Archive for August, 2013

How do I – Play the TNG Red Alert (or any audio file for that matter) in my WinForms C# app

Written by Cornelius J. van Dyk on . Posted in Blog, How Do I...

Out of the box, C# and .NET supports the playing of any .WAV file.  The code is pretty straight forward.  We simply need to reference the system media class to create a SoundPlayer{} object thus:

System.Media.SoundPlayer p = new System.Media.SoundPlayer(@"C:\Media\MySoundEffect.wav");
Once we have the object, we simply invoke the Play() method thus:
p.Play();

So in two simple lines of code, we are able to play any .wav file from our application.  There are some more embedded problems that may not immediately be obvious.  Allow me to explain.

Suppose I’m trying to add the Star Trek TNG Red Alert sound to my app for an emergency notification.  I begin by locating the sound in question.  A quick web search takes me to the http://www.trekcore.com/audio/ site where the Red Alert section has several samples to choose from.  Once I locate the sound sample that I wish to use, I click the link and download the file.

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PROBLEM #1:  The file is in the .mp3 audio format.  Attempting to use it in the instantiation of the SoundPlayer() method fails with the message that only .wav files are supported.

RESOLUTION We could use a custom media player class, or we could just let the internet do some work for us.  A quick search pointed me to the http://media.io/ online audio conversion web site.  The simple interface couldn’t be cleaner or more straight forward:

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Simply take the .mp3 file we previously downloaded and upload and convert it on this site.  Now we finally have a .wav file that we can use in our project.  Now we would like the alert sound to be played 3 times and a popup window present the error notification.  That’s easy, right?  We simply use a for() loop that looks like this:

for (int i = 0; i <= 2; i++)
{
    System.Media.SoundPlayer p = new System.Media.SoundPlayer(@"TNG-Red-Alert.wav");
    p.Play();
}
MessageBox.Show("There is an error!", "ERROR", MessageBoxButtons.OK, MessageBoxIcon.Error);

We compile and run the app and expect the alert sound to play 3 times… only… it doesn’t.  So why doesn’t it play our audio?  It seems the problem is related to the fact that the asynchronous .Play() method, being spun from the current executing thread, does not have enough time to execute before the modal .Show() method is executed.  As you know, the MessageBox.Show() method will block the existing thread from executing any further until user action is taken on the window.  As such, the Play() method is queued really quickly given present computer CPU speeds, and once the.Show() method is invoked, it aborts the asynchronous threads to the .Play() method.  To solve the problem we have to allow the .Play() method some time to begin execution.  The easiest way to do that is to simply .Sleep() the current thread.  By injecting this line of code:

System.Threading.Thread.Sleep(1500);

right after the .Play() call, the currently executing thread will pause for 1.5 seconds.  Depending on what audio you’re playing, you can tweak this value (in milliseconds) to match accordingly.

At this point, the alert message and audio work correctly… but the OCD in me still isn’t happy with the effect we get.  When the error condition is generated, the audio alert is played three times, per our code, and then the error alert is popped up.  The problem I have with that is that the audio warning gets my attention, but then I have to wait for it to finish playing three times before the error message with useful information pops up.  That should be easy to fix, right?  Why not just simply move the .Show() method call to before the for() loop containing the .Play() call?

Unfortunately, this doesn’t work as you’d expect.  Because of the fact that the .Show() call actually freezes the current thread, the message box is displayed and then awaits user interaction before it allows the audio code to execute.  What we need is for the .Show() code to be spun off in another thread so as to allow the audio alert to play while the message is displayed.  To do this, we create a new method thus:

public void ShowAlert()
{
    System.Threading.Thread t = new System.Threading.Thread(() =>
    {
        MessageBox.Show("There is an error!", "ERROR", MessageBoxButtons.OK, MessageBoxIcon.Error);
    });
    t.Start();
}

Once we have the message box contained in a separate thread, we simply make that call prior to playing our audio thus:

ShowAlert();
for (int i = 0; i <= 2; i++)
{
    System.Media.SoundPlayer p = new System.Media.SoundPlayer(@"TNG-Red-Alert.wav");
    p.Play();
    System.Threading.Thread.Sleep(1500);
}

Once the user interacts with the message box, the thread (t) will terminate gracefully.  In the mean time our main app is free to continue execution of our loop to play the alert sound.



Cheers
C




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Fixing Visual Studio 2012 defaults

Written by Cornelius J. van Dyk on . Posted in Annoyances, How Do I...

One of the biggest pet peeves I experienced when switching to Visual Studio 2012 was the fact that the default command buttons were changed.  In going for a cleaner look, many of the main command buttons most developers use most frequently, was removed from the toolbar interface and buried in the menu structure instead.

Personally, the buttons I find myself using most frequently are the Navigate Backwards and Navigate Forwards (image ), Comment Selected Lines and Uncomment Selected Lines (image ) and lastly Increase Line Indent and Decrease Line Indent (image ).

The Navigate functions are still there, but the Comment and Indent functions are buried deep within the Edit/Advanced menu.  While it’s true that the Comment functions do have hot keys attached to them, I hardly consider Ctrl+K,Ctrl+C for a single click to be useful to most developers save the few that know the hotkeys by heart.

As for the Indent commands, they don’t have any hotkeys and you’d have to click through Edit/Advanced/Indent to get the action.  Though small annoyances, these can be addressed by simply adding the commands back to the command bar.  Here’s how to do just that:

  1. Click Tools on the menu bar.
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  3. On the popup menu, click “Customize”.
  4. After the Customize dialog window opens, click over to the “Commands” tab.
  5. Select the “Toolbar” radio button.
  6. In the dropdown to the right of the Toolbar radio button, select the “Standard” toolbar to work with.
  7. The toolbar’s controls will be previewed in the bottom left of the dialog window.
  8. To the right of the preview, click the “Add Command” button.
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  10. In the Add Command dialog window that opens up, select the “Edit” category to the left.
  11. On the right, scroll down through the commands and locate the “Line Indent” command.
  12. Select the command and click the “OK” button.
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  14. The command will be added to the top of the Controls preview.
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  16. Repeat steps 8 through 12 for the “Line Unindent”, “Selection Comment” and “Selection Uncomment” commands as well.  The interface doesn’t allow multi-select, though that would be nice touch in a future update.
  17. Once you have all the commands, use the “Move Up” and “Move Down” buttons to the right to arrange the commands in the order you wish them to appear on the toolbar.
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  19. When you’re happy with the arrangement, click the “Close” button.  Your new toolbar should now reflect your favorite buttons again. 🙂
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Cheers
C




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How do I – Scroll the Telerik RadGridView to the top after a data refresh?

Written by Cornelius J. van Dyk on . Posted in How Do I...

What seems like a very simple thing to do, and quite frankly it should be, turned out to be a little more tricky than I thought. Setting the Scene The app has a RadGridView control that displays information from a SQL database. The data is presented to the control via a simple Linq2SQL DataSet. Given that the RadGridView control has a .CurrentRow property which is updatable, logic dictates that a simple statement such as this:

 1:  grdContentSources.CurrentRow = grdContentSources.Rows[0];
would take care of moving the cursor to the top after the data refresh. Alas, it doesn’t. Next I experimented with disconnecting the data source, filling the table adapter and then reconnecting the data source to the grid, but that didn’t work either. Internet searches, especially the very helpful Telerik support site, indicated that we should be using the .IsCurrent() method of the row instead. So this should solve the problem, right?
 1:  grdContentSources.Rows[0].IsCurrent = true;
Unfortunately, that didn’t solve the problem either. Then I found an obscure comment from “Jack”, and Admin on the Telerik team, that pointed me towards the .ChildRows collection for sorted data instead. Since I did have some sorting on the grid, I tried it and it worked! Here’s the complete code:
 1:  Cursor.Current = Cursors.WaitCursor;
   2:  this.crawlManDBDataSet.vwContentSourceCrawlHistory.Clear();
   3:  this.vwContentSourceCrawlHistoryTableAdapter.Fill(
   4:    this.crawlManDBDataSet.vwContentSourceCrawlHistory);
   5:  grdContentSources.ChildRows[0].IsCurrent = true;
   6:  Cursor.Current = Cursors.Default;
Since the operation takes some time, in line 1 we set the cursor to the hour glass. In line 2 we clear the source table for the grid. In line 3 we refill the table to get refreshed data. This reflects back onto the grid as it triggers a .Changed() event to refresh the grid view. Line 5 is where the magic happens as we simply set the .IsCurrent property of the .ChildRows[0] row to be true. Using zero takes the grid back to the top. We could set this to any value within the range of the grid e.g. we could have used:
 1:  grdContentSources.ChildRows[
   2:    grdContentSources.ChildRows.Count - 1].IsCurrent = true;
in order to scroll the grid to the bottom instead.

Cheers
C




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