title: Drawing lines with array
body: <p>I'm working on an app where I need to draw lines on Canvas, these lines need to be in an array so I can still add changes to it (Resizeable and color). I'm trying to build a paint-like function.</p>
  
  <p>This is my code</p>
  
  <pre><code>private void w_Canvas_MouseMove(object sender, MouseEventArgs e)
  {
      if (isDrawing)
      {
          if (e.LeftButton == MouseButtonState.Pressed)
          {
              //lineStartPoint = e.GetPosition(w_Canvas);
              //Thread.Sleep(2);
  
              Line[] l = new Line[999999];
              for (int d = 0; d &lt; 999999; d++)
              {
                  Point lineStartPoint = e.GetPosition(w_Canvas);
  
                  l[d].X1 = lineStartPoint.X;
                  l[d].Y1 = lineStartPoint.Y;
  
                  Thread.Sleep(1);
                  Point lineEnd = e.GetPosition(w_Canvas);
                  l[d].X2 = lineEnd.X;
                  l[d].Y2 = lineEnd.Y;
  
                  l[d].Stroke = brush;
                  l[d].StrokeThickness = 3;
                  //lineStartPoint = lineEnd;
                  //probeert ee nproperty the accessen warvan de property 0 is
              }
              DrawLines(l);
          }
      }
  }
  
  private void DrawLines(Line[] l)
  {
      foreach (Line line in l)
      {
          w_Canvas.Children.Add(line);
      }
  }
  
  private void w_Canvas_MouseUp(object sender, MouseButtonEventArgs e)
  {
      isDrawing = false;
  }
  </code></pre>
  
  <p>Currently I'm getting a 'System.NullReferenceException' where an object reference isn't installed on a copy of an object.</p>