426 Part III Designing the User Interface
- Scroll to the top of the form, and then enter the following code:
Imports System.IO 'for FileStream class
Imports System.Drawing.Printing
These statements make it easier to reference the FileStream class and the classes for
printing.- Move the cursor below the Public Class Form1 statement, and then enter the following
variable declarations:
Private PrintPageSettings As New PageSettings
Private StringToPrint As String
Private PrintFont As New Font("Arial", 10)
These statements define important information about the pages that will be printed. - Scroll to the btnOpenClick event procedure, and then type the following program
code:
Dim FilePath As String
'Display Open dialog box and select text file
OpenFileDialog1.Filter = "Text files (.txt)|.txt"
OpenFileDialog1.ShowDialog()
'If Cancel button not selected, load FilePath variable
If OpenFileDialog1.FileName <> "" Then
FilePath = OpenFileDialog1.FileName
Try
'Read text file and load into RichTextBox1
Dim MyFileStream As New FileStream(FilePath, FileMode.Open)
RichTextBox1.LoadFile(MyFileStream,
RichTextBoxStreamType.PlainText)
MyFileStream.Close()
'Initialize string to print
StringToPrint = RichTextBox1.Text
'Enable Print button
btnPrint.Enabled = True
Catch ex As Exception
'display error messages if they appear
MessageBox.Show(ex.Message)
End Try
End If
When the user clicks the Open button, this event procedure displays an Open dialog
box using a filter that displays only text files. When the user selects a file, the file name
is assigned to a public string variable named FilePath, which is declared at the top of
the event procedure. The procedure then uses a Try... Catch error handler to load the
text file into the RichTextBox1 object. To facilitate the loading process, I’ve used the
FileStream class and the Open file mode, which places the complete contents of the
text file into the MyFileStream variable. Finally, the event procedure enables the Print
button (btnPrint) so that the user can print the file. In short, this routine opens the file
and enables the print button on the form but doesn’t do any printing itself.
Now you’ll add the necessary program code to display the Print dialog box and print the file
by using logic that monitors the dimensions of the current text page.