QCG defaultDrawOptions


I’m trying to convince QCG to plot an histogram in COLZ. I’m using TObjectManager::setDefaultDrawOptions but with no luck so far. Is there anything special to be done ?

Also, the axis rendering of (I assume jsroot) is a bit strange, see the attached screenshot with the ROOT plot on the left and the QCG on the right. Note how the x-axis seems off (by 0.5 ?), the first bin label is repeated and the angle is different. (on this screenshot the qcq is in COLZ, but I had to do it by clicking).


Could you show me the line where you set the draw options ?
There is nothing special to be done.
It used to work but it might be that there is a problem

For the axis, you could check with the ROOT browser in the QCDB. If it is the same problem, please download the ROOT object and send it to the ROOT team for investigation.


Hi Barth,

For the line, in the original post there’s actually a link to it :wink:

For the rest, I’ll test as soon as I can and let you know.

Thanks :slight_smile:
I have created a ticket : Cern Authentication

Hi Laurent,

for TPC we are using a bit different way of applying draw options to histograms. We have developed a small helper class, of which one function is called inside the initialize function of the QC task for each histogram. To set the colz option we then simply do:


For more details you can have a look at this post.

I just checked, with O2 and QC from today this version is (still) working, so there is no general issue in applying draw options to histograms, but it seems that somehow the setDefaultDrawOptions does not work.


@bvonhall Root ticket : Axis "shifted" in JSROOT - ROOT - ROOT Forum

@stefan thanks for the hint, which indeed works fine !

Dear all,

we are looking into the Draw Options (eg. logx, gridx) for canvas on the QCG via the SetDisplayHint
option. Unfortunately this option is not working at the moment. Similar to the setDefaultDrawOptions(), the function setDisplayHint() calls addOrUpdateMetadata(gDrawOptionsKey, options) from the MonitorObject and this information seems not be propagated to the QCG. This problem we tried to solve using our Helper Class where we can set options for the histograms but not for the canvases as they are not available at this point.

Additionally we would like to use SetTick() for x and y axis so we would like to request to include those in the list.

In order to be able to use the functionalities on the canvas we need the setDisplayHint() .
Any help would be very much appreciated.

Stefan and Bhawani

Hi, sorry, late reply.

Could you create a ticket in JIRA, or rather several tickets, for the various problems and new features requests ?

Thank you

Hi Barth,

actually for the original issue with the draw options you had opened a ticket yourself, which can be found here. I added in this ticket the issue with the canvas options (setDisplayHint), as I assume, the have the same origin. If not, I also could open a new ticket.

For the feature request on the ticks, I have opened a new ticket here.


Hi all,

Both qcg-test and qcg production received an update that fixes the bug in which both drawOptions and displayHints are taken into consideration when ploting the objects. This can also be ignored when in LayoutView by editing the layout and selecting “Ignore Defaults”
More instructions: WebUi/README.md at dev · AliceO2Group/WebUi · GitHub

Please let me know your feedback and if anything does not work as expected