Hi Rooters,
I have a problem with using 'the' default/basic colors for TAttLine etc..
(i.e. indixed by Color_t). When I used a TCanvas somehwere in my code
it seemed that the colors where not defined. This problem occured
somewhere deep in my class structure. I have traced the problem
done to the following:
code:
----------------
// Create Canvas before
//TCanvas *cBefore = new TCanvas("cBefore","canvasBefore",600,10,600,400);
// get picture from picture pool...
// gClient->GetPicture("home_t.xpm");
gClient->GetPicture("LHCb2.xpm");
// Create Canvas after
TCanvas *cAfter = new TCanvas("cAfter","canvasAfter",600,10,600,400);
---------------
The 'basic color' table is initialized the first time when a TCanvas is
made (i.e. by TCanvas::Build()). In this method it is checked if the color
list (i.e. retrieved by gROOT->GetListofColors()) is empty, if this is so
the 'basic colors' are added.
In this way everything should go well if the list of colors remains empty
until the first canvas is constructed.
In my particlar case (see above). It seems that by retrieving the picture
'LHCb2.xpm', somehow the list isn't empty anymore. Consequently if I make
a canvas (cAfter) after retrieving the picture the 'basic colors' are not
initialized. If I first add a canvas (cBefore) the list is correctly
initialized. (I checked this by doing View->Colors in the canvas menubar)
I hardly know anything about the xpm format. I also don't know what
exactly happens by retrieving such a picture inside gClient. So I don't
know if it is strange that the retrieving the picture LHCb2.xpm causes the
addition of colors (if I add the standard home_t.xpm, there are no
problems!)
In much more general terms though, it seems strange to me that before
using the 'basic colors' I should first make a TCanvas. If the colors are
mend to be some sort of 'default ROOT colors' I think they should be
initialized even before constructing the first TCanvas (maybe when gClient
is made?). In my specific case I need to get the picture before
constructing the TCanvas. I might even think of situations where you
use the colors without making a TCanvas at all...
Are the 'basic colors' mend to be as I describe above (i.e. ROOT default)?
Thanks,
Rutger
p.s. Fons/Rene I could send you LHCb2.xpm if you want it.
p.s.2 HP-UX 10 aCC compiler
This archive was generated by hypermail 2b29 : Tue Jan 04 2000 - 00:34:37 MET