Graphics

class SomeForm : Form
{
  private Bitmap _theImage;
  private bool _working = false;

  void worker_DoWork(object sender, DoWorkEventArgs e)
  {
    // make sure the image is initialized (may as well do it on the background thread).
    if (_theImage == null)
    {
      int width = (int)Math.Round(Width * fDPIX);
      int height = LogHeightPixels;
      _theImage = new Bitmap(width, height/*, System.Drawing.Imaging.PixelFormat.Gdi/*.Format32bppArgb*/);
    }
    // note, you may need to clear the bitmap in this method call.
    // it all depends on what the draw log method is doing.
    DrawLogToBitmap(_theImage);
  }

  void worker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
  {
    _working = false;
    Refresh();
  }

  public override void Draw(Graphics gfx, Rectangle rect)
  {
    gfx.ScaleTransform(zoom, zoom);

    // Update the bitmap (only as needed)
    if (bDirty)
    {
       // I'm assuming this method starts the worker thread - if so:
       _working = true;
       UpdateBitmap(gfx);
    }

    if (_working || worker.IsBusy)
    {
       gfx.DrawString("Updating Bitmap, please wait!", this.Font, Brushes.Black, new PointF(0, 0));
       return;
    }

    RectangleF rcSource = new RectangleF(-horizontalOffset, -verticalOffset, ClientRectangle.Width/zoom, ClientRectangle.Height/zoom);
    RectangleF rcDest = new RectangleF(ClientRectangle.Location.X, ClientRectangle.Location.Y, ClientRectangle.Size.Width/zoom, ClientRectangle.Size.Height/zoom);

    try
    {
       gfx.DrawImage(_theImage, rcDest, rcSource, GraphicsUnit.Pixel);
    }
    catch (Exception exc)
    {
       gfx.DrawString(exc.Message, Font, Brushes.Black, new PointF(0,0));
    }
    etc....
  }
}

JUNEYT wrote:

All I need is an accurate advise or direction how to setup an algorithm to find the exact colors of the picture.

Mark Salsbery wrote:

Damn! I wanted to read that pdf but it froze while loading