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Combine BarChart and PointChart

由 帅比萌擦擦* 提交于 2019-11-29 17:01:06

!! See the update below !!

If you really want to create a StackedBar chart, your chart has two issues:

  • If you want to stack datapoints they need to have meaningful x-values; without them how can it know what to stack on each other?

You add strings, which look fine but simply don't work. That is because the DataPoint.XValue field is double and when you add string into it it is set to 0 !! Your string is copied to the Label but otherwise lost.

So you need to come up with a suitable numeric value you use for the x-values..

  • And you also need to group the series you want to stack. For this there is a special property called StackedGroupName which serves to group those series that shall be stacked.

Here is how you can use it: 

yourSeries1.SetCustomProperty("StackedGroupName", "Group1");

For a full example see this post !

It also shows one way of setting the Labels with string values of your choice..

This is the way to go for real StackedBar charts. Your workaround may or may not work. You could try to make the colors transparent or equal to the chart's backcolor; but it won't be more than a hack, imo.

Update

I guess I have misread the question. From what I see you do not really want to create a stacked chart.

Instead you struggle with these issues:

  • displaying bars at the same y-spot
  • making some bars invisible
  • displaying a vertical line as a marker

Let's tackle each:

  • Some column types including all Bars, Columns and then some have a little known special property called DrawSideBySide.

By default is is set to Auto, which will work like True. This is usually fine as we don't want bars to sit upon each other, effectively hiding all or part of the overlaid points.

But here we do want them to share the same y-position, so we need to set the property to false for at least one Series; the others (on Auto) will follow..:

You can do it either like this:

aSeries["DrawSideBySide"] = "false";

or like this:

aSeries.SetCustomProperty("DrawSideBySide", "false");
  • Next we hide the overlaid Series; this is simple:
aSeries.Color = Color.Transparent;
  • The last issue is displaying a line marker. There is no such MarkerStyle, so we need to use a custom style. For this we need to create a suitable bitmap and add it as a NamedImage to the chart's Images collection.

This sounds more complicated than it is; however the MarkerImage will not be scaled, so we need to created suitable sizes whenever we resize the Chart or add/remove points. I will ignore this complication for now..

int pointCount = 10;
Bitmap bmp = new Bitmap(2, chart.ClientSize.Height / pointCount - 5);
using (Graphics g = Graphics.FromImage(bmp)) g.Clear(Color.Black);
NamedImage marker = new NamedImage("marker", bmp);
chart.Images.Clear();  // quick & dirty
chart.Images.Add(marker);

Here is the result:

A few notes:

  • I would recommend to use variables for all chart elements you refer to repeatedly instead of using indexed references all the time. Less code, easier to read, a lot easier to maintain, and probably better performance.

  • Since your code called for the visible datapoints to be either red or green the Legend will not show a good representation. See here for an example of drawing a multi-colored legend item..

  • I used the chart height; this is not really recommended as there may be Titles or Legends or even more ChartAreas; instead you should use the height of the ChartArea, or even more precise, the height of the InnerPlotPosition. You would need to convert those from percentages to pixels. Not too hard, see below or see here or here for more examples!

  • The markers should be adapted from the Resize and probably from the AxisViewChanged events. Putting it in a nice function to call (e.g. void setMarkerImage(Chart chart, Series s, string name, int width, Color c)) is always a good idea.

  • If you need to adapt the size of the marker image repeatedly, you may want to write better code for clearing the old one; this should include disposing of the Bitmap that was used before..

Here is an example:

var oldni = chart.Images.FindByName("marker");
if (oldni != null)
{
    oldni.Image.Dispose();
    chart.Images.Remove(oldni);
    oldni.Dispose();
}
  • In some situations one needs to nudge the Chart to update some of its properties; RecalculateAxesScale is one such nudge.

Example for calculating a suitable marker height:

ChartArea ca = chart.ChartAreas[0];
ca.RecalculateAxesScale();
float cah = ca.Position.Height;
float iph = ca.InnerPlotPosition.Height;
float h = chart3.ClientSize.Height * cah / 100f * iph / 100f;
int mh = (int)(h / s.Points.Count);
  • Final note: The original answer stressed the importance of using meaningful x-values. Strings are useless! This was important for stacking bars; but it is equally important now, when we want bars to sit at the same vertical positions! Adding the x-values as strings is again resulting in nonsense..

(Since we have Bars the x-values go along the vertical axis and vice versa..)

标签
c#
charts
bar-chart
series
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