Out of Memory Exception (Graphics.DrawImage)

Well...at first:
I did use the search function and yes, I found tons of related posts and threads but in none of them I could find my answer.

Now about the problem:
I try to do some kind of 'pencil' that draws an 32 x 32 area of an image in an invisible 32x32spacing grid. And it works pretty well except the OoM Exception after some scribbling around.

Codesnippet (Error is thrown in pb_map_pencil):

Code:

---

                private void pb_map_pencil(object sender, EventArgs e)
                {
                        //Get MouseCoords
                        int x = (e as MouseEventArgs).X;
                        int y = (e as MouseEventArgs).Y;
                        x = (int)(x / 32.0);
                        y = (int)(y / 32.0);
                        //Check if targeted area already drawn
                        if (this.mouse_old_position == new Point(x, y))
                        {
                                return;
                        }
                        this.mouse_old_position = new Point(x, y);

                        //Drawing Code
                        Graphics g;
                        Image img = Image.FromFile(this.runtime.Source); //Load ImageSource
                        //if no Image exists on Picture Box, create one (looks like the source)
                        if (this.pb_map.Image == null)
                        {
                                this.pb_map.Image = img;
                        }
                        g = Graphics.FromImage(this.pb_map.Image); //create Graphics Object
                        //draw area
                        g.DrawImage(img, x * 32, y * 32, new Rectangle(this.runtime.Selector.X * 32, this.runtime.Selector.Y * 32, 32, 32), GraphicsUnit.Pixel); //(here's the Exception thrown)
                        //invalidate Picturebox
                        this.pb_map.Invalidate();
                }

//MouseControl on pictureBox
                private void pb_map_MouseDown(object sender, MouseEventArgs e)
                {
                        this.mouse_down = true;
                        this.mouse_old_position = new Point(-1,-1);
                        this.pb_map_pencil(sender, e);
                }

                private void pb_map_MouseMove(object sender, MouseEventArgs e)
                {
                        if (this.mouse_down)
                        {
                                this.pb_map_pencil(sender, e);
                        }
                }

                private void pb_map_MouseUp(object sender, MouseEventArgs e)
                {
                        this.mouse_down = false;
                }

---

Stacktrace:

Quote:

---

bei System.Drawing.Graphics.CheckErrorStatus(Int32 status)
bei System.Drawing.Graphics.DrawImage(Image image, Int32 x, Int32 y, Rectangle srcRect, GraphicsUnit srcUnit)
bei RGM.frm_main.pb_map_pencil(Object sender, EventArgs e) in C:\Users\xxx\documents\visual studio 2010\Projects\RGM\RGM\frm_main.cs:Zeile 136.
bei RGM.frm_main.pb_map_MouseMove(Object sender, MouseEventArgs e) in C:\Users\xxx\documents\visual studio 2010\Projects\RGM\RGM\frm_main.cs:Zeile 152.
bei System.Windows.Forms.Control.OnMouseMove(MouseEventArgs e)
bei System.Windows.Forms.Control.WmMouseMove(Message& m)
bei System.Windows.Forms.Control.WndProc(Message& m)
bei System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
bei System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
bei System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
bei System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg)
bei System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr dwComponentID, Int32 reason, Int32 pvLoopData)
bei System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
bei System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
bei System.Windows.Forms.Application.Run(Form mainForm)
bei RGM.Program.Main() in C:\Users\xxx\documents\visual studio 2010\Projects\RGM\RGM\Program.cs:Zeile 15.
bei System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
bei System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
bei Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
bei System.Threading.ThreadHelper.ThreadStart_Context(Object state)
bei System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean ignoreSyncCtx)
bei System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
bei System.Threading.ThreadHelper.ThreadStart()

---

I think I overlooked something very basic but I don't get it :(
Maybe it's about an using the Image or because nothing is explicit disposed by myself. But whenever I try to dispose the Image img by myself or using the using the main function throws an invalid argument exception at Application.Run without any usable infos for me...

So any help with that problem would be great :)

Dispose of your images and graphics when you're done with them. If that doesn't work, paste the error you get.

Wasn't that easy to dispose the Image, since this

Code:

---

this.pb_map.Image = img;

---

img.dispose() does not only dispose the img alone but since its referenced also by the pictureBox.Image which still is needed (thats why the invalid paramter exceptions are thrown after dispose() i mentioned before).
Took me a while until i saw that.

Now I'm doing it this way:

Code:

---

//if no Image exists on Picture Box, create one (looks like the source)
                        if (this.pb_map.Image == null)
                        {
                                this.pb_map.Image = (Image)img.Clone();  //Make it not the Image itself but a clone of it (so im can be disposed)
                        }
                        g = Graphics.FromImage(this.pb_map.Image); //create Graphics Object
                        //draw area
                        g.DrawImage(img, x * 32, y * 32, new Rectangle(this.runtime.Selector.X * 32, this.runtime.Selector.Y * 32, 32, 32), GraphicsUnit.Pixel);
                        img.Dispose();

---

Now I can't reproduce the OoM-Exception but to be honest, I can't believe that this solution is the best (I don't like to copy or to clone...) so I'm asking what do you think about this idea?