Beginning REALbasic - From Novice To Professional (2006)

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On Linux, you can get to a command prompt by opening a Terminal window. On Windows, you can get to the command prompt by clicking Start Accessories Command Prompt. On Mac OS X, you can get to the command prompt by opening the Applications folder, followed by the Utilities folder, where you find the Terminal utility.

Once you successfully run the application, create a new REALbasic desktop application and add the database it. Next, double-click the database to open the Database Editor and select the BookCollection table. You should see the columns Figure 10-19 shows.

Figure 10-19. Examining the schema for the PersonalBookDB database, as seen on Linux

Next, click the Query button and submit a query to make sure all three initial records were added to the database. To do so, click the Advanced button, type Select * From BookCollection, and then click Select. If everything looks in order, you are ready to continue and create the desktop application that will let you add new book entries into the database. Go ahead and keep this new project open because you use it in the next section to create a frontend database application.

Creating a Utility to Add New Books

To create a front-end database desktop application that enables you to add additional books to the PersonalBookDB, take the new project you just created and added the database to, and save it as DBAdd. Begin by selecting the Title property for Window1 to RB Book Add. Next, add six StaticText and six EditField controls in two columns. Then, add a PushButton control to the window, and align it and the rest of the controls, as Figure 10-20 shows.

Figure 10-20. Building a front-end user interface for the PersonalBookDB database, as seen on Linux

Next, modify the properties belonging to the controls you just added to the windows, as Table 10-1 specifies.

Table 10-1. Modifying Properties Belonging to Controls on the DBAdd Application

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As you can see from the name assigned to the StaticText and EdifField controls, they are individually associated with specific columns in the database. Next, add the following program code to the pbnAdd PushButton control’s Action Event Handler.

Dim dbFile As FolderItem

Dim BookDB As REALSQLdatabase

Dim DBRecord As DatabaseRecord 'Declare a variable representing a DatabaseRecord Dim TargetFile As FolderItem 'Declare a variable representing a FolderItem

If edfTitle.Text <> "" Then

BookDB = New REALSQLdatabase

TargetFile = GetFolderItem("PersonalBookDB")

BookDB.DatabaseFile = TargetFile

If BookDB.Connect() then

DBRecord = New DatabaseRecord 'Instantiate a new record

'Assign elements to table columns DBRecord.Column("Title") = edfTitle.Text DBRecord.Column("Author") = edfAuthor.Text DBRecord.Column("Publisher") = edfPublisher.Text DBRecord.Column("Location") = edfLocation.Text DBRecord.Column("Category") = edfCategory.Text DBRecord.Column("ISBN") = edfISBN.Text

'Use the InsertRecord method to add the record to the table BookDB.InsertRecord("BookCollection", DBRecord) BookDB.Commit 'Complete the database transaction

BookDB.Close 'Terminate the database connection

MsgBox "Book added to database"

'Clear out the EditField controls to allow for a new entry edfTitle.Text = ""

edfAuthor.Text = "" edfPublisher.Text = "" edfLocation.Text = "" edfCategory.Text = "" edfISBN.Text = ""

Else

'Display the error message that occurred

MSgBox "DataBase Error: " + BookDB.ErrorMessage

End If

Else

MsgBox "Error: Empty database records cannot be processed."

End If

This code executes each time the pbnAdd PushButton control is clicked. The job of the pbnAdd PushButton is to collect data keyed in by the user and to load it into the database as a new record. Note, to prevent blank records from being added to the PersonalBookDB, a check is made to ensure the user has entered something into the EditField control representing the Title column in the database’s BookCollection table.

Once you finish adding the required program code, save the DBAdd application and compile it. Add a few new book entries to the database. Then, close the application and return to the REALbasic IDE. Open the Project Editor and double-click the PersonalBookDB item. Check to make sure the new records you just added were properly added to the database.

Summary

In this chapter, you learned a little about the basics of database program development. This included learning how to open and create REAL SQL databases, using both the REALbasic GUI and program code. You also learned how to specify database schema, and how to add and modify database records. You learned how to work with both the Database Query and DataControl controls, as well as how to work programmatically with a number of REALbasic database-related classes.

the Project screen. You can then play the sound file by referring to it by name, and then calling on the Sound class’s Play method, as the following shows.

Welcome.Play

Here, a sound file named Welcome was imported into the project making it available for play using the previous code statement. Similarly, you can play the sound file over and over again, as the following shows.

Welcome.PlayLooping

You can also stop playing the sound file at any time, as shown here.

Welcome.Stop

Playing an imported sound file is an effective option when you want to play custom sound files and distribute them as part of your application.

Pointing to External Sound Files

Another way to play sound files is to use the FolderItem class and the GetFolderItem function, as the following shows.

Dim TargetFile As FolderItem 'Declare a FolderItem object

This example sets up the playing of a wave file stored in the same folder as the REALbasic application by instantiating a FolderItem object and specifying the path of the sound file. A check is then made to ensure the sound file exists before using the FolderItem class’s OpenAsSound method to retrieve a reference to the sound file, which is then played.

■Note The FolderItem class’ OpenAsSound method provides you with the capability to open a sound file, which can then be programmatically played, paused, restarted, and stopped using methods and properties belonging to the Sound class. On Macintosh, you can play any Macintosh System 7 audio files. You can also play any sound file supported by QuickTime on Windows and Macintosh, including MP3 files. The Sound class can also play wave files on Windows using DirectSound, which is a component of Microsoft’s DirectX (Microsoft’s high-performance graphic and sound engine).

When you use this option for playing sound files, you must ensure in advance that the sound files exist in the specified location on the computer where the application will run. You can ensure this by installing copies of the sound files yourself in the appropriate folders or by using sound files that ship as part of the operating system (OS).

Playing User Selections

A third option for playing sound files is to let the user specify the location of their sound files, as the following example shows.

If TargetFile <> Nil Then 'Proceed if the user did not click on Cancel

End If

In this example, the GetOpenFolderItem function is used to display a generic Open window dialog, enabling the user to specify the name and location of the sound file to be played.

Giving Your Application a Voice

If you are developing your REALbasic applications exclusively for Macintosh or Windows, you might want to take advantage of REALbasic’s Speak method. This method provides you with the capability to use the operating system’s built-in speech synthesizer to pronounce text strings and has the following syntax.

Speak(TextPhrase, [Interrupt])

TextPhrase is a placeholder representing the text string to be pronounced. Interrupt is an optional parameter, which, when set equal to True, cancels any previous calls made to the Speak method.

The Speak method is easy to use. For example, start up a new REALbasic project and add an EditField control and three PushButton controls. Enable the EditField control’s Multiline property and label the three PushButton controls as Instructions, Talk, and Clear, as Figure 11-1 shows.

Figure 11-1. Creating a REALbasic application that pronounces text strings, as seen on Windows

Add the following code statement to the PushButton labeled Instructions.

Speak "Type anything you wish into the entry field and click on the " _ + "talk button to listen."

When clicked, this button pronounces the supplied text string. Next, add the following code statement to the button labeled Talk.

Speak EditField1.Text

When clicked, this control pronounces any text typed into the EditField1 control. Finally, add the following code statement to the PushButton control labeled Clear.

EditField1.Text = ""

When clicked, this button clears out any text entered into the EditField1 control, enabling the user to enter new text.

■Note You can find a working example of this application on this book’s companion CD-ROM.

Making Music

As you can see, REALbasic provides robust audio capabilities. In addition to playing Beeps, audio sounds, and supporting speech pronunciation on Macintosh and Windows, REALbasic also supports the playing of musical notes using the NotePlayer control (on Macintosh when QuickTime is installed and on Windows via MIDI functions).