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165
Draw a zero line
posted

Hi everbody,

 I'm using a UltraChart component to draw a barChart. The values can be positive or negative. Depending on values (max minus min),  I calculate and update the rangeMax, the rangeMin and the TickmarkInterval to obtain a good looking graph. (the customer wanted to display tickmark with round values).

Now, I'd like how I could draw a single line horizontally on the graph (where the zero value is). just a single black line starting for a specific point and ending at another one.

My idea is to add a layer and draw the line myself (http://devcenter.infragistics.com/Support/KnowledgeBaseArticle.Aspx?ArticleID=5432) but is it the best solution?

 here is a an exemple: I'd like to draw the line to separate clearly positive and negative values.

 

 

thanks in advance

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  • 10880
    posted

    If you are using a recent version of NetAdvantage you can just use the FillSceneGraph event.  If that event is not available then you would use a custom layer.

    Here is a blog post that talks about the fillscenegraph event in the 301 section:

    http://blogs.infragistics.com/blogs/skim/archive/2008/09/05/chart-university-chart-101-and-some-201-301-401-stuff.aspx

    Modified code for plotting a line at zero:

    private void ultraChart1_FillSceneGraph(object sender, Infragistics.UltraChart.Shared.Events.FillSceneGraphEventArgs e)

    {

        //gets the X and Y axis

     

        IAdvanceAxis x = (IAdvanceAxis)e.Grid["X"];

        IAdvanceAxis y = (IAdvanceAxis)e.Grid["Y"];

     

        //checks if axis exist

     

        if (x != null)

        {

            //figures out the coordinate to draw

            //a line at y=0

     

            int target = 0;

            int yVal = (int)y.Map(target);

            //note: the x axis is a string axis

            //that means that 0 stands for the first

            //column and 50 stands for the 50th

            //column               

            int xStart = (int)x.Map(0);

            int xEnd = (int)x.Map(50);

            //creates the line primitive based

            //on the coordinates

            Line l = new Line(new Point(xStart, yVal), new Point(xEnd, yVal));

            //sets the color of the line

            l.PE.Stroke = Color.Black;

            l.PE.StrokeWidth = 2;

            //adds it to the scene

            e.SceneGraph.Add(l);

        }

    }

     

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