Imports System
Imports System.Drawing
Imports System.Windows.Forms
Imports System.ComponentModel
Imports System.Text
Imports System.IO
' A simple form that represents a window in our application
Public Class AppForm1
Inherits System.Windows.Forms.Form
Public Sub New()
MyBase.New()
Me.Size = New System.Drawing.Size(300, 300)
Me.Text = "AppForm1"
End Sub
End Class
' A simple form that represents a window in our application
Public Class AppForm2
Inherits System.Windows.Forms.Form
Public Sub New()
MyBase.New()
Me.Size = New System.Drawing.Size(300, 300)
Me.Text = "AppForm2"
End Sub
End Class
' The class that handles the creation of the application windows
Public Class MyApplicationContext
Inherits ApplicationContext
Private formCount As Integer
Private form1 As AppForm1
Private form2 As AppForm2
Private form1Position As Rectangle
Private form2Position As Rectangle
Private userData As FileStream
Public Sub New()
MyBase.New()
formCount = 0
' Handle the ApplicationExit event to know when the application is exiting.
AddHandler Application.ApplicationExit, AddressOf OnApplicationExit
Try
' Create a file that the application will store user specific data in.
userData = New FileStream(Application.UserAppDataPath + "\appdata.txt", FileMode.OpenOrCreate)
Catch e As IOException
' Inform the user that an error occurred.
MessageBox.Show("An error occurred while attempting to show the application." + _
"The error is:" + e.ToString())
' Exit the current thread instead of showing the windows.
ExitThread()
End Try
' Create both application forms and handle the Closed event
' to know when both forms are closed.
form1 = New AppForm1()
AddHandler form1.Closed, AddressOf OnFormClosed
AddHandler form1.Closing, AddressOf OnFormClosing
formCount = formCount + 1
form2 = New AppForm2()
AddHandler form2.Closed, AddressOf OnFormClosed
AddHandler form2.Closing, AddressOf OnFormClosing
formCount = formCount + 1
' Get the form positions based upon the user specific data.
If (ReadFormDataFromFile()) Then
' If the data was read from the file, set the form
' positions manually.
form1.StartPosition = FormStartPosition.Manual
form2.StartPosition = FormStartPosition.Manual
form1.Bounds = form1Position
form2.Bounds = form2Position
End If
' Show both forms.
form1.Show()
form2.Show()
End Sub
Private Sub OnApplicationExit(ByVal sender As Object, ByVal e As EventArgs)
' When the application is exiting, write the application data to the
' user file and close it.
WriteFormDataToFile()
Try
' Ignore any errors that might occur while closing the file handle.
userData.Close()
Catch
End Try
End Sub
Private Sub OnFormClosing(ByVal sender As Object, ByVal e As CancelEventArgs)
' When a form is closing, remember the form position so it
' can be saved in the user data file.
If TypeOf sender Is AppForm1 Then
form1Position = CType(sender, Form).Bounds
ElseIf TypeOf sender Is AppForm2 Then
form2Position = CType(sender, Form).Bounds
End If
End Sub
Private Sub OnFormClosed(ByVal sender As Object, ByVal e As EventArgs)
' When a form is closed, decrement the count of open forms.
' When the count gets to 0, exit the app by calling
' ExitThread().
formCount = formCount - 1
If (formCount = 0) Then
ExitThread()
End If
End Sub
Private Function WriteFormDataToFile() As Boolean
' Write the form positions to the file.
Dim encoding As UTF8Encoding = New UTF8Encoding()
Dim rectConv As RectangleConverter = New RectangleConverter()
Dim form1pos As String = rectConv.ConvertToString(form1Position)
Dim form2pos As String = rectConv.ConvertToString(form2Position)
Dim dataToWrite As Byte() = encoding.GetBytes("~" + form1pos + "~" + form2pos)
Try
' Set the write position to the start of the file and write
userData.Seek(0, SeekOrigin.Begin)
userData.Write(dataToWrite, 0, dataToWrite.Length)
userData.Flush()
userData.SetLength(dataToWrite.Length)
Return True
Catch
' An error occurred while attempting to write, return false.
Return False
End Try
End Function
Private Function ReadFormDataFromFile() As Boolean
' Read the form positions from the file.
Dim encoding As UTF8Encoding = New UTF8Encoding()
Dim data As String
If (userData.Length <> 0) Then
Dim dataToRead(userData.Length) As Byte
Try
' Set the read position to the start of the file and read.
userData.Seek(0, SeekOrigin.Begin)
userData.Read(dataToRead, 0, dataToRead.Length)
Catch e As IOException
Dim errorInfo As String = e.ToString()
' An error occurred while attempt to read, return false.
Return False
End Try
' Parse out the data to get the window rectangles
data = encoding.GetString(dataToRead)
Try
' Convert the string data to rectangles
Dim rectConv As RectangleConverter = New RectangleConverter()
Dim form1pos As String = data.Substring(1, data.IndexOf("~", 1) - 1)
form1Position = CType(rectConv.ConvertFromString(form1pos), Rectangle)
Dim form2pos As String = data.Substring(data.IndexOf("~", 1) + 1)
form2Position = CType(rectConv.ConvertFromString(form2pos), Rectangle)
Return True
Catch
' Error occurred while attempting to convert the rectangle data.
' Return false to use default values.
Return False
End Try
Else
' No data in the file, return false to use default values.
Return False
End If
End Function
End Class
Public Module MyApplication
Public Sub Main()
' Create the MyApplicationContext, that derives from ApplicationContext,
' that manages when the application should exit.
Dim context As MyApplicationContext = New MyApplicationContext()
' Run the application with the specific context. It will exit when
' all forms are closed.
Application.Run(context)
End Sub
End Module