Member Avatar for qauaan

I want to select the pictures (They are select during program is running) and show them on the form. for that i take a panel on the form and populate the panel with pictureboxes.i write the following code for that but it is very time consuming:

if(openDialoge1.ShowDialog() == DialogResult.OK)
                    {
                       string[] fileName = open.FileNames;
                       foreach (string s in fileName)
                       {
                            pBox = new PictureBox();
                            pBox.Size = new System.Drawing.Size(w, h);
                            pBox.Location = new System.Drawing.Point(x, y);
                            pBox.Image = Image.FromFile(s);
                           // .
                            //.//here i add some eventHandler of picture boxes.

                            this.panel1.Controls.Add(pBox);
                            x += pBox.Width + 4;
                         }
                     }

This code work well, but it is very time consuming and take much time to populate the panel with picture boxes. for example when i slect the 20,30 pictures, it take much time.
Is there any way that reduce the time to populate the panel with pictureboxes.

Thanks in advance.

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  • 4 Replies
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  • 7 Hours Discussion Span
  • Latest Post Latest Post by qauaan

Dani AI

Generated

Good direction from — the slowdown is usually two things: synchronous image I/O on the UI thread and creating/laying out a large number of controls at once. A practical pattern that helps a lot is: (1) read files off the UI thread, (2) create small thumbnails (not full-size images) in background work, (3) marshal a quick UI update for each thumbnail (add one PictureBox at a time), and (4) dispose images when no longer needed.

Example: load thumbnails into a List<Image> on a background thread and add PictureBoxes on the UI thread as each thumbnail is ready. This keeps the UI responsive and spreads layout cost over time.

List<Image> thumbs = new List<Image>();

Task.Run(() =>
{
    foreach (var path in files)
    {
        using (var fs = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.Read))
        using (var img = Image.FromStream(fs))
        {
            var thumb = new Bitmap(120, 90);
            using (var g = Graphics.FromImage(thumb))
            {
                g.InterpolationMode = InterpolationMode.HighQualityBicubic;
                g.DrawImage(img, 0, 0, thumb.Width, thumb.Height);
            }

            lock (thumbs) thumbs.Add(thumb);

            this.BeginInvoke((Action)(() =>
            {
                var pb = new PictureBox { Image = thumb, SizeMode = PictureBoxSizeMode.Zoom, Size = thumb.Size };
                panel1.Controls.Add(pb);
            }));
        }
    }
});

A few more practical tips:

  • Use a FlowLayoutPanel (or a subclass with DoubleBuffered enabled) to avoid repeated manual positioning and reduce flicker. Example subclass:
public class DoubleBufferedFlowLayoutPanel : FlowLayoutPanel
{
    public DoubleBufferedFlowLayoutPanel() { DoubleBuffered = true; ResizeRedraw = true; }
}
  • Dispose images when removing controls: call pb.Image.Dispose() before removing the PictureBox.
  • For very large sets, prefer a virtualized UI (ListView in virtual mode + ImageList, or custom owner-draw) and persistent thumbnail caching on disk so thumbnails are reused instead of regenerated.

This approach builds on ’s suggestion and gives a concrete way for to populate a List<Image> and update the panel without blocking the UI.

Recommended Answers

All 4 Replies

Member Avatar for kvprajapati

I think Image.FromFile() will affect the performance. Load the images into a List<> first, using a separate thread or background worker.

Member Avatar for qauaan

I have no idea that how can i use the seperate thread. can u explain with coding

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