Develop Reference

OxyPlot Refresh Issue

I am using a OxyPlot to Real time changing data.
I do this using a Dispatcher Timer in a WPF C# app.
plotTimer.Interval = TimeSpan.FromMilliseconds(1000);
plotTimer.Tick += PlotTimer_Tick;
plotTimer.Start();
SensorPlotModel is a class of primarily the OxyPlot plotmodel with some properties to help keep track of which sensors it is for.
<oxy:PlotView Grid.Row="2" Grid.RowSpan="5" Grid.Column="1" Grid.ColumnSpan="4" Model="{Binding graphPlotModel}" MinHeight="250" MinWidth="1200"/>
The plotModel is then bound in this way to the xaml, where graphPlotModel is a property of the dataContext.
The graph works well when the sensor value is changing. When the value is not changing, the graph seems to be updated with the values, however, the zoom is not changing meaning that the past values can be seen but not the new ones.
I suspect Oxyplot is optimising by not zooming to the new values.
Please let me know if there a problem in the code.
FYI, the graphs are initialised as so:
DateTimeAxis dateAxis = new DateTimeAxis();
dateAxis.Position = AxisPosition.Bottom;
dateAxis.StringFormat = "mm:ss";
dateAxis.MajorGridlineStyle = LineStyle.Solid;
dateAxis.MinorGridlineStyle = LineStyle.Dot;
dateAxis.MinimumMajorStep = 1;
dateAxis.IntervalType = DateTimeIntervalType.Minutes;
//dateAxis.MaximumRange = 10;
//dateAxis.IntervalLength = 5;
plotModel.Axes.Add(dateAxis);
LinearAxis valueAxis = new LinearAxis();
valueAxis.Position = AxisPosition.Left;
valueAxis.StartPosition = 0;
valueAxis.MajorGridlineStyle = LineStyle.Solid;
valueAxis.MinorGridlineStyle = LineStyle.Dot;
valueAxis.Maximum = max;
valueAxis.Minimum = min;
plotModel.Axes.Add(valueAxis);

I hope I understand your question here correctly. You could re-adjust the Axis.Minimum and Axis.Maximum as the new data comes in. For example,
var series = SensorPlotModel.Series.OfType<LineSeries>().First();
var dateTimeAxis = SensorPlotModel.Axes.OfType<DateTimeAxis>().First();
// set Initial axis Range
if (!series.Points.Any())
{
dateTimeAxis.Minimum = DateTimeAxis.ToDouble(DateTime.Now);
dateTimeAxis.Maximum = DateTimeAxis.ToDouble(DateTime.Now.AddSeconds(MaxSecondsToShow));
}
foreach (var newItem in newItems)
{
if(newItem is SensorData sensorData)
{
series.Points.Add(new DataPoint(DateTimeAxis.ToDouble(sensorData.TimeStamp), sensorData.Data));
}
}
// Reset the axis range when axis is out of range
if (DateTimeAxis.ToDouble(DateTime.Now) > dateTimeAxis.Maximum)
{
dateTimeAxis.Minimum = DateTimeAxis.ToDouble(DateTime.Now.AddSeconds(-1 * MaxSecondsToShow));
dateTimeAxis.Maximum = DateTimeAxis.ToDouble(DateTime.Now);
dateTimeAxis.Reset();
}
SensorPlotModel.InvalidatePlot(true);
NotifyOfPropertyChange(nameof(SensorPlotModel));

How Do I Get The Scale of The Secondary Axis to be Based on My Series Values?

I'm using System.Web.UI.DataVisualization. Charting to create charts in MVC.
I have a chart displaying values in a StackedColumn100 SeriesChartType with the corresponding y-axis values on the primary y-axis on the left side.
Since it is a 100% stacked column series, the primary y-axis is scaled from 0 to 100.
I have then added a secondary series in the form of a Line SeriesChartType tied to a secondary axis (on the right side). I would like this axis to adjust its scale based on the values in the series but it doesn't. No matter what the highest value of this series is, the secondary y-axis also has a scale between 0 to 100.
If I manually set the maximum value for the secondary y-axis the following way:
chart.ChartAreas[0].AxisY2.Maximum = 20;. It works but I don't want to do that since the maximum value can differ greatly based on the search criteria used.
I have really tried to find a solution for this but I can't. According to the documentation and samples it seems that the scale should be based on the series values but I don't get it to work that way. Any help would be greatly appreciated!
Below is a stand alone test function that recreates the problem. I call the function from my view with the following line:
<p><img src="#Url.Action("CreateChart_TestSecondaryAxis")" /> </p>
public FileResult CreateChart_TestSecondaryAxis()
{
System.Web.UI.DataVisualization.Charting.Chart chart = new System.Web.UI.DataVisualization.Charting.Chart();
chart.Width = 800;
chart.Height = 400;
chart.BackColor = Color.FromArgb(211, 223, 240);
chart.BorderlineDashStyle = ChartDashStyle.Solid;
chart.BackSecondaryColor = Color.White;
chart.BackGradientStyle = GradientStyle.TopBottom;
chart.BorderlineWidth = 1;
chart.Palette = ChartColorPalette.BrightPastel;
chart.BorderlineColor = Color.FromArgb(26, 59, 105);
chart.RenderType = RenderType.BinaryStreaming;
chart.BorderSkin.SkinStyle = BorderSkinStyle.Emboss;
chart.AntiAliasing = AntiAliasingStyles.All;
chart.TextAntiAliasingQuality = TextAntiAliasingQuality.Normal;
ChartArea chartArea = new ChartArea();
chartArea.Name = "TestSecondaryAxis";
chartArea.BackColor = Color.Transparent;
chartArea.AxisX.IsLabelAutoFit = false;
chartArea.AxisY.IsLabelAutoFit = false;
chartArea.AxisX.LabelStyle.Font =
new Font("Verdana,Arial,Helvetica,sans-serif",
8F, FontStyle.Regular);
chartArea.AxisY.LabelStyle.Font =
new Font("Verdana,Arial,Helvetica,sans-serif",
8F, FontStyle.Regular);
chartArea.AxisY.LineColor = Color.FromArgb(64, 64, 64, 64);
chartArea.AxisX.LineColor = Color.FromArgb(64, 64, 64, 64);
chartArea.AxisY.MajorGrid.LineColor = Color.FromArgb(64, 64, 64, 64);
chartArea.AxisX.MajorGrid.LineColor = Color.FromArgb(64, 64, 64, 64);
chartArea.AxisX.Title = "Airport";
chartArea.AxisY.Title = "LandingConf";
chartArea.AxisY.TextOrientation = TextOrientation.Rotated270;
chartArea.AxisX.LabelStyle.IsEndLabelVisible = true;
chart.ChartAreas.Add(chartArea);
Series seriesPrimaryAxisConf3 = new Series();
seriesPrimaryAxisConf3.Name = "Conf 3";
seriesPrimaryAxisConf3.IsValueShownAsLabel = false;
seriesPrimaryAxisConf3.Color = Color.Blue;
seriesPrimaryAxisConf3.ChartType = SeriesChartType.StackedColumn100;
seriesPrimaryAxisConf3.BorderWidth = 2;
seriesPrimaryAxisConf3.ChartArea = "TestSecondaryAxis";
DataPoint point;
for (int i = 1; i < 11; i++)
{
point = new DataPoint();
point.AxisLabel = "Airport" + i.ToString();
point.YValues = new double[] { i };
seriesPrimaryAxisConf3.Points.Add(point);
}
chart.Series.Add(seriesPrimaryAxisConf3);
Series seriesPrimaryAxisConfFull = new Series();
seriesPrimaryAxisConfFull.Name = "Conf Full";
seriesPrimaryAxisConfFull.IsValueShownAsLabel = false;
seriesPrimaryAxisConfFull.Color = Color.Red;
seriesPrimaryAxisConfFull.ChartType = SeriesChartType.StackedColumn100;
seriesPrimaryAxisConfFull.BorderWidth = 2;
seriesPrimaryAxisConfFull.ChartArea = "TestSecondaryAxis";
for (int i = 1; i < 11; i++)
{
point = new DataPoint();
point.AxisLabel = "Airport" + i.ToString();
point.YValues = new double[] { 11-i };
seriesPrimaryAxisConfFull.Points.Add(point);
}
chart.Series.Add(seriesPrimaryAxisConfFull);
Series seriesSecondaryAxisNoOfFlights = new Series();
seriesSecondaryAxisNoOfFlights.Name = "NoOfFLights";
seriesSecondaryAxisNoOfFlights.IsValueShownAsLabel = false;
seriesSecondaryAxisNoOfFlights.Color = Color.Red;
seriesSecondaryAxisNoOfFlights.ChartType = SeriesChartType.Line;
seriesSecondaryAxisNoOfFlights.BorderWidth = 2;
seriesSecondaryAxisNoOfFlights.ChartArea = "TestSecondaryAxis";
for (int i = 1; i < 11; i++)
{
point = new DataPoint();
point.AxisLabel = "Airport" + i.ToString();
point.YValues = new double[] { i };
seriesSecondaryAxisNoOfFlights.Points.Add(point);
}
chart.Series.Add(seriesSecondaryAxisNoOfFlights);
chart.Series["NoOfFLights"].YAxisType = AxisType.Secondary;
chart.ChartAreas["TestSecondaryAxis"].AxisY2.LineColor = Color.Transparent;
chart.ChartAreas["TestSecondaryAxis"].AxisY2.MajorGrid.Enabled = false;
chart.ChartAreas["TestSecondaryAxis"].AxisY2.MajorTickMark.Enabled = false;
MemoryStream ms = new MemoryStream();
chart.SaveImage(ms);
return File(ms.GetBuffer(), #"image/png");
}

MSChart is a nice control but unfortunately Microsoft has always failed to properly document it.
And with the latest changes at MSDN things have gone from bad to worse, so I can't actually point to the rules that go for the various ChartTypes.
In your case I deduct this (rather wacky) rule:
To attach a non 100%-series to an indepently scaled secondary y-axis
it must be the first series but the stacked series still must be added
first.
So, if you want to get a result like this:
..you need to adapt the code. Here are the changes and additions needed..:
First we have to insert the line series at the front but do that after the stack100 series have beeen added..:
chart.Series.Insert(0, seriesSecondaryAxisNoOfFlights); // instead of adding it
Next we need to owner-draw the line as it would get burried under the columns otherwise.
Code the PostPaint event like this:
private void Chart_PostPaint(object sender, ChartPaintEventArgs e)
{
Chart chart = sender as Chart; //*
Series s = chart.Series[0]; // make sure to pick the right one!
Axis ax = chart.ChartAreas[0].AxisX;
Axis ay = chart.ChartAreas[0].AxisY2; // !!
var pts = s.Points.Select(x =>
new PointF((float)ax.ValueToPixelPosition(x.XValue),
(float)ay.ValueToPixelPosition(x.YValues[0])));
using (Pen pen = new Pen(s.Color, s.BorderWidth))
e.ChartGraphics.Graphics.DrawLines(pen, pts.ToArray());
}
For this to work the series need valid x-values. So add this line:
point.XValue = i; // set both x and y-values!
I also added a few nudges to the axis positioning:
ChartArea ca = chart.ChartAreas["TestSecondaryAxis"];
ca.AxisY.Maximum = 100;
ca.AxisX.Minimum = 0.5;
ca.AxisX.IntervalOffset = 0.5;

Dynamically creating charts

I am trying to dynamically create a chart for each drive in the computer, inside a form.
Each chart should be a pie chart that contains the amount of free space (colored green) and used space(colored red) in GBs.
But when I run the following code the only thing I see is blank rectangles with the titles of "C:\", "D:\" and so on.
Here is the code :
public static void DrawCharts()
{
Chart[] charts = new Chart[DriveInfo.GetDrives().Length];
DriveInfo[] drives = DriveInfo.GetDrives();
for (int i = 0; i < drives.Length; i++)
{
charts[i] = new Chart();
charts[i].Palette = ChartColorPalette.BrightPastel;
charts[i].Titles.Add(drives[i].Name);
charts[i].Series.Add("Storage");
charts[i].Series[0].ChartType = SeriesChartType.Pie;
charts[i].Location = new System.Drawing.Point(20 + i * 231, 30);
charts[i].Size = new System.Drawing.Size(230, 300);
DataPoint d = new DataPoint();
d.XValue = 1;
double[] p = { (double)drives[i].TotalFreeSpace / 1000000000 };
d.YValues = p;
d.Color = System.Drawing.Color.YellowGreen;
d.Label = "Free Space";
charts[i].Series[0].Points.Add(d);
d.Label = "Used Space";
d.XValue = 2;
double[] a = { (double)((drives[i].TotalSize - drives[i].TotalFreeSpace) / 1000000000) };
d.YValues = a;
d.Color = System.Drawing.Color.Red;
charts[i].Series[0].Points.Add(d);
Form1.tabs.TabPages[1].Controls.Add(charts[i]);
charts[i].Invalidate();
}
}
Thanks.

You are almost there.
But the most basic thing you need to add to a dynamically created chart..:
charts[i] = new Chart();
..is a ChartArea:
charts[i].ChartAreas.Add("CA1"); // pick your name!
Without it no Series can display..
Use it to style the axis with TickMarks, GridLines or Labels or to set Minima and Maxima and Intervals. Well, at least for most other ChartTypes; Pies don't need any of this anyway..
Note that you can have several ChartAreas in one Chart.
Also note that it still will display nothing until at least one Series has at least one DataPoint..

Add annotations in MS chart (e.g. (10, 20) (20, 39) etc) and horizontal Scroll Bar

I want to add text(say, annotations) in MS chart(winforms) like (10, 20) , (30, 40) where I already have a scroll bar.
I can able to draw strings(graphics.drawstring) in Chart, but on scrolling the horizontal scroll bar, the text which I have drawn remains static and immovable.
On scrolling the scrollbar, the text which I have drawn also should move along with my horizontal scrolling.
My code follows:
chart2.BorderSkin.SkinStyle = BorderSkinStyle.Emboss;
chart2.BorderlineColor = System.Drawing.Color.FromArgb(26, 59, 105);
chart2.BorderlineWidth = 3;
chart2.BackColor = Color.White;
chart2.ChartAreas.Add("chtArea");
chart2.ChartAreas[0].AxisX.Title = "Category Name";
chart2.ChartAreas[0].AxisX.TitleFont =
new System.Drawing.Font("Verdana", 11, System.Drawing.FontStyle.Bold);
chart2.ChartAreas[0].AxisY.Title = "UnitPrice";
chart2.ChartAreas[0].AxisY.TitleFont =
new System.Drawing.Font("Verdana", 11, System.Drawing.FontStyle.Bold);
chart2.ChartAreas[0].BorderDashStyle = ChartDashStyle.Solid;
chart2.ChartAreas[0].BorderWidth = 2;
chart2.ChartAreas["chtArea"].AxisX.ScrollBar.Enabled = true;
chart2.ChartAreas["chtArea"].CursorX.IsUserEnabled = true;
chart2.ChartAreas["chtArea"].CursorX.IsUserSelectionEnabled = true;
chart2.ChartAreas["chtArea"].AxisX.ScaleView.Zoomable = false;
chart2.ChartAreas["chtArea"].AxisX.ScrollBar.IsPositionedInside = true;
chart2.ChartAreas["chtArea"].AxisX.ScaleView.Size = 20;
chart2.ChartAreas[0].AxisX.ScaleView.SmallScrollSizeType = DateTimeIntervalType.Seconds;
chart2.ChartAreas[0].AxisX.ScaleView.SmallScrollSize = 1;
chart2.Legends.Add("UnitPrice");
chart2.Series.Add("UnitPrice");
chart2.Series[0].ChartType = SeriesChartType.Line;
Random rand = new Random();
var valuesArray = Enumerable.Range(0, 500).Select(x => rand.Next(0, 100)).ToArray();
for (int i = 0; i < 500; i++)
{
chart2.Series["UnitPrice"].Points.AddXY(i+10, valuesArray[i]);
}
I tried TextAnnotaions, Line annotations, etc Nothing helped me.
Then I tried drawing dynamic labels inside MS chart also. Labels remain immovable while scrolling horizontal scroll bar.
This code works perfectly in your machine also.

Sounds a lot as if you want to add TextAnnotations.
If you want them to stick with your data points you should anchor them to the points they shall stay with.
Here are a few examples:
// directly anchored to a point
TextAnnotation TA1 = new TextAnnotation();
TA1.Text = "DataPoint 222";
TA1.SetAnchor(chart2.Series["UnitPrice"].Points[222]);
chart2.Annotations.Add(TA1);
// anchored to a point but shifted down
TextAnnotation TA2 = new TextAnnotation();
TA2.Text = "DataPoint 111";
TA2.AnchorDataPoint = chart2.Series["UnitPrice"].Points[111];
TA2.AnchorY = 0;
chart2.Annotations.Add(TA2);
// this one is not anchored on a point:
TextAnnotation TA3 = new TextAnnotation();
TA3.Text = "At 50% width BC";
TA3.AnchorX = 50; // 50% of chart width
TA3.AnchorY = 20; // 20% of chart height, from top!
TA3.Alignment = ContentAlignment.BottomCenter; // try a few!
chart2.Annotations.Add(TA3);
By default they either anchor to DataPoints or are positioned in % of the chart size.
It is also possible to set the positions according to pixel coordinates, but for this you need to calculate the positions each time the chart changes its view!
See here for an example how to transform chart data positions to chart control coordinates and vice versa.. (Not really recommended, though)

Plotting overlapping column or bar chart

I need to plot 4 series data to MSChart using column or bar type. Can I plot those 4 series so that the data is overlapped instead of being stacked.
I just found there is a ChartGroup.Overlap property for office Excel.
How can I do it in MSChart? If not, what chart control can do this? Any info will be much appreciated.

C# chart has properties for each series. The "column" chart type has property especially for that overlapping problem
chart_1.Series["col_name"].CustomProperties = "DrawSideBySide=False";

Not sure if this is the ideal solution but if you create two ChartAreas in a chart and then just plot one on top of the other you can overlap series. This requires a lot of fiddling around with positions, sizes, axis etc to get them to line up so requires a bit of effort but produces the following
Chart _chart = new Chart();
TabPage2.Controls.Add(_chart);
_chart.Location = new Point(469, 37);
_chart.Name = "chart1";
_chart.Size = new Size(448, 260);
DataTable dt1 = new DataTable();
dt1.Columns.Add("XVals", typeof(string));
dt1.Columns.Add("YVals1", typeof(int));
dt1.Columns.Add("YVals2", typeof(int));
foreach (string c in "ABCDEF".ToCharArray()) {
dt1.Rows.Add(c, Convert.ToInt32(Math.Ceiling(VBMath.Rnd() * 20)), Convert.ToInt32(Math.Ceiling(VBMath.Rnd() * 20)));
}
ChartArea firstArea = _chart.ChartAreas.Add("First Area");
Series seriesFirst = _chart.Series.Add("First Series");
seriesFirst.ChartType = SeriesChartType.Column;
ChartArea secondArea = _chart.ChartAreas.Add("Second Area");
secondArea.BackColor = Color.Transparent;
secondArea.AlignmentOrientation = AreaAlignmentOrientations.All;
secondArea.AlignmentStyle = AreaAlignmentStyles.All;
secondArea.AlignWithChartArea = firstArea.Name;
secondArea.AxisY.LabelStyle.Enabled = false;
secondArea.AxisX.LabelStyle.Enabled = false;
Series seriesSecond = _chart.Series.Add("Second Series");
seriesSecond.ChartType = SeriesChartType.Column;
seriesSecond.ChartArea = secondArea.Name;
_chart.DataSource = dt1;
seriesFirst.Points.DataBind(dt1.DefaultView, "XVals", "YVals1", null);
seriesSecond.Points.DataBind(dt1.DefaultView, "XVals", "YVals2", null);
//Aligning the Y axis of the two chart areas
//I am assuming here the x values for both series are similar and dont need to be altered
//If using bar chart then x axis would be modifed not the y axis
secondArea.AxisY = firstArea.AxisY;
// *** Set locational values here for your first chart area***
int heightAboveChartArea = 20;
int heightBelowChartArea = 20;
int axisLabelHeight = 40;
int widthLeftOfChartArea = 20;
int widthRightOfChartArea = 20;
int heightPerBar = 20;
int numberOfPoints = _chart.Series(0).Points.Count;
// *** The following code should not normally be modified ***
_chart.ChartAreas(0).Position.X = widthLeftOfChartArea / _chart.Width * 100;
_chart.ChartAreas(0).Position.Width = 100 - (widthRightOfChartArea / _chart.Width * 100) - _chart.ChartAreas(0).Position.X;
_chart.ChartAreas(0).Position.Y = (heightAboveChartArea / _chart.Height * 100);
_chart.ChartAreas(0).Position.Height = 100 - (heightBelowChartArea / _chart.Height * 100) - _chart.ChartAreas(0).Position.Y;