how do i use background Worker in this for loop c#

Question

How do I use a background worker in this for loop?

int tmax = 10;
int xmax = newbitmap.Width;
int ymax = newbitmap.Height;
for (int t = 0; t <= tmax; t += 1)
{
  for (int x = 0; x < xmax; x++)
  {
    for (int y = 0; y < ymax; y++)
    {
      if ((x / xmax) > (t / tmax))
      {
        Color originalco = newbitmap2.GetPixel(x, y);
        outp.SetPixel(x, y, originalco);
      }
      else
      {
        Color originalco3 = newbitmap.GetPixel(x, y); ;
        outp.SetPixel(x, y, originalco3);
      }

    }

    pictureBox1.Image = outp;
  }
}

This loop is a wipe transition from right to left, but it doesn't display the transition.

Answer 1

That because the backgroundWorker works in a different thread. You can use backgroundworker.ReportProgress(0, outp)

So: You need to register to the event BackgroundWorker.ProgressChanged from the events window in Vistual Studio, or with this line:

backgroundWorker1.ProgressChanged += new ProgressChangedEventHandler(backgroundWorker1_ProgressChanged);

The method:

    private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
    {
        var outp = (Bitmap)e.UserState;
        prictureBox.Image = outp;
    }

Your code sould be then:

        int tmax = 10;
        int xmax = newbitmap.Width;
        int ymax = newbitmap.Height;
        for (int t = 0; t <= tmax; t += 1)
        {

            for (int x = 0; x < xmax; x++)
            {
                for (int y = 0; y < ymax; y++)
                {
                    if ((x / xmax) > (t / tmax))
                    {
                        Color originalco = newbitmap2.GetPixel(x, y);
                        outp.SetPixel(x, y, originalco);
                    }
                    else
                    {
                        Color originalco3 = newbitmap.GetPixel(x, y); ;
                        outp.SetPixel(x, y, originalco3);
                    }

                }

                backgroundWorker1.ReportProgress(t, outp);

            }
        }

Answer 2

First, you should use direct pixel manipulation as described here: http://msdn.microsoft.com/en-us/library/5ey6h79d.aspx

Then, you should use an array as lookup for all your threads which line has already been drawn and which hasn't. The threads look for a new line in this array and then draw it. But remember to lock the lookup array!

Answer 3

Your Do work method would look something like this: -

private void bgWorker_DoWork(object sender, DoWorkEventArgs e)
{
     Bitmap newbitmap = (Bitmap)e.Argument;

     int tmax = 10;
     int xmax = newbitmap.Width;
     int ymax = newbitmap.Height;
     for (int t = 0; t <= tmax; t += 1)
     {

         for (int x = 0; x < xmax; x++)
         {
              for (int y = 0; y < ymax; y++)
              {
                   if ((x / xmax) > (t / tmax))
                   {
                       Color originalco = newbitmap2.GetPixel(x, y);
                       outp.SetPixel(x, y, originalco);
                   }
                   else
                   {
                       Color originalco3 = newbitmap.GetPixel(x, y); ;
                       outp.SetPixel(x, y, originalco3);
                   }

               }
               pictureBox1.Image = outp;
         }
      }
      bgWorker.ReportProgress(0,outp);
}

Then when your worker reports progress, it would raise the following event where you can safely update the UI:

private void bgWorker_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
    //UPDATE YOUR UI HERE
}

Answer 4

You can use the ReportProgress method of Background Worker to update the UI.

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