title: How to make all points in a line chart appear to scroll leftward with each new point added at the right edge
body: <p>I have a line chart, and with each new point added at the right, I want all the old line points to scroll one point position on the x-axis leftward, so that it appears to be sliding leftward.</p>
  
  <p>I've used .AddXY to add all the points to fill the chart, and this works.</p>
  
  <pre><code>Me.Chart_window.Series( my_series ).Points.AddXY( x_axis_point, y_value)
  </code></pre>
  
  <p>But I can't figure out how to man</p>
  
  <p>But I can't figure out how to manipulate the .Series.Points DataPointCollection to make the displayed line points appear to scroll leftward.  </p>
  
  <p>I tried .RemoteAt( 0 ) but this only deleted point at (0) without affecting displayed position of the other points.</p>
  
  <p>I thought of copying all the existing points leftward one x-axis position before I append a new point, but I can't figure out how.</p>
  
  <pre><code>if CHART_IS_FILLING
      ' Graph not full of points yet, so new samples appear appending rightward.
      ' Show previous samples as same as before, and next samples appending:
      Me.Chart_antenna_window.ChartAreas("ChartArea1").AxisX.IntervalAutoMode = IntervalAutoMode.VariableCount
      ' Plot next point:
              Me.Chart_antenna_window.Series( present_series_name &amp; "_I" &amp; graph_freq_index).Points.AddXY( x_axis_point, antenna_amplitude_I)
          x_axis_point += 1
  
  else      ' CHART IS FULL, SO START SLIDING LEFTWARD
      ' (Overaly graph is now full, so scroll it leftward by deleting leftmost sample before each new sample appended at right.)
      ' Scroll graph leftward:
      ' (ie. Remove left-point point, which is now beyond overlay window x-axis (ie. time) size):
      ' Shift all points leftward:
                  Me.Chart_antenna_window.Series( present_series_name &amp; "_I" &amp; graph_freq_index).Points.RemoveAt(0)
  
  
                  ' HOW DO I SHIFT ALL THE POINTS LEFTWARD?    I can't see a way to read a point from DataPointCollection so that I can
                  ' store it in the next index down.
  
          ' (All points shift left.)
      Me.Chart_antenna_window.ChartAreas("ChartArea1").AxisX.IntervalAutoMode = IntervalAutoMode.VariableCount
      ' Plot next point at right-most chart point:
              Me.Chart_antenna_window.Series( present_series_name &amp; "_I" &amp; graph_freq_index).Points.AddXY( x_axis_point, antenna_amplitude_I)
  end if
  </code></pre>