[2005] GDI+ Out of memory

I've created a custom control that is a level meter (a bar that shows audio levels visually). So this gets refreshed about every 200 milliseconds. I am running into an issue when the app runs for somewhere between 12 - 16 hours one of the 4 meters that are displayed on the screen goes white with the red X through it. A message pops up saying OutOfMemory error. Does anyone have an idea why this would be happening? The system memory is always in normal range when this happens. I also added try catch to everything and if an error was thrown it would write the info in a log. This doesn't happen though.

I first draw this control to a bitmap, then draw the bitmap to the control. I override the onpaint event and use the onpaint eventArg to draw to the control.

Do you Dispose each of these Bitmaps after you've finished with it? I would think that the Bitmap would be unnecessary anyway. Wouldn't it be better to just draw directly to the control surface using GDI+?

When I draw directly to the surface I get flashing, because the control is refreshed so often. The bitmap is declared at the class level and is only disposed and recreated if the control is resized. This is a manual way of doing DoubleBuffering. But everything else that can be disposed is disposed.

You are right to use a bitmap as a backbuffer.

GDI+ sometimes gives OOM errors for non-memory related problems, for example tryin to create a 256 color palletised bitmap. Unless you post some code, we aren't going to know what the problem is :)

Here is the code for the drawing

VB Code:

If _BackBuffer Is Nothing Then
                _BackBuffer = New Bitmap(Me.ClientSize.Width, Me.ClientSize.Height)
            End If
 
            Dim x As Integer
            Dim y As Integer
            Dim rect As Rectangle
            Dim cnt As Integer = 0
            Dim g As Graphics = Graphics.FromImage(_BackBuffer)
            Dim p As Pen = Nothing
            Dim b As LinearGradientBrush = Nothing
            Dim mAv As Integer  'is the actual value taking in consideration the number of led lights compared to the maximum
            Dim Hav As Integer  'is the most recent High Value it hovers for a few seconds then fades until another value is greater
 
 
            g.Clear(Color.White)
            g.SmoothingMode = SmoothingMode.AntiAlias
            Dim c1 As Color
            Dim c2 As Color
 
            If _Orientation = Windows.Forms.Orientation.Vertical Then
                x = 0
                y = Me.Height - H - 1
            Else
                x = 0
                y = 0
            End If
 
 
            mAv = CInt((AV * _Value) / _Max)
            Hav = CInt((AV * _HighValue) / _Max)
 
            Do Until cnt >= AV
                rect = New Rectangle(x, y, W, H)
                If cnt <= AV / 2 Then
                    If cnt <= mAv AndAlso cnt <> Hav Then
                        b = New LinearGradientBrush(rect, Color.LightGreen, Color.LightGreen, LinearGradientMode.Vertical)
                        p = New Pen(Color.Green, 1)
                    ElseIf cnt > mAv AndAlso cnt <> Hav Then
                        c1 = ColorChanger.SetBrightness(Color.Green, 0.1)
                        c1 = ColorChanger.SetSaturation(c1, 0.2)
 
                        c2 = ColorChanger.SetBrightness(Color.Green, 0.2)
                        c2 = ColorChanger.SetSaturation(c2, 0.3)
 
                        b = New LinearGradientBrush(rect, c1, c2, LinearGradientMode.Vertical)
                        p = New Pen(c1, 1)
                    ElseIf cnt = Hav Then
                        b = New LinearGradientBrush(rect, Color.LightBlue, Color.LightBlue, LinearGradientMode.Vertical)
                        p = New Pen(Color.DarkBlue)
                    End If
                ElseIf cnt > AV / 2 And cnt <= (AV / 4) * 3 Then
                    If cnt <= mAv AndAlso cnt <> Hav Then
                        b = New LinearGradientBrush(rect, ColorChanger.ModifyBrightness(Color.Yellow, 1.3), ColorChanger.ModifyBrightness(Color.Yellow, 1.3), LinearGradientMode.Vertical)
                        p = New Pen(ColorChanger.ModifyBrightness(Color.Yellow, 0.5), 1)
                    ElseIf cnt > mAv AndAlso cnt <> Hav Then
                        c1 = ColorChanger.SetBrightness(Color.Yellow, 0.3)
                        c1 = ColorChanger.SetSaturation(c1, 0.4)
 
                        c2 = ColorChanger.SetBrightness(Color.Yellow, 0.4)
                        c2 = ColorChanger.SetSaturation(c2, 0.5)
 
                        b = New LinearGradientBrush(rect, c1, c2, LinearGradientMode.Vertical)
                        p = New Pen(c1, 1)
                    ElseIf cnt = Hav Then
                        b = New LinearGradientBrush(rect, Color.LightBlue, Color.LightBlue, LinearGradientMode.Vertical)
                        p = New Pen(Color.DarkBlue)
                    End If
 
                ElseIf cnt > (AV / 4) * 3 Then
                    If cnt <= mAv AndAlso cnt <> Hav Then
                        b = New LinearGradientBrush(rect, Color.Red, Color.Red, LinearGradientMode.Vertical)
                        p = New Pen(ColorChanger.ModifyBrightness(Color.DarkRed, 0.2), 1)
                    ElseIf cnt > mAv AndAlso cnt <> Hav Then
                        c1 = ColorChanger.SetBrightness(Color.DarkRed, 0.3)
                        c1 = ColorChanger.SetSaturation(c1, 0.4)
 
                        c2 = ColorChanger.SetBrightness(Color.DarkRed, 0.4)
                        c2 = ColorChanger.SetSaturation(c2, 0.5)
 
                        p = New Pen(c1, 1)
                        b = New LinearGradientBrush(rect, c1, c2, LinearGradientMode.Vertical)
                    ElseIf cnt = Hav Then
                        b = New LinearGradientBrush(rect, Color.LightBlue, Color.LightBlue, LinearGradientMode.Vertical)
                        p = New Pen(Color.LightBlue)
                    End If
 
                End If
 
 
                g.FillRectangle(b, rect)
                g.DrawRectangle(p, rect)
 
                If _Orientation = Windows.Forms.Orientation.Vertical Then
                    y -= H
                ElseIf _Orientation = Windows.Forms.Orientation.Horizontal Then
                    x += W
                End If
                cnt += 1
                rect = Nothing
                p.Dispose()
                b.Dispose()
            Loop
            g.Dispose()
            e.DrawImageUnscaled(_BackBuffer, 0, 0)
            e.Dispose()     'originally I didn't dispose of this manually.  But I added it, and still got the error

Just a few notes:
w, and h are declared as integers at the class level. I have them set in the sizeChange event.

ColorChanger is a color manipulation class that I got from Bob Powels website.

AV is declared as an integer at the class level. This is _value converted to work with however many rectangles there actually are.

e is the graphics from th onpain argument passed to this method.

Does the error occur at the same line each time?

That's part of the problem. It doesn't give me a line number. This doesn't happen on my development machine(it has other issues and won't run long enough). So it is on a test machine that I have a debug install on (debug builds and pdb files) Other errors I do get a line, but not this one. I also have this entire method in a try catch, that is supposed to write to a to a file the error and display a messagebox. But it doesn't do that.

I've attached a picture of the error it give me