Chart - transparency and text quality RSS

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  xdzgor

  Member

  6 Points

  17 Posts

  Chart - transparency and text quality

  Feb 22, 2011 07:36 PM|LINK

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  Hi

  I have a wep-app which generates a chart, and streams it on the response output to the client. This all works quite ok. But I want the chart to have a transparent background (so PNG seems a good choice).

  But when I set transparent background, the quality of the axis labels falls dramatically. How do I fix this? See the following code (a simple console app to show the problem). As it stands, the chart has a transparent background, as I want, but the text quality is atrocious. If I comment out the two "Color.Transparent" settings, then the text quality is nice, but the background is not transparent.

  How do I get transparency and nice text?

  public static void Main(string[] args)
  {
    Chart c = new Chart();
    c.TextAntiAliasingQuality = TextAntiAliasingQuality.High;
  
    Series s = new Series("Series1");
    c.Series.Clear();
    c.Series.Add(s);
    s.ChartType = SeriesChartType.Line;
  
    s.Color = Color.Black;
  
    ChartArea chartArea = new ChartArea("ChartArea1");
    c.ChartAreas.Clear();
    c.ChartAreas.Add(chartArea);
  
    chartArea.BackColor = Color.FromArgb(255, 255, 255);
    chartArea.BackSecondaryColor = Color.FromArgb(220, 220, 220);
    chartArea.BackGradientStyle = GradientStyle.TopBottom;
  
    chartArea.AxisX.LineColor = Color.Gray;
    chartArea.AxisX.LineWidth = 2;
    chartArea.AxisX.LineDashStyle = ChartDashStyle.Solid;
  
    chartArea.AxisY.LineColor = Color.Gray;
    chartArea.AxisY.LineWidth = 2;
    chartArea.AxisY.LineDashStyle = ChartDashStyle.Solid;
  
    chartArea.AxisX.MajorGrid.LineColor = Color.LightGray;
    chartArea.AxisX.MajorGrid.LineDashStyle = ChartDashStyle.Dash;
  
    chartArea.AxisY.MajorGrid.LineColor = Color.LightGray;
    chartArea.AxisY.MajorGrid.LineDashStyle = ChartDashStyle.Dash;
  
    c.BackColor = Color.Transparent;
    chartArea.BackColor = Color.Transparent;
  
  
    double[] x = new double[] { 1999, 2005 };
    double[] y = new double[] { 3210, 13456 };
  
    Axis ay = chartArea.AxisY;
    ay.Maximum = 13456;
    ay.Minimum = 3210;
  
    Axis ax = chartArea.AxisX;
    ax.Maximum = 2005;
    ax.Minimum = 1999;
  
    for (int i = 0; i < x.Length; i++)
    {
      double xvalue = x[i];
      double yvalue = y[i];
      s.Points.AddXY(xvalue, yvalue);
     }
  
     // Save chart-image to disk:
     c.SaveImage("chartimage.png", ChartImageFormat.Png);
  }

  Thanks,
  Peter

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  SGWellens

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  Re: Chart - transparency and text quality

  Feb 23, 2011 01:46 AM|LINK

  This seems to fix it:

  c.TextAntiAliasingQuality = TextAntiAliasingQuality.SystemDefault;

   

  Steve Wellens
  
  My blog
  
  • Marked as answer by xdzgor on Feb 23, 2011 05:32 AM
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  xdzgor

  Member

  6 Points

  17 Posts

  Re: Chart - transparency and text quality

  Feb 23, 2011 05:34 AM|LINK

  Wow - easy answer, thanks a lot. I had tried setting the anti-aliasing to "high", which I though meant "best quality". But "system-default" (which I thought it would have been if I hadn't set it at all) definitely does the trick.

  Thanks, Peter