PictureBox memory leak

wouterk

Hello,

I'm trying to show a selected image from a ListView in a PictureBox.

When I select an Image from the ListView it does show up. but each time I do this the memory usage of my app shoots up and doesn't go down (I'm using rather big images)

Working code with memory issue:

        Bitmap originalImg;

        private void listView1_SelectedIndexChanged(object sender, EventArgs e)
        {
            for (int i = 0; i < listView1.Items.Count; i++)
            {
                if (listView1.Items[i].Selected == true)
                {
                    originalImg = new Bitmap(folderPath + "/" + listView1.Items[i].SubItems[0].Text);
                }
            }
           
            pictureBox1.Image = tempImg;
        }

I tried disposing the image before another one is loaded but I get a null pointer exception the second time an image is selected in the ListView.

        Bitmap originalImg, tempImg;
        
        private void listView1_SelectedIndexChanged(object sender, EventArgs e)
        {
            for (int i = 0; i < listView1.Items.Count; i++)
            {
                if (listView1.Items[i].Selected == true)
                {
                    tempImg = new Bitmap(folderPath + "/" + listView1.Items[i].SubItems[0].Text);
                }
            }
            
            originalImg = (Bitmap)tempImg.Clone();
            tempImg.Dispose();
            OriginalPictureBox.Image = originalImg;
        }
    }

What am I overlooking?

Thanks in advance :)

4 Replies

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Felipe Ramos16y ago
Thats a good find, I didn't consider clearing out the previous image.
wouterk16y ago
Ah I fixed it :)

adding the lines:

if (OriginalPictureBox.Image != null)
{
   OriginalPictureBox.Image.Dispose();
}

Did the trick.

Full code:
private void listView1_SelectedIndexChanged(object sender, EventArgs e)
   {
   for (int i = 0; i < listView1.Items.Count; i++)
   {
   if (listView1.Items[i].Selected == true)
   {
                   if (OriginalPictureBox.Image != null)
                     {
                     OriginalPictureBox.Image.Dispose();
                     }
   OriginalPictureBox.Image = new Bitmap(folderPath + "/" + listView1.Items[i].SubItems[0].Text);
   break;
   }
   }
   }
wouterk16y ago
Thank you for your quick reply :)

No particular reason for the two global bitmaps, just an attempt to fix the problem.

I tried your solution but the memory usage of my app still goes up (by the amount of the size of the picture) each time a picture from the listView is selected, even if the picture has been selected before, so switching between just 2 images results in increasing memory usage up to the point where an 'Out of memery exception' occurs.

It seems like somewhere a copy of the image is kept in the memory :(

commenting the line: OriginalPictureBox.Image = new Bitmap(folderPath + "/" + listView1.Items[i].SubItems[0].Text);
results in a stable memory usage, but ofcourse the picture is not loaded. (so I think it's safe to assume it has to do something wiith that particular line)

(and indeed that adding that 'break;' was a good idea :D, thanks! )
Felipe Ramos16y ago
Try something like this: (I am not sure why you have two Bitmap global intances, if you need access to the bitmap again just grab it from the PictureBox)

private void listView1_SelectedIndexChanged(object sender, EventArgs e)
   {
   for (int i = 0; i < listView1.Items.Count; i++)
   {
   if (listView1.Items[i].Selected == true)
   {
   OriginalPictureBox.Image = new Bitmap(folderPath + "/" + listView1.Items[i].SubItems[0].Text);
   break; // You found your selection break out
   }
   }
   }