Memory allocation is not released

[Bamelis Steve]

Hi,

I'm working with CF2.0 VB.NET 2005.

I have an application running on PPC.
The structure is as follows:
1. startup form (main) has a button to open an other form
2. form1 has a custom image button and normal button
3. form2 had a custom image button and normal buttion

for 2 and 3 the custombutton onclick switches between form1 and form2.
Always disposing the previous form.
So if I click on form1, he closes himself, raiseevent to the main form and from the main form I open form2. This is the same for form2.

On form1 and form2 I paint a background image on the form.
In my dispose of my forms I always dispose that image.

If I run the windows CE remote performance monitor and monitor the memory load I have the following.

Start app: memory load 38MB
open form1: Jumps to 44MB
open form2 from form1: go's to 45MB
switching between to's two doesn't change in memory. Always 44MB and 45MB with sometimes a peak to 47MB and back to 45MB.
Eventually closing the form1 or form2 and returning to the main form result's in the memory load staying at 44MB.
My two forms are disposed and still it doesn't return to the 38MB initial load of the main form.

Could somebody explain this to me or help me resolve this issue.

The Code:

' Main form
Public Class main
Public iCurrentForm As Integer = 1

    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        Me.Close()
    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim frm As New Form1
        iCurrentForm = 1
        AddHandler frm.openNext, AddressOf openNext
        frm.Show()
        frm.BringToFront()
    End Sub

    Private Sub openNext()
        If iCurrentForm = 1 Then
            Dim frm As New Form2
            iCurrentForm = 2
            AddHandler frm.openNext, AddressOf openNext
            frm.Show()
            frm.BringToFront()
        Else
            Dim frm As New Form1
            iCurrentForm = 1
            AddHandler frm.openNext, AddressOf openNext
            frm.Show()
            frm.BringToFront()
        End If
    End Sub
End Class

' Form1
Imports D8D.PPC.iGuide.Resources.MyResources
' namespace has the images in them

Public Class Form1

    Public Event openNext()

    Private _background As Bitmap

    Protected Overrides Sub OnPaintBackground(ByVal e As System.Windows.Forms.PaintEventArgs)
        If Not _background Is Nothing Then
            e.Graphics.DrawImage(_background, New Rectangle(0, 0, Me.Width, Me.Height), New Rectangle(0, 0, _background.Width, _background.Height), GraphicsUnit.Pixel)
        Else
            MyBase.OnPaintBackground(e)
        End If
    End Sub

    Public Sub New()

        ' This call is required by the Windows Form Designer.
        InitializeComponent()

        ' Add any initialization after the InitializeComponent() call.
        _background = Images.LoadBitmap("bkgBiografie")
        btnClose.ImageUp = Images.LoadBitmap("btnClose")
        btnClose.ImageDown = Images.LoadBitmap("btnClose_down")
    End Sub

    Private Sub btnClose_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnClose.Click
        Me.Close()
        RaiseEvent openNext()
        Me.Dispose()

    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Me.Close()
    End Sub

    Protected Overrides Sub Finalize()
        Dispose(False)
        MyBase.Finalize()
    End Sub

End Class
'form1 designer

<Global.Microsoft.VisualBasic.CompilerServices.DesignerGenerated()> _
Partial Public Class Form1
    Inherits System.Windows.Forms.Form
    Implements IDisposable

    Shadows disposed As Boolean = False

    'Form overrides dispose to clean up the component list.
    <System.Diagnostics.DebuggerNonUserCode()> _
    Protected Overrides Sub Dispose(ByVal disposing As Boolean)
        If Not Me.Disposed Then
            If disposing Then
                If Not _background Is Nothing Then
                    _background.Dispose()
                    _background = Nothing
                End If
            End If
            If disposing AndAlso components IsNot Nothing Then
                components.Dispose()
            End If
        End If
        Me.Disposed = True
        MyBase.Dispose(disposing)
    End Sub

    'Required by the Windows Form Designer
    Private components As System.ComponentModel.IContainer

    'NOTE: The following procedure is required by the Windows Form Designer
    'It can be modified using the Windows Form Designer.  
    'Do not modify it using the code editor.
    <System.Diagnostics.DebuggerStepThrough()> _
    Private Sub InitializeComponent()
        Me.btnClose = New D8D.PPC.Controls.UI.Buttons.ImageButton
        Me.Button1 = New System.Windows.Forms.Button
        Me.SuspendLayout()
        '
        'btnClose
        '
        Me.btnClose.Location = New System.Drawing.Point(67, 61)
        Me.btnClose.Name = "btnClose"
        Me.btnClose.Size = New System.Drawing.Size(352, 64)
        Me.btnClose.TabIndex = 0
        Me.btnClose.Text = "ImageButton1"
        '
        'Button1
        '
        Me.Button1.Location = New System.Drawing.Point(165, 336)
        Me.Button1.Name = "Button1"
        Me.Button1.Size = New System.Drawing.Size(144, 40)
        Me.Button1.TabIndex = 1
        Me.Button1.Text = "Button1"
        '
        'Form1
        '
        Me.AutoScaleDimensions = New System.Drawing.SizeF(192.0!, 192.0!)
        Me.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Dpi
        Me.ClientSize = New System.Drawing.Size(480, 640)
        Me.ControlBox = False
        Me.Controls.Add(Me.Button1)
        Me.Controls.Add(Me.btnClose)
        Me.FormBorderStyle = System.Windows.Forms.FormBorderStyle.None
        Me.Location = New System.Drawing.Point(0, 0)
        Me.MinimizeBox = False
        Me.Name = "Form1"
        Me.Text = "Form1"
        Me.TopMost = True
        Me.WindowState = System.Windows.Forms.FormWindowState.Maximized
        Me.ResumeLayout(False)

    End Sub
    Friend WithEvents btnClose As D8D.PPC.Controls.UI.Buttons.ImageButton
    Friend WithEvents Button1 As System.Windows.Forms.Button

End Class

'form2 is the same as form1

[Shaggy Hiker]

Don't worry about it.

That's the simple answer. When you get rid of an item, it isn't destroyed, and the memory isn't freed. All that happens is that it gets flagged for destruction. When the Garbage Collector runs, it will get destroyed at that point. As for memory, if the program needs more, it gets it from the OS pool. If the pool gets low, the OS can reclaim it, but unless the pool gets low, the OS won't bother.

Edit: By the way, you might search in this forum for using panels. In my opinion, no CF program should have more than a single form unless the second form handles almost a different program (the one time I used two forms was for that case). Forms are just too slow, and, as you have noted, they have some memory overhead....not that that matters any.