Reputation: 43
I'm trying to use the C# Charting API for the first time and am having some problems. I have two hardware signals that I want to plot on a graph that has an x-axis that goes from -10 to 10 and a y-axis also from -10 to 10. I'm using the SeriesChartType.Point chart type for this and in all but one case the code works the way I expect. I'm adding points to the chart by using the AddXY function. In reality the values are coming from hardware but for this example I simply hard coded the values.
The problem I'm having is that if the very first point to be plotted has an x-axis value of 0 the chart seems to ignore the 0 and simply increment the x-axis value by one for each subsequent point that is plotted.
I created the following simplified example to demonstrate my problem. I hard coded my x-axis value as 0 and my y-axis value at 2. When it plots points the first point is plotted at (1,2), the next at (2,2), then (3,2), (4,2) and finally (5,2).
I should note that this only happens if the very first point to be plotted has an x-axis value of 0, if it has ANY other value the chart will function correctly forever. I'm at a loss as to what could be causing this.
Please see the following example code:
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
ConfigureChartSettings();
AddFakeData();
}
private void AddFakeData()
{
this.chart1.Series["Series1"].Points.AddXY(0, 2); //Gets plotted at (1,2)
this.chart1.Series["Series1"].Points.AddXY(0, 2); //Gets plotted at (2,2)
this.chart1.Series["Series1"].Points.AddXY(0, 2); //Gets plotted at (3,2)
this.chart1.Series["Series1"].Points.AddXY(0, 2); //Gets plotted at (4,2)
this.chart1.Series["Series1"].Points.AddXY(0, 2); //Gets plotted at (5,2)
}
private void ConfigureChartSettings()
{
//Set point chart type
this.chart1.Series["Series1"].ChartType = SeriesChartType.Point;
//Set the market size
this.chart1.Series["Series1"].MarkerSize = 5;
//Set the marker shape to a circle
this.chart1.Series["Series1"].MarkerStyle = MarkerStyle.Circle;
//X and Y values are both between -10 and 10 so set the x and y axes accordingly
this.chart1.ChartAreas["ChartArea1"].AxisX.Minimum = -10.0;
this.chart1.ChartAreas["ChartArea1"].AxisX.Maximum = 10.0;
this.chart1.ChartAreas["ChartArea1"].AxisY.Minimum = -10.0;
this.chart1.ChartAreas["ChartArea1"].AxisY.Maximum = 10.0;
//Set the titles of the X and Y axes
this.chart1.ChartAreas["ChartArea1"].AxisX.Title = "XSignalName";
this.chart1.ChartAreas["ChartArea1"].AxisY.Title = "YSignalName";
//Set the Intervals of the X and Y axes,
this.chart1.ChartAreas["ChartArea1"].AxisX.Interval = 5;
this.chart1.ChartAreas["ChartArea1"].AxisY.Interval = 5;
//Set the MajorGrid interval to 5.
this.chart1.ChartAreas["ChartArea1"].AxisX.MajorGrid.Interval = 5;
this.chart1.ChartAreas["ChartArea1"].AxisY.MajorGrid.Interval = 5;
//Set the MinorGrid interval to 1.
this.chart1.ChartAreas["ChartArea1"].AxisX.MinorGrid.Interval = 1;
this.chart1.ChartAreas["ChartArea1"].AxisY.MinorGrid.Interval = 1;
//Set the MinorGrid style to Dot so that it is less obstructive.
this.chart1.ChartAreas["ChartArea1"].AxisX.MinorGrid.LineDashStyle = ChartDashStyle.Dot;
this.chart1.ChartAreas["ChartArea1"].AxisY.MinorGrid.LineDashStyle = ChartDashStyle.Dot;
//Enable the minor grids.
this.chart1.ChartAreas["ChartArea1"].AxisX.MinorGrid.Enabled = true;
this.chart1.ChartAreas["ChartArea1"].AxisY.MinorGrid.Enabled = true;
}
}
I've already wasted a bunch of time trying to figure out why this could happen and I'm sure it is something incredibly simple but I can't seem to find the answer. Any help would be greatly appreciated.
Upvotes: 2
Views: 4390
Reputation: 6591
In this case MsChart is trying to be too helpful. It detects you have inserted data points with identical X == 0
and so auto-magically switch to using the point index as X value. Note that it only happens if X is 0.
You can fix it by adding an extra empty point with a X != 0
. So adding this at the start of your data entry will give you the plot you want.
// insert an empty point with X != 0
this.chart1.Series["Series1"].Points.AddXY(10, 10);
this.chart1.Series["Series1"].Points[0].IsEmpty = true;
// add your points as normal
this.chart1.Series["Series1"].Points.AddXY(0, 2);
this.chart1.Series["Series1"].Points.AddXY(0, 2);
this.chart1.Series["Series1"].Points.AddXY(0, 2);
this.chart1.Series["Series1"].Points.AddXY(0, 2);
this.chart1.Series["Series1"].Points.AddXY(0, 2);
Upvotes: 2