A simple C# library for graph plotting

• Download demo - 32.98 KB
• Download source - 243.08 KB

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:

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

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.

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