JSROOT Legend Title

[MarkD32]

Hi experts,

Is is possible to add a title to my TLegend in JSROOT. For instance if I wanted to add a title to the legend here:

https://root.cern.ch/js/latest/api.htm#custom_html_tlegend

As a bonus, I don’t suppose it’s possible to create a TPaveText object in native JSROOT?

-Mark

[linev]

Hi Mark,

@MarkD32

Is is possible to add a title to my TLegend in JSROOT. For instance if I wanted to add a title to the legend here:

JavaScript ROOT API examples

Title in TLegend is just first entry, which does not have associated object. In mentioned example you can just create such header, calling:

   leg.fPrimitives.Add(CreateLegendEntry(null, "TLegend title"));
   leg.fPrimitives.Add(CreateLegendEntry(graph1, "Math.sin " + cnt));
   leg.fPrimitives.Add(CreateLegendEntry(graph2, "Math.cos " + cnt));

@MarkD32

I don’t suppose it’s possible to create a TPaveText object in native JSROOT?

It is possible to create TPaveText object in JSROOT. Just do:

  var pt = JSROOT.Create("TPaveText");
  pt.fName = "anyName";
  pt.AddText("Any text");

Regards,
Sergey

[MarkD32]

Thank you Sergey!

Only issue is that this draws a little black line next to the legend title as if it were the label for some nonexistent line.

-Mark

[linev]

@MarkD32

Only issue is that this draws a little black line next to the legend title as if it were the label for some nonexistent line.

There is simple solution. You need to modify function:

 function CreateLegendEntry(obj, lbl, opt) {
         var entry = JSROOT.Create("TLegendEntry");
         entry.fObject = obj;
         entry.fLabel = lbl;
         entry.fOption = opt || "l";
         return entry;
      }

and when calling it:

   leg.fPrimitives.Add(CreateLegendEntry(null, "TLegend title","h"));
   leg.fPrimitives.Add(CreateLegendEntry(graph1, "Math.sin " + cnt));
   leg.fPrimitives.Add(CreateLegendEntry(graph2, "Math.cos " + cnt));

[MarkD32]

Thank you! That works perfectly. And thank you for this great tool.