The Common Dialog control is used to display dialog boxes commonly found in windows applications (hence the name!) Some common dialogs include: Open File, Save File, Print File, and Color.

Installing the Common Dialog Box

The Common Dialog box may NOT be your standard VB toolbox. It looks like this:

If it is NOT installed, follow these steps.

Select Components from the Project Menu (or press Control-T), You will see the Components Dialog box as shown below. Make sure the Controls tab is selected.

Scroll Down and check Microsoft Common Dialog Control 6.0

Click OK

You should now see the control in your toolbox.

The Many Methods of the Dialog Box

The common dialog box is one of the most complex controls in Visual Basic. The various behaviors of the box is controlled by the following methods:

To experiment with some of these methods.

Step 2: Set the Properties

There is nothing special about the text box and six buttons other than the fact that a vertical scroll bar was added to the text box. Name the controls: 

	txtDisplay
	cmdOpenFile
	cmdSaveFile
	cmdFont
	cmdPrint
	cmdTextColor
	cmdBackColor

Visual Basic allows you to write code that handles errors. The method is based on the traditional programming idea of a "flag." The computer raises an error flag when an error occurs. Your VB code can then intercept the error before the program crashes. To use error trapping, follow the following steps.

 As it turns out, Visual Basic considers selecting Cancel from a dialog box

Example:

Sub cmdFont_Click( )

CommonDialog1.CancelError = False 'set the error flag
On Error GoTo FontError ‘where to go

…The code goes here

… and here

FontError: ‘this is a label

Exit Sub

FontError:

End Sub

Some methods of the Common Dialog box use other flags to control behaviors. The Font dialog Flags property must be set to the value 1 to load the system fonts.

After the font dialog box appears and selections are made, the values the user selected are available to the program.

The psuedocode for the font subroutine is:

Set Cancel Error flag
Error handler
Set Flags property to 1
Display the dialog box
Set font properties for bold, italic, font strike through font size, font name, and properties of text box (example: txtFontBold = CommonDialog1.FontBold)

Error label (in this case, we don’t need ANY code here!)

Rather than typing

etc,, we can use a shortcut

The Code for the Font Dialog is

When an Open File dialog box appears, the user is presented with a selection of file types to choose from, with one type being the default (like *.doc files in Word). This is controlled by the .Filter and .FilterIndex properties. The .Filter describes the file types in a drop down menu.

note: the Filter begins and ends with a quote marks. The pipe | is used as a separator.

these pipes come RIGHT AFTER the file type (no space)

CommonDialog1.Filter = "Text Files (*.txt) | *.txt| All Files (*.*) |*.*|HTML Files (*.htm)|*.htm*"

to make the first item -"Text Files (*.txt) the default, use the FilterIndex Property

CommonDialog1.FilterIndex = 1

The code for the Open File dialog is:

On Error GoTo OpenError
Dim F As Integer
F = FreeFile
CommonDialog1.CancelError = True
CommonDialog1.Filter = "Text Files (*.txt)|*.txt| Web Files (*.htm)|*.htm"
CommonDialog1.ShowOpen
Open CommonDialog1.FileName For Input As F
txtWord.Text = Input(LOF(F), F)
Close #F

Exit Sub

OpenError:

Files

The values returned from the dialog box are used to open a file. Computers do not write or read directly to files, they use buffers. A buffer number and a file name must be obtained, then the file can be assigned to a buffer and used. The psuedocode looks like this:

To display the Print Dialog, use

Some of the properties returned are:

Printing is easy. Visual Basic considers the printer to be an object, and uses the object's Print method.

Thus to print the contents of a text box, use

Printer.Print txtWord.Text
Printer.EndDoc

Of course, you can use the properties returned by the Printer Dialog to control how the printer works. For example, you can use the Copies properties in a For loop to have the page printer more than once.

To save a file, use the Print# command with the buffer number.

Before you do this, you must:

If the user chooses Save As, they should always be shown the Save common dialog box. However, if the choose Save, the computer must make a decision.

Because the Save dialog must always be shown when the user chooses SaveAs, we will actually be adding the dialog box  mnuSaveAs rather that mnuSave.

How do we know if the file has a name?To do this, we will create a global string variable called FileName. We will set this name to "nothing" in Form_Load. In our mnuSaveAs subroutine, we will assign FileName the name of the file being saved. In mnuOpen, we must also assign the opened file name to FileName. In mnuNew, we will set it back to "nothing." (Remember, in programming "nothing" is indicated by using two quote marks with NOTHING between them - not even a space!) In sum,

	On Form_Load - Set FileName to ""
	mnuSaveAs - Set FileName to CommonDialog1.FileName
	mnuOpen - Set FileName to CommonDialog1.FileName
	mnuNew - Set FileName to ""

These lines must be added to the appropriate subroutines.

The psuedocode needed to save a file are:

You should now be able to add save, save as, open, print, and set font to your word processor!