Out of memory exception in c# when drawing trains in picturebox

Question

I am trying to create an application that shows the online trains in picturebox

So to implement this i create a worker thread to get the online train position .so i define the thread as you can see here :

private Thread workerThread = null;
private delegate void UpdateListBoxDelegate();
private UpdateListBoxDelegate UpdateListBox = null;

In Form_load i call these:

            UpdateListBox = new UpdateListBoxDelegate(this.UpdateStatus);
            // Initialise and start worker thread
            workerThread = new Thread(new ThreadStart(this.GetOnlineTrain));
            workerThread.Start();

My method that delegate handles that is :

private void UpdateStatus()
{
    foreach (TimeTable onlineTrain in OnlineTrainList.ToList())
    {
        if (lstSensorLeft.Count != 0 || lstSensorRight.Count != 0)
        {
            pictureBoxonlineTrain.Image = null;

            DrawOnlineTrain();
        }
        else
        {
            pictureBoxonlineTrain.Image = null;
        }
    }

    this.Invalidate();
}

The GetOnlineTrain get the position of online train as you can see here :

public void GetOnlineTrain()
{
    try
    {
        while (true)
        {
            TimeTableRepository objTimeTableREpository = new TimeTableRepository();
            OnlineTrainList = objTimeTableREpository.GetAll().ToList();
            objTimeTableREpository = null;
            Invoke(UpdateListBox);
        }
    }
    catch(Exception a)
    {
    }

}

And the final function draws the online trains on the picturebox :

   public void DrawOnlineTrain()
        {
            Bitmap map=null;
            if (OnlineTrainList.Count > 0)
            {
                map = new Bitmap(pictureBoxonlineTrain.Size.Width, pictureBoxonlineTrain.Size.Height);

                var graph = Graphics.FromImage(map);

                foreach (TimeTable t in OnlineTrainList.ToList())
                {
                   // graph.Dispose();
                    Rectangle rectTrainState = new Rectangle(t.XTrainLocation.Value - 3,
                                                             t.YTrainLocation.Value - 3,
                                                             15, 15);
                    graph.FillRectangle(RedBrush, rectTrainState);
                    graph.DrawString(t.TrainId.ToString(), pictureBoxonlineTrain.Font, Brushes.White, t.XTrainLocation.Value  -3, t.YTrainLocation.Value -3);

                }
            }
            pictureBoxonlineTrain.Image = map;
          //  pictureBoxonlineTrain.Image.Save(@"C:\RailwayShiraz\ShirazMetro\ShirazRailWayWeb\Images\Train.jpg");
        }

but my application spends a lot of memory and sometimes i got the Out of memory exception and sometimes my trains Disappears from the picturebox. To draw online train first time i draw the map of trains (lines ,stations ,...) on picturebox with size x=A and y=b after that i create another picturebox with the same size and put the second picturebox on first picturebox using this code:

    pictureBoxonlineTrain.Parent = pictureBoxMetroMap;

I think maybe some part of my code consumes a lot of memory and i should use Dispose or something else .Sometime i got out of memory exception and the error is caused by graphic i am not sure !And sometimes i got the error from this line :

   map = new Bitmap(pictureBoxonlineTrain.Size.Width, pictureBoxonlineTrain.Size.Height);

Could you please give me some help .is there any class that i should dispose that?or the problem is caused by my implementation

I trace the memory usage from taskmanager and some times my usage reach to 1,666,881 and my application exits.

Best regards

score 3 · Accepted Answer · answered Jul 05 '14 at 18:59

3

Dispose bitmaps which you no longer need. They consume huge amounts of unmanaged memory. The GC is not aware of unmanaged memory and cannot trigger a collection based on unreachable unmanaged memory.

answered Jul 05 '14 at 18:59

usr

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Thank you which part of code i should dispose the bitmap ? – Ehsan Akbar Jul 05 '14 at 19:00
Do it as soon as you know the bitmap is no longer used but not before. – usr Jul 05 '14 at 19:01
i my code i use this :pictureBoxonlineTrain.Image = null; can i change it to pictureBoxonlineTrain.Image.Dispose();? – Ehsan Akbar Jul 05 '14 at 19:03
First, assign null to Image or else you'll have a disposed image configured. Who knows what that even does. – usr Jul 05 '14 at 19:12
Wrap both `map` and `graph` in `using` blocks. They're both disposable. – Matthew Strawbridge Jul 05 '14 at 19:57
@MatthewStrawbridge how can i do that – Ehsan Akbar Jul 06 '14 at 04:27
@MatthewStrawbridge could you please give me an example and in which part of code i should use that? – Ehsan Akbar Jul 06 '14 at 04:27
@MatthewStrawbridge i asked this question here :http://stackoverflow.com/questions/24592729/bitmap-and-picturebox-cause-out-of-memory-exception – Ehsan Akbar Jul 06 '14 at 04:34

Out of memory exception in c# when drawing trains in picturebox

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