Question

I’m using a TWAIN control to scan images, this works fine and I can scan an image and display it in pictureBox1. I’m struggling with adding multiple images to a stream and then using a Previous and Next button to step through them.

Can someone please help, my code below does not work, I’m now in a fog of confusion. Thanks

//The axTwain1_OnAcquire event runs on each scanned page.        

private void axTwain1_OnAcquire(object sender, EventArgs e)
{
    images = new List<Image>();
    pageCount = pageCount + 1;
    axTwain1.SaveToFile(Environment.GetFolderPath(Environment.SpecialFolder.Desktop) + "\\" + pageCount +".jpg");
    FileStream stream = File.OpenRead(Environment.GetFolderPath(Environment.SpecialFolder.Desktop) + "\\" + pageCount + ".jpg");
    images.Add(Image.FromStream(stream));
    pictureBox1.Image = System.Drawing.Bitmap.FromStream(stream);

}

private void btnNext_Click(object sender, EventArgs e)
{

    index++;
    if (index < 0 || index >= images.Count)
        index = 0;
    pictureBox1.Image = images[index];
    int count = index + 1;
    //labelCount.Text = "Showing " + count.ToString() + " of " + images.Count;
}

private void btnPrevious_Click(object sender, EventArgs e)
{
    index++;
    if (index < 0 || index >= images.Count)
        index = 0;
    pictureBox1.Image = images[index];
    int count = index + 1;
}

Answer 1

You’re logic looks a bit screwy. In both the previous and next functions, you have the conditional statement:

index < 0 || index >= images.Count

For a next, your logic should look something like:

index < images.Count -- then increment.

and for your previous:

index > 0 -- then decrement.

So essentially, your functions should look like:

private void btnNext_Click(object sender, EventArgs e)
{
   if(index < images.Count) {
      index++;
      pictureBox1.Image = images[index];
   }
}

private void btnPrevious_Click(object sender, EventArgs e)
{
   if(index > 0)
   {
      index--;
      pictureBox1.Image = images[index];
   }
}