays a set of text or image hyperlinks that enable users to more easily navigate a Web site, while taking a minimal amount of page space.

The SiteMapPath control provides a space-saving way to easily navigate a site and serves as a point of reference for where the currently displayed page is within a site. This type of control is commonly called a breadcrumb, or eyebrow, because it displays a hierarchical path of hyperlinked page names that provides an escape up the hierarchy of pages from the current location. SiteMapDataSource.

For more information:

SiteMap Class

Menu Class

SiteMapPath Class

mike mcintyre http://www.getdotnetcode.com

How To Use Lazy Initialization VB.NET and Visual Basic 2005 Part Two

Mike McIntyre [MVP Visual Basic] — Tue, 30 Jan 2007 07:10:00 GMT

Source Code: How To Use Lazy Initialization VB.NET and Visual Basic 2005 Pt2

How To Use Lazy Initialization VB.NET and Visual Basic 2005 Part Two

This is part two of a two part article and source code which explains the lazy initialization pattern and how to implement it in an order entry scenario with VB.NET and Visual Basic 2005. In object-oriented programming (OOP), lazy initialization is the strategy of improving application performance by delaying the creation of an object, the calculation of a value, or some other process until the first time the object is needed.

Click to read part one -> Part 1

In part two, ADO.NET code is implemented for the Customer class' lazy initialization processes to load orders and order lines from a database.

Example Application Screen Shot

The example application loads a list of customers from the Northwind database.

When a user clicks the row header for a customer row, a Customer object is created.

When the user clicks the LoadOrderLines button the the Customer object loads the customers orders and orders lines.

Customer Class from Part 2 Source Code

The customer class' LoadOrders and LoadOrderLines methods are implemented.

Public Class Customer

' Name field.

Private m_Name As String

' Name property.

Public Property Name() As String

Get

Return Me.m_Name

End Get

Set(ByVal value As String)

Me.m_Name = value

End Set

End Property

' ID field.

Private m_ID As String

' ID property.

Public Property ID() As String

Get

Return Me.m_ID

End Get

Set(ByVal value As String)

Me.m_ID = value

End Set

End Property

' Constructor

Private Sub New()

' Parameterless constructor made private so only

' a parameterized constructor can be called.

End Sub

Public Sub New(ByVal name As String, ByVal id As String)

Me.Name = Name

Me.ID = id

End Sub

' Orders field.

' Intialized to nothing when Customer object is created.

Private m_CustomerOrders As New List(Of CustomerOrder)

' Lazy initialization flag for Orders collection.

Private ordersLoaded As Boolean = False

' Orders property.

Public Property CustomerOrders() As List(Of CustomerOrder)

Get

' Lazy intialization code for Orders.

If Not ordersLoaded Then

Me.LoadOrders()

End If

Return Me.m_CustomerOrders

End Get

Set(ByVal value As List(Of CustomerOrder))

Me.m_CustomerOrders = value

End Set

End Property

' OrderLines field.

' Intialized to nothing when Customer object is created.

Private m_OrderLines As New List(Of OrderLine)

' Lazy initialization flag for OrderLines collection.

Private ordersLinesLoaded As Boolean = False

' OrderLines property.

Public Property OrderLines() As List(Of OrderLine)

Get

' Lazy initialization code.

If Not Me.ordersLinesLoaded Then

Me.ordersLinesLoaded = True

End If

Return Me.m_OrderLines

End Get

Set(ByVal value As List(Of OrderLine))

Me.m_OrderLines = value

End Set

End Property

Private Sub LoadOrders()

' Load customers orders here.

Dim theNorthwindDataSet As New NorthwindDataSet

Dim x As New NorthwindDataSetTableAdapters.OrdersTableAdapter

x.FillByCustomerId(theNorthwindDataSet.Orders, Me.ID)

For Each row As NorthwindDataSet.OrdersRow In theNorthwindDataSet.Orders

Me.m_CustomerOrders.Add(New CustomerOrder(row.OrderID, row.CustomerID, row.OrderDate))

Me.ordersLoaded = True

Me.LoadOrderLines()

End Sub

Private Sub LoadOrderLines()

' Load orderLines here.

Dim theNorthwindDataSet As New NorthwindDataSet

Dim x As New NorthwindDataSetTableAdapters.Order_DetailsTableAdapter

For Each item As CustomerOrder In Me.m_CustomerOrders

x.FillByOrderId(theNorthwindDataSet.Order_Details, item.OrderID)

For Each order_detail As NorthwindDataSet.Order_DetailsRow In theNorthwindDataSet.Order_Details

Me.m_OrderLines.Add(New OrderLine(order_detail.OrderID, order_detail.ProductID, order_detail.UnitPrice))

Me.ordersLinesLoaded = True

End Sub

Public Overrides Function ToString() As String

Return Me.ID & " " & Me.Name

End Function

End Class

mike mcintyre http://www.getdotnetcode.com

How To Compare Two Files using HMACSHA1 with VB.NET or VB2005

Mike McIntyre [MVP Visual Basic] — Tue, 23 Jan 2007 11:53:00 GMT

Source Code: How To Compare Two Files using HMACSHA1 with VB.NET or VB2005

How To Compare Two Files using HMACSHA1 with VB.NET or VB2005

This article is similar to the article How To Compare Two Files with VB.NET and VB2005.

The difference is this file comparison article and source code use the .NET System.Security.Cryptography HMACSHA1 Class to compare two files. The suggestion to use HMACSHA1 was made by reader Jim Parzych.

In tests I conducted, the HMACSHA1 class provided better performance than the byte-by-byte comparison in the first article.

The file comparison looks at file paths, file lengths, and file contents. NOTE: While source code for VB.NET is not provided, the code included in this article will work with VB.NET too. Be sure to Import System.IO.

Application Screen Shot

The source code includes a Windows Forms application.

Source Code Excerpt

After a user makes two file selections and clicks the 'Compare Files' button, the CompareFiles function in the source code performs the file comparison.

First CompareFiles compares the path to file one to the path to file two. If they are the same, file one and file two are the same.

Next, CompareFiles compares the length of file one to the length of file two. If they are different the files are not equal.

Finally, if file paths are different and the length of file one and file two are the same, CompareFiles compares the contents of file one to file two using hashes created by a HMACSHA1 object. If the bytes in file one are equal to the bytes in file two, the files are equal.

 
Private Function CompareFiles(ByVal filePathOne As String, ByVal filePathTwo As String) As Boolean
 

' If user has selected the same file as file one and file two..

If (filePathOne = filePathTwo) Then

' Files are the same.

Me.ResultsRichTextBox.Text = "Files are the same; file one is file two."

Return True

End If

' // User selected two different files; Compare length of file one to file two.

Dim fileOneStream As FileStream

Dim fileTwoStream As FileStream

' Open a FileStream for each file.

fileOneStream = New FileStream(filePathOne, FileMode.Open)

fileTwoStream = New FileStream(filePathTwo, FileMode.Open)

' If the files are not the same length...

If (fileOneStream.Length <> fileTwoStream.Length) Then

fileOneStream.Close()

fileTwoStream.Close()

' File's are not equal.

Me.ResultsRichTextBox.Text = "Files are not the same length; they are not equal."

Return False

Else

fileOneStream.Close()

fileTwoStream.Close()

End If

' // Files are the same length; compare file contents using .NET HMACSHA1 Class

Dim fileOneHash As Byte() = ComputeFileHashUsingHMACSHA1(filePathOne)

Dim fileTwoHash As Byte() = ComputeFileHashUsingHMACSHA1(filePathTwo)

Dim areFilesEqual As Boolean = True

' Make a byte-by-byte comparrison of file one's hash to file two's hash.

For i As Integer = 0 To UBound(fileOneHash)

' If a byte from file one is not equal to a byte from file two..

If (fileOneHash(i) <> fileTwoHash(i)) Then

' Files are not equal; byte in file one hash <> byte in file two hash.

Me.ResultsRichTextBox.Text = "Files are not equal; contents are different."

areFilesEqual = False

Exit For

End If

' // Message user and return areFilesEqual

If areFilesEqual Then

' Files are equal; bytes in file one hash = bytes in file two hash.

Me.ResultsRichTextBox.Text = "Files are equal; contents are the same."

areFilesEqual = False

End If

Return areFilesEqual

End Function

Public Function ComputeFileHashUsingHMACSHA1(ByVal filePath As String) As Byte()

' Declare variable named theHMACSHA1 of type HMACSHA1.

Dim theHMACSHA1 As HMACSHA1

' Declare variable named theKeyValue of type Byte().

Dim theKeyValue As Byte()

' Declare variable named theHashValue of type Byte().

Dim theHashValue As Byte()

' Declare variable named theInStream of type Stream.

Dim theInStream As Stream

' Call the UnicodeEncoding class' shared GetBytes method to initialize theKeyValue object.

theKeyValue = (New System.Text.UnicodeEncoding).GetBytes("HashingKey")

' Call the HMACSHA1 class' constructor method to initialize theKeyValue object.

theHMACSHA1 = New HMACSHA1(theKeyValue, True)

' Open theInStream.

theInStream = New FileStream(filePath, FileMode.Open, FileAccess.Read)

' Calculate theHashValue.

theHashValue = theHMACSHA1.ComputeHash(theInStream)

' Close theInStream.

theInStream.Close()

' Return theHashValue.

Return theHashValue

 
End Function

For more information:

FileStream Class

HMACSHA1 Class

mike mcintyre http://www.getdotnetcode.com