Beginning REALbasic - From Novice To Professional (2006)

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Coding the Print Menu Item

The next step is to add the code for the FilePrint menu handler. Begin by keying in the following code statements.

Dim PrintSettings As PrinterSetup 'Declare a PrinterSetup variable

Dim StpObject As StyledTextPrinter			'Declare StyledTextPrinter variable
Dim GObject As	Graphics	'Declare	a Graphics	object variable
'Set default width and height settings
Dim PrintWidth	As Integer	= 504	'504 pixels	equals	7.5 inches
Dim PrintHeight As Integer = 648			'648 pixels	equals	9 inches

As you can see, a PrinterSetup object is declared, followed by a StyledTextPrinter and a Graphics object. The StyledTextPrinter object is used to allow the application to print styled text and the Graphics object’s DrawBlock method is used to print the text document. A pair of variables is then declared. These variables are used to define the width and height of printed pages.

Next, append the following code statements to the FilePrint menu handler. Because Linux does not provide support for the Print Setup dialog, a #If…#EndIf block is set up to allow the embedded code statements to execute only on Windows and Macintosh.

#If TargetLinux = False Then 'Linux does not have a Print Setup dialog

PrintSettings = New PrinterSetup 'Instantiate the PrinterSetup object

'Load any settings previously specified by the user If PageSetup <> "" Then

PrintSettings.SetupString = PageSetup 'Assign saved print settings End if

'Display the Page Setup dialog and collect setting updates If PrintSettings.PageSetupDialog Then

PageSetup = PrintSettings.SetupString 'Save print settings End if

If PageSetup	<>	"" Then	'If	specified		use Page	Setup settings
PrintSettings.SetupString =				PageSetup		'Assign	the	settings
PrintWidth	= PrintSettings.Width				'Retrieve the width setting
PrintHeight =		PrintSettings.Height				'Retrieve	the	height setting

'Display the Print dialog using the above settings GObject = OpenPrinterDialog(PrintSettings)

Else 'Use hardcoded value for page height and width

GObject = OpenPrinterDialog() ' Display default Print dialog End If

#Else

GObject = OpenPrinterDialog() 'Display the Print dialog on Linux #Endif

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As you can see, a PrinterSetup object is instantiated. Then, any previously specified print settings set by the user are assigned to the SetupString property belonging to the PrintSettings PrinterSetup object. A Page Setup dialog is then displayed, enabling the user to change print settings. If the user made any changes to the page Setup settings, they are retrieved and passed to the OpenPrinterDialog function. If the user did not make any change to the Page Setup settings, the OpenPrinterDialog is called without being passed any settings.

The last statement embedded in the #If…#EndIf block only executes if the application is run on a Linux system, in which case all the preceding statements are skipped and the OpenPrinterDialog functions is executed. Note, each time the OpenPrinterDialog function is called, a value is assigned to GObject. Now, to finish the FilePrint menu handler, append the following code statements to the statements you just keyed in.

If GObject <> Nil Then 'Make sure the user did not press Cancel button

'Pass the graphics object to the EditField's StyledTextPrinter method 'Pad the PrintWidth value by a half inch to accomidate styled text StpObject = edfTextArea.StyledTextPrinter(GObject, PrintWidth - 36)

Do Until StpObject.EOF	'Loop until		every page has been printed
'Set the location of	the upper	left-hander corner
StpObject.DrawBlock 36, 36, PrintHeight
If Not StpObject.EOF	Then 'if	not	at end of page keep going
GObject.NextPage	'Set up a	new	page
End If
Loop

End If

These code statements check to make sure the user did not click the Print Dialog’s Cancel button and are responsible for printing document text a page at a time, using the Graphic class’s DrawBlock method.

Coding the Exit (Quit) Menu Item

The following shows the code for the FileQuit menu handler. It uses the MessageDialog class to display a pop-up dialog window in case the user tries to close down the application without saving any unsaved changes in a text file.

If NewChanges = True Then 'Display popup if there are unsaved changes

'Declare and instantiate a MessageDialog object Dim mdgAbout as New MessageDialog

Dim mdbResult as MessageDialogButton 'Declare variable to hold result

'Update the display of text in the titlebar mdgAbout.Title = "Warning: You have unsaved changes!"

mdgAbout.icon = MessageDialog.GraphicCaution		'Display caution icon
mdgAbout.ActionButton.Caption = "Quit Anyway"		'Set ActionButton text
mdgAbout.CancelButton.Visible = True	'Display	of the Cancel button
mdgAbout.Message = "You have unsaved	changes."	'Display a summary

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'Display primary warning message mdgAbout.Explanation = _

"Please confirm that you still want to close this application."

mdbResult = mdgAbout.ShowModal 'Display the popup dialog

If mdbResult = mdgAbout.CancelButton Then 'The user clicked on Cancel Return True 'Prevent the window from closing

End If End If

Note the Return True statement in the last If…Then statement. This statement executes when the user elects to click the pop-up dialog window’s Cancel button. By returning a value of True, this statement stops the application from closing. This enables the user to save any unsaved text files before exiting the RB Word Processor application.

Coding the Help Menu’s About Menu Item

The following shows the code for the HelpAbout menu handler. It uses the MessageDialog class to display a pop-up dialog window that gives the user a little information about the application and its author.

'Declare and instantiate a MessageDialog object Dim mdgAbout as New MessageDialog

Dim mdbResult as MessageDialogButton 'Declare a variable to hold result

mdgAbout.Title = cTitlebarMsg	'Display a message in the		titlebar
mdgAbout.icon=MessageDialog.GraphicNote		'Display a note	icon
mdgAbout.ActionButton.Caption="OK"		'Specify ActionButton text

mdgAbout.Message="RB Word Processor" mdgAbout.Explanation="By Jerry Ford - 2006"

mdbResult = mdgAbout.ShowModal 'Display the popup dialog

Adding Code That Supports the Window and Its Controls

To wrap up your work on the RB Word Processor application, you need to add the code statements required to make the application’s controls function. This includes BevelButton controls, the three PushButton controls, and the addition of a little code to the EditField control’s SelChange event handler.

Coding the bbFontType Control

Let’s begin by selecting the bbFontType control’s Action event handler and adding the following code statements. The first code statement is responsible for displaying whichever font the user might select in the BevelButton control’s Caption.

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'Set the BevelButton's caption equal to the value selected by the user bbFontType.Caption = bbFontType.List(bbFontType.MenuValue)

'Set the font type of the selected text equal to the font type 'specified in the BevelButton control's Caption edfTextArea.SelTextFont = bbFontType.Caption

Earlier, when you added the application’s EditField control, you left its TextFont and TextSize properties equal to System and 0. The result of this is the default font and font size of each OS is used as the application’s default font and font size. By selecting a different font type from the BevelButton control’s drop-down list, the user can change the font type applied by the word processor. The last statement’s job is to update the font type applied to any currently selected text.

For the user to be able to select a font type, a list of available fonts must first be loaded into the BevelButton control. You can accomplish this by adding the following code statements to the bbFontType control’s Open event handler.

'Declare variable to be used as a counter in a For...Next loop Dim intCounter As Integer

'Loop through each font and add to list in the BevelButton control 'FontCount is a function that returns the number of fonts installed For intCounter = 1 to FontCount – 1

'Font is a function that retrieves the names of fonts bbFontType.AddRow Font(intCounter)

Next

'Set value displayed on BevelButton equal to currently selected font bbFontType.Caption = edfTextArea.SelTextFont

Note, the last code statement sets the BevelButton control’s Caption based on the EditField control’s default font type (which is set by the OS).

To finish your work on the first BevelButton control, you must add the following code statements to the EditField control’s SelChange event handler.

'Update the caption of the BevelButton that represents font type each 'time the user repositions the cursor

If edfTextArea.SelTextFont <> bbFontType.Caption Then bbFontType.Caption = edfTextArea.SelTextFont

End If

The SelChange event occurs whenever the user repositions the cursor in the EditField control. These statements check to see if the currently selected font type matches the font type displayed in the bbFontType control’s Caption and changes the value assigned to the Caption property if no match occurs.

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Coding the bbFontSize Control

Next, you need to set up the BevelButton control (bbFontSize) with the capability to display different font sizes. Do so by opening the control’s Action event handler and entering the following code statements.

'Set the BevelButton's caption equal to the value selected by the user bbFontSize.Caption = bbFontSize.List(bbFontSize.MenuValue)

'Set the text size of the selected area in the EditField equal to the 'font size specified in the BevelButton control's Caption edfTextArea.SelTextSize = Val(bbFontSize.Caption)

For the user to be able to pick a font size, you need to populate the second BevelButton control (bbFontSize) with a list of font sizes. To do so, add the following code statements to the control’s Open event handler.

'Populate this menu with a list of typical font size values bbFontSize.AddRow "8"

bbFontSize.AddRow "9" bbFontSize.AddRow "10" bbFontSize.AddRow "11" bbFontSize.AddRow "12" bbFontSize.AddRow "14" bbFontSize.AddRow "16" bbFontSize.AddRow "18" bbFontSize.AddRow "20" bbFontSize.AddRow "22" bbFontSize.AddRow "24" bbFontSize.AddRow "26" bbFontSize.AddRow "28" bbFontSize.AddRow "36" bbFontSize.AddRow "48" bbFontSize.AddRow "72"

'Set the BevelButton's Caption display the default font size bbFontSize.Caption = Str(edfTextArea.SelTextSize)

Note, the last statement updated the control’s Caption, based on the EditField control’s currently selected font size.

Like the BevelButton control that manages the display of the font type, the bbFontSize control is responsible for keeping the user abreast of the size of the currently selected font size when the user repositions the cursor to a different location in the EditField control. To accomplish this, add the following code statements to the edfTextArea control’s SelChange event handler.

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'Update the caption of the BevelButton representing font size each time 'the user repositions the cursor

If Str(edfTextArea.SelTextSize) <> bbFontSize.Caption Then

'If more than one font size is selected display a empty string in the 'BevelButton representing font size. Otherwise display the font size If edfTextArea.SelTextSize <= 0 Then

bbFontSize.Caption = "" Else

bbFontSize.Caption = Str(edfTextArea.SelTextSize) End If

End If

In the event the user selects text made up of different size fonts, REALbasic sets the value of SelTextSize equal to zero. Rather than showing this value to the user, the last If…Then…Else code block substitutes an empty string.

Coding the bbBold Control

Now, let’s move on to the bbBold PushButton control and add the following code statements to its Action event.

'Use the EditField's ToggleSelectionBold method to apply or remove ' bold text formatting

edfTextArea.ToggleSelectionBold

When executed, the net effect of this code is to toggle any selected text off from nonbold to bold and vice versa.

Coding the bbItalics Control

Next, add the following code statements to the bbItalics control’s Action event handler.

'Use the EditField's ToggleSelectionBold method to apply or remove ' italic text formatting

edfTextArea.ToggleSelectionItalic

Coding the bbUnderline Control

Finally, add the following code statements to the bbUnderline control’s Action event handler.

'Use the EditField's ToggleSelectionBold method to apply or remove ' underline text formatting

edfTextArea.ToggleSelectionUnderline

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Testing RB Word Processor

That’s it! Go ahead and save and test the RB Word Processor application. Given the size and complexity of this application, you’re probably going to have a few typos to deal with. If you don’t have the time to create this application from scratch, but you still want to see how it works, you can find its source code on this book’s companion CD-ROM. Once you get the application to compile successfully, save it, and then put it through its paces by testing and validating the operation of all its features and functionality.

Summary

In this chapter, you learned how to work with text files and folders, including special folders. You learned how to define the file types your applications will be able to work with. You learned how to create, open, format, save, and print text files. You also learned how to work with an assortment of new functions and classes that provide access to standard windows, such as the Open and Save As dialogs.

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Working with Databases

In Chapter 9, you learned how to programmatically create and work with text files. REALbasic also provides robust support for databases. REALbasic’s own database, the REAL SQL database, is built right into REALbasic Standard and Professional. REALbasic can also be set up to work with a number of popular third-party databases. Using REALbasic to create a front-end database interface, you can build applications that can send and retrieve any amount of data to and from back-end databases. This chapter demonstrates how to set up and programmatically interact with REAL SQL Databases.

Specifically, you learn how to

•Create new REAL SQL databases from both program code and the REALbasic IDE

•Define database schemas

•Add, modify, and delete database records

•Create database front ends

REALbasic’s Database Support

A database is a repository for storing and retrieving data. Databases can be used to store small collections of data, such as information about a personal collection of books, music, or videos. Databases can also be used to efficiently store enormous amounts of data. For example, your local utility company, cable company, and telephone company all store information about you stored in a database somewhere. Using this information, they keep track of where you live, how much you spend, when your next payment is due, and whether you owe them any money.

REALbasic’s built-in database, the REAL SQL database, is not only perfect for developing small database applications, it is also capable of handling massive amounts of data. However, it is a file-based database, as opposed to a server database, which means only one person at a time can access and work with a REAL SQL database.

The REAL SQL database is included in both the Standard and Professional Editions of REALbasic. Other third-party databases (such as MySQL and SQL Server) are only supported by the Professional Edition of REALbasic. While the REAL SQL database isn’t sufficient for large industrial-sized databases, you might also use it as a temporary database when you develop database front-end applications. Once completed, you can modify the application to use

the database of your choice.

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■Note A front-end database application is simply a graphical user interface (GUI) that provides the user with access to the data stored in a database. The job of the front-end application is to submit requests to the back-end “database” and retrieve any returned data. In database terminology, the back-end database application is also referred to as a data source.

Database Plug-Ins

To work with a third-party database, you need to add a plug-in for that database to REALbasic’s plug-ins folder. A plug-in is a file that provides REALbasic with everything it needs to work with a particular database. You can find a collection of plug-ins for a number of popular databases located in the download area at www.realbasic.com.

■Tip If you want to work with a database for which no plug-in is available at REALbasic’s website, visit that database vendor’s website to see if they provide a plug-in of their own for REALbasic. In addition, REAL Software provides a plug-in software developer’s kit (SDK), which you or a third party can use to create a plug-in for virtually any database. You can download this SDK from the download area at www.realbasic.com.

Structured Query Language

The job of the front-end database application is to package database requests and submit them to the back-end database, which might be a REAL SQL database or one of the many supported third-party databases. To accomplish this task, REALbasic front-end applications use Structured Query Language (SQL) statements to request data from the database. For third-party database back-ends, the job of the associated plug-in is to translate front-end application commands into a format the database understands and to pass it along.

■Tip A complete overview of SQL is beyond the scope of this book. Instead, this book endeavors to present you with the basic steps required to perform common database tasks. REALbasic’s built-in database, the REAL SQL database, is based on the SQLite database, which provides support for a subset of SQL. For specifics on the supported SQL commands, check out www.sqlite.org. If you are working with a different database, you need to refer to the vendor’s website for that database to see what documentation is available regarding the database’s SQL support.

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Creating and Opening REAL SQL Databases

REALbasic provides you with everything you need to create new databases using commands available within the REALbasic IDE. This includes creating new REAL SQL databases or any third-party database for which plug-ins have been added to REALbasic’s plug-ins folder. In addition, using the REALbasic REALSQLDatabase class, you can programmatically create new REAL SQL databases.

Creating a New REAL SQL Database from the IDE

To create a new REAL SQL database from the REALbasic IDE, open the Project screen and click Project Add Database New REAL SQL database. (Note, if you installed any third-party database plug-ins, you should also see entries for those databases listed.) REALbasic responds by displaying a standard Save or Save As dialog, enabling you to specify the name and location of the database you want to create.

Once added to your REALbasic application, the new database is displayed as a file item in the Projects screen, as shown in Figure 10-1.

Figure 10-1. Adding a new REAL SQL database to your application, as shown on Mac OS X