Back then one of the assignments I had was to write a random walk function.  Imagine standing next to a lamppost on the street.  From the lamppost you can take a step in one of four directions; North, South, East, or West.  You take a step in a random direction and then look at where you are.  From your new location you take another step in a random direction and you keep taking these random steps for a while.  Finally you stop and look up, how far away from the lamppost are you?

The following function does that only much faster than you or I could.  It takes 20,000 steps total and colors them along the way.  Every 2,000 steps it will change colors leaving a cool trail as it goes along.

Public Sub TakeAWalk()
    Workbooks("themikecom_vba_helloworld.xls").Activate
    ActiveWorkbook.Worksheets("Board").Select
 
    ' Where on the sheet should we start?
    ActiveSheet.Range("EE150").Select
 
    ' How many steps per turn should we take?
    STEPS_PER_TURN = 2000
 
    ' How many turns should we take?
    TURNS = 10
 
    For j = 3 To (TURNS + 3)
    For i = 0 To STEPS_PER_TURN
 
        ' Should we step east or west?
        randomX = Int(4 * Rnd)
 
        ' Should we step north or south?
        randomY = Int(4 * Rnd)
 
        ' Move west-east
        Select Case randomX
            Case 2 ' Move one step west
                If ActiveCell.Column < 1 Then ' Do not overstep the west border
                    ActiveCell.Offset(0, -1).Select
                End If
 
            ' Case 1 - Stay in the same spot

            Case 0 ' Move one step east
                If ActiveCell.Column <= 255 Then ' Do not overstep the east border                     ActiveCell.Offset(0, 1).Select                 End If         End Select         ' Move north-south         Select Case randomY             Case 2 ' Move one step north                 If ActiveCell.Row > 1 Then ' Do not overstep the north border
                    ActiveCell.Offset(-1, 0).Select
                End If
 
            ' Case 1 - Stay in the same spot

            Case 0 ' Move one step south
                If ActiveCell.Row <= 65535 Then ' Do not overstep the south border
                    ActiveCell.Offset(1, 0).Select
                End If
        End Select
 
        ' Leave a trail
        ActiveCell.Interior.ColorIndex = j
 
    Next i
    Next j
End Sub

With that done I wanted to add another function to learn how to create a menu.  I came up with the square flower.  This function will generate a square of random size with each section of the square filled with a different color.  This function taught me some tricks about looping in VBA, some ways are a lot faster than others.

Public Sub Flower()
    Workbooks("themikecom_vba_helloworld.xls").Activate
    ActiveWorkbook.Worksheets("Board").Select
 
    Dim start As Range
    Dim Length As Integer
    Dim Width As Integer
    Dim Color As Integer
 
    ' The starting point of the flower
    Set start = ActiveCell
 
    ' The maximum size of the flower
    size = Int(57 * Rnd)
 
    ' Ignore boundry errors for now
    On Error Resume Next
 
    For z = 0 To size
        ' Generate a random color for this row
        Color = Int((56 - 1 + 1) * Rnd + 1)
 
        ' Left side
        Range(start.Offset(0, 0), start.Offset(Length, 0)).Interior.ColorIndex = Color
 
        ' Bottom side
        Range(start.Offset(Length, 0), start.Offset(Length, Length)).Interior.ColorIndex = Color
 
        ' Upper side
        Range(start.Offset(0, 0), start.Offset(0, Width)).Interior.ColorIndex = Color
 
        ' Right side
        Range(start.Offset(0, Width), start.Offset(Width, Width)).Interior.ColorIndex = Color
 
        Set start = start.Offset(-1, -1)
        Length = Length + 2
        Width = Width + 2
    Next z
 
    On Error GoTo 0
End Sub

So what did I learn after all of this?  Mostly that I have a strong dislike for VBA.  It works well for small projects with small data sets.  However those small projects quickly expand into real programs which need to be maintained.  You are better off doing it right the first time instead of maintaining a large clunky macro.

Download the complete macro here. You will need to enable macros in your security settings to get them to work.  Once enabled, select “Random Walk” from the “theMike.com – Hello World VBA” menu.  This will start a random walk which will finish after a couple of seconds.  The “Square Flower” menu item will create a square flower under your cursor.

iTunes makes it easy to create a music file for the iPod. You can insert a CD and iTunes will import it at the push of a button. Creating a proper audiobook however, is difficult with iTunes. You could import a whole CD as a single file but what if your audiobook covers multiple CDs?

I’ve had this problem for a while now. My initial solution involved importing each track and numbering them in a way that they would line up in a playlist. This works, but it’s annoying. I can play the book but if I stop I have to remember which chapter I left off with. If I don’t go back to the book for a couple of days I forget where I am and have to start over. A couple of weeks ago I finally had enough and went searching for a better solution.

The solution to my problem came from a program called Chapter and Verse by lodensoftware.com.  The program will take a list of AAC (.m4a) files and convert them into one single audiobook (.m4b).  This makes creating an audiobook from a CD very easy.  Simply import the CD using iTunes in the AAC format and then use Chapter and Verse to make the conversion.

Chapter and Verse is not perfect however.  If files are not in the AAC format it will have to convert them into this format before creating the audiobook.  If you use a free audiobook solution such as librivox.org this means it’ll have to convert each file before combining them into one.  Not too big of a deal, just plan a little extra time when creating an audiobook from a set of mp3s.

Quick Audiobook Tutorial

Creating an audiobook is very easy in Chapter and Verse.  First download and install the application.  You will need to make sure iTunes is installed as well because it is used by Chapter and Verse to convert files.

Once Chapter and Verse is installed start the application and it will load to an empty project screen.  Each project contains a set of AAC audio files which will end up being the chapters in this simple tutorial.

Begin by clicking the “Add Files” button to add the audio files you want to be a part of the audiobook.  The open file dialog only shows MP4 files by default so be sure to change the filter if you are adding say .mp3 files.

If you added a file that is not in the AAC format Chapter and Verse will attempt to convert the file using iTunes.  In that case click “Yes – Convert” on the conversion screen.  iTunes will open for the conversion, do not close it until it’s done.  When Chapter and Verse is done with the conversion your files will be added to the “Input Files” tab.

Click on the “Chapters” tab to change each chapter’s name.  On this tab you can rename each chapter in the audiobook.  For my audiobooks I generally set each chapter name to be the same as that of the file.  There are several options here that you may wish to explore.  Near the bottom of the tab there is an “Input Files” dropdown where you can choose prefixes for the chapter names.  I usually to choose the <Filename> option and leave the rest of the settings at their defaults.

The “Metadata” tab allows you to change the file information for the audiobook.  I usually set the title because that is displayed in the track listing on the device.

Finally make sure “Autobuild” is on and then click the “Build Audiobook” button.  Chapter and Verse will ask you where to save the file and then will create the book.

So to sum it all up

1. Click Add Files to add your audio tracks, Chapter and Verse will convert them if necessary.
2. Edit the chapter titles on the “Chapters” tab.
3. Edit the final file information on the “Metadata” tab.
4. Build the audiobook

The code required to launch such an application is very straight forward. The login form needs to be displayed and when it is dismissed the secondary form can be shown. The third screen can be launched off of the second and will stay alive as long as the second is open.

Program.cs

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///
/// Entry point for the test application
///
static class Program
{
    ///
    /// The main entry point for the application.
    ///
    [STAThread]
    static void Main()
    {
        Application.EnableVisualStyles();
        Application.SetCompatibleTextRenderingDefault(false);
 
        // Ask the user to login
        Login.LoginScreen login = new Login.LoginScreen();
        Application.Run(login);
 
        if (login.DialogResult == DialogResult.OK)
        {
            // Run the main application
            Application.Run(new NewWindowApp());
        }
    }
}

Take a look at lines 17 and 22 in the code sample from Program.cs.  The calls to Application.Run(Form) start a message loop on the current thread enabling the form to receive Windows messages.  Application.Run(Form) essentially says to Windows, “Here take this form and show it to the user.”  The form that is supplied can launch other child forms but when it dies so does the whole application.

My goal this week has been to make Sally’s job a little easier by removing the secondary screen and building its functionality into the third screen.  Now normally this would be as simple as replacing line ten with Application.Run(new ThirdForm());.  However that will not work in this case because the third form has a very useful “New Window” button.

Oh, it will work just fine for a while. Sally can click the button leaving her with two views of the application. However the message loop is only hooked up to the first form and if it is closed both forms will die off.

The solution to this problem is in an overload to the Application.Run method that takes an ApplicationContext property. In fact the documentation at MSDN shows a partial solution to my problem.

Instead of supplying Windows with a Form to display to the user I now supply a custom ApplicationContext object.  This custom context can manage the new window call and keep the application alive no mater which form is closed.

Context.cs

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/// <summary>
/// Does the work of firing off new application windows.
/// </summary>
internal class Context : ApplicationContext
{
    // The number of windows currently open
    private int mWindowCount;
 
    /// <summary>
    /// Initializes a new instance of the <see cref="Context"/> class.
    /// </summary>
    public Context()
    {
        this.NewWindow();
    }
 
    /// <summary>
    /// Creates and shows a new window.
    /// </summary>
    public void NewWindow()
    {
        NewWindow window = new NewWindow(this);
 
        window.FormClosed += new FormClosedEventHandler(window_FormClosed);
 
        ++this.mWindowCount;
 
        window.Show();
    }
 
    // Close out the application when all windows have been exited
    private void window_FormClosed(object sender, FormClosedEventArgs e)
    {
        NewWindow window = sender as NewWindow;            
        if (window != null)
        {
            window.FormClosed -= this.window_FormClosed;
        }
 
        --this.mWindowCount;
 
        if (this.mWindowCount <= 0)
        {
            this.ExitThread();
        }
    }
}

It’s important to note that this object knows how many windows there are.  Also note that as each window is created by NewWindow() a listener is added to the FormClosed event.  These two elements allow the context to know when the last form is closed and therefore when to finally exit.

Full source code for the project.