[ROOT] redrawing a pad

From: Franz Pröbst (proebst@mppmu.mpg.de)
Date: Tue May 14 2002 - 19:37:06 MEST


Hi,

I am using root to make a number of simple online displays for a DAQ. 
The displays are shown as pads in a single canvas. Some of the pads show 
scatter plots, others histograms or the time dependence of some quantity 
as a line.

In the scatter plots I add new acquired points as TMarker objects.
TMarker *m =new TMarker(x,y,style);
m->Draw();
c1->Update;

The c1->Update redraws all objects in the pad. This can take a long time 
and a considerable fraction of the CPU time when there are already many 
points in sevearal pads. Is there a way that only the last point is 
added without redrawing the other points already there?


In the line plots I just add a line segment connecting the newly 
acquired point with the previeous. It would also be nice not to redraw 
the whole line.


The active pad is decorated with a red frame. Is there a way to switch 
off this decoration. The pads are updated relatively fast and the random 
jumping of the red box is a little bit disturbing.



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