Hi people,

I'd like to know how can handl GDI in .NET (C#), probably you could explain me more detailed basic aspects or/and show an example or/and provide me with helpful links.

Thank you in advance !

It is very difficult to leak GDI+ objects, they all have a finalizer. The tool you need is built into Windows: Start + Run, Taskmgr.exe, Processes tab. View + Select columns, check "GDI Objects". You'd better add USER32 Objects too, that's the more typical leak.

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Hans Passant.

.net actually uses GDI+, which is kind of like GDI (though I am not sure how as I have never used, personally, GDI).

Here is an example of GDI+:

public class MyControl : System.Windows.Forms.Control
{
public MyControl()
{
}

public override OnPaint(object sender, System.Windows.Forms.PaintEventArgs pe)
{
System.Drawing.Rectangle rect = new System.Drawing.Rectangle(10,10,10,10);
pe.Graphics.DrawRectangle(Pens.Black, rect);
}
}

The above example will draw a rectangle on your control. I believe that all of the GDI+ methods are contained in the System.Drawing.Graphics class. This class is sealed, so it can't be inherited from. Also, the class, on it's own does nothing. You can override the OnPaint event of any control and use the PaintEventArgs.Graphics, or you can use the System.Windows.Forms.Control.CreateGraphics() method.

I hope thid helps.

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There are 10 types of people in this world, those who understand Binary, and those who don't.

Well, probably I have ask in not very correct form. Actually I need to find approach how to check for GDI leaks.

Scenario:

Run an application, and check if all GDI objects are disposed when I go to close the window. Because I think that probably not all GDI object are disposed. I need to have kind of app. that could monitoring this process.


Thank you

Hi Julian,

This article discusses about how to dispose GDI+ resources: http://www.codeproject.com/KB/GDI-plus/DisposeGDI.aspx?display=Print.
This article is about .Net memory leak: http://blogs.msdn.com/tess/archive/2009/02/03/net-memory-leak-to-dispose-or-not-to-dispose-that-s-the-1-gb-question.aspx.

Let me know if this helps or not.
Aland Li

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Please mark the replies as answers if they help and unmark if they don't. This can be beneficial to other community members reading the thread.

It is very difficult to leak GDI+ objects, they all have a finalizer. The tool you need is built into Windows: Start + Run, Taskmgr.exe, Processes tab. View + Select columns, check "GDI Objects". You'd better add USER32 Objects too, that's the more typical leak.

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Hans Passant.

Is there some add-ins for VS2008 (C#) that could detect GDI leaks and show where exactly in the source code each GDI object was created ?

A profiler, maybe. They tend to track managed objects, not unmanaged ones like a GDI handle. Shop around and read the small print.

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Hans Passant.