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A simple C# library for graph plotting

By , 8 Jul 2009
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Introduction

In our application, we had to display the output of a multichannel ECG (Electro Cardiograph) device. I had a look at some commercial libraries, but none of them met by demands. So, I decided to design a simple solution by myself.

This is my attempt to design a flexible, easy to use library for drawing graphs.

The library is capable of displaying multiple graphs in different layouts. Right now, five modes of display are possible:

  • Normal: means that all data sources are displayed in one graph window, with separate ordinates.
  • Stacked: means that all data sources are displayed in one graph window, stacked vertically, with shared ordinate and shared abscissa.
  • Vertical aligned: means that the graph windows are displayed vertically aligned, with separate ordinates and shared abscissa.
  • Tiled horizontal: means that the data sources are displayed in tiled windows (preferred alignment direction is horizontal).
  • Tiled vertically: means that the data sources are displayed in tiled windows (preferred alignment direction is vertical).

Graphs can be displayed unscaled or auto-scaled. In the auto-scale mode, the visible graph is automatically fit to the visible area.

The following images show examples for the different display modes:

Normal:

graph_normal.png

Stacked:

graph_stacked.png

Tiled horizontal:

graph_tiled_horizontal.png

Tiled vertical:

graph_tiled_vertically.png

Vertical aligned:

graph_vertically_aligned.png

Autoscaled X-Axis

graph_fixed_x_range.png

The following images show a sample of an ECG application, where eight data sources are displayed vertically tiled and auto-scaled.

sample_2.jpg

Using the Code

The control is very simple to use. Just have a look at the sample application. The following code shows how the part in the demo application where the graphs for the different examples are generated:

        protected void CalcDataGraphs()
        {

            this.SuspendLayout();
           
            display.DataSources.Clear();
            display.SetDisplayRangeX(0, 400);

            for (int j = 0; j < NumGraphs; j++)
            {
                display.DataSources.Add(new DataSource());
                display.DataSources[j].Name = "Graph " + (j + 1);                
                display.DataSources[j].OnRenderXAxisLabel += RenderXLabel;
              
                switch (CurExample)
                {
                    case  "NORMAL":
                        this.Text = "Normal Graph";
                        display.DataSources[j].Length = 5800;
                        display.PanelLayout = PlotterGraphPaneEx.LayoutMode.NORMAL;
                        display.DataSources[j].AutoScaleY = false;
                        display.DataSources[j].SetDisplayRangeY(-300, 300);
                        display.DataSources[j].SetGridDistanceY(100);
                        display.DataSources[j].OnRenderYAxisLabel = RenderYLabel;
                        CalcSinusFunction_0(display.DataSources[j], j);      
                        break;

                    case "NORMAL_AUTO":
                        this.Text = "Normal Graph Autoscaled";
                        display.DataSources[j].Length = 5800;
                        display.PanelLayout = PlotterGraphPaneEx.LayoutMode.NORMAL;
                        display.DataSources[j].AutoScaleY = true;
                        display.DataSources[j].SetDisplayRangeY(-300, 300);
                        display.DataSources[j].SetGridDistanceY(100);
                        display.DataSources[j].OnRenderYAxisLabel = RenderYLabel;
                        CalcSinusFunction_0(display.DataSources[j], j);
                        break;

                    case "STACKED":
                        this.Text = "Stacked Graph";
                        display.PanelLayout = PlotterGraphPaneEx.LayoutMode.STACKED;
                        display.DataSources[j].Length = 5800;
                        display.DataSources[j].AutoScaleY = false;
                        display.DataSources[j].SetDisplayRangeY(-250, 250);
                        display.DataSources[j].SetGridDistanceY(100);
                        CalcSinusFunction_1(display.DataSources[j], j);
                        break;

                    case "VERTICAL_ALIGNED":
                        this.Text = "Vertical aligned Graph";
                        display.PanelLayout = 
                            PlotterGraphPaneEx.LayoutMode.VERTICAL_ARRANGED;
                        display.DataSources[j].Length = 5800;
                        display.DataSources[j].AutoScaleY = false;
                        display.DataSources[j].SetDisplayRangeY(-300, 300);
                        display.DataSources[j].SetGridDistanceY(100);
                        CalcSinusFunction_2(display.DataSources[j], j);    
                        break;

                    case "VERTICAL_ALIGNED_AUTO":
                        this.Text = "Vertical aligned Graph autoscaled";
                        display.PanelLayout = 
                            PlotterGraphPaneEx.LayoutMode.VERTICAL_ARRANGED;
                        display.DataSources[j].Length = 5800;
                        display.DataSources[j].AutoScaleY = true;
                        display.DataSources[j].SetDisplayRangeY(-300, 300);
                        display.DataSources[j].SetGridDistanceY(100);
                        CalcSinusFunction_2(display.DataSources[j], j);
                        break;

                    case "TILED_VERTICAL":
                        this.Text = "Tiled Graphs (vertical prefered)";
                        display.PanelLayout = PlotterGraphPaneEx.LayoutMode.TILES_VER;
                        display.DataSources[j].Length = 5800;
                        display.DataSources[j].AutoScaleY = false;
                        display.DataSources[j].SetDisplayRangeY(-300, 600);
                        display.DataSources[j].SetGridDistanceY(100);
                        CalcSinusFunction_2(display.DataSources[j], j);    
                        break;

                    case "TILED_VERTICAL_AUTO":
                        this.Text = "Tiled Graphs (vertical prefered) autoscaled";
                        display.PanelLayout = PlotterGraphPaneEx.LayoutMode.TILES_VER;
                        display.DataSources[j].Length = 5800;
                        display.DataSources[j].AutoScaleY = true;
                        display.DataSources[j].SetDisplayRangeY(-300, 600);
                        display.DataSources[j].SetGridDistanceY(100);
                        CalcSinusFunction_2(display.DataSources[j], j);
                        break;

                    case "TILED_HORIZONTAL":
                        this.Text = "Tiled Graphs (horizontal prefered)";
                        display.PanelLayout = PlotterGraphPaneEx.LayoutMode.TILES_HOR;
                        display.DataSources[j].Length = 5800;
                        display.DataSources[j].AutoScaleY = false;
                        display.DataSources[j].SetDisplayRangeY(-300, 600);
                        display.DataSources[j].SetGridDistanceY(100);
                        CalcSinusFunction_2(display.DataSources[j], j);    
                        break;

                    case "TILED_HORIZONTAL_AUTO":
                        this.Text = "Tiled Graphs (horizontal prefered) autoscaled";
                        display.PanelLayout = PlotterGraphPaneEx.LayoutMode.TILES_HOR;
                        display.DataSources[j].Length = 5800;
                        display.DataSources[j].AutoScaleY = true;
                        display.DataSources[j].SetDisplayRangeY(-300, 600);
                        display.DataSources[j].SetGridDistanceY(100);
                        CalcSinusFunction_2(display.DataSources[j], j);
                        break;

                    case "ANIMATED_AUTO":
                       
                        this.Text = "Animated graphs fixed x range";
                        display.PanelLayout = PlotterGraphPaneEx.LayoutMode.TILES_HOR;
                        display.DataSources[j].Length = 402;
                        display.DataSources[j].AutoScaleY = false;
                        display.DataSources[j].AutoScaleX = true;
                        display.DataSources[j].SetDisplayRangeY(-300, 500);
                        display.DataSources[j].SetGridDistanceY(100);
                        display.DataSources[j].XAutoScaleOffset = 50;
                        CalcSinusFunction_3(display.DataSources[j], j, 0);
                        display.DataSources[j].OnRenderYAxisLabel = RenderYLabel;
                        break;
                }             
            }
            
            ApplyColorSchema();

            this.ResumeLayout();
            display.Refresh();
           
        }

The functions CalcSinusFunction_0 CalcSinusFunction_1 and CalcSinusFunction_2 are used to calculate the different sinus functions for the graphs:

protected void CalcSinusFunction_0(DataSource src, int idx)
{
    for (int i = 0; i  < src.Length; i++)
    {
        src.Samples[i].x = i;
        src.Samples[i].y = (float)(((float)200 * Math.Sin((idx + 1) *(
            i + 1.0) * 48 / src.Length)));
    }    
}

The functions RenderYLabel and RenderXLabel are used to render the X and Y legends of the graph.

private String RenderXLabel(DataSource s, int idx)
{
    if (s.AutoScaleX)
    {         
        int Value = (int)(s.Samples[idx].x );
        return "" + Value;     
    }
    else
    {
        int Value = (int)(s.Samples[idx].x / 200);
        String Label = "" + Value + "\"";
        return Label;
    }    
}

private String RenderYLabel(DataSource s, float value)
{ 
    return String.Format("{0:0.0}", value);
}

Summary

There are lots of parameters that can be twisted which are not explained here - just look at the code. This library is far from being finished, but it is a good point to start from. The code is simple and self-explaining. From here, it will be simple to adopt the code for your needs.

I got so much inputs from here, and I wanted to give something back. So, here is my first article on The Code Project. I hope you like it.

To Do

  • code clean ups.

Version History

  • 12.07.2009 - Updated article.
  • 12.02.2009 - Implemented x autoscaling.
  • 28.01.2009 - Some more cleanups. Implemented Print Form.
  • 27.01.2009 - New display mode, some cleanups.
  • 25.01.2009 - Initial release.

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

About the Author

Zimmermann Stephan
Software Developer (Senior)
Austria Austria
I have started programming at the age of 13 on the commodore 64.
 
Ever since then I have been programming on many systems in many languages.
 
During the last 12 years I have been working as professional programmer in different companies and different areas.
 
Now I am working as freelancer programmer / consultant

Comments and Discussions

 
QuestionProvide Sample Data PinmemberEsty Chowdhury8-Mar-14 9:02 
QuestionOnRenderXAxisLabel [modified] PinmemberMBSMBS27-Nov-13 22:27 
GeneralVery well done!!! PinmemberJoel Smit13-Nov-13 1:45 
QuestionEKG data for plot Pinmemberronaldj1003-Nov-13 12:48 
GeneralMy vote of 5 PinmemberMBSMBS10-Oct-13 21:38 
GeneralThat's I'm looking for PinmemberLauchael17-Aug-13 3:11 
GeneralMy vote of 5 PinmemberMaryami.bagheri16-Jul-13 21:27 
QuestionSerial port PinmemberAmila Amarasinghe10-Jul-13 5:30 
AnswerRe: Serial port PinmemberMember 1040798117-Nov-13 19:47 
GeneralMy vote of 5 Pinmembergfazzola20-Jun-13 4:12 
QuestionHow can i add zoom capability to the library? PinmemberMaryami.bagheri11-Jun-13 2:15 
QuestionTrain Graphs PinmemberSarith Senadheera28-May-13 7:07 
GeneralMy vote of 5 [modified] Pinmembercoder6315-Mar-13 23:49 
Questionlooking good PinmemberRobertJohn19-Feb-13 4:09 
QuestionGood One Pinmemberpraveen22562712-Feb-13 19:58 
GeneralMy vote of 5 PinmemberSalmanSamian15-Dec-12 1:01 
QuestionSimply amazing work.. !! Pinmembershyambs858-Dec-12 7:05 
You should have rather got it patented Wink | ;) Smile | :)
QuestionZoom? Pinmembermoep12325-Nov-12 10:56 
GeneralA simple C# library for graph plotting Pinmemberoleg.panichev9-Oct-12 3:13 
QuestionHelp PinmemberTsheole26-Jul-12 7:39 
Questionpagal PinmemberMember 803962823-Jul-12 21:29 
Questionlog scale Pinmembermanaruto2-Jun-12 5:20 
QuestionAsking for a some kind of favor..??? PinmemberMember 874942725-Apr-12 7:06 
QuestionECG graph plotting PinmemberMember 777247323-Apr-12 6:33 
QuestionEasy way to remove control panel? Pinmembercclaunch13-Apr-12 5:12 

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