Low memmory. What to do?

[Norkis]

Hey, I have made app, which repaints and changes wallpaper after some period. But something goes wrong. Every time then function is called ~7 MB of memory are "ate". How to free it after doing job? I tried dispose, but nothing.

Public Function Paint_text(ByVal txt As String) As Bitmap
 
Dim bm_source As New Bitmap(Image.FromFile("C:\piv.bmp"))
Dim bm_dest As New Bitmap(CInt(bm_source.Width), CInt(bm_source.Height)
Dim gr_dest As Graphics = Graphics.FromImage(bm_dest)
gr_dest.DrawImage(bm_source, 0, 0, bm_dest.Width, bm_dest.Height)
 
Dim mybrush As New Drawing2D.LinearGradientBrush(ClientRectangle, FontDialog1.Color, FontDialog1.Color, Drawing2D.LinearGradientMode.Horizontal)
 Dim myFont As New Font("Verdana",  12, FontStyle.Regula)
gr_dest.DrawString(txt, myFont, mybrush, New RectangleF(x1 , y1 , x2 - x1, y2 - y1)
Paint_text = bm_dest
 
        gr_dest.Dispose()
        mybrush.Dispose()
        mypen.Dispose()
        myFont.Dispose()
        bm_source.Dispose()
        bm_source = Nothing
        bm_dest = Nothing
 
    End Function

Then I set returned image to picturebox (~3MB). But it's OK. This is not why after every function call memory isn't cleared.

[lianwk]

Hi,

I think your function is holding the buffer. Try to clear the buffer by using "Paint_text=Nothing"after you have transfer the data to somewhere....

[Andy]

try using the "unlockbits" method of your new object

[pax]

Hi.

This is a no-no and a bad way of doing things, but it works.

Use GC.Collect.

That will force the garbagecollector to clean up.
I have had a few situations where I used som API BitBlt'ing, and for some reason I couldn't get it to release my memory even though I did release HDC's and Destroy and everything else I could think of to clean up.

The only way I could solve this (on my own, anyway...) was using GC.Collect.

[Norkis]

Can you give me an exmaple, how to use it?

[pax]

Hi.

Just put it in the end of you function.

Public Function Paint_text(ByVal txt As String) As Bitmap
 
Dim bm_source As New Bitmap(Image.FromFile("C:\piv.bmp"))
Dim bm_dest As New Bitmap(CInt(bm_source.Width), CInt(bm_source.Height)
Dim gr_dest As Graphics = Graphics.FromImage(bm_dest)
gr_dest.DrawImage(bm_source, 0, 0, bm_dest.Width, bm_dest.Height)
 
Dim mybrush As New Drawing2D.LinearGradientBrush(ClientRectangle, FontDialog1.Color, FontDialog1.Color, Drawing2D.LinearGradientMode.Horizontal)
 Dim myFont As New Font("Verdana",  12, FontStyle.Regula)
gr_dest.DrawString(txt, myFont, mybrush, New RectangleF(x1 , y1 , x2 - x1, y2 - y1)
 
        gr_dest.Dispose()
        mybrush.Dispose()
        mypen.Dispose()
        myFont.Dispose()
        bm_source.Dispose()
        bm_source = Nothing
 
GC.Collect
 
Paint_text = bm_dest
    End Function

You might have noticed that I have moved Paint_Text=bm_Dest to the bottom and deleted the bm_dest=Nothing.

Usually you would use Return bm_Dest and that would exit the function, and your dispose commands would not be called.
So always dispose everything you can before returning the result.